Contents
- QoS-MQC Support for MTR
- Finding Feature Information
- Prerequisites for QoS-MQC Support for MTR
- Restrictions for QoS-MQC Support for MTR
- Information About QoS-MQC Support for MTR
- MTR Traffic Classification
- How to Configure QoS-MQC Support for MTR
- Configuring MTR Traffic Classification
- Configuration Examples for QoS-MQC Support for MTR
- Examples: MTR Traffic Classification
- Additional References
- Feature Information for QoS-MQC Support for MTR
- Glossary
QoS-MQC Support for MTR
The QoS-MQC Support for MTR feature enables Multitopology Routing (MTR) traffic classification. Traffic classification is used to associate different classes of traffic with different topologies when multiple topologies are configured on the same device. This module describes how to configure quality of service (QoS) with modular QoS CLI (MQC) support for MTR.
- Finding Feature Information
- Prerequisites for QoS-MQC Support for MTR
- Restrictions for QoS-MQC Support for MTR
- Information About QoS-MQC Support for MTR
- How to Configure QoS-MQC Support for MTR
- Configuration Examples for QoS-MQC Support for MTR
- Additional References
- Feature Information for QoS-MQC Support for MTR
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for QoS-MQC Support for MTR
Be familiar with the concepts documented in the “MTR Traffic Classification” section.
Define a topology globally rather than at the interface level as in quality of service (QoS) before configuring traffic classification
Ensure that all devices throughout the network have the same definition of classifiers and the same sequencing of classifiers.
Carefully coordinate simultaneous configuration in a network where Multitopology Routing (MTR) and QoS traffic classification are configured.
Restrictions for QoS-MQC Support for MTR
Multitopology Routing (MTR) classification values must be unique for each topology. An error message is generated if you attempt to configure overlapping values.
A topology cannot be placed in the shutdown state if it is referenced by any active policy map.
A subset of differentiated services code point (DSCP) bits is used to encode classification values in the IP packet header. Certain DSCP values are reserved. These DSCP values are commonly used by routing software components for purposes unrelated to MTR (for example, Open Shortest Path First [OSPF], Bidirection Forwarding Detection [BFD], and Simple Network Management Protocol [SNMP]). If you use these values for MTR classification, they are likely to interfere with correct operation of the device and is strongly discouraged. These DSCP values are:
Information About QoS-MQC Support for MTR
MTR Traffic Classification
Multitopology Routing (MTR) cannot be enabled on a device until traffic classification is configured, even if only one class-specific topology is configured. Traffic classification is used to configure topology-specific forwarding behaviors when multiple topologies are configured on the same device. Traffic classification must be applied consistently throughout the network. Class-specific packets are associated with the corresponding topology table forwarding entries.
Traffic classification is configured when you use the modular quality of service (QoS) CLI (MQC). MTR traffic classification is similar to QoS traffic classification. However, there is an important distinction. MTR traffic classification is defined globally for each topology, rather than at the interface level as in QoS.
A subset of differentiated services code point (DSCP) bits is used to encode classification values in the IP packet header. You configure a class map to define the traffic class by entering the class-map class-map-name command in global configuration mode. Only the match-any keyword is supported for MTR. You associate the traffic class with a policy by configuring the policy-map type class-routing ipv4 unicast command in global configuration mode. You activate the policy for the topology by configuring the service-policy type class-routing command in global address family configuration mode. Then you associate the service policy with all interfaces on the device.
You can configure MTR traffic classification and IP Differentiated Services or IP Precedence-based traffic classification in the same network. However, MTR requires exclusive use of some subset of the DSCP bits in the IP packet header for specific topology traffic. In a network where MTR and QoS traffic classification are configured, you must carefully coordinate simultaneous configuration.
How to Configure QoS-MQC Support for MTR
Configuring MTR Traffic Classification
 Note | Following the correct order of the commands in this task is very important. Ensure that all configuration that affects traffic classification is complete before entering the service-policy type class-routing command. |
1.
enable
2.
configure terminal
3.
class-map match-any
class-map-name
4.
match [ip]
dscp
dscp-value [dscp-value
dscp-value
dscp-value
dscp-value
dscp-value
dscp-value
dscp-value]
5.
exit
6.
policy-map type class-routing ipv4 unicast
policy-map-name
7.
class {class-name |
class-default}
8.
select-topology
topology-name
9.
exit
10.
exit
11.
global-address-family ipv4 [multicast |
unicast]
12.
service-policy type class-routing
policy-map-name
13.
end
14.
show topology detail
15.
show policy-map type class-routing ipv4 unicast [interface [type number]]
16.
show mtm table
DETAILED STEPS
Configuration Examples for QoS-MQC Support for MTR
Examples: MTR Traffic Classification
The following example shows how to configure classification and activate Multitopology Routing (MTR) for two topologies:
global-address-family ipv4 topology VOICE all-interfaces exit topology VIDEO forward-base maximum routes 1000 90 exit exit class-map match-any VOICE-CLASS match ip dscp 9 exit class-map match-any VIDEO-CLASS match ip dscp af11 exit policy-map type class-routing ipv4 unicast MTR class VOICE-CLASS select-topology VOICE exit class VIDEO-CLASS select-topology VIDEO exit exit global-address-family ipv4 service-policy type class-routing MTR end
The following example shows how to display detailed information about the VOICE and VIDEO topologies:
Device# show topology detail
Topology: base
Address-family: ipv4
Associated VPN VRF is default
Topology state is UP
Associated interfaces:
Ethernet0/0, operation state: UP
Ethernet0/1, operation state: DOWN
Ethernet0/2, operation state: DOWN
Ethernet0/3, operation state: DOWN
Loopback0, operation state: UP
Topology: VIDEO
Address-family: ipv4
Associated VPN VRF is default
Topology state is UP
Topology fallback is enabled
Topology maximum route limit 1000, warning limit 90% (900)
Associated interfaces:
Topology: VOICE
Address-family: ipv4
Associated VPN VRF is default
Topology state is UP
Topology is enabled on all interfaces
Associated interfaces:
Ethernet0/0, operation state: UP
Ethernet0/1, operation state: DOWN
Ethernet0/2, operation state: DOWN
Ethernet0/3, operation state: DOWN
Loopback0, operation state: UP
Topology: base
Address-family: ipv4 multicast
Associated VPN VRF is default
Topology state is DOWN
Multicast multi-topology mode is enabled.
Route Replication Enabled:
from unicast topology VOICE all route-map BLUE
Associated interfaces:
Ethernet0/0, operation state: UP
Ethernet0/1, operation state: DOWN
Ethernet0/2, operation state: DOWN
Ethernet0/3, operation state: DOWN
Loopback0, operation state: UP
The following example shows how to display the classification values for the VOICE and VIDEO topologies:
Device# show mtm table MTM Table for VRF: default, ID:0 Topology Address Family Associated VRF Topo-ID base ipv4 default 0 VOICE ipv4 default 2051 Classifier: ClassID:3 DSCP: cs1 DSCP: 9 VIDEO ipv4 default 2054 Classifier: ClassID:4 DSCP: af11
Additional References
Related Documents
Related Topic |
Document Title |
|---|---|
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Cisco IOS commands |
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Multitopology Routing (MTR) commands |
|
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QoS commands |
|
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QoS concepts and tasks |
Quality of Service Solutions Configuration Guide Library |
Technical Assistance
Description |
Link |
|---|---|
|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for QoS-MQC Support for MTR
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
QoS-MQC Support for MTR |
12.2(33)SRB 15.0(1)S |
This feature enables Multitopology Routing (MTR) traffic classification. Traffic classification is used to associate different classes of traffic with different topologies when multiple topologies are configured on the same device. A subset of differentiated services code point (DSCP) bits is used to encode classification values in the IP packet header and mark the packet for classification. When MTR traffic classification is enabled, MTR is activated and ready for the routing protocols to start contributing to the topologies. The following commands were introduced or modified: policy-map type class-routing ipv4 unicast, select topology, service-policy type class-routing, show mtm table, show policy-map type class-routing ipv4 unicast. |
Glossary
base topology—The entire network for which the usual set of routes are calculated. This topology is the same as the default global routing table that exists without Multitopology Routing (MTR) being used.
class-specific topology—New topologies that are defined over and above the existing base topology; each class-specific topology is represented by its own Routing Information Base (RIB) and Forwarding Information Base (FIB).
classification—Selection and matching of traffic that needs to be provided with a different treatment based on its mark. Classification is a read-only operation.
DSCP—differentiated services code point. Six bits in the Type of Service (ToS) field. Two bits are used for Explicit Congestion Notification, which are used to mark the packet.
incremental forwarding mode—Incremental forwarding mode is designed to support transitional or incremental deployment of MTR, where devices are in the network that are not MTR enabled. In this mode, the device looks for a forwarding entry first in the class-specific FIB. If an entry is not found, the device then looks for the longest match in the base topology FIB. If an entry is found in the base topology FIB, the packet is forwarded on the base topology. If a forwarding entry is not found in the base topology FIB, the packet is dropped.
marking—Setting a value in the packet or frame. Marking is a read and write operation.
multitopology—Multitopology means that each topology routes and forward a subset of the traffic as defined by the classification criteria.
NLRI—Network Layer Reachability Information.
strict forwarding mode—Strict forwarding mode is the default forwarding mode for MTR. Only routes in the topology-specific routing table are considered. Among these, the longest match for the destination address is used. If no route containing the destination address can be found in the topology specific table, the packet is dropped.
TID—Topology Identifier. Each topology is configured with a unique topology ID. The topology ID is configured under the routing protocol and is used to identify and group NLRI for each topology in updates for a given protocol.