Subject: [bess] ​Question on EVPN Default Gateway MAC Address Aliasing

From: Muthu Arul Mozhi Perumal <[email-masked]>
Date: Wed, 17 Apr 2019 11:39:23 +0530

Section 10.1 of RFC7432 describes the MAC address aliasing procedure. It
describes how a PE that acts as a default gateway advertises the default
gateway MAC address using the MAC/IP route together with the Default
Gateway EC. It says that:

   - The IP Address field of the MAC/IP route is set to the default gateway
   IP address.
   - The ESI field is set to 0.
   - MPLS label is set to a downstream assigned label.

It however does not say anything about MPLS Label2 (neither
does draft-ietf-bess-evpn-inter-subnet-forwarding). I think MPLS Label2
does not serve any purpose here since the receiver is not expected to
import the IP address into its IP-VRF as it is the default gateway
anycast IP address.

However, I think the MAC/IP route should be advertised with both the
MAC-VRF and IP-VRF RTs to enable the receiving PE to check its configured
default gateway IP address against the one received in the MAC/IP route and
log an should there be a discrepancy.

Is my understanding correct?

Does this clarification belong to RFC7432bis or
bess-evpn-inter-subnet-forwarding?

Regards,
Muthu