Bridge Domain Interface (BID)

An Ethernet flow point (EFP) service instance is a logical interface that connects a bridge domain to a physicalport or to an EtherChannel group. An incoming frame is matched against EFP matching criteria on the interface,learned on the matching EFP, and forwarded to one or more EFPs in the bridge domain. If there are no matchingEFPs, the frame is dropped. EFP is the building block for Ethernet Virtual Circuit, bridged EVC hop-by-hop,EoMPLS or VPLS. An EFP can be viewed as switch access port but more powerful as it can manipulate the framesby removing and imposing vlan tags. The following EFP matches incoming dot1q vlan 10, removes the vlan tagand forwards into bridge-domain 10. On egress direction, a frame will be imposed vlan 10 before sending out onthe wire.

The Cisco ASR 903 router does not support sub-interfaces as on the other Cisco platforms but a workaround can be used by pairing an Ethernet flow point (EFP) with a bridge domain interface (BDI).

•BDI is similar to SVI on the switch.
•At least one EFP must be associated with BDI to have line protocol up.
•EFP must make the packet native, one tag or two tags popping may be needed.
•Bridge-domain interface supports routing.
•Symmetric keyworld is required for push or pop operation.

The following shows an example how to create “sub-interface” off the interface of Gigabit Ethernet 0/2/0 on CiscoASR 903 router. The EFP will match encapsulation with vlan tag 10, pop the dot1q header in ingress direction,forward the packet into bridge-domain 10 (think BD as Vlan domain as on the switch)

https://www.cisco.com/c/en/us/td/docs/wireless/asr_900/feature/guides/evc.html
https://www.manualslib.com/manual/576793/Cisco-Asr-903.html?page=9#manual
http://networkerslog.blogspot.com/2012/12/concept-of-bridge-domain-interfaces-bdi.html

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