SR policies define the behavior of headend routers in managing and directing traffic through a network. The headend router is responsible for initiating and enforcing these policies. SR supports these headend behaviors.

• H.Encaps.Red—H.Encaps with Reduced Encapsulation

• H.Insert.Red—H.Insert with reduced insertion

The SR Headend with Encapsulation behaviors are documented in the IETF RFC 8986 SRv6 Network Programming.

The SR Headend with Insertion head-end behaviors are documented in the following IETF draft:

https://datatracker.ietf.org/doc/draft-filsfils-spring-srv6-net-pgm-insertion/

Default Headend Behaviour

Starting from Cisco IOS XR Release 24.3.1, the H.Insert.Red headend behavior is supported only on routers with P100 based line cards. Based on the available line cards, the default headend behavior varies. The table summarizes the default behavior.

Comparision between H.Encaps.Red and H.Insert.Red Headend Behaviors

This table describes the difference between the H.Encaps and H.Insert.Red head-end behaviors.

SRv6 Endpoint Behaviors

The SRv6 endpoint behaviors are documented in the IETF RFC 8986 SRv6 Network Programming.

The following is a subset of defined SRv6 endpoint behaviors that can be associated with a SID.

• End—Endpoint function. The SRv6 instantiation of a Prefix SID [RFC8402].

• End.X—Endpoint with Layer-3 cross-connect. The SRv6 instantiation of an Adj SID [RFC8402].

• End.DX6—Endpoint with decapsulation and IPv6 cross-connect (IPv6-L3VPN - equivalent to per-CE VPN label).

• End.DX4—Endpoint with decapsulation and IPv4 cross-connect (IPv4-L3VPN - equivalent to per-CE VPN label).

• End.DT6—Endpoint with decapsulation and IPv6 table lookup (IPv6-L3VPN - equivalent to per-VRF VPN label).

• End.DT4—Endpoint with decapsulation and IPv4 table lookup (IPv4-L3VPN - equivalent to per-VRF VPN label).

• End.DT46—Endpoint with decapsulation and specific IP table lookup (IP-L3VPN - equivalent to per-VRF VPN label).

• End.DX2—Endpoint with decapsulation and L2 cross-connect (L2VPN use-case).

• End.B6.Encaps—Endpoint bound to an SRv6 policy with encapsulation. SRv6 instantiation of a Binding SID.

• End.B6.Encaps.RED—End.B6.Encaps with reduced SRH. SRv6 instantiation of a Binding SID.

SRv6 Endpoint Behavior Variants

Depending on how the SRH is handled, different behavior variants are defined for the End and End.X behaviors. The End and End.X behaviors can support these variants, either individually or in combinations.

• Penultimate Segment Pop (PSP) of the SRH variant—An SR Segment Endpoint Nodes receive the IPv6 packet with the Destination Address field of the IPv6 Header equal to its SID address.

  A penultimate SR Segment Endpoint Node is one that, as part of the SID processing, copies the last SID from the SRH into the IPv6 Destination Address and decrements the Segments Left value from one to zero.

  The PSP operation takes place only at a penultimate SR Segment Endpoint Node and does not happen at non-penultimate endpoint nodes. When a SID of PSP-flavor is processed at a non-penultimate SR Segment Endpoint Node, the PSP behavior is not performed since Segments Left would not be zero.

  The SR Segment Endpoint Nodes advertise the SIDs instantiated on them via control plane protocols. A PSP-flavored SID is used by the Source SR Node when it needs to instruct the penultimate SR Segment Endpoint Node listed in the SRH to remove the SRH from the IPv6 header.

• Ultimate Segment Pop (USP) of the SRH variant—The SRH processing of the End and End.X behaviors are modified as follows:

  If Segments Left is 0, then:

  1. Update the Next Header field in the preceding header to the Next Header value of the SRH

  2. Decrease the IPv6 header Payload Length by 8*(Hdr Ext Len+1)

  3. Remove the SRH from the IPv6 extension header chain

  4. Proceed to process the next header in the packet

  One of the applications of the USP flavor is when a packet with an SRH is destined to an application on hosts with smartNICs implementing SRv6. The USP flavor is used to remove the consumed SRH from the extension header chain before sending the packet to the host.

• Ultimate Segment Decapsulation (USD) variant—The Upper-layer header processing of the End and End.X behaviors are modified as follows:

  • End behavior: If the Upper-layer Header type is 41 (IPv6), then:

    1. Remove the outer IPv6 Header with all its extension headers

    2. Submit the packet to the egress IPv6 FIB lookup and transmission to the new destination

    3. Else, if the Upper-layer Header type is 4 (IPv4)

    4. Remove the outer IPv6 Header with all its extension headers

    5. Submit the packet to the egress IPv4 FIB lookup and transmission to the new destination

    6. Else, process as per Section 4.1.1 (Upper-Layer Header) of IETF RFC 8986 SRv6 Network Programming

  • End.X behavior: If the Upper-layer Header type is 41 (IPv6) or 4 (IPv4), then:

    1. Remove the outer IPv6 Header with all its extension headers

    2. Forward the exposed IP packet to the L3 adjacency J

    3. Else, process as per Section 4.1.1 (Upper-Layer Header) of IETF RFC 8986 SRv6 Network Programming

  One of the applications of the USD flavor is the case of TI-LFA in P routers with encapsulation with H.Encaps. The USD flavor allows the last Segment Endpoint Node in the repair path list to decapsulate the IPv6 header added at the TI-LFA Point of Local Repair and forward the inner packet.

• uSID Block

  The uSID block is an IPv6 prefix that defines a block of SRv6 uSIDs. This can be an IPv6 prefix allocated to the provider (for example, /22, /24, and so on.), or it can be any well-known IPv6 address block generally available for private use, such as the ULA space FC/8, as defined in IETF draft RFC4193.

  An SRv6 network may support more than a single uSID block.

  The length of block [prefix] is defined in bits. From a hardware-friendliness perspective, it is expected to use sizes on byte boundaries (16, 24, 32, and so on).

• uSID ID

  The length of uSID ID is defined in bits. From a hardware-friendliness perspective, it is expected to use sizes on byte boundaries (8, 16, 24, 32, and so on).

The uSID carrier format is specified using the notation "Fbbuu" , where “bb” is size of block and “uu” is size of ID. For example, "F3216" is a format with a 32-bit uSID block and 16-bit uSID IDs.

Key Concepts and Terminologies

The architecture for uSID specifies both globally scoped and locally scoped uSIDs.

• Global ID block (GIB): The set of IDs available for globally scoped uSID allocation.

  A globally scoped uSID is the type of uSID that provides reachability to a node. A globally scoped uSID typically identifies a shortest path to a node in the SR domain. An IP route (for example, /48) is advertised by the parent node to each of its globally scoped uSIDs, under the associated uSID block. The parent node executes a variant of the END behavior.

  The “nodal” uSID (uN) is an example of a globally scoped behavior defined in uSID architecture.

  A node can have multiple globally scoped uSIDs under the same uSID blocks (for example, one uSID per IGP flex-algorithm). Multiple nodes may share the same globally scoped uSID (Anycast).

• Local ID block (LIB): The set of IDs available for locally scoped uSID allocation.

  A locally scoped uSID is associated to a local (end-point) behavior, and therefore must be preceded by a globally scoped uSID of the parent node when relying on routing to forward the packet.

  A locally scoped uSID identifies a local micro-instruction on the parent node; for example, it may identify a cross-connect to a direct neighbor over a specific interface or a VPN context. Locally scoped uSIDs are not routeable.

  For example, if N1 and N2 are two different physical nodes of the uSID domain and L is a locally scoped uSID value, then N1 and N2 may bind two different behaviors to L.

• Wide LIB (W-LIB): The extended set of IDs available for local uSID allocation.

  The extended set of IDs is useful when a PE with large-scale Pseudowire termination requires more local uSIDs than provided from the LIB.

Example: uSID Allocation

The request to allocate locally scoped uSIDs comes from SRv6 clients (such as IS-IS or BGP). The request can be to allocate any available ID (dynamic allocation) or to allocate a specific ID (explicit allocation).

Consider the following example:

• uSID Locator Block length: 32 bits

• uSID Locator Block: FCBB:BB00::/32 (with B being a nibble value picked by operator)

• uSID length (Locator Node ID / Function ID): 16 bits

• uSID: FCBB:BB00:XYWZ::/48 (with XYWZ being variable nibbles)

A uSID FCBB:BB00:XYWZ::/48 is said to be allocated from its block (FCBB:BB00::/32).

A uSID is allocated from the GIB or LIB of block FCBB:BB00::/32 depending on the value of the "X" nibble:

• GIB: nibble X from hex(0) to hex(D)

• LIB: nibble X hex(E) or hex(F)

With this allocation scheme, the uSID Block FCBB:BB00::/32 supports up to 57343 global uSIDs (routers) with each router supporting up to 8192 local uSIDs.

For example, the following picture depicts the global uSIDs allocated for 3 nodes within the SRv6 domain.

Looking further into R1, this node also has Local uSIDs associated with uA end-point behaviors:

• Function ID 0xE000 – cross-connect to L3 neighbor R2

• Function ID 0xE001 – cross-connect to L3 neighbor R3

The underlay uSIDs present on R1 are:

• FCBB:BB00:0001::/48

• FCBB:BB00:0001:E000::/64

• FCBB:BB00:0001:E001::/64

GIB and LIB – IOS-XR Implementation

In Cisco IOS XR Release 7.5.2 and earlier, the following functionality is supported:

• GIB for user-assigned IDs of global segments (uNs)

• LIB for dynamically assigned IDs of local segments

  • uA end-point behavior

  • Service de-multiplexing end-point behaviors (for example, End.DT, End.DX, End.DX2)

A uSID FCBB:BB00:XYWZ::/48 is said to be allocated from its block FCBB:BB00::/32.

The range of IDs supported by the Cisco IOS XR 7.5.2 and earlier implementation are as follows:

• The range of IDs in the GIB is 0x000 to 0xDFFF.

• The range of IDs by default in the LIB is divided as follows:

  • Dynamic: 0xE000 to 0xFDFF

  • Reserved: 0xFE00 to 0xFFFF

Starting with Cisco IOS XR Release 7.5.3, the following functionality is added:

• Configurable explicit LIB range

• Explicit LIB for user-assigned IDs of local segments

• Manual uDT46 from explicit LIB

• Wide LIB (W-LIB)

• Configurable explicit W-LIB range

• Explicit W-LIB for user-assigned IDs of local segments

• Manual uDT46 from explicit W-LIB

The range of IDs supported by the IOS XR implementation are as follows:

• The range of IDs in the GIB is 0x000 to 0xDFFF.

• The range of IDs by default in the LIB is divided as follows:

  • Dynamic: 0xE000 to 0xFDFF

  • Explicit: 0xFE00 to 0xFEFF

  • Reserved: 0xFF00 to 0xFFEF and 0xFFF8 to 0xFFFF

• The range of IDs by default in the W-LIB is divided as follows:

  • Reserved: 0xFFF0 to 0xFFF6

  • Explicit: 0xFFF7

Usage Guidelines and Limitations

• SRv6 locator can be assigned globally, for all VRFs, for an individual VRF or per-prefix.

• Per-VRF allocation mode is supported (uDT4 behavior)

• Per-VRF-46 allocation mode is supported (uDT46 behavior)

• Dual-Stack L3VPN Services (IPv4, IPv6) are supported

• Equal-Cost Multi-path (ECMP) and Unequal Cost Multipath (UCMP) are supported.

• eBGP, OSPF, Static are supported as PE-CE protocol.

• BGP (iBGP, eBGP), OSPF, Static are supported as PE-CE protocol.

• BGP route leaking between BGP Global and L3VPN is supported. Refer to the Implementing BGP chapter in the BGP Configuration Guide for Cisco 8000 Series Routers.

• MPLS L3VPN and SRv6 L3VPN interworking gateway is supported.

• Per-CE allocation mode is not supported (uDX4 behavior)

Configuring SRv6 based IPv4 L3VPN

To enable SRv6-based L3VPN, you need to enable SRv6 under BGP, specify the locator, and configure the SID allocation mode. The assignment of the locator can be done in different places under the router bgp configuration. See #concept_f11_rmx_lvb_8k.

Use Case 1: Assigning SRv6 Locator Globally

This example shows how to enable SRv6 and configure the SRv6 locator name under BGP Global:

Node1(config)# router bgp 100
Node1(config-bgp)# segment-routing srv6
Node1(config-bgp-gbl-srv6)# locator Node1-locator
Node1(config-bgp-gbl-srv6)# exit
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::1:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv4 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust1
Node1(config-bgp-vrf)# rd 100:1
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# commit

Running Config

router bgp 100
 segment-routing srv6
  locator Node1-locator
 !
 address-family vpnv4 unicast
 !
 neighbor 3001::1:1:1:4
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf vrf_cust1
  rd 100:1
  address-family ipv4 unicast
  !
 !
!
end

Use Case 2: Assigning SRv6 Locator for All VRFs

To configure the SRv6 locator for all VRFs under VPNv4 Address Family and specify the allocation mode, use the following commands:

• router bgp as-number address-family vpnv4 unicast vrf all segment-routing srv6: Enable SRv6

• router bgp as-number address-family vpnv4 unicast vrf all segment-routing srv6 alloc mode {per-vrf | per-vrf-46}: Specify the SID behavior (allocation mode)

  • Use the per-vrf keyword to specify that the same service SID (uDT4 behavior) be used for all the routes advertised from a unique VRF.

  • Use the per-vrf-46 keyword to specify that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. BGP will program two paths for this SID route: one for VPNv4 table and one for VPNv6 table.

• router bgp as-number address-family vpnv4 unicast vrf all segment-routing srv6 locator WORD: Specify the locator

This example shows how to enable SRv6 and configure the SRv6 locator for all VRFs under VPNv4 Address Family, with per-VRF label allocation mode:

Node1(config)# router bgp 100
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::1:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv4 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust1
Node1(config-bgp-vrf)# rd 100:1
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# commit

Running Config

router bgp 100
 address-family vpnv4 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf
   !
  !
 !
 neighbor 3001::1:1:1:4
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf vrf_cust1
  rd 100:1
  address-family ipv4 unicast
  !
 !
!
end

Node1(config)# router bgp 200
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::1:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv4 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust1
Node1(config-bgp-vrf)# rd 100:1
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# commit

router bgp 200
 address-family vpnv4 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
 address-family vpnv6 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
 neighbor 3001::1:1:1:4
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf vrf_cust1
  rd 100:1
  address-family ipv4 unicast
  !
 !
!
end

Use Case 3: Assigning SRv6 Locator for a specific VRF

To configure the SRv6 locator for a specific VRF under IPv4 Address Family and specify the allocation mode, use the following commands:

• router bgp as-number vrf WORD address-family ipv4 unicast segment-routing srv6: Enable SRv6

• router bgp as-number vrf WORD address-family ipv4 unicast segment-routing srv6 alloc mode { per-vrf | per-vrf-46}: Specify the SID behavior (allocation mode)

  • Use the per-vrf keyword to specify that the same service SID (uDT4 behavior) be used for all the routes advertised from a unique VRF.

  • Use the per-vrf-46 keyword to specify that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. BGP will program two paths for this SID route: one for VPNv4 table and one for VPNv6 table.

• router bgp as-number vrf WORD address-family ipv4 unicast segment-routing srv6 locator WORD: Specify the locator

This example shows how to configure the SRv6 locator for an individual VRF, with per-VRF label allocation mode:

Node1(config)# router bgp 100
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::1:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv4 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust1
Node1(config-bgp-vrf)# rd 100:1
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf
Node1(config-bgp-vrf-af-srv6)# commit

Running Config

router bgp 100
 address-family vpnv4 unicast
 !
 neighbor 3001::1:1:1:4
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf vrf_cust1
  rd 100:1
  address-family ipv4 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf
   !
  !
 !
!
end

Node1(config)# router bgp 200
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::1:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv4 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust1
Node1(config-bgp-vrf)# rd 100:1
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-vrf-af-srv6)# exit
Node1(config-bgp-vrf-af)# exit
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-vrf-af-srv6)# commit

router bgp 200
 address-family vpnv4 unicast
 !
 neighbor 3001::1:1:1:4
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf vrf_cust1
  rd 100:1
  address-family ipv4 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
  address-family ipv6 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
!
end

Verification

The following figure shows a VPNv4 scenario. The sequence of commands included correspond to router Node1 acting as Ingress PE, and routers Node4 and Node5 acting as Egress PEs.

The following example shows how to verify the SRv6 based L3VPN configuration using the show segment-routing srv6 sid command.

In this example, we can observe the uDT4 SIDs associated with the IPv4 L3VPN; where uDT4 behavior represents Endpoint with decapsulation and IPv4 table lookup.

Node1# show segment-routing srv6 sid

*** Locator: 'Node1-locator' ***

SID                         Behavior          Context                           Owner               State  RW
--------------------------  ----------------  ------------------------------    ------------------  -----  --
cafe:0:1::                  uN (PSP/USD)      'default':1                       sidmgr              InUse  Y
cafe:0:1:e000::             uA (PSP/USD)      [Hu0/0/0/0, Link-Local]:0         isis-1              InUse  Y
cafe:0:1:e001::             uA (PSP/USD)      [Hu0/0/0/1, Link-Local]:0         isis-1              InUse  Y
cafe:0:1:e002::             uDT4              'vrf_cust1'                       bgp-100             InUse  Y
cafe:0:1:e003::             uDT4              'vrf_cust2'                       bgp-100             InUse  Y
cafe:0:1:e004::             uDT4              'vrf_cust3'                       bgp-100             InUse  Y
cafe:0:1:e005::             uDT4              'vrf_cust4'                       bgp-100             InUse  Y
cafe:0:1:e006::             uDT4              'vrf_cust5'                       bgp-100             InUse  Y

The following example shows how to verify the SRv6 based L3VPN configuration using the show segment-routing srv6 SID-prefix detail command.

Node1# show segment-routing srv6 sid cafe:0:1:e002:: detail
Tue Feb  9 17:50:40.621 UTC

*** Locator: 'Node1-locator' ***

SID                         Behavior          Context                                 Owner               State  RW
--------------------------  ----------------  ------------------------------          ------------------  -----  --
cafe:0:1:e002::             uDT4              'vrf_cust1'                             bgp-100             InUse  Y
  SID Function: 0xe002
  SID context: { table-id=0xe0000011 ('vrf_cust1':IPv4/Unicast) }
  Locator: 'Node1-locator'
  Allocation type: Dynamic
  Created: Feb  9 17:41:07.475 (00:09:33 ago)
 

The following example shows how to verify the SRv6 based L3VPN configuration using the show bgp vpnv4 unicast commands on Egress PE.

Node1# show bgp vpnv4 unicast summary

BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 36
BGP NSR Initial initsync version 16 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker              36         36         36         36          36           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
cafe:0:4::4       0   100      47      48       36    0    0 00:40:05          5
cafe:0:5::5       0   100      47      47       36    0    0 00:39:56          5


Node1# show bgp vpnv4 unicast rd 100:1

BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 36
BGP NSR Initial initsync version 16 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:1 (default for vrf vrf_cust1)
*> 12.1.1.1/32        0.0.0.0                  0         32768 ?
*>i12.4.4.4/32        cafe:0:4::4              0    100      0 ?
*>i12.5.5.5/32        cafe:0:5::5              0    100      0 ?

Processed 3 prefixes, 3 paths


Node1# show bgp vpnv4 unicast rd 100:1 12.4.4.4/32

BGP routing table entry for 12.4.4.4/32, Route Distinguisher: 100:1
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                 22          22
Last Modified: Feb 23 22:57:56.756 for 00:40:08
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    cafe:0:4::4 (metric 30) from cafe:0:4::4 (1.1.1.4)
      Received Label 0xe00400
      Origin incomplete, metric 0, localpref 100, valid, internal, best, group-best, import-candidate, imported
      Received Path ID 0, Local Path ID 1, version 22
      Extended community: RT:1:1 RT:100:1
      PSID-Type:L3, SubTLV Count:1
       SubTLV:
        T:1(Sid information), Sid:cafe:0:4::, Behavior:63, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
      Source AFI: VPNv4 Unicast, Source VRF: vrf_cust1, Source Route Distinguisher: 100:1

The following examples show how to verify the BGP prefix information for VRF instances using the show bgp vrf commands:

Node1# show bgp vrf vrf_cust1 ipv4 unicast

BGP VRF vrf_cust1, state: Active
BGP Route Distinguisher: 100:1
VRF ID: 0x60000002
BGP router identifier 1.1.1.1, local AS number 100
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000011   RD version: 32
BGP main routing table version 36
BGP NSR Initial initsync version 16 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:1 (default for vrf vrf_cust1)
*> 12.1.1.1/32        0.0.0.0                  0         32768 ?
*>i12.4.4.4/32        cafe:0:4::4              0    100      0 ?
*>i12.5.5.5/32        cafe:0:5::5              0    100      0 ?

Processed 3 prefixes, 3 paths


Node1# show bgp vrf vrf_cust1 ipv4 unicast 12.4.4.4/32
Tue Feb 23 23:39:57.499 UTC
BGP routing table entry for 12.4.4.4/32, Route Distinguisher: 100:1
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                 22          22
Last Modified: Feb 23 22:57:56.756 for 00:42:01
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    cafe:0:4::4 (metric 30) from cafe:0:4::4 (1.1.1.4)
      Received Label 0xe00400
      Origin incomplete, metric 0, localpref 100, valid, internal, best, group-best, import-candidate, imported
      Received Path ID 0, Local Path ID 1, version 22
      Extended community: RT:1:1 RT:100:1
      PSID-Type:L3, SubTLV Count:1
       SubTLV:
        T:1(Sid information), Sid:cafe:0:4::, Behavior:63, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
      Source AFI: VPNv4 Unicast, Source VRF: vrf_cust1, Source Route Distinguisher: 100:1

The following example shows how to verify the SRv6 based L3VPN configuration using the show route vrf commands.

Node1# show route vrf vrf_cust1

Codes: C - connected, S - static, R - RIP, B - BGP, (>) - Diversion path
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - ISIS, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, su - IS-IS summary null, * - candidate default
       U - per-user static route, o - ODR, L - local, G  - DAGR, l - LISP
       A - access/subscriber, a - Application route
       M - mobile route, r - RPL, t - Traffic Engineering, (!) - FRR Backup path

Gateway of last resort is not set

L    12.1.1.1/32 is directly connected, 00:44:43, Loopback100
B    12.4.4.4/32 [200/0] via cafe:0:4::4 (nexthop in vrf default), 00:42:45
B    12.5.5.5/32 [200/0] via cafe:0:5::5 (nexthop in vrf default), 00:42:45


Node1# show route vrf vrf_cust1 12.4.4.4/32

Routing entry for 12.4.4.4/32
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Feb 23 22:57:56.746 for 00:43:12
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Nexthop in Vrf: "default", Table: "default", IPv6 Unicast, Table Id: 0xe0800000
      Route metric is 0
  No advertising protos.


Node1# show route vrf vrf_cust1 12.4.4.4/32 detail

Routing entry for 12.4.4.4/32
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Feb 23 22:57:56.746 for 00:43:37
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Nexthop in Vrf: "default", Table: "default", IPv6 Unicast, Table Id: 0xe0800000
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      Source RD attributes: 0x0000:100:1
      NHID:0x0(Ref:0)
      SRv6 Headend: H.Encaps.Red [f3216], SID-list {cafe:0:4:e004::}
  Route version is 0x1 (1)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_RECURSIVE (12) SVD Type RIB_SVD_TYPE_REMOTE
  Download Priority 3, Download Version 3
  No advertising protos.

The following example shows how to verify the SRv6 based L3VPN configuration using the show cef vrf commands.

Node1# show cef vrf vrf_cust1

Prefix              Next Hop            Interface
------------------- ------------------- ------------------
0.0.0.0/0           drop                default handler
0.0.0.0/32          broadcast
12.1.1.1/32         receive             Loopback100
12.4.4.4/32         cafe:0:4::/128      <recursive>
12.5.5.5/32         cafe:0:5::/128      <recursive>
224.0.0.0/4         0.0.0.0/32
224.0.0.0/24        receive
255.255.255.255/32  broadcast


Node1# show cef vrf vrf_cust1 12.4.4.4/32

12.4.4.4/32, version 3, SRv6 Headend, internal 0x5000001 0x30 (ptr 0x78b9a61c) [1], 0x0 (0x0), 0x0 (0x88873720)
 Updated Feb 23 22:57:56.749
 Prefix Len 32, traffic index 0, precedence n/a, priority 3
   via cafe:0:4::/128, 3 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78e2da14 0x0]
    next hop VRF - 'default', table - 0xe0800000
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e004::}


Node1# show cef vrf vrf_cust1 12.4.4.4/32 detail

12.4.4.4/32, version 3, SRv6 Headend, internal 0x5000001 0x30 (ptr 0x78b9a61c) [1], 0x0 (0x0), 0x0 (0x88873720)
 Updated Feb 23 22:57:56.749
 Prefix Len 32, traffic index 0, precedence n/a, priority 3
  gateway array (0x88a740a8) reference count 5, flags 0x2010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x789cbcc8) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Feb 23 22:57:56.749
 LDI Update time Feb 23 22:57:56.754

  Level 1 - Load distribution: 0
  [0] via cafe:0:4::/128, recursive

   via cafe:0:4::/128, 3 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78e2da14 0x0]
    next hop VRF - 'default', table - 0xe0800000
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e004::}

    Load distribution: 0 1 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   HundredGigE0/0/0/1        remote
    1     Y   HundredGigE0/0/0/0        remote

Usage Guidelines and Limitations

• SRv6 locator can be assigned globally, for all VRFs, for an individual VRF, or per-prefix.

• Per-VRF allocation mode is supported (uDT6 behavior)

• Per-VRF-46 allocation mode is supported (uDT46 behavior) - see Per-VRF-46 Allocation Mode

• Dual-Stack L3VPN Services (IPv4, IPv6) are supported

• Equal-Cost Multi-path (ECMP) and Unequal Cost Multipath (UCMP) are supported.

• BGP (iBGP, eBGP), OSPF, Static are supported as PE-CE protocol.

• BGP route leaking between BGP Global and L3VPN is supported. Refer to the Implementing BGP chapter in the Routing Configuration Guide for Cisco 8000 Series Routers .

• MPLS L3VPN and SRv6 L3VPN interworking gateway is supported.

• Per-CE allocation mode is not supported (uDX6 behavior)

Configuring SRv6-based IPv6 L3VPN

To enable SRv6-based L3VPN, you need to enable SRv6 under BGP, specify the locator, and configure the SID allocation mode. The assignment of the locator can be done in different places under the router bgp configuration. See SRv6 Locator Inheritance Rules.

Use Case 1: Assigning SRv6 Locator Globally

This example shows how to configure the SRv6 locator name under BGP Global:

Node1(config)# router bgp 100
Node1(config-bgp)# segment-routing srv6
Node1(config-bgp-gbl-srv6)# locator Node1-locator
Node1(config-bgp-gbl-srv6)# exit
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::12:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv6 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust6
Node1(config-bgp-vrf)# rd 100:6
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# commit

Running Configuration

router bgp 100
 segment-routing srv6
  locator Node1-locator
 !
 address-family vpnv6 unicast
 !
 neighbor 3001::12:1:1:4
  remote-as 100
  address-family vpnv6 unicast
  !
 !
 vrf vrf_cust6
  rd 100:6
  address-family ipv6 unicast
  !
 !
!
end

Use Case 2: Assigning SRv6 Locator for All VRFs

To configure the SRv6 locator for all VRFs under VPNv6 Address Family and specify the allocation mode, use the following commands:

• router bgp as-number address-family vpnv6 unicast vrf all segment-routing srv6: Enable SRv6

• router bgp as-number address-family vpnv6 unicast vrf all segment-routing srv6 alloc mode {per-vrf | per-vrf-46}: Specify the SID behavior (allocation mode)

  • Use the per-vrf keyword to specify that the same service SID (uDT6 behavior) be used for all the routes advertised from a unique VRF.

  • Use the per-vrf-46 keyword to specify that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. BGP will program two paths for this SID route: one for VPNv4 table and one for VPNv6 table.

• router bgp as-number address-family vpnv6 unicast vrf all segment-routing srv6 locator WORD: Specify the locator

This example shows how to configure the SRv6 locator for all VRFs under VPNv6 Address Family, with per-VRF label allocation mode:

Node1(config)# router bgp 100
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::12:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv6 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust6
Node1(config-bgp-vrf)# rd 100:6
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# commit

Running Configuration

router bgp 100
 address-family vpnv6 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf
   !
  !
 !
 neighbor 3001::12:1:1:4
  remote-as 100
  address-family vpnv6 unicast
  !
 !
 vrf vrf_cust6
  rd 100:6
  address-family ipv6 unicast
  !
 !
!
end

Node1(config)# router bgp 200
Node1(config-bgp)# address-family vpnv4 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# vrf all
Node1(config-bgp-af-vrfall)# segment-routing srv6
Node1(config-bgp-af-vrfall-srv6)# locator Node1-locator
Node1(config-bgp-af-vrfall-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-vrfall-srv6)# exit
Node1(config-bgp-af-vrfall)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::12:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv6 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust6
Node1(config-bgp-vrf)# rd 100:6
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# commit

router bgp 200
 address-family vpnv4 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
 address-family vpnv6 unicast
  vrf all
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
 neighbor 3001::12:1:1:4
  remote-as 100
  address-family vpnv6 unicast
  !
 !
 vrf vrf_cust6
  rd 100:6
  address-family ipv6 unicast
  !
 !
!
end

Use Case 3: Assigning SRv6 Locator for a specific VRF

To configure the SRv6 locator for a specific VRF under IPv6 Address Family and specify the allocation mode, use the following commands:

• router bgp as-number vrf WORD address-family ipv6 unicast segment-routing srv6: Enable SRv6

• router bgp as-number vrf WORD address-family ipv6 unicast segment-routing srv6 alloc mode { per-vrf | per-vrf-46}: Specify the SID behavior (allocation mode)

  • Use the per-vrf keyword to specify that the same service SID (uDT6 behavior) be used for all the routes advertised from a unique VRF.

  • Use the per-vrf-46 keyword to specify that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. BGP will program two paths for this SID route: one for VPNv4 table and one for VPNv6 table.

• router bgp as-number vrf WORD address-family ipv6 unicast segment-routing srv6 locator WORD: Specify the locator

This example shows how to configure the SRv6 locator for an individual VRF, with per-VRF label allocation mode:

Node1(config)# router bgp 100
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::12:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv6 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust6
Node1(config-bgp-vrf)# rd 100:6
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf
Node1(config-bgp-vrf-af-srv6)# commit

Running Configuration

router bgp 100
 address-family vpnv6 unicast
 !
 neighbor 3001::12:1:1:4
  remote-as 100
  address-family vpnv6 unicast
  !
 !
 vrf vrf_cust6
  rd 100:6
  address-family ipv6 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf
   !
  !
 !
!
end

Node1(config)# router bgp 200
Node1(config-bgp)# address-family vpnv6 unicast
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 3001::12:1:1:4
Node1(config-bgp-nbr)# remote-as 100
Node1(config-bgp-nbr)# address-family vpnv6 unicast
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# vrf vrf_cust6
Node1(config-bgp-vrf)# rd 100:6
Node1(config-bgp-vrf)# address-family ipv4 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-vrf-af-srv6)# exit
Node1(config-bgp-vrf-af)# exit
Node1(config-bgp-vrf)# address-family ipv6 unicast
Node1(config-bgp-vrf-af)# segment-routing srv6
Node1(config-bgp-vrf-af-srv6)# locator Node1-locator
Node1(config-bgp-vrf-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-vrf-af-srv6)# commit

router bgp 200
 address-family vpnv6 unicast
 !
 neighbor 3001::12:1:1:4
  remote-as 100
  address-family vpnv6 unicast
  !
 !
 vrf vrf_cust6
  rd 100:6
  address-family ipv4 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
  address-family ipv6 unicast
   segment-routing srv6
    locator Node1-locator
    alloc mode per-vrf-46
   !
  !
 !
!
end

Verification

The following figure shows a VPNv6 scenario. The sequence of commands included correspond to router Node1 acting as Ingress PE, and routers Node4 and Node5 acting as Egress PEs.

The following examples shows how to verify the SRv6 based L3VPN configurations for an Individual VRF with per VRF label allocation mode.

In this example, we can observe the uDT6 SID associated with the IPv6 L3VPN, where uDT6 behavior represents Endpoint with decapsulation and IPv6 table lookup.

Node1# show segment-routing srv6 sid
Fri Jan 29 19:31:53.293 UTC

*** Locator: 'Node1-locator' ***

SID                         Behavior          Context                           Owner               State  RW
--------------------------  ----------------  ------------------------------    ------------------  -----  --
cafe:0:1::                  uN (PSP/USD)      'default':1                       sidmgr              InUse  Y
cafe:0:1:e000::             uA (PSP/USD)      [Hu0/0/0/0, Link-Local]:0         isis-1              InUse  Y
cafe:0:1:e001::             uA (PSP/USD)      [Hu0/0/0/1, Link-Local]:0         isis-1              InUse  Y
cafe:0:1:e002::             uDT4              'vrf_cust1'                       bgp-100             InUse  Y
cafe:0:1:e003::             uDT4              'vrf_cust2'                       bgp-100             InUse  Y
cafe:0:1:e004::             uDT4              'vrf_cust3'                       bgp-100             InUse  Y
cafe:0:1:e005::             uDT4              'vrf_cust4'                       bgp-100             InUse  Y
cafe:0:1:e006::             uDT4              'vrf_cust5'                       bgp-100             InUse  Y
cafe:0:1:e007::             uA (PSP/USD)      [Hu0/0/0/0, Link-Local]:0:P       isis-1              InUse  Y
cafe:0:1:e008::             uA (PSP/USD)      [Hu0/0/0/1, Link-Local]:0:P       isis-1              InUse  Y
cafe:0:1:e009::             uDT6              'default'                         bgp-100             InUse  Y
cafe:0:1:e00a::             uDT6              'vrf_cust6'                       bgp-100             InUse  Y

The following examples show how to verify the SRv6 based L3VPN configuration using the show bgp vpnv6 unicast commands on the Ingress PE.

Node1# show bgp vpnv6 unicast summary
Fri Jan 29 19:33:01.177 UTC
BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 6
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker               6          6          6          6           6           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
cafe:0:4::4       0   100     122     123        6    0    0 00:20:05          1
cafe:0:5::5       0   100     111     111        0    0    0 00:49:46          1

Node1# show bgp vpnv6 unicast rd 100:6
Fri Jan 29 19:41:01.334 UTC
BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 8
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:6 (default for vrf vrf_cust6)
*> 3001::12:1:1:1/128 ::                       0         32768 ?
*>i3001::12:1:1:4/128 cafe:0:4::4              0    100      0 ?
*>i3001::12:1:1:5/128 cafe:0:5::5              0    100      0 ?

Processed 3 prefixes, 3 paths

Node1# show bgp vpnv6 unicast rd 100:6 3001::12:1:1:4/128
Fri Jan 29 19:41:42.008 UTC
BGP routing table entry for 3001::12:1:1:4/128, Route Distinguisher: 100:6
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                  6           6
Last Modified: Jan 29 19:29:35.858 for 00:12:06
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    cafe:0:4::4 (metric 30) from cafe:0:4::4 (1.1.1.4)
      Received Label 0xe00a00
      Origin incomplete, metric 0, localpref 100, valid, internal, best, group-best, import-candidate, imported
      Received Path ID 0, Local Path ID 1, version 6
      Extended community: RT:100:6
      PSID-Type:L3, SubTLV Count:1
       SubTLV:
        T:1(Sid information), Sid:cafe:0:4::, Behavior:62, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
      Source AFI: VPNv6 Unicast, Source VRF: vrf_cust6, Source Route Distinguisher: 100:6

The following examples show how to verify the BGP prefix information for VRF instances:

Node1# show bgp vrf vrf_cust6 ipv6 unicast
Fri Jan 29 19:42:05.675 UTC
BGP VRF vrf_cust6, state: Active
BGP Route Distinguisher: 100:6
VRF ID: 0x60000007
BGP router identifier 1.1.1.1, local AS number 100
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800016   RD version: 8
BGP main routing table version 8
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:6 (default for vrf vrf_cust6)
*> 3001::12:1:1:1/128 ::                       0         32768 ?
*>i3001::12:1:1:4/128 cafe:0:4::4              0    100      0 ?
*>i3001::12:1:1:5/128 cafe:0:5::5              0    100      0 ?

Processed 3 prefixes, 3 paths

Node1# show bgp vrf vrf_cust6 ipv6 unicast 3001::12:1:1:4/128

BGP routing table entry for 3001::12:1:1:4/128, Route Distinguisher: 100:6
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                 17          17
Last Modified: Jan 15 16:50:44.032 for 01:48:21
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    cafe:0:4::4 (metric 30) from cafe:0:4::4 (1.1.1.4)
      Received Label 0xe00a00
      Origin incomplete, metric 0, localpref 100, valid, internal, best, group-best, import-candidate, imported
      Received Path ID 0, Local Path ID 1, version 17
      Extended community: RT:100:6
      PSID-Type:L3, SubTLV Count:1
       SubTLV:
        T:1(Sid information), Sid:cafe:0:4::, Behavior:62, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
      Source AFI: VPNv6 Unicast, Source VRF: vrf_cust6, Source Route Distinguisher: 100:6

The following examples show how to verify the current routes in the Routing Information Base (RIB):

Node1# show route vrf vrf_cust6 ipv6 unicast
Fri Jan 29 19:43:28.067 UTC

Codes: C - connected, S - static, R - RIP, B - BGP, (>) - Diversion path
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - ISIS, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, su - IS-IS summary null, * - candidate default
       U - per-user static route, o - ODR, L - local, G  - DAGR, l - LISP
       A - access/subscriber, a - Application route
       M - mobile route, r - RPL, t - Traffic Engineering, (!) - FRR Backup path

Gateway of last resort is not set

L    3001::12:1:1:1/128 is directly connected,
      01:01:23, Loopback105
B    3001::12:1:1:4/128
      [200/0] via cafe:0:4::4 (nexthop in vrf default), 00:13:52
B    3001::12:1:1:5/128
      [200/0] via cafe:0:5::5 (nexthop in vrf default), 00:05:53

Node1# show route vrf vrf_cust6 ipv6 unicast 3001::12:1:1:4/128
Fri Jan 29 19:43:55.645 UTC

Routing entry for 3001::12:1:1:4/128
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Jan 29 19:29:35.696 for 00:14:20
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Nexthop in Vrf: "default", Table: "default", IPv6 Unicast, Table Id: 0xe0800000
      Route metric is 0
  No advertising protos.

Node1# show route vrf vrf_cust6 ipv6 unicast 3001::12:1:1:4/128 detail
Fri Jan 29 19:44:17.914 UTC

Routing entry for 3001::12:1:1:4/128
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Jan 29 19:29:35.696 for 00:14:42
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Nexthop in Vrf: "default", Table: "default", IPv6 Unicast, Table Id: 0xe0800000
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      Source RD attributes: 0x0000:100:6
      NHID:0x0(Ref:0)
      SRv6 Headend: H.Encaps.Red [f3216], SID-list {cafe:0:4:e00a::}
  Route version is 0x1 (1)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_RECURSIVE (12) SVD Type RIB_SVD_TYPE_REMOTE
  Download Priority 3, Download Version 3
  No advertising protos.

The following examples show how to verify the current IPv6 Cisco Express Forwarding (CEF) table:

Node1# show cef vrf vrf_cust6 ipv6
Fri Jan 29 19:44:56.888 UTC

::/0
  drop       default handler
3001::12:1:1:1/128
  receive    Loopback105
3001::12:1:1:4/128
  recursive    cafe:0:4::/128
3001::12:1:1:5/128
  recursive    cafe:0:5::/128
fe80::/10
  receive
ff02::/16
  receive
ff02::2/128
  receive
ff02::1:ff00:0/104
  receive
ff05::/16
  receive
ff12::/16
  receive

Node1# show cef vrf vrf_cust6 ipv6 3001::12:1:1:4/128
Fri Jan 29 19:45:23.607 UTC
3001::12:1:1:4/128, version 3, SRv6 Headend, internal 0x5000001 0x30 (ptr 0x78f2e0e0) [1], 0x0 (0x0), 0x0 (0x888a3ac8)
 Updated Jan 29 19:29:35.700
 Prefix Len 128, traffic index 0, precedence n/a, priority 3
   via cafe:0:4::/128, 7 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78cd2a14 0x0]
    next hop VRF - 'default', table - 0xe0800000
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e00a::}

Node1# show cef vrf vrf_cust6 ipv6 3001::12:1:1:4/128 detail
Fri Jan 29 19:45:55.847 UTC
3001::12:1:1:4/128, version 3, SRv6 Headend, internal 0x5000001 0x30 (ptr 0x78f2e0e0) [1], 0x0 (0x0), 0x0 (0x888a3ac8)
 Updated Jan 29 19:29:35.700
 Prefix Len 128, traffic index 0, precedence n/a, priority 3
  gateway array (0x78afe238) reference count 1, flags 0x2010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x78ba9a60) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Jan 29 19:29:35.699
 LDI Update time Jan 29 19:29:35.701

  Level 1 - Load distribution: 0
  [0] via cafe:0:4::/128, recursive

   via cafe:0:4::/128, 7 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78cd2a14 0x0]
    next hop VRF - 'default', table - 0xe0800000
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e00a::}

    Load distribution: 0 1 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   HundredGigE0/0/0/0        remote
    1     Y   HundredGigE0/0/0/1        remote

Usage Guidelines and Limitations

• SRv6 locator can be assigned globally or under IPv4 unicast address family

• Equal-Cost Multi-path (ECMP) and Unequal Cost Multipath (UCMP) are supported.

• BGP, OSPF, Static are supported as PE-CE protocol.

• BGP route leaking between BGP Global and L3VPN is supported. Refer to theImplementing BGP chapter in the Routing Configuration Guide for Cisco 8000 Series Routers

• Dual-Stack L3 Services (IPv4 BGP global, IPv6 BGP global) are supported.

BGP Global IPv4 Over SRv6 with Per-CE SID Allocation Mode (End.DX4)

The following example shows how to configure BGP global IPv4 over SRv6 with per-CE SID allocation.

router bgp 1
 bgp router-id 10.1.0.1
 address-family ipv4 unicast
  segment-routing srv6
   alloc mode per-ce  
  !
 !
 neighbor 60::2
  remote-as 1
  update-source Loopback1
  address-family ipv4 unicast
   route-policy passall in
   encapsulation-type srv6
   route-policy passall out
  !
 !
 neighbor 52.52.52.1
  remote-as 3
  address-family ipv4 unicast
   route-policy passall in
   route-policy passall out
  !
 !
!

BGP Global IPv4 Over SRv6 with Per-AFI SID Allocation Mode (uDT4/uDT46)

To configure BGP global IPv4 over SRv6, use the following commands:

• router bgp as-number address-family ipv4 unicast segment-routing srv6: Enable SRv6

• router bgp as-number address-family ipv4 unicast segment-routing srv6 alloc mode {per-vrf | per-vrf-46 | route-policy policy_name}: Specify the SID behavior (allocation mode).

  • per-vrf: Specifies that the same label is be used for all the routes advertised from a unique VRF.

  • per-vrf-46: Specifies that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. See Per-VRF-46 Allocation Mode.

  • route-policy policy_name: Uses a route policy to determine the SID allocation mode and locator (if provided) for given prefix.

• router bgp as-number address-family ipv4 unicast segment-routing srv6 locator WORD: Specify the locator

• router bgp as-number {af-group WORD| neighbor-group WORD | neighbor ipv6-addr} address-family ipv4 unicast encapsulation-type srv6: Specify the encapuslation type for SRv6.

  • Use af-group WORD to apply the SRv6 encapsulation type to the address family group for BGP neighbors.

  • Use neighbor-group WORDto apply the SRv6 encapsulation type to the neighbor group for BGP neighbors.

  • Use neighbor ipv6-addr to apply the SRv6 encapsulation type to the specific BGP neighbor.

Use Case 1: BGP Global IPv4 over SRv6 with Per-AFI SID Allocation

The following example shows how to configure BGP global IPv4 over SRv6 with per-AFI SID allocation.

Node1(config)# router bgp 1
Node1(config-bgp)# bgp router-id 10.1.0.1
Node1(config-bgp)# address-family ipv4 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 60::2
Node1(config-bgp-nbr)# remote-as 1
Node1(config-bgp-nbr)# update-source Loopback1
Node1(config-bgp-nbr)# address-family ipv4 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# neighbor 52.52.52.1
Node1(config-bgp-nbr)# remote-as 3
Node1(config-bgp-nbr)# address-family ipv4 unicast
Node1(config-bgp-nbr-af)# route-policy passall in
Node1(config-bgp-nbr-af)# route-policy passall out
Node1(config-bgp-nbr-af)# commit

Running Configuration

router bgp 1
 bgp router-id 10.1.0.1
 address-family ipv4 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf
  !
 !
 neighbor 60::2
  remote-as 1
  update-source Loopback1
  address-family ipv4 unicast
   encapsulation-type srv6
  !
 !
 neighbor 52.52.52.1
  remote-as 3
  address-family ipv4 unicast
   route-policy passall in
   route-policy passall out
  !
 !
!

Node1(config)# router bgp 1
Node1(config-bgp)# bgp router-id 10.1.0.1
Node1(config-bgp)# address-family ipv4 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# address-family ipv6 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor 60::2
Node1(config-bgp-nbr)# remote-as 1
Node1(config-bgp-nbr)# update-source Loopback1
Node1(config-bgp-nbr)# address-family ipv4 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# neighbor 52.52.52.1
Node1(config-bgp-nbr)# remote-as 3
Node1(config-bgp-nbr)# address-family ipv4 unicast
Node1(config-bgp-nbr-af)# route-policy passall in
Node1(config-bgp-nbr-af)# route-policy passall out
Node1(config-bgp-nbr-af)# commit

router bgp 1
 bgp router-id 10.1.0.1
 address-family ipv4 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf-46
  !
 !
 address-family ipv6 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf-46
  !
 !
 neighbor 60::2
  remote-as 1
  update-source Loopback1
  address-family ipv4 unicast
   encapsulation-type srv6
  !
 !
 neighbor 52.52.52.1
  remote-as 3
  address-family ipv4 unicast
   route-policy passall in
   route-policy passall out
  !
 !
!

Node1(config)# route-policy set_per_prefix_locator_rpl
Node1(config-rpl)# if destination in (1.1.1.0/24) then
Node1(config-rpl-if)# set srv6-alloc-mode per-vrf locator locator1
Node1(config-rpl-if)# elseif destination in (2.2.2.0/24) then
Node1(config-rpl-elseif)# set srv6-alloc-mode per-vrf locator locator2
Node1(config-rpl-elseif)# elseif destination in (3.3.3.0/24) then
Node1(config-rpl-elseif)# set srv6-alloc-mode per-vrf
Node1(config-rpl-elseif)# elseif destination in (4.4.4.0/24) then
Node1(config-rpl-elseif)# set srv6-alloc-mode per-ce
Node1(config-rpl-elseif)# else
Node1(config-rpl-else)# drop
Node1(config-rpl-else)# endif
Node1(config-rpl)# end-policy
Node1(config)#

Node1(config)# router bgp 100
Node1(config-bgp)# address-family ipv4 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# alloc mode route-policy set_per_prefix_locator_rpl

route-policy set_per_prefix_locator_rpl
  if destination in (1.1.1.0/24) then
    set srv6-alloc-mode per-vrf locator locator1
  elseif destination in (2.2.2.0/24) then
    set srv6-alloc-mode per-vrf locator locator2
  elseif destination in (3.3.3.0/24) then
    set srv6-alloc-mode per-vrf
  elseif destination in (4.4.4.0/24) then
    set srv6-alloc-mode per-ce
  else
    drop
  endif
end-policy
!
router bgp 100
 address-family ipv4 unicast
  segment-routing srv6
   alloc mode route-policy set_per_prefix_locator_rpl
  !
 !
!

Node1# show bgp ipv4 unicast local-sids 
…
Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Local Sid                                   Alloc mode   Locator
*> 1.1.1.0/24         fc00:8:1:41::                               per-vrf      locator2
*> 2.2.2.0/24         fc00:0:1:41::                               per-vrf      locator1
*> 3.3.3.0/24         fc00:9:1:42::                               per-vrf      locator4
*> 4.4.4.0/24         fc00:9:1:43::                               per-ce       locator4
*> 1.1.1.5/32         NO SRv6 Sid                                 -            -
* i8.8.8.8/32         NO SRv6 Sid                                 -            -

Node1# show bgp ipv4 unicast received-sids 
…
Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop                            Received Sid
*> 1.1.1.0/24         66.2.2.2                            NO SRv6 Sid
*> 2.2.2.0/24         66.2.2.2                            NO SRv6 Sid
*> 3.3.3.0/24         66.2.2.2                            NO SRv6 Sid
*> 4.4.4.0/24         66.2.2.2                            NO SRv6 Sid
*> 1.1.1.5/32         66.2.2.2                            NO SRv6 Sid
* i8.8.8.8/32         77.1.1.2                            fc00:0:2:41::

Usage Guidelines and Limitations

• SRv6 locator can be assigned globally or under IPv6 unicast address family

• Equal-Cost Multi-path (ECMP) and Unequal Cost Multipath (UCMP) are supported.

• BGP, OSPF, Static are supported as PE-CE protocol.

• Dual-Stack L3 Services (IPv4 BGP global, IPv6 BGP global) are supported.

BGP Global IPv6 Over SRv6 with Per-AFI SID Allocation Mode (uDT6)

To configure BGP global IPv6 over SRv6, use the following commands:

• router bgp as-number address-family ipv6 unicast segment-routing srv6: Enable SRv6

• router bgp as-number address-family ipv6 unicast segment-routing srv6 alloc mode {per-vrf | per-vrf-46 | route-policy policy_name}: Specify the SID behavior (allocation mode).

  • per-vrf: Specifies that the same label is be used for all the routes advertised from a unique VRF.

  • per-vrf-46: Specifies that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF. See Per-VRF-46 Allocation Mode.

  • route-policy policy_name: Uses a route policy to determine the SID allocation mode and locator (if provided) for given prefix.

• router bgp as-number address-family ipv6 unicast segment-routing srv6 locator WORD: Specify the locator

• router bgp as-number {af-group WORD| neighbor-group WORD | neighbor ipv6-addr} address-family ipv6 unicast encapsulation-type srv6: Specify the encapuslation type for SRv6.

  • Use af-group WORD to apply the SRv6 encapsulation type to the address family group for BGP neighbors.

  • Use neighbor-group WORDto apply the SRv6 encapsulation type to the neighbor group for Border Gateway Protocol (BGP) neighbors.

  • Use neighbor ipv6-addr to apply the SRv6 encapsulation type to the specific BGP neighbor.

The following example shows how to configure BGP global IPv6 over SRv6 with per-AFI SID allocation.

Node1(config)# router bgp 100
Node1(config-bgp)# bgp router-id 1.1.1.1
Node1(config-bgp)# segment-routing srv6
Node1(config-bgp-gbl-srv6)# locator Node1
Node1(config-bgp-gbl-srv6)# exit
Node1(config-bgp)# address-family ipv6 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor cafe:0:4::4
Node1(config-bgp-nbr)# address-family ipv6 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# neighbor cafe:0:5::5
Node1(config-bgp-nbr)# address-family ipv6 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# commit

Running Configuration

router bgp 100
 bgp router-id 1.1.1.1
 segment-routing srv6
  locator Node1
 !
 address-family ipv6 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf
  !
 !
 neighbor cafe:0:4::4
  address-family ipv6 unicast
   encapsulation-type srv6
  !
 !
 neighbor cafe:0:5::5
  address-family ipv6 unicast
   encapsulation-type srv6

Node1(config)# router bgp 200
Node1(config-bgp)# bgp router-id 1.1.1.1
Node1(config-bgp)# segment-routing srv6
Node1(config-bgp-gbl-srv6)# locator Node1
Node1(config-bgp-gbl-srv6)# exit
Node1(config-bgp)# address-family ipv4 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# address-family ipv6 unicast
Node1(config-bgp-af)# segment-routing srv6
Node1(config-bgp-af-srv6)# locator Node1
Node1(config-bgp-af-srv6)# alloc mode per-vrf-46
Node1(config-bgp-af-srv6)# exit
Node1(config-bgp-af)# exit
Node1(config-bgp)# neighbor cafe:0:4::4
Node1(config-bgp-nbr)# address-family ipv6 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# exit
Node1(config-bgp-nbr)# exit
Node1(config-bgp)# neighbor cafe:0:5::5
Node1(config-bgp-nbr)# address-family ipv6 unicast
Node1(config-bgp-nbr-af)# encapsulation-type srv6
Node1(config-bgp-nbr-af)# commit

router bgp 200
 bgp router-id 1.1.1.1
 segment-routing srv6
  locator Node1
 !
 address-family ipv4 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf-46
  !
 !
 address-family ipv6 unicast
  segment-routing srv6
   locator Node1
   alloc mode per-vrf-46
  !
 !
 neighbor cafe:0:4::4
  address-family ipv6 unicast
   encapsulation-type srv6
  !
 !
 neighbor cafe:0:5::5
  address-family ipv6 unicast
   encapsulation-type srv6

Verification

The following figure shows a IPv6 BGP global scenario. The sequence of commands included correspond to router Node1 acting as Ingress PE, and routers Node4 and Node5 acting as Egress PEs.

The following examples show how to verify the BGP global IPv6 configuration using the show bgp ipv6 unicast commands.

Node1# show bgp ipv6 unicast summary
Fri Jan 29 19:48:23.255 UTC
BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 4
BGP main routing table version 4
BGP NSR Initial initsync version 2 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker               4          4          4          4           4           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
cafe:0:4::4       0   100     137     138        4    0    0 00:35:27          1
cafe:0:5::5       0   100     138     137        4    0    0 00:10:54          1
  
Node1# show bgp ipv6 unicast
Fri Jan 29 19:49:05.688 UTC
BGP router identifier 1.1.1.1, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0800000   RD version: 4
BGP main routing table version 4
BGP NSR Initial initsync version 2 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> 3001::13:1:1:1/128 ::                       0         32768 i
*>i3001::13:1:1:4/128 cafe:0:4::4              0    100      0 i
*>i3001::13:1:1:5/128 cafe:0:5::5              0    100      0 i

Processed 3 prefixes, 3 paths
  
Node1# show bgp ipv6 unicast 3001::13:1:1:4/128
Fri Jan 29 19:49:22.067 UTC
BGP routing table entry for 3001::13:1:1:4/128
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                  3           3
Last Modified: Jan 29 19:14:13.858 for 00:35:08
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local
    cafe:0:4::4 (metric 30) from cafe:0:4::4 (1.1.1.4)
      Origin IGP, metric 0, localpref 100, valid, internal, best, group-best
      Received Path ID 0, Local Path ID 1, version 3
      PSID-Type:L3, SubTLV Count:1
       SubTLV:
        T:1(Sid information), Sid:cafe:0:4:e009::, Behavior:62, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):

The following examples show how to verify the current routes in the Routing Information Base (RIB):

Node1# show route ipv6 3001::13:1:1:4/128
Fri Jan 29 19:53:26.839 UTC

Routing entry for 3001::13:1:1:4/128
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Jan 29 19:14:13.397 for 00:35:28
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Route metric is 0
  No advertising protos.

Node1# show route ipv6 3001::13:1:1:4/128 detail
Fri Jan 29 19:50:08.601 UTC

Routing entry for 3001::13:1:1:4/128
  Known via "bgp 100", distance 200, metric 0, type internal
  Installed Jan 29 19:14:13.397 for 00:35:55
  Routing Descriptor Blocks
    cafe:0:4::4, from cafe:0:4::4
      Route metric is 0
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      NHID:0x0(Ref:0)
      SRv6 Headend: H.Encaps.Red [f3216], SID-list {cafe:0:4:e009::}
  Route version is 0x1 (1)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_RECURSIVE (12) SVD Type RIB_SVD_TYPE_LOCAL
  Download Priority 4, Download Version 106
  No advertising protos.

The following examples show how to verify the current IPv6 Cisco Express Forwarding (CEF) table:

Node1# show cef ipv6 3001::13:1:1:4/128
Fri Jan 29 19:50:29.149 UTC
3001::13:1:1:4/128, version 106, SRv6 Headend, internal 0x5000001 0x40 (ptr 0x78    cd3944) [1], 0x0 (0x0), 0x0 (0x888a3a80)
 Updated Jan 29 19:14:13.401
 Prefix Len 128, traffic index 0, precedence n/a, priority 4
   via cafe:0:4::/128, 7 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78cd2a14 0x0]
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e009::}

Node1# show cef ipv6 3001::13:1:1:4/128 detail
Fri Jan 29 19:51:00.920 UTC
3001::13:1:1:4/128, version 106, SRv6 Headend, internal 0x5000001 0x40 (ptr 0x78cd3944) [1], 0x0 (0x0), 0x0 (0x888a3a80)
 Updated Jan 29 19:14:13.401
 Prefix Len 128, traffic index 0, precedence n/a, priority 4
  gateway array (0x78afe150) reference count 1, flags 0x2010, source rib (7), 0 backups
                [1 type 3 flags 0x48441 (0x78ba99e8) ext 0x0 (0x0)]
  LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0]
  gateway array update type-time 1 Jan 29 19:14:13.401
 LDI Update time Jan 29 19:14:13.401

  Level 1 - Load distribution: 0
  [0] via cafe:0:4::/128, recursive

   via cafe:0:4::/128, 7 dependencies, recursive [flags 0x6000]
    path-idx 0 NHID 0x0 [0x78cd2a14 0x0]
    next hop cafe:0:4::/128 via cafe:0:4::/48
    SRv6 H.Encaps.Red SID-list {cafe:0:4:e009::}

    Load distribution: 0 1 (refcount 1)

    Hash  OK  Interface                 Address
    0     Y   HundredGigE0/0/0/0        remote
    1     Y   HundredGigE0/0/0/1        remote

Need for BGP Signaling Over SRv6 core

BGP now supports sending internet service over an SRv6 core, assuming that all Global Routing Table (GRT) routes are advertised with an SRv6-SID.

To differentiate between the SRv6 core and non-SRv6 core sides, an "encapsulation-type SRv6" was introduced under the IPv6 BGP peer for the IPv4 unicast address-family. When the "encapsulation-type srv6" is enabled, routes without an SRv6-SID are not sent to the neighbor sessions during update generation. For more information, see Configuring SRv6 BGP-Based Services and https://datatracker.ietf.org/doc/rfc9252/.

However, in some networks, there may be a mix of GRT routes with SRv6 SID encapsulation and without SRv6 encapsulation. Hence, there is a need for BGP to allow SRv6-enabled GRT to support the co-existence and signaling of IP routes with or without an SRv6-SID on the same IPv6 neighbor session.

Co-existence of IP routes with or without SRv6 SID

This feature adds a new BGP encapsulation type called SRv6 relax-SID, which allows the advertisement of prefixes with or without SRv6 SID over the same BGP session. This is in contrast to the existing encapsulation type "srv6", which did not advertise prefixes without an SRv6 SID. The configuration allows for the specification of route policies that set the SRv6 allocation mode based on the destination prefix, enabling the coexistence of IP routes with or without SRv6 SID.

Benefits

The benefits of the co-existence of IP routes with or without SRv6 SID over an SRv6 core are numerous and significant for network operations as listed.

• Enhanced Network Efficiency: Allows seamless integration of SRv6 capabilities into existing network infrastructures, which can lead to more efficient routing and resource utilization.

• Simplified Operations: By supporting the coexistence of IP routes with or without SRv6 SID, network operators can manage their networks better without maintaining separate BGP peer sessions to support advertising both type of routes.

• Future-Proofing the Network: As networks evolve, the ability to support IP routes with or without SRv6 SID ensures that the network is prepared to enable customer to support use cases such as overlay and underlay route separation in a GRT table.

• Cost Savings: Reduce operations cost by streamlining network efficiency by optimizing BGP session management.

• Flexibility and Scalability: The feature provides the flexibility to apply SRv6 where it is needed while maintaining IP routing, allowing the network to scale efficiently.

• Transition to New Technologies: It facilitates a smoother transition to newer routing technologies like SRv6, which is designed to meet the demands of modern network applications and services.

These benefits contribute to a more robust, agile, and cost-effective network that can adapt to the changing needs of service providers and their customers.

Usage Guidelines and Restrictions

• This feature can only be configured for bundle interfaces.

• When an EVPN Ethernet Segment (ES) is configured with port-active load-balancing mode, you cannot configure ACs of that bundle on bridge-domains with a configured EVPN instance (EVI). EVPN Layer 2 bridging service is not compatible with port-active load-balancing.

Usage Guidelines and Limitations

Interworking between EVPN RT5 over SRv6 core and EVPN RT5 over MPLS core is supported. See L3 EVPN/SRv6 and L3 EVPN/MPLS Interworking Gateway.

Interworking between EVPN RT5 over SRv6 core and L3VPN over MPLS core is supported. See L3 EVPN/SRv6 and L3VPN/MPLS Interworking Gateway.

BGP does not support dual VPNv4/v6 address family and EVPN RT5 address family on the same BGP session. For the route reflector (RR) to receive both Type-5 EVPN route and VPNv4/v6 address family, we recommend that you configure two pairs of loopback interfaces and configure two BGP loopback sessions between the RR and the PE: one session for VPNv4/v6 address family and one session for EVPN address family.

BGP sends all VRF routes via either VPNv4/v6 or EVPN address family. We recommend that you mark the VRF route via export route-policy and use neighbor out policy to either drop or pass the route for an address family to achieve the same net effect.

The following behaviors are supported:

• IPv4, IPv6, and IPv4/IPv6 (dual stack) L3 EVPN over SRv6

• uDT4

• uDT6

• uDT46

• Automated Steering to Flex-Algo (BGP per-VRF locator Flex-Algo (per-prefix))

• Automated Steering to SRv6 Policy (ODN/AS)

Configuring SRv6-based L3 EVPN

To enable SRv6-based L3 EVPN, you must enable SRv6 under BGP, specify the locator, and configure the SID allocation mode. The assignment of the locator can be done in multiple ways under the router bgp configuration. See SRv6 Locator Inheritance Rules

Configure the VRF (Dual-Stack IPv4/IPv6)

Router(config)# vrf VPN1
Router(config-vrf)# address-family ipv4 unicast 
Router(config-vrf-af)# import route-target
Router(config-vrf-import-rt)# 1:1
Router(config-vrf-import-rt)# exit
Router(config-vrf-af)# export route-target
Router(config-vrf-export-rt)# 1:1
Router(config-vrf-export-rt)# exit
Router(config-vrf)# address-family ipv6 unicast 
Router(config-vrf-af)# import route-target
Router(config-vrf-import-rt)# 1:1
Router(config-vrf-import-rt)# exit
Router(config-vrf-af)# export route-target
Router(config-vrf-export-rt)# 1:1
Router(config-vrf-export-rt)# exit
Router(config-vrf-af)# 

Configure the SRv6 Locator for an Individual VRF, with Per-VRF Label Allocation Mode

To configure the SRv6 locator for a specific VRF under IPv4 or IPv6 Address Family and specify the allocation mode, use the following commands:

• router bgp as-number vrf WORD address-family {ipv4 | ipv6} unicast segment-routing srv6: Enables SRv6

• router bgp as-number vrf WORD address-family {ipv4 | ipv6} unicast segment-routing srv6 alloc mode {per-vrf | per-vrf-46 }: Specifies the SID behavior (allocation mode).

  • per-vrf: Specifies that the same service SID (uDT6 behavior) is used for all the routes advertised from a unique VRF.

  • per-vrf-46: Specifies that the same service SID (uDT46 behavior) be used for all the routes advertised from a unique VRF.

• router bgp as-number vrf WORD address-family {ipv4 | ipv6} unicast segment-routing srv6 locator WORD: Specifies the locator

Router(config)# router bgp 100
Router(config-bgp)# address-family vpnv4 unicast
Router(config-bgp-af)# additional-paths receive
Router(config-bgp-af)# additional-paths send
Router(config-bgp-af)# additional-paths selection route-policy add-path
Router(config-bgp-af)# exit
Router(config-bgp)# address-family vpnv6 unicast
Router(config-bgp-af)# additional-paths receive
Router(config-bgp-af)# additional-paths send
Router(config-bgp-af)# additional-paths selection route-policy add-path
Router(config-bgp-af)# exit
Router(config-bgp)# address-family l2vpn evpn
Router(config-bgp-af)# additional-paths receive
Router(config-bgp-af)# additional-paths send
Router(config-bgp-af)# additional-paths selection route-policy add-path
Router(config-bgp-af)# exit

Router(config-bgp)# neighbor 1111::1
Router(config-bgp-nbr)# remote-as 100
Router(config-bgp-nbr)# address-family l2vpn evpn
Router(config-bgp-nbr-af)# advertise vpnv4 unicast
Router(config-bgp-nbr-af)# advertise vpnv6 unicast
Router(config-bgp-nbr-af)# exit
Router(config-bgp-nbr)# exit

Router(config-bgp)# vrf VPN1
Router(config-bgp-vrf)# rd 100:1
Router(config-bgp-vrf)# address-family ipv4 unicast
Router(config-bgp-vrf-af)# segment-routing srv6
Router(config-bgp-vrf-af-srv6)# locator LOC1
Router(config-bgp-vrf-af-srv6)# alloc mode per-vrf
Router(config-bgp-vrf-af-srv6)# exit
Router(config-bgp-vrf-af)# exit
Router(config-bgp-vrf)# address-family ipv6 unicast
Router(config-bgp-vrf-af)# segment-routing srv6
Router(config-bgp-vrf-af-srv6)# locator LOC1
Router(config-bgp-vrf-af-srv6)# alloc mode per-vrf-46
Router(config-bgp-vrf-af-srv6)# exit
Router(config-bgp-vrf-af)# exit

Router(config-bgp-vrf)# neighbor 1.1.1.1
Router(config-bgp-vrf-nbr)# remote-as 200
Router(config-bgp-vrf-nbr)# address-family ipv4 unicast
Router(config-bgp-vrf-nbr-af)# exit
Router(config-bgp-vrf-nbr)# exit
Router(config-bgp-vrf)# neighbor 3333::3
Router(config-bgp-vrf-nbr)# remote-as 200
Router(config-bgp-vrf-nbr)# address-family ipv6 unicast

Running Configuration

vrf VPN1
 address-family ipv4 unicast
  import route-target
   1:1
  !
  export route-target
   1:1
  !
 !
 address-family ipv6 unicast
  import route-target
   1:1
  !
  export route-target
   1:1
  !
 !
!
router bgp 100
 address-family vpnv4 unicast
  additional-paths receive
  additional-paths send
  additional-paths selection route-policy add-path
 !
 address-family vpnv6 unicast
  additional-paths receive
  additional-paths send
  additional-paths selection route-policy add-path
 !
 address-family l2vpn evpn
  additional-paths receive
  additional-paths send
  additional-paths selection route-policy add-path
 !
 neighbor 1111::1 
  remote-as 100
  address-family l2vpn evpn
   advertise vpnv4 unicast
   advertise vpnv6 unicast
  !
 !
 vrf VPN1
  rd 100:1
  address-family ipv4 unicast
   segment-routing srv6
    locator LOC1
    alloc mode per-vrf
   !
  !
  address-family ipv6 unicast
   segment-routing srv6
    locator LOC1
    alloc mode per-vrf-46
   !
  !
  neighbor 1.1.1.1
   remote-as 200
   address-family ipv4 unicast
   !
  !
  neighbor 3333::3
   remote-as 200
   address-family ipv6 unicast
   !
  !
 !
!

Example

The following example shows output of a BGP route table for a VPNv4 prefix learned from three egress PEs:

• BGP Path 1 from next-hop 7::1 and a 32-bit uDT4 function (0xfff0 4002) allocated from W-LIB

• BGP Path 2 from next-hop 9::1 and a 16-bit uDT4 function (0x4002) allocated from LIB

• BGP Path 3 from next-hop 8::1 and a 16-bit uDT4 function (0x4002) allocated from LIB

Note the following fields in the output:

• Function length of 16 bits for LIB and 32 bits for W-LIB

• Transposition offset (Tpose-offset) value of 48 bits for LIB and 64 bits for W-LIB

• Transposition length (Tpose-len) value of 16 bits for LIB/W-LIB

Router# show bgp vpnv4 unicast rd 100:2 2.2.0.1/32 detail 

BGP routing table entry for 2.2.0.1/32, Route Distinguisher: 100:2
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                5314         5314
    Flags: 0x20061292+0x00060000; multipath; backup available; 
Last Modified: Jan 20 14:37:59.189 for 00:00:19
Paths: (3 available, best #1)
  Not advertised to any peer
 Path #1: Received by speaker 0
  Flags: 0x2000000085070005+0x00, import: 0x39f
  Not advertised to any peer
  Local
    7::1 (metric 20) from 2::1 (192.0.0.1), if-handle 0x00000000
      Received Label 0x40020
      Origin IGP, localpref 150, valid, internal, best, group-best, multipath, import-candidate, imported
      Received Path ID 1, Local Path ID 1, version 5314
      Extended community: RT:100:2 
      Originator: 192.0.0.1, Cluster list: 2.0.0.1
      PSID-Type:L3, SubTLV Count:1, R:0x00,
       SubTLV:
        T:1(Sid information), Sid:fccc:cc00:7001:fff0::, F:0x00, R2:0x00, Behavior:63, R3:0x00, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
           Length [Loc-blk,Loc-node,Func,Arg]:[32,16,32,0], Tpose-len:16, Tpose-offset:64
      Source AFI: VPNv4 Unicast, Source VRF: VRF_2, Source Route Distinguisher: 100:2
  Path #2: Received by speaker 0
  Flags: 0x2000000084060005+0x00, import: 0x096
  Not advertised to any peer
  Local
    9::1 (metric 20) from 2::1 (192.0.0.3), if-handle 0x00000000
      Received Label 0x40020
      Origin IGP, localpref 100, valid, internal, backup(protect multipath), add-path, import-candidate, imported
      Received Path ID 2, Local Path ID 5, version 5314
      Extended community: RT:100:2 
      Originator: 192.0.0.3, Cluster list: 2.0.0.1
      PSID-Type:L3, SubTLV Count:1, R:0x00,
       SubTLV:
        T:1(Sid information), Sid:fccc:cc00:9001::, F:0x00, R2:0x00, Behavior:63, R3:0x00, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
           Length [Loc-blk,Loc-node,Func,Arg]:[32,16,16,0], Tpose-len:16, Tpose-offset:48
      Source AFI: VPNv4 Unicast, Source VRF: VRF_2, Source Route Distinguisher: 100:2
  Path #3: Received by speaker 0
  Flags: 0x2000000084070005+0x00, import: 0x296
  Not advertised to any peer
  Local
    8::1 (metric 20) from 2::1 (192.0.0.2), if-handle 0x00000000
      Received Label 0x40020
      Origin IGP, localpref 150, valid, internal, multipath, backup, add-path, import-candidate, imported
      Received Path ID 3, Local Path ID 4, version 5314
      Extended community: RT:100:2 
      Originator: 192.0.0.2, Cluster list: 2.0.0.1
      PSID-Type:L3, SubTLV Count:1, R:0x00,
       SubTLV:
        T:1(Sid information), Sid:fccc:cc00:8001::, F:0x00, R2:0x00, Behavior:63, R3:0x00, SS-TLV Count:1
         SubSubTLV:
          T:1(Sid structure):
           Length [Loc-blk,Loc-node,Func,Arg]:[32,16,16,0], Tpose-len:16, Tpose-offset:48
      Source AFI: VPNv4 Unicast, Source VRF: VRF_2, Source Route Distinguisher: 100:2

Usage Guidelines and Limitations

This feature is supported on Cisco 8000 Series Routers and Line Cards with Cisco Silicon One Q200 and P100 ASICs.

This feature is not supported on Cisco 8000 Series Routers and Line Cards with Cisco Silicon One Q100 ASICs.

Configuration

Use the usid allocation wide-local-id-block command to enable the allocation and advertisement of an SRv6 Service SID with wide function (W-LIB) for L3 services.

The precedence rules for the W-LIB allocation mode are applied at different levels:

• W-LIB uSID Allocation Applied Globally under BGP:

  router bgp 1
    segment-routing srv6
      usid allocation wide-local-id-block
    !
  
  

• W-LIB uSID Allocation Applied at the IPv4/v6 Address Family under BGP:

  router bgp 1
    address-family ipv4 unicast
      segment-routing srv6
        usid allocation wide-local-id-block
     !
    address-family ipv6 unicast
      segment-routing srv6
        usid allocation wide-local-id-block
  
  

• W-LIB uSID Allocation Applied for all VPNv4/v6 Address Family:

  router bgp 1
    address-family vpnv4 unicast
      vrf all
        segment-routing srv6
          usid allocation wide-local-id-block
      !
    address-family vpnv6 unicast
      vrf all
        segment-routing srv6
          usid allocation wide-local-id-block
  
  

• W-LIB uSID Allocation Applied at the VRF IPv4/v6 Address Family:

  router bgp 1
    vrf foo
      address-family ipv4 unicast
        segment-routing srv6 
          usid allocation wide-local-id-block 
      !
      address-family ipv6 unicast
        segment-routing srv6 
          usid allocation wide-local-id-block 
  
  

Verification

The following ouput shows the W-LIB uSID allocation:

RP/0/0/CPU0:PE1# show bgp ipv4 unicast process

BGP Process Information:
BGP is operating in STANDALONE mode
Autonomous System number format: ASPLAIN
Autonomous System: 100
Router ID: 192.168.0.1
Default Cluster ID: 192.168.0.1
Active Cluster IDs:  192.168.0.1
Fast external fallover enabled
Platform Loadbalance paths max: 16
Platform RLIMIT max: 2147483648 bytes
Maximum limit for BMP buffer size: 409 MB
Default value for BMP buffer size: 307 MB
Current limit for BMP buffer size: 307 MB
Current utilization of BMP buffer limit: 0 B
Neighbor logging is enabled
Enforce first AS enabled
AS Path multipath-relax is enabled
Use SR-Policy admin/metric of color-extcomm Nexthop during path comparison: disabled
Default local preference: 100
Default keepalive: 60
Graceful restart enabled
Restart time: 120
Stale path timeout time: 360
RIB purge timeout time: 600
Non-stop routing is enabled
ExtComm Color Nexthop validation: RIB

Update delay: 120
Generic scan interval: 15
Configured Segment-routing Local Block: [0, 0]
In use Segment-routing Local Block: [15000, 15999]
Platform support mix of sr-policy and native nexthop: No
Segment Routing SRv6 Locator Name: LOC2
Segment Routing SRv6 uSID WLIB allocation: Enforced

Address family: IPv4 Unicast
Dampening is enabled
Client reflection is enabled in global config
Dynamic MED is Disabled
Dynamic MED interval : 10 minutes
Dynamic MED Timer : Running, will expire in 342 seconds
Dynamic MED Periodic Timer : Running, will expire in 42 seconds
Scan interval: 60
Total prefixes scanned: 42
Prefixes scanned per segment: 100000
Number of scan segments: 1
Nexthop resolution minimum prefix-length: 0 (not configured)
IPv6 Nexthop resolution minimum prefix-length: 0 (not configured)
Main Table Version: 44
Table version synced to RIB: 44
Table version acked by RIB: 44
IGP notification: IGPs notified
RIB has converged: version 0
RIB table prefix-limit reached ?  [No], version 0
Permanent Network Unconfigured
Segment Routing SRv6 Alloc Mode: 0
Segment Routing SRv6 uSID WLIB allocation: Enforced

RP/0/0/CPU0:PE1# show bgp vrf all ipv4 unicast process

VRF: foo
-------

BGP Process Information: VRF foo
BGP Route Distinguisher: 23:1

BGP is operating in STANDALONE mode
Autonomous System number format: ASPLAIN
Autonomous System: 100
Router ID: 192.168.0.1
Default Cluster ID: 192.168.0.1
Active Cluster IDs:  192.168.0.1
Fast external fallover enabled
Platform Loadbalance paths max: 16
Platform RLIMIT max: 2147483648 bytes
Maximum limit for BMP buffer size: 409 MB
Default value for BMP buffer size: 307 MB
Current limit for BMP buffer size: 307 MB
Current utilization of BMP buffer limit: 0 B
Neighbor logging is enabled
Enforce first AS enabled
iBGP to IGP redistribution enabled
AS Path multipath-relax is enabled
Use SR-Policy admin/metric of color-extcomm Nexthop during path comparison: disabled
Default local preference: 100
Default keepalive: 60
Graceful restart enabled
Restart time: 120
Stale path timeout time: 360
RIB purge timeout time: 600
Non-stop routing is enabled
ExtComm Color Nexthop validation: RIB

Update delay: 120
Generic scan interval: 15
Configured Segment-routing Local Block: [0, 0]
In use Segment-routing Local Block: [15000, 15999]
Platform support mix of sr-policy and native nexthop: No
Segment Routing SRv6 Locator Name: LOC2 (WLIB allocation enforced)
Segment Routing SRv6 uSID WLIB allocation: Enforced

VRF foo Address family: IPv4 Unicast
Dampening is enabled
Client reflection is not enabled in global config
Dynamic MED is Disabled
Dynamic MED interval : 10 minutes
Dynamic MED Timer : Not Running
Dynamic MED Periodic Timer : Not Running
Scan interval: 60
Total prefixes scanned: 85
Prefixes scanned per segment: 100000
Number of scan segments: 1
Nexthop resolution minimum prefix-length: 0 (not configured)
IPv6 Nexthop resolution minimum prefix-length: 0 (not configured)
Main Table Version: 152
Table version synced to RIB: 152
Table version acked by RIB: 152
IGP notification: IGPs notified
RIB has converged: version 1
RIB table prefix-limit reached ?  [No], version 0
Permanent Network Unconfigured
Segment Routing SRv6 uSID WLIB allocation: Enforced

The following output shows the advertized SRv6 W-LIB uSID for the default VRF:

RP/0/0/CPU0:PE1# show bgp ipv4 unicast 192.168.4.1/32

BGP routing table entry for 192.168.4.1/32
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                 419          419
    SRv6-VPN SID: fccc:cccc:a:fff0:4::/80
Last Modified: Apr  3 10:35:41.000 for 136y10w
Paths: (1 available, best #1)
  Advertised IPv4 Unicast paths to peers (in unique update groups):
    192::4
  Path #1: Received by speaker 0
  Advertised IPv4 Unicast paths to peers (in unique update groups):
    192::4
  Local
    0.0.0.0 from 0.0.0.0 (192.168.0.1)
      Origin incomplete, metric 0, localpref 100, weight 32768, valid, redistributed, best, group-best
      Received Path ID 0, Local Path ID 1, version 419

The following output shows the advertized SRv6 W-LIB uSID for a specific VRF (foo):

RP/0/0/CPU0:PE1# show bgp vrf foo 192.168.7.1/32 

BGP routing table entry for 192.168.7.1/32, Route Distinguisher: 23:1
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                 439          439
    SRv6-VPN SID: fccc:cccc:a:fff0:4::/80
Last Modified: Apr  3 10:31:00.000 for 00:00:44
Paths: (1 available, best #1)
  Advertised to PE peers (in unique update groups):
    192::4
  Advertised to CE peers (in unique update groups):
    10.10.10.2
  Path #1: Received by speaker 0
  Advertised to PE peers (in unique update groups):
    192::4
  Advertised to CE peers (in unique update groups):
    10.10.10.2
  Local
    0.0.0.0 from 0.0.0.0 (192.168.0.1)
      Origin incomplete, metric 0, localpref 100, weight 32768, valid, redistributed, best, group-best, import-candidate
      Received Path ID 0, Local Path ID 1, version 439
      Extended community: RT:23:23

Configuration

To configure explicit uDT46 IDs allocated from the LIB or W-LIB range, use the segment-routing srv6 static endpoint sid prefix behavior end-udt46 command.

Use the allocation-context vrf vrf-name command to associate an explicit uDT46 ID allocated from the LIB or W-LIB to a VRF. Use the forwarding keyword if VRF-Lite (the deployment of VRFs without BGP/MPLS) is enabled.

RP/0/RP0/CPU0:ios(config)# segment-routing
RP/0/RP0/CPU0:ios(config-sr)# srv6
RP/0/RP0/CPU0:ios(config-srv6)# static
RP/0/RP0/CPU0:ios(config-srv6-static)# endpoint
RP/0/RP0/CPU0:ios(config-srv6-static-endpoint)# sid fcbb:bb00:10:fe0a:: behavior end-udt46
RP/0/RP0/CPU0:ios(config-srv6-static-sid)# allocation-context vrf VRF-A
RP/0/RP0/CPU0:ios(config-srv6-static-sid)# forwarding
RP/0/RP0/CPU0:ios(config-srv6-static-sid)# exit
RP/0/RP0/CPU0:ios(config-srv6-static-endpoint)# sid fcbb:bb00:11:fff7:d:: behavior end-udt46
RP/0/RP0/CPU0:ios(config-srv6-static-sid)# allocation-context vrf VRF-D

Running Config

segment-routing
 srv6
  static
   endpoint
    sid fcbb:bb00:10:fe0a:: behavior end-udt46
     allocation-context vrf VRF-A
     forwarding
     !
    !
    sid fcbb:bb00:11:fff7:d:: behavior end-udt46
     allocation-context vrf VRF-D

Initiators and Reflectors

SBFD runs in an asymmetric behavior, using initiators and reflectors.

The following figure represents the roles of the SBFD initiator and reflector.

The initiator is an SBFD session on a network node that performs a continuity test to a remote entity by sending SBFD packets. The initiator injects the SBFD packets into the SR-TE policy. The initiator triggers the SBFD session and maintains the BFD state and client context.

The reflector is an SBFD session on a network node that listens for incoming SBFD control packets to local entities and generates response SBFD control packets. The reflector is stateless and only reflects the SBFD packets back to the initiator.

Note	Cisco 8000 series routers support reflector mode only.

Discriminators

The BFD control packet carries 32-bit discriminators (local and remote) to demultiplex BFD sessions. SBFD requires globally unique SBFD discriminators that are known by the initiator.

The SBFD Discriminator must be unique within an administrative domain. If multiple network nodes allocate the same SBFD Discriminator value, then SBFD Control packets falsely terminating on a wrong network node can result in a Reflector BFD session generating a response back because of a matching Your Discriminator value.

The SBFD control packets contain the discriminator of the initiator, which is created dynamically, and the discriminator of the reflector, which is configured as a local discriminator on the reflector.

Supported Traffic Types

• IPv6 packets.

• SRv6 packets with the local SID as the top SID.

  • If the top SID is a local uN, traffic is counted against the remote locator prefix of the next SID.

  • Traffic is not counted if the top SID is a local uA.

• SRv6 VPNv4

• SRv6 VPNv6

• SRv6 INETv4

• SRv6 INETv6

Limitations

• Supports a minimum telemetry pull interval of 30 seconds.

• Ethernet header is considered for bytes accounting.

• SRv6 traffic accounting does not count locally generated control plane packets such as ping to the remote locator.

• Packets aren’t counted if the local uA is the top SID.

• SRv6 traffic accounting is not supported with SRv6 TE policy.

• No additional MIBs are supported to retrieve SRv6 traffic statistics. We recommend to use telemetry through the newly added sensor-path in Cisco-IOS-XR-fib-common-oper to retrieve these statistics.

Configuration Example

To enable SRv6 traffic accounting:

Router#configure
Router(config)#accounting
Router(config-acct)#prefixes ipv6 mode per-prefix per-nexthop srv6-locators 
Router(config-acct)#commit 

Running Configuration

Router#show run
accounting
 prefixes 
  ipv6    
   mode per-prefix per-nexthop srv6-locators
  !       
 !        
! 

Verification

Verify the Stats ID allocated for remote locator. The following example shows the SRv6 locator ID and the stats ID allocated for the prefixes with the locator ID.

Router#show route ipv6  fccc:cc00:1:: detail 
 
Routing entry for fccc:cc00:1::/48
  Known via "isis 100", distance 115, metric 101, SRv6-locator, type level-1  <=========  locator flag
  Installed Jun  1 11:59:10.941 for 00:00:04
  Routing Descriptor Blocks
    fe80::1, from 1::1, via Bundle-Ether1201, Protected, ECMP-Backup (Local-LFA)
      Route metric is 101
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      Path id:2       Path ref count:1
      NHID: 0x2001b (Ref: 79)
      Stats-NHID: 0x2001c (Ref: 6)
      Backup path id:1
    fe80::1, from 1::1, via TenGigE0/1/0/5/2, Protected, ECMP-Backup (Local-LFA)
      Route metric is 101
      Label: None
      Tunnel ID: None
      Binding Label: None
      Extended communities count: 0
      Path id:1       Path ref count:1
      NHID: 0x2001a (Ref: 79)
      Stats-NHID: 0x2001d (Ref: 6)    <=========  Stats-NHID is allocated for prefixes with locator flag
      Backup path id:2
  Route version is 0x68 (104)
  No local label
  IP Precedence: Not Set
  QoS Group ID: Not Set
  Flow-tag: Not Set
  Fwd-class: Not Set
  Route Priority: RIB_PRIORITY_NON_RECURSIVE_LOW (8) SVD Type RIB_SVD_TYPE_LOCAL
  Download Priority 2, Download Version 39779
  No advertising protos. 

Configuring Telemetry Data

Configure the sensory path to retrieve the accounting data using telemetry:

Router#configure
Router(config)#grpc 
Router(config-grpc)#port 57400
Router(config-grpc)#no-tls
Router(config-grpc)#commit
Router(config-grpc)#exit 
Router(config)#telemetry model-driven 
Router(config-model-driven)#sensor-group s1
Router(config-model-driven-snsr-grp)#sensor-path Cisco-IOS-XR-fib-common-oper:cef-accounting/vrfs/vrf[vrf-name='default']/af$
Router(config-model-driven-snsr-grp)#exit
Router(config-model-driven)#subscription sub1
Router(config-model-driven-subs)#sensor-group-id s1 sample-interval 30000
Router(config-model-driven-subs)#commit
Router(config-model-driven-subs)#root
Router(config)#exit
Router#

Running Configuration for Configuring Telemetry Data

The following shows the show running configuration:

Router#show run
grpc
 port 57400
 no-tls
!
telemetry model-driven
 sensor-group s1
  sensor-path Cisco-IOS-XR-fib-common-oper:cef-accounting/vrfs/vrf[vrf-name='default']/afis/afi[afi-type=ipv6]/pfx/srv6locs/srv6loc
 !
 subscription sub1
  sensor-group-id s1 sample-interval 30000
 !
!

Verification for Configuring Telemetry Data

Verify the counters using the telemetry data. The following example shows the accounting data with the number of packets and the bytes transmitted through the interface.

 
{
"Cisco-IOS-XR-fib-common-oper:cef-accounting": {
  "vrfs": {
   "vrf": [
    {
     "vrf-name": "default",
     "afis": {
      "afi": [
       {
        "afi-type": "ipv6",
        "pfx": {
         "srv6locs": {
          "srv6loc": [
           {
            "ipv6-address": " fccc:cc00:1::",
            "prefix-length": 48,
            "ipv6-prefix": " fccc:cc00:1::",
            "ipv6-prefix-length": 48,
            "accounting-information": [
             {
              "number-of-tx-packets": "1500000",           <=========  Accounting data
              "number-of-tx-bytes": "378000000",          <=========  Accounting data
              "path-index": 0,
              "outgoing-interface": "Bundle-Ether1201",
              "nexthop-addr": "fe80::2/128"
             },
             {
              "number-of-tx-packets": "1000000",           <=========  Accounting data
              "number-of-tx-bytes": "252000000",          <=========  Accounting data
              "path-index": 1,
              "outgoing-interface": "TenGigE0/0/0/22",
              "nexthop-addr": "fe80::2/128"
             }
            ],
            "total-number-of-packets-switched": "2500000",
            "total-number-of-bytes-switched": "630000000"
           }
          ]
         }
        }
       }
      ]
     }
    }
   ]
  }
}
}
 

Run sh cef ipv6 accounting command to display the packets per bytes:

Router#sh cef ipv6 accounting
fccc:cc00:33::/48
Accounting: 0/0 packets/bytes output (per-prefix-per-path mode)
 via fe80::2/128, Bundle-Ether1201
  path-idx 0
  next hop fe80::2/128
  Accounting: 0/0 packets/bytes output
fccc:cc05:2::/48
Accounting: 0/0 packets/bytes output (per-prefix-per-path mode)
 via fe80::2/128, Bundle-Ether1201
  path-idx 0
  next hop fe80::2/128
  Accounting: 0/0 packets/bytes output
fccc:cc3e:2::/48
Accounting: 0/0 packets/bytes output (per-prefix-per-path mode)
 via fe80::2/128, Bundle-Ether1201
  path-idx 0
  next hop fe80::2/128
  Accounting: 0/0 packets/bytes output
fccc:cc3e:3::/48
Accounting: 0/0 packets/bytes output (per-prefix-per-path mode)
 via fe80::2/128, Bundle-Ether1201
  path-idx 0
  next hop fe80::2/128
  Accounting: 200000/58400000 packets/bytes output  <<< for prefix fccc:cc3e:3:: we can see 2lac packets count