Cisco IOS IBM Networking Command Reference

bridge acquire

To forward any frames for stations that the system has learned about dynamically, use the bridge acquire command in global configuration mode. To disable the behavior, use the no form of this command.

bridge bridge-group acquire

no bridge bridge-group acquire

Syntax Description

Defaults

Enabled.

Command Modes

Global configuration

Command History

Usage Guidelines

When using the command default, the Cisco IOS software forwards any frames from stations that it has learned about dynamically. If you use the no form of this command, the bridge stops forwarding frames to stations it has dynamically learned about through the discovery process and limits frame forwarding to statically configured stations. That is, the bridge filters out all frames except those whose sourced-by or destined-to addresses have been statically configured into the forwarding cache. The no form of this command prevents the forwarding of a dynamically learned address.

Examples

The following example shows how to prevent the forwarding of dynamically determined source and destination addresses:

no bridge 1 acquire

Related Commands

bridge address

To filter frames with a particular MAC-layer station source or destination address, use the bridge address in global configuration mode. To disable the filtering of frames, use the no form of this command.

bridge bridge-group address mac-address {forward | discard} [interface]

no bridge bridge-group address mac-address

Syntax Description

Defaults

Disabled.

Command Modes

Global configuration

Command History

Usage Guidelines

Any number of addresses can be configured into the system without a performance penalty.

Note MAC addresses on Ethernet are "bit-swapped" when compared with MAC addresses on Token Ring and FDDI. For example, address 0110.2222.3333 on Ethernet is 8008.4444.CCCC on Token Ring and FDDI. Access lists always use the canonical Ethernet representation. When using different media and building access lists to filter on MAC addresses, remember this point. Note that when a bridged packet traverses a serial link, it has an Ethernet-style address.

Examples

The following example shows how to enable frame filtering with MAC address 0800.cb00.45e9. The frame is forwarded through Ethernet interface 1:

bridge 1 address 0800.cb00.45e9 forward ethernet 1

The following example shows how to disable the ability to forward frames with MAC address 0800.cb00.45e9:

no bridge 1 address 0800.cb00.45e9

Related Commands

bridge bitswap-layer3-addresses

To enable transparent bridging or source-route translational bridging or IP Advanced
Research Projects Agency (ARPA) between canonical and noncanonical media types, use the
bridge bitswap-layer3-addresses command in global configuration mode. To revert to the default setting, use the no form of this command.

bridge bridge-group bitswap-layer3-addresses

no bridge bridge-group bitswap-layer3-addresses

Syntax Description

Defaults

Disabled.

Command Modes

Global configuration

Command History

Usage Guidelines

This command "bit-swaps" (to and from noncanonical format) the hardware addresses that are embedded in layer 3 of ARP and Reverse Address Resolution Protocol (RARP) frames. This function enables IP communication between Token Ring and non-Token Ring media in a transparent-bridging environment. Because transparent bridging views the source-route bridge domain as a Token Ring media, enabling this command for a transparent bridge group also enables this function for source-route translational bridging (SR/TLB).

The user must ensure the frames are small enough to be sent on all media types because there is no end to end bridging protocol to negotiate the largest frame size.

There is no attempt to reformat ARP frames between ARP and Subnetwork Access Protocol (SNAP) formats.

Examples

The following example shows how to enable bit-swapping of addresses to and from noncanonical form in a transparent-bridged environment:

no ip routing

!

interface ethernet 0

 bridge-group 1

!

interface token-ring 0

 bridge-group 1

!

!

bridge 1 protocol ieee

bridge 1 bitswap-layer3-addresses

bridge bridge

To enable the bridging of a specified protocol in a specified bridge group, use the bridge bridge command in global configuration mode. To disable the bridging of a specified protocol in a specified bridge group, use the no form of this command.

bridge bridge-group bridge protocol

no bridge bridge-group bridge protocol

Syntax Description

Defaults

Bridge every protocol.

Command Modes

Global configuration

Command History

Usage Guidelines

When integrated routing and bridging (IRB) is enabled, the default route/bridge behavior in a bridge group is to bridge all protocols. You need not use the bridge bridge command to enable bridging.

You can use the no bridge bridge command to disable bridging in a bridge group so that it does not bridge a particular protocol. When you disable bridging for a protocol in a bridge group, routable packets of this protocol are routed when the bridge is explicitly configured to route this protocol, and nonroutable packets are dropped because bridging is disabled for this protocol.

Note Packets of nonroutable protocols, such as local-area transport (LAT), are bridged only. You cannot disable bridging for the nonroutable traffic.

Examples

The following example shows how to disable bridging of IP in bridge group 1:

no bridge 1 bridge ip

Related Commands

bridge circuit-group pause

To configure the interval during which transmission is suspended in a circuit group after circuit group changes take place, use the bridge circuit-group pause command in global configuration mode.

bridge bridge-group circuit-group circuit-group pause milliseconds

Syntax Description

Defaults

The default forward delay interval is 0.

Command Modes

Global configuration

Command History

Usage Guidelines

Circuit-group changes include the addition or deletion of an interface and interface state changes.

There is not a no form for this command.

Examples

The following example shows how to set the circuit group pause to 5000 ms:

bridge 1 circuit-group 1 pause 5000

Related Commands

bridge circuit-group source-based

To use just the source MAC address for selecting the output interface, use the bridge circuit-group source-based command in global configuration mode. To remove the interface from the bridge group, use the no form of this command.

bridge bridge-group circuit-group circuit-group source-based

no bridge bridge-group circuit-group circuit-group source-based

Syntax Description

Defaults

No bridge-group interface is assigned.

Command Modes

Global configuration

Command History

Usage Guidelines

For applications that depend on the ordering of mixed unicast and multicast traffic from a given source, load distribution must be based on the source MAC address only. The bridge circuit-group source-based command modifies the load distribution strategy to accommodate such applications.

Examples

The following example uses the source MAC address for selecting the output interface to a bridge group:

bridge 1 circuit-group 1 source-based

Related Commands

bridge cmf

To enable constrained multicast flooding (CMF) for all configured bridge groups, use the bridge cmf command in global configuration mode. To disable constrained multicast flooding, use the no form of this command.

bridge cmf

no bridge cmf

Syntax Description

This command has no arguments or keywords.

Defaults

CMF is disabled.

Command Modes

Global configuration

Command History

Examples

The following example shows how to enable CMF for all configured bridge groups:

bridge cmf

Related Commands

bridge crb

To enable the Cisco IOS software to both route and bridge a given protocol on separate interfaces within a single router, use the bridge crb command in global configuration mode. To disable the feature, use the no form of this command.

bridge crb

no bridge crb

Syntax Description

This command has no arguments or keywords.

Defaults

Concurrent routing and bridging is disabled. When concurrent routing and bridging has been enabled, the default behavior is to bridge all protocols that are not explicitly routed in a bridge group.

Command Modes

Global configuration

Command History

Usage Guidelines

When concurrent routing and bridging is first enabled in the presence of existing bridge groups, it command generates a bridge route configuration command for any protocol for which any interface in the bridge group is configured for routing. This precaution applies only when concurrent routing and bridging is not already enabled, bridge groups exist, and the bridge crb command is encountered.

Once concurrent routing and bridging has been enabled, you must configure an explicit bridge route command for any protocol that is to be routed on interfaces in a bridge group (in addition to any required protocol-specific interface configuration).

Examples

The following command shows how to enable concurrent routing and bridging:

bridge crb

Related Commands

bridge domain

To establish a domain by assigning it a decimal value from 1 and 10, use the bridge domain command in global configuration mode. To return to a single bridge domain by choosing domain zero (0), use the no form of this command.

bridge bridge-group domain domain-number

no bridge bridge-group domain

Syntax Description

Defaults

Single bridge domain. The default domain number is 0.

Command Modes

Global configuration

Command History

Usage Guidelines

Cisco has implemented a proprietary extension to the IEEE spanning-tree software in order to support multiple spanning-tree domains. You can place any number of routers within the domain. The routers in the domain, and only those routers, will then share spanning-tree information.

Use this feature when multiple routers share the same cable, and you want to use only certain discrete subsets of these routers to share spanning-tree information with each other. This function is most useful when running other applications, such as IP User Datagram Protocol (UDP) flooding, that use the IEEE Spanning Tree Protocol. It can also be used to reduce the number of global reconfigurations in large bridged networks.

Caution Use multiple spanning-tree domains with care. Because bridges in different domains do not share spanning-tree information, bridge loops can be created if the domains are not carefully planned.

Note This command works only when the bridge group is running the IEEE Spanning Tree Protocol.

Examples

The following example shows how to place bridge group 1 in bridging domain 3. Only other routers that are in domain 3 will accept spanning-tree information from this router.

bridge 1 domain 3

Related Commands

bridge forward-time

To specify the forward delay interval for the Cisco IOS software, use the bridge forward-time command in global configuration mode. To return to the default interval, use the no form of this command.

bridge bridge-group forward-time seconds

no bridge bridge-group forward-time seconds

Syntax Description

Defaults

30-second delay.

Command Modes

Global configuration

Command History

Usage Guidelines

The forward delay interval is the amount of time the software spends listening for topology change information after an interface has been activated for bridging and before forwarding actually begins.

Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration.

Examples

The following example shows how to set the forward delay interval to 60 seconds:

bridge 1 forward-time 60

Related Commands

bridge hello-time

To specify the interval between hello bridge protocol data units (BPDUs), use the bridge hello-time command in global configuration mode. To return the default interval, use the no form of this command.

bridge bridge-group hello-time seconds

no bridge bridge-group hello-time

Syntax Description

Defaults

1 second.

Command Modes

Global configuration

Command History

Usage Guidelines

Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration.

Examples

The following example shows how to set the interval to 5 seconds:

bridge 1 hello-time 5

Related Commands

bridge irb

To enable the Cisco IOS software to route a given protocol between routed interfaces and bridge groups or to route a given protocol between bridge groups, use the bridge irb command in global configuration mode. To disable the feature, use the no form of this command.

bridge irb

no bridge irb

Syntax Description

This command has no arguments or keywords.

Defaults

Integrated routing and bridging (IRB) is disabled.

Command Modes

Global configuration

Command History

Usage Guidelines

IRB is supported for transparent bridging, but not for source-route bridging. IRB is supported on all interface media types except X.25 and ISDN bridged interfaces.

Examples

The following shows how to enable integrated routing and bridging:

bridge irb

Related Commands

bridge lat-service-filtering

To specify local-area transport (LAT) group-code filtering, use the bridge lat-service-filtering command in global configuration mode. To disable the use of LAT service filtering on the bridge group, use the no form of this command.

bridge bridge-group lat-service-filtering

no bridge bridge-group lat-service-filtering

Syntax Description

Defaults

LAT service filtering is disabled.

Command Modes

Global configuration

Command History

Usage Guidelines

This command informs the system that LAT service advertisements require special processing.

Examples

The following example specifies that LAT service announcements traveling across bridge group 1 require some special processing:

bridge 1 lat-service-filtering

Related Commands

bridge max-age

To change the interval the bridge will wait to hear Bridge Protocol Data Unit (BPDU)s from the root bridge, use the bridge max-age command in global configuration mode. To return to the default interval, use the no form of this command.

bridge bridge-group max-age seconds

no bridge bridge-group max-age

Syntax Description

Defaults

15 seconds.

Command Modes

Global configuration

Command History

Usage Guidelines

Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration. If a bridge does not receive BPDUs from the root bridge within this specified interval, it considers the network to be changed and will recompute the spanning-tree topology.

Examples

The following example increases the maximum idle interval to 20 seconds:

bridge 1 max-age 20

Related Commands

bridge multicast-source

To configure bridging support to allow the forwarding, but not the learning, of frames received with multicast source addresses, use the bridge multicast-source command in global configuration mode. To disable this function on the bridge, use the no form of this command.

bridge bridge-group multicast-source

no bridge bridge-group multicast-source

Syntax Description

Defaults

Disabled.

Command Modes

Global configuration

Command History

Usage Guidelines

If you need to bridge Token Ring over another medium, remote source-route bridging (RSRB) is recommended.

Examples

The following example allows the forwarding, but not the learning, of frames received with multicast source addresses:

bridge 2 multicast-source

Related Commands

bridge priority

To configure the priority of an individual bridge, or the likelihood that it will be selected as the root bridge, use the bridge priority command in global configuration mode.

bridge bridge-group priority number

Syntax Description

Defaults

When the IEEE Spanning Tree Protocol is enabled on the router: 32768
When the Digital Spanning Tree Protocol is enabled on the router: 128

Command Modes

Global configuration

Command History

Usage Guidelines

When two bridges tie for position as the root bridge, an interface priority determines which bridge will serve as the root bridge. Use the bridge-group priority command in interface configuration mode to control an interface priority.

There is not a no form for this command.

Examples

The following example establishes this bridge as a likely candidate to be the root bridge:

bridge 1 priority 100

Related Commands

bridge protocol

To define the type of Spanning Tree Protocol, use the bridge protocol command in global configuration mode. To delete the bridge group, use the no form of this command with the appropriate keywords and arguments.

bridge bridge-group protocol {dec | ibm | ieee | vlan-bridge}

no bridge bridge-group protocol {dec | ibm | ieee | vlan-bridge}

Syntax Description

Defaults

No Spanning Tree Protocol is defined.

Command Modes

Global configuration

Command History

Usage Guidelines

The routers support two Spanning Tree Protocols: the IEEE 802.1 standard and the earlier Digital Spanning Tree Protocol upon which the IEEE standard is based. Multiple domains are supported for the IEEE 802.1 Spanning Tree Protocol.

Note The IEEE 802.1D Spanning Tree Protocol is the preferred way of running the bridge. Use the Digital Spanning Tree Protocol only for backward compatibility.

Examples

The following example shows bridge 1 as using the Digital Spanning Tree Protocol:

bridge 1 protocol dec

Related Commands

bridge protocol ibm

To create a bridge group that runs the automatic spanning-tree function, use the bridge protocol ibm command in global configuration mode. To cancel the previous assignment, use the no form of this command.

bridge bridge-group protocol ibm

no bridge bridge-group protocol ibm

Syntax Description

Defaults

No bridge group is defined.

Command Modes

Global configuration

Command History

Examples

The following example specifies bridge 1 to use the automatic spanning-tree function:

bridge 1 protocol ibm

Related Commands

bridge route

To enable the routing of a specified protocol in a specified bridge group, use the bridge route command in global configuration mode. To disable the routing of a specified protocol in a specified bridge group, use the no form of this command.

bridge bridge-group route protocol

no bridge bridge-group route protocol

Syntax Description

Defaults

No default bridge group or protocol is specified.

Command Modes

Global configuration

Command History

Examples

In the following example, AppleTalk and IP are routed on bridge group 1:

bridge crb

bridge 1 protocol ieee

bridge 1 route appletalk

bridge 1 route ip

Related Commands

bridge subscriber-policy

To bind a bridge group with a subscriber policy, use the bridge subscriber-policy command in global configuration mode. To disable the subscriber bridge group feature, use the no form of this command.

bridge bridge-group subscriber-policy policy

no bridge bridge-group subscriber-policy policy

Syntax Description

Defaults

Table 5 shows the default values that are applied if no forward or filter decisions have been specified for the subscriber policy:

Command Modes

Global configuration

Command History

Usage Guidelines

Standard access lists can coexist with the subscriber policy. However, subscriber policy will take precedence over the access list by being checked first. A packet permitted by the subscriber policy will be checked against the access list if it is specified. A packet denied by subscriber policy will be dropped with no further access list checking.

Examples

The following example forms a subscriber bridge group using policy 1:

bridge 1 subscriber-policy 1

Related Commands

bridge-group

To assign each network interface to a bridge group, use the bridge-group command in interface configuration mode. To remove the interface from the bridge group, use the no form of this command.

bridge-group bridge-group

no bridge-group bridge-group

Syntax Description

Defaults

No bridge group interface is assigned.

Command Modes

Interface configuration

Command History

Usage Guidelines

You can bridge on any interface, including any serial interface, regardless of encapsulation. Bridging can be configured between interfaces on different cards, although the performance is lower compared with interfaces on the same card. Also note that serial interfaces must be running with high-level data link control (HLDC), X.25, or Frame Relay encapsulation.

Note Several modifications to interfaces in bridge groups, including adding interfaces to bridge groups, will result in any Token Ring or FDDI interfaces in that bridge group being re initialized.

Examples

In the following example, Ethernet interface 0 is assigned to bridge group 1, and bridging is enabled on this interface:

interface ethernet 0

 bridge-group 1 

Related Commands

bridge-group aging-time

To set the length of time that a dynamic entry can remain in the bridge table from the time the entry was created or last updated, use the bridge-group aging-time command in global configuration mode. To return to the default aging-time interval, use the no form of this command.

bridge-group bridge-group aging-time seconds

no bridge-group bridge-group aging-time

Syntax Description

Defaults

300 seconds.

Command Modes

Global configuration

Command History

Usage Guidelines

If hosts on a bridged network are likely to move, decrease the aging time to enable the bridge to adapt quickly to the change. If hosts do not send continuously, increase the aging time to record the dynamic entries for a longer time and thus reduce the possibility of flooding when the hosts send again.

Examples

The following example sets the aging time to 200 seconds:

bridge-group 1 aging-time 200

Related Commands

bridge-group cbus-bridging

To enable autonomous bridging on a ciscoBus2 controller, use the bridge-group cbus-bridging command in interface configuration mode. To disable autonomous bridging, use the no form of this command.

bridge-group bridge-group cbus-bridging

no bridge-group bridge-group cbus-bridging

Syntax Description

Defaults

Autonomous bridging is disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Normally, bridging takes place on the processor card at interrupt level. When autonomous bridging is enabled, bridging takes place entirely on the ciscoBus2 controller, substantially improving performance.

You can enable autonomous bridging on Ethernet, FDDI (FCIT) and High-Speed Serial Interface (HSSI) interfaces that reside on a ciscoBus2 controller. Autonomous bridging is not supported on Token Ring interfaces, regardless of the type of bus in use.

To enable autonomous bridging on an interface, first define that interface as part of a bridge group. When a bridge group includes both autonomously and normally bridged interfaces, packets are autonomously bridged in some cases, but bridged normally in others. For example, when packets are forwarded between two autonomously bridged interfaces, those packets are autonomously bridged. But when packets are forwarded between an autonomously bridged interface and one that is not, the packet must be normally bridged. When a packet is flooded, the packet is autonomously bridged on autonomously bridged interfaces, but must be normally bridged on any others.

Note In order to maximize performance when using a ciscoBus2 controller, use the bridge-group cbus-bridging command to enable autonomous bridging on any Ethernet, FDDI, or HSSI interface.

Note You can filter by MAC-level address on an interface only when autonomous bridging is enabled on that interface; autonomous bridging disables all other filtering and priority queueing.

Examples

In the following example, autonomous bridging is enabled on Ethernet interface 0:

interface ethernet 0

 bridge-group 1

 bridge-group 1 cbus-bridging

Related Commands

bridge-group circuit-group

To assign each network interface to a bridge group, use the bridge-group circuit-group command in interface configuration mode. To remove the interface from the bridge group, use the no form of this command.

bridge-group bridge-group circuit-group circuit-group

no bridge-group bridge-group circuit-group circuit-group

Syntax Description

Defaults

No bridge group interface is assigned.

Command Modes

Interface configuration

Command History

Usage Guidelines

Circuit groups are primarily intended for use with High-Speed Serial Interface (HSSI)-encapsulated serial interfaces. They are not supported for packet-switched networks such as X.25 or Frame Relay. Circuit groups are best applied to groups of serial lines of equal bandwidth, but can accommodate mixed bandwidths.

Note You must configure bridging before you configure a circuit group on an interface.

Examples

In the following example, Ethernet interface 0 is assigned to circuit group 1 of bridge group 1:

interface ethernet 0

 bridge-group 1 circuit-group 1

Related Commands

bridge-group input-address-list

To assign an access list to a particular interface, use the bridge-group input-address-list command in interface configuration mode. This access list is used to filter packets received on that interface based on their MAC source addresses. To remove an access list from an interface, use the no form of this command.

bridge-group bridge-group input-address-list access-list-number

no bridge-group bridge-group input-address-list access-list-number

Syntax Description

Defaults

No access list is assigned.

Command Modes

Interface configuration

Command History

Examples

The following example assumes you want to disallow the bridging of Ethernet packets of all Sun workstations on Ethernet interface 1. Software assumes that all such hosts have Ethernet addresses with the vendor code 0800.2000.0000. The first line of the access list denies access to all Sun workstations, and the second line permits everything else. You then assign the access list to the input side of Ethernet interface 1.

access-list 700 deny 0800.2000.0000 0000.00FF.FFFF

access-list 700 permit 0000.0000.0000 FFFF.FFFF.FFFF

!

interface ethernet 1

 bridge-group 1 input-address-list 700

Related Commands

bridge-group input-lat-service-deny

To specify the group codes by which to deny access upon input, use the bridge-group input-lat-service-deny command in interface configuration mode. To remove this access condition, use the no form of this command.

bridge-group bridge-group input-lat-service-deny group-list

no bridge-group bridge-group input-lat-service-deny group-list

Syntax Description

Defaults

No group codes are specified.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

This command prevents the system from bridging any LAT service advertisement that has any of the specified groups set.

Examples

The following example causes any advertisements with groups 6, 8, and 14 through 20 to be dropped:

interface ethernet 0

 bridge-group 1 input-lat-service-deny 6 8 14-20

Related Commands

bridge-group input-lat-service-permit

To specify the group codes by which to permit access upon input, use the bridge-group input-lat-service-permit command in interface configuration mode. To remove this access condition, use the no form of this command.

bridge-group bridge-group input-lat-service-permit group-list

no bridge-group bridge-group input-lat-service-permit group-list

Syntax Description

Defaults

No group codes are specified.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

This command causes the system to bridge only those service advertisements that match at least one group in the group list specified by the group-list argument.

If a message specifies group codes in both the deny and permit list, the message is not bridged.

Examples

The following example bridges any advertisements from groups 1, 5, and 12 through 14:

interface ethernet 1

 bridge-group 1 input-lat-service-permit 1 5 12-14

Related Commands

bridge-group input-lsap-list

To filter IEEE 802.2-encapsulated packets on input, use the bridge-group input-lsap-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group input-lsap-list access-list-number

no bridge-group bridge-group input-lsap-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

This access list is applied to all IEEE 802.2 frames received on that interface prior to the bridge-learning process. Subnetwork Access Protocol (SNAP) frames must also pass any applicable Ethernet type-code access list.

Examples

The following example specifies access list 203 on Ethernet interface 1:

interface ethernet 1

 bridge-group 3 input-lsap-list 203

Related Commands

bridge-group input-pattern-list

To associate an extended access list with a particular interface in a particular bridge group, use the bridge-group input-pattern-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group input-pattern-list access-list-number

no bridge-group bridge-group input-pattern-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

Examples

The following command applies access list 1101 to bridge group 3 using the filter defined in group 1:

interface ethernet 0

bridge-group 3 input-pattern-list 1101

Related Commands

bridge-group input-type-list

To filter Ethernet- and Subnetwork Access Protocol (SNAP)-encapsulated packets on input, use the bridge-group input-type-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group input-type-list access-list-number

no bridge-group bridge-group input-type-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

For SNAP-encapsulated frames, the access list is applied against the 2-byte Type field given after the destination service access point (DSAP)/source service access point (SSAP)/Organizationally Unique Identifier (OUI) fields in the frame.

This access list is applied to all Ethernet and SNAP frames received on that interface prior to the bridge learning process. SNAP frames must also pass any applicable IEEE 802 DSAP/SSAP access lists.

Examples

The following example shows how to configure a Token Ring interface with an access list that allows only the local-area transport (LAT) protocol to be bridged:

interface tokenring 0

 ip address 131.108.1.1 255.255.255.0

 bridge-group 1

 bridge-group 1 input-type-list 201

Related Commands

bridge-group lat-compression

To reduce the amount of bandwidth that local-area transport (LAT) traffic consumes on the serial interface by specifying a LAT-specific form of compression, use the bridge-group lat-compression command in interface configuration mode. To disable LAT compression on the bridge group, use the no form of this command.

bridge-group bridge-group lat-compression

no bridge-group bridge-group lat-compression

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

Compression is applied to LAT frames being sent out the router through the interface in question.

LAT compression can be specified only for serial interfaces. For the most common LAT operations (user keystrokes and acknowledgment packets), LAT compression reduces LAT's bandwidth requirements by nearly a factor of two.

Examples

The following example compresses LAT frames on the bridge assigned to group 1:

bridge-group 1 lat-compression

Related Commands

bridge-group output-address-list

To assign an access list to a particular interface for filtering the MAC destination addresses of packets that would ordinarily be forwarded out that interface, use the bridge-group output-address-list command in interface configuration mode. To remove an access list from an interface, use the no form of this command.

bridge-group bridge-group output-address-list access-list-number

no bridge-group bridge-group output-address-list access-list-number

Syntax Description

Defaults

No access list is assigned.

Command Modes

Interface configuration

Command History

Examples

The following example assigns access list 703 to Ethernet interface 3:

interface ethernet 3

 bridge-group 5 output-address-list 703

Related Commands

bridge-group output-lat-service-deny

To specify the group codes by which to deny access upon output, use the bridge-group output-lat-service-deny command in interface configuration mode. To cancel the specified group codes, use the no form of this command.

bridge-group bridge-group output-lat-service-deny group-list

no bridge-group bridge-group output-lat-service-deny group-list

Syntax Description

Defaults

No group codes are assigned.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

This command causes the system to not bridge onto this output interface any service advertisements that contain groups matching any of those in the group list.

Examples

The following example prevents bridging of LAT service announcements from groups 12 through 20:

interface ethernet 0

 bridge-group 1

 bridge-group 1 output-lat-service-deny 12-20

Related Commands

bridge-group output-lat-service-permit

To specify the group codes by which to permit access upon output, use the bridge-group output-lat-service-permit command in interface configuration mode. To cancel specified group codes, use the no form of this command.

bridge-group bridge-group output-lat-service-permit group-list

no bridge-group bridge-group output-lat-service-permit group-list

Syntax Description

Defaults

No group codes are specified.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

This command causes the system to bridge onto this output interface only those service advertisements that match at least one group in the specified group code list.

Note If a message matches both a deny and a permit condition, it will not be bridged.

Examples

The following example allows only LAT service announcements from groups 5, 12, and 20 on this bridge:

interface ethernet 0

 bridge-group 1 output-lat-service-permit 5 12 20

Related Commands

bridge-group output-lsap-list

To filter IEEE 802-encapsulated packets on output, use the bridge-group output-lsap-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group output-lsap-list access-list-number

no bridge-group bridge-group output-lsap-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

Subnetwork Access Protocol (SNAP) frames must also pass any applicable Ethernet type-code access list. This access list is applied just before sending out a frame to an interface.

For performance reasons, specify both input and output type code filtering on the same interface.

Access lists for Ethernet- and IEEE 802-encapsulated packets affect only bridging functions. Such access lists cannot be used to block frames with protocols that are being routed.

Packets bearing an 802.2 LSAP of 0xAAAA qualify for LSAP filtering because they are inherently in 802.3 format. However, because they also carry a Type field, they are matched against any Type filters. Therefore, if you use Link Service Access Point (LSAP) filters on an interface that may bear SNAP-encapsulated packets, you must explicitly permit 0xAAAA.

Examples

The following example specifies access list 204 on Ethernet interface 0:

interface ethernet 0

 bridge-group 4 output-lsap-list 204

Related Commands

bridge-group output-pattern-list

To associate an extended access list with a particular interface, use the bridge-group output-pattern-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group output-pattern-list access-list-number

no bridge-group bridge-group output-pattern-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

Examples

The following example filters all packets sent by bridge group 3 using the filter defined in access list 1102:

interface ethernet 0

 bridge-group 3 output-pattern-list 1102

Related Commands

bridge-group output-type-list

To filter Ethernet- and Subnetwork Access Protocol (SNAP)-encapsulated packets on output, use the bridge-group output-type-list command in interface configuration mode. To disable this capability, use the no form of this command.

bridge-group bridge-group output-type-list access-list-number

no bridge-group bridge-group output-type-list access-list-number

Syntax Description

Defaults

Disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

Autonomous bridging must be disabled to use this command.

Examples

The following example specifies access list 202 on Ethernet interface 0:

interface ethernet 0

 bridge-group 2 output-type-list 202

Related Commands

bridge-group path-cost

To set a different path cost, use the bridge-group path-cost command in interface configuration mode. To choose the default path cost for the interface, use the no form of this command.

bridge-group bridge-group path-cost cost

no bridge-group bridge-group path-cost cost

Syntax Description

Defaults

The default path cost is computed from the interface's bandwidth setting. The following are IEEE default path cost values. The Digital path cost default values are different.

•Ethernet—100

•16-Mb Token Ring—62

•FDDI—10

•HSSI—647

•MCI/SCI Serial—647

Command Modes

Interface configuration

Command History

Usage Guidelines

By convention, the path cost is 10000/data rate of the attached LAN (IEEE), or 100000/data rate of the attached LAN (Digital), in megabits per second.

Examples

The following example changes the default path cost for Ethernet interface 0:

interface ethernet 0

 bridge-group 1 path-cost 250

Related Commands

bridge-group priority

To set an interface priority, use the bridge-group priority command in interface configuration mode. The interface priority is used to select the designated port for this bridge-group on the connected media. One designated port on each medium is needed to compute the spanning tree.

bridge-group bridge-group priority number

Syntax Description

Defaults

When the IEEE Spanning Tree Protocol is enabled on the router: 32768
When the Digital Spanning Tree Protocol is enabled on the router: 128

Command Modes

Interface configuration

Command History

Usage Guidelines

The lower the number, the more likely it is that the bridge on the interface will be chosen as the root.

There is not a no form for this command.

Examples

The following example increases the likelihood that the root bridge will be the one on Ethernet interface 0 in bridge group 1:

interface ethernet 0

 bridge-group 1 priority 0

The following example shows the bridge-group priority help information for 9-bit port number size:

Router(config-if)# bridge-group 1 priority ?

<0-255> increments of 2 for IEEE or vlan-bridge, others 1

The following example shows the bridge-group priority help information for 10-bit port number size:

Router(config-if)# bridge-group 1 priority ?

<0-255> increments of 4 for IEEE or vlan-bridge, others 1

Related Commands

bridge-group spanning-disabled

To disable the spanning tree on a given interface, use the bridge-group spanning-disabled command in interface configuration mode. To enable the spanning tree on a given interface, use the no form of this command.

bridge-group bridge-group spanning-disabled

no bridge-group bridge-group spanning-disabled

Syntax Description

Defaults

Spanning tree is enabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

To enable transparent bridging on an interface, use the bridge protocol command to specify the type of Spanning Tree Protocol to be used. The bridge-group spanning-disabled command can be used to disable that spanning tree on that interface.

When a loop-free path exists between any two bridged subnetworks, you can prevent Bridge Protocol Data Unit (BPDU)s generated in one transparent bridging subnetwork from impacting nodes in the other transparent bridging subnetwork, yet still permit bridging throughout the bridged network as a whole.

For example, when transparently bridged LAN subnetworks are separated by a WAN, you can use this command to prevent BPDUs from traveling across the WAN link. You would apply this command to the serial interfaces connecting to the WAN in order to prevent BPDUs generated in one domain from impacting nodes in the remote domain. Because these BPDUs are prevented from traveling across the WAN link, using this command also has the secondary advantage of reducing traffic across the WAN link.

Note In order to disable the spanning tree, you must make sure that no parallel paths exist between transparently bridged interfaces in the network.

Examples

In the following example, the spanning tree for the serial interface 0 is disabled:

interface serial 0

 bridge-group 1 spanning-disabled

Related Commands

bridge-group sse

To enable the Cisco silicon switching engine (SSE) switching function, use the bridge-group sse command in interface configuration mode. To disable SSE switching, use the no form of this command.

bridge-group bridge-group sse

no bridge-group bridge-group sse

Syntax Description

Defaults

Disabled

Command Modes

Interface configuration

Command History

Examples

The following shows how to enable SSE switching:

bridge-group 1 sse

Related Commands

bridge-group subscriber-loop-control

To enable loop control on virtual circuits associated with a bridge group, use the bridge-group subscriber-loop-control command in interface configuration mode. To disable loop control, use the no form of this command.

bridge-group bridge-group subscriber-loop-control

no bridge-group bridge-group subscriber-loop-control

Syntax Description

Defaults

Loop control is disabled.

Command Modes

Interface configuration

Command History

Examples

The following shows how to enable loop control on virtual circuits associated with bridge group 1:

bridge-group 1 subscriber-loop-control

Related Commands

bridge-group subscriber-trunk

To specify that an interface is at the upstream point of traffic flow, use the bridge-group subscriber-trunk command in interface configuration mode. To remove the specification and reset the interface to a non trunking port, use the no form of this command.

bridge-group bridge-group subscriber-trunk

no bridge-group bridge-group subscriber-trunk

Syntax Description

Defaults

The interface is set to a non-trunking port.

Command Modes

Interface configuration

Command History

Examples

The following example sets bridge group 1 as the upstream point of traffic flow:

bridge-group 1 subscriber-trunk

Related Commands

bsc char-set

To specify the character set used by the Bisync support feature in this serial interface as either EBCDIC or ASCII, use the bsc char-set command in interface configuration mode. To cancel the character set specification, use the no form of this command.

bsc char-set {ascii | ebcdic}

no bsc char-set {ascii | ebcdic}

Syntax Description

Defaults

EBCDIC

Command Modes

Interface configuration

Command History

Examples

The following command specifies that the ASCII character set will be used:

bsc char-set ascii

bsc contention

To specify an address on a contention interface, use the bsc contention command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc contention address

no bsc contention

Syntax Description

Defaults

The default address is 0x01 to accommodate backward compatibility to the previous point-to-point contention implementation.

Command Modes

Interface configuration

Command History

Examples

The following command specifies address 20 on the remote device:

bsc contention 20

Related Commands

bsc dial-contention

To specify a router at the central site as a central router with dynamic allocation of serial interfaces, use the bsc dial-contention command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc dial-contention timeout

no bsc dial-contention

Syntax Description

Defaults

5 seconds

Command Modes

Interface configuration

Command History

Usage Guidelines

A timeout value is configurable to ensure that an interface does not get locked out because of a device outage during sending of data.

Examples

The following command defines a dial-in interface at the central site with an idle timeout of 10 seconds:

bsc dial-contention 10

Related Commands

bsc host-timeout

To detect deactivation of devices at the host, use the bsc host-timeout command in interface configuration mode. To cancel the configuration, use the no form of this command.

bsc host-timeout interval

no host-timeout interval

Syntax Description

Defaults

The default interval is 600 deciseconds (60 seconds).

Command Modes

Interface configuration

Command History

Usage Guidelines

This command is used to detect deactivation of devices at the host. If the host is told to deactivate or not poll a device, time will be required for the signal to propagate the network and get the remote end from polling. The timeout can be used to fine-tune the delay in detecting the host outage. The remote peer will stop polling the control unit that has timed out in the interval one to two times the configured timeout value.

Examples

The following example shows how to configure a timeout of 500 deciseconds:

bsc host-timeout 500

Related Commands

bsc pause

To specify the interval, to the tenth of a second, between starts of the polling cycle, use the bsc pause command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc pause time 

no bsc pause time

Syntax Description

Defaults

30 tenths of a second (3 seconds)

Command Modes

Interface configuration

Command History

Examples

The following command sets the interval to 20 tenths of a second (2 seconds):

bsc pause 20

bsc poll-timeout

To specify the timeout, in tenths of a second, for a poll or select sequence, use the bsc poll-timeout command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc poll-timeout time 

no bsc poll-timeout time

Syntax Description

Defaults

30 tenths of a second (3 seconds).

Command Modes

Interface configuration

Command History

Examples

The following command sets the interval to 20 tenths of a second (2 seconds):

bsc poll-timeout 20

bsc primary

To specify that the router is acting as the primary end of the Bisync link connected to the serial interface, and that the attached remote devices are Bisync tributary stations, use the bsc primary command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc primary

no bsc primary

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values.

Command Modes

Interface configuration

Command History

Usage Guidelines

The Bisync support feature in the serial interface uses the address of the incoming encapsulation for reply.

Examples

The following example specifies the router as the primary role:

bsc primary

Related Commands

bsc retries

To specify the number of retries performed before a device is considered to have failed, use the bsc retries command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc retries retries 

no bsc retries retries

Syntax Description

Defaults

Five retries.

Command Modes

Interface configuration

Command History

Examples

The following command sets the retry count to 10:

bsc retries 10

bsc secondary

To specify that the router is acting as the secondary end of the Bisync link connected to the serial interface, and the attached remote device is a Bisync control station, use the bsc secondary command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc secondary

no bsc secondary

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values.

Command Modes

Interface configuration

Command History

Usage Guidelines

The Bisync support feature in this serial interface uses the address of the poll or selection block in the framing encapsulation. It also generates an end of transmission (EOT) frame preceding each Bisync poll and selection.

Examples

The following example specifies the router as the secondary role:

bsc secondary

Related Commands

bsc servlim

To specify the number of cycles of the active poll list that are performed between polls to control units in the inactive poll list, use the bsc servlim command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc servlim servlim-count

no bsc servlim servlim-count

Syntax Description

Defaults

Three cycles.

Command Modes

Interface configuration

Command History

Examples

The following command sets the number of cycles to 2:

bsc servlim 2

bsc spec-poll

To set specific polls, rather than general polls, used on the host-to-router connection, use the bsc spec-poll command in interface configuration mode. To cancel the specification, use the no form of this command.

bsc spec-poll

no spec-poll

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values.

Command Modes

Interface configuration

Command History

Usage Guidelines

Use the bsc spec-poll command when a router is connected to a host, and only when that host issues specific polls rather than general polls. Tandem hosts that poll ATM cash machines are typically configured to use specific polls rather than general polls.

Configuring a downstream (control-unit/device connected) router to support specific polling has no effect.

Examples

The following commands configure serial interface 0 to use specific poll:

interface serial 0

 description Connection to host.

 encapsulation bstun

 bstun group 1

 bsc secondary

 bsc spec-poll

 bsc char-set ebcdic

 bstun route all tcp 10.10.14.122

bstun group

To specify the block serial tunnel (BSTUN) group to which the interface belongs, use the bstun group command in interface configuration mode. To remove the interface from the BSTUN group, use the no form of this command.

bstun group group-number 

no bstun group group-number

Syntax Description

Defaults

No default behavior or values.

Command Modes

Interface configuration

Command History

Usage Guidelines

Each BSTUN-enabled interface must be placed in a BSTUN group that was previously defined by the bstun protocol-group command. Packets travel only between BSTUN-enabled interfaces that are in the same group.

Examples

The following example specifies that serial interface 1 belongs to the previously defined protocol group 1:

interface serial 1

 encapsulation bstun

 bstun group 1

Related Commands

bstun keepalive-count

To define the number of times to attempt a peer connection before declaring the peer connection to be down, use the bstun keepalive-count command in global configuration mode. To cancel the definition, use the no form of this command.

bstun keepalive-count count 

no bstun keepalive-count

Syntax Description

Defaults

No default behavior or values

Command Modes

Global configuration

Command History

Usage Guidelines

The following example sets the number of times to retry a connection to a peer to 4:

bstun keepalive-count 4

Related Commands

bstun lisnsap

To configure a service access point (SAP) on which to listen for incoming calls, use the bstun lisnsap command in global configuration mode. To cancel the SAP on which to listen, use the no form of this command.

bstun lisnsap sap-value

no bstun lisnsap

Syntax Description

Defaults

The default SAP value is 04.

Command Modes

Global configuration

Command History

Usage Guidelines

Changes to the bstun lisnsap command configuration will not take effect until after the router has been reloaded.

Examples

The following example shows how to configure SAP for listening:

bstun lisnsap

Related Commands

bstun peer-map-poll

To map the state of the peer to polling, use the bstun peer-map-poll command in global configuration mode. To disable mapping of the peer state to polling and map to the received status messages, use the no form of this command.

bstun peer-map-poll

no bstun peer-map-poll

Syntax Description