RFC 9135, "Integrated Routing and Bridging in Ethernet VPN (EVPN)", October 2021

Errata ID: 8375
Status: Verified
Type: Technical
Publication Format(s) : TEXT, PDF, HTML
Reported By: Alexander ("Sasha") Vainshtein
Date Reported: 2025-04-06
Verifier Name: Gunter Van de Velde
Date Verified: 2025-05-02

Section 6.3 says:

The ingress PE gets the destination TS's MAC address for that TS's IP 
address from its ARP table or NDP cache. It encapsulates the packet 
with that destination MAC address and a source MAC address 
corresponding to that IRB interface and sends the packet to its 
destination subnet MAC-VRF/BT.

It should say:

The ingress PE gets the destination TS's MAC address for that TS's IP 
address from its ARP table or NDP cache. It encapsulates the packet 
with that destination MAC address and a source MAC address 
corresponding to that IRB interface. 
In addition, if all following conditions for the EVPN instance in 
question are met:

- uses MPLS encapsulation
- implements VLAN-aware bundle service interface as defined in 
  Section 6.3 of RFC 7432

then the VLAN tag with the "normalized VID" of the corresponding BT 
is pushed on the customer IP packet.

The resulting packet is sent to its destination subnet MAC-VRF/BT.

Notes:

Section 6.3 of RFC 743 OPTIONALLY allows a MAC-VRF that implements VLAN-aware bundle service interface and uses MPLS encapsulation to advertise the same label for all its broadcast domains. This option is only allowed when each broadcast domain in such a MAC-VRF is represented by the same VID in all the PEs. With this option, a VLAN tag with the "normalized" VID of the specific ingress domain MUST be present when the packet crosses the underlay, and MUST be used for identification of the specific broadcast domain in the egress PE.

In the case of inter-subnet forwarding, the original VLAN tag of IP packets undergoing such forwarding does not identify the broadcast domain to which the packet would be sent.

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