Subject: [bess] Comment on MAC Mobility Procedure in draft-ietf-bess-evpn-inter-subnet-forwarding

From: Muthu Arul Mozhi Perumal <[email-masked]>
Date: Sat, 30 Mar 2019 21:02:14 +0530

Section 4.1 of draft-ietf-bess-evpn-inter-subnet-forwarding describes the
mobility procedure when a host initiates an ARP request upon a move.

It says the following regarding the source NVE:

<snip>
   Furthermore, it sends an ARP probe locally to
   ensure that the MAC is gone.  If an ARP response is received, the
   source NVE updates its ARP entry for that <IP, MAC> and re-advertises
   an EVPN MAC/IP route for that <IP, MAC> along with MAC Mobility
   Extended Community with the sequence number incremented by one. The
   source NVE also exercises the MAC duplication detection procedure in
   section 15.1 of [RFC7432].
</snip>

Here, the source NVE is trying to verify if the TS has actually moved back.
However, initiating an ARP probe looks redundant here since the host would
anyway initiate an ARP request upon a move (which is the assumption in that
section). So, the source NVE will anyway detect that the host has moved
back if it re-learns the MAC/IP locally through the ARP request, right?

Regards,
Muthu