This topic describes the guidelines and restrictions to configure Integrated Routing and Bridging (IRB), including BVI-to-bridge-domain limits, unsupported features on the BVI, supported bridge-domain characteristics, subinterface encapsulation rules, and QoS restrictions.
BVI-to-bridge-domain relationship
Before configuring IRB, consider these restrictions:
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Only one BVI can be configured in any bridge domain.
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The same BVI can not be configured in multiple bridge domains.
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The BVI must be assigned to an IPv4 or IPv6 address that is in the same subnet as the hosts in the bridged segments.
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If the bridged network has multiple IP networks, then the BVI must be assigned secondary IP addresses for each network.
Features not supported on the BVI
The following features are not supported on the BVI:
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IP fast reroute (FRR)
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MoFRR
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Traffic mirroring
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Unnumbered interface for BVI
Supported features and protocols with IRB
The following features and protocols are supported when configuring IRB:
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Multi protocol Label Switching (MPLS) on BVI is supported.
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IRB with 802.1ah (BVI and Provider Backbone Bridge (PBB) should not be configured in the same bridge domain).
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PIM snooping. (Need to use selective flood.)
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VRF-aware DHCP relay is supported.
Supported bridge-domain characteristics for BVIs
BVIs are supported only on bridge domains with the following characteristics:
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The bridge domain supports single and double-tagged dot1q- and dot1ad-encapsulated EFPs with non-ambiguous or "exact match" EFP encapsulations. Single and double-tagged encapsulation can be specified as long as the rewrite ingress tag pop symmetric command is configured.
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All Layer 2 tags must be removed. VLAN ranges are not supported.
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Untagged EFPs are supported.
Subinterface encapsulation combinations on the same physical interface
To use the sub-interface configurations encapsulation dot1ad (or encapsulation dot1q ) and encapsulation dot1ad second-dot1q any (or encapsulation dot1q second-dot1q any ) together on the same physical interface, use the exact keyword as shown below. Else, it results in traffic loss.
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Router(config)# interface hundredGigE 0/0/0/0.0 Router(config-subif)# encapsulation dot1ad 200 exact -
Router(config)# interface hundredGigE 0/0/0/0.1 Router(config-subif)# encapsulation dot1ad 200 dot1q any Router(config-subif)# commit
QoS on BVI restriction
QoS on BVI is not supported on Cisco 8000 routers. Any QoS policy configuration on BVI will be rejected.