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Cisco Bridge-Group Virtual Interface(BVI)Configuration for High Availability

By admin on Oct 26, 2011 with Comments 5

Cisco Bridge-group Virtual Interface (BVI)

A BVI (Bridge Group Virtual Interface) is a routed interface that represents a set of Ethernetinterfaces that gets bridged. By using a Bridge group Virtual Interface, you can convert multipleRouter Ethernet WAN interfaces as members of a common Ethernet broadcast domain(Like L3Switch). The figure below shows a sample High Availability LAN configuration. It eliminatesthe single point of failure in cascading switches topology in which a switch failure would resultin total outage of the LAN.

This configuration allows bridging IP between two Ethernet interfaces, and routing IP from bridged interfaces using a Bridge Virtual Interface (BVI). By using Integrated Routing and Bridging (IRB) technique, a Cisco router can be turned into a L3 switch. IP addresses can beassigned on Bridge-Group Virtual Interfaces (BVIs), similar to VLAN interfaces as in L3switches. A BVI is a virtual routed interface that has all network layer attributes, eg: a network address can be assigned to it, able to perform filtering, and does not support bridging.

Bridge groups are defined by a unique number and are used for router bridging configuration. Network traffic is bridged between all interfaces that belong to the same bridge group.

Step by Step Bridge Group Virtual Interface (BVI)Configuration

Integrated Routing and Bridging configuration on Router1:

Router (config)# int fa0/0

http://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/http://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/http://www.ciscoconsole.com/author/admin/http://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/#commentshttp://www.ciscoconsole.com/wp-content/uploads/2011/10/Bridging-Fastethernet.pnghttp://www.ciscoconsole.com/author/admin/http://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/#commentshttp://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/http://www.ciscoconsole.com/lan-man/ethernet/cisco-bridge-group-virtual-interface-bvi-configuration-for-high-availability.html/

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Router (config-if)# bridge-group 1

Router (config-if)# no shut

Router(config-if)# exit

Router (config)#

Router (config-if)# int fa1/0

Router(config-if)# bridge-group 1

Router (config-if)# no shut

Router(config-if)# exit

Router(config)#

Create Bridge Group Virtual Interface (BVI) and configurethe IP and Routing credentials.

Router1(config)# bridge irb

Router (config)# int bvi1

Router(config-if)# ip add 192.168.2.1 255.255.255.0

Router(config-if)# exit

Router(config)# bridge 1 protocol ieee

Router (config)# bridge 1 route ip

Router(config)#

Note: The bridge 1 protocol ieee global configuration command removes bridge-group 1spanning-disabled interface subcommand on Fa0/0 and Fa1/0 and hence enables STP on

bridged interfaces.

Find Bridge Group Virtual Interface (BVI) show commandoutputs

Router# sh spanning-tree brief

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Bridge group 1

Spanning tree enabled protocol ieee

Root ID Priority 32768

Address cc01.01e0.0000

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32768

Address cc01.01e0.0000

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300

Interface Designated

Name Port ID Prio Cost Sts Cost Bridge ID Port ID

- -

FastEthernet0/0 128.2 128 19 FWD 0 32768 cc01.01e0.0000 128.2

FastEthernet1/0 128.3 128 19 FWD 0 32768 cc01.01e0.0000 128.3

Router#

Router# sh bridge group

Bridge Group 1 is running the IEEE compatible Spanning Tree protocol

Port 2 (FastEthernet0/0) of bridge group 1 is forwarding

Port 3 (FastEthernet1/0) of bridge group 1 is forwarding

Router#

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show interfaces [ interface ] irb

This command displays the protocols that can be routed or bridged for the specified interface, asfollows:

Router# show interface e0 irb

Ethernet0

Routed protocols on Ethernet0:

ip

Bridged protocols on Ethernet0:

ip ipx

IP protocol is routed as well as bridged.

Software MAC address filter on Ethernet0

Hash Len Address Matches Act Type

000: 0 ffff.ffff.ffff 0 RCV Physical broadcast

0x2A: 0 0900.2b01.0001 0 RCV DEC spanning tree

0x9E: 0 0000.0c3a.5092 0 RCV Interface MAC address

0x9E: 1 0000.0c3a.5092 0 RCV Bridge-group Virtual Interface

0xC0: 0 0100.0ccc.cccc 157 RCV CDP

0xC2: 0 0180.c200.0000 0 RCV IEEE spanning tree

0xC2: 1 0180.c200.0000 0 RCV IBM spanning tree

Router#