Hi Neeraj,

Please provide your inputs on the below queries.

Thanks
Saumya.

From: Neeraj Malhotra (nmalhotr) [mailto:nmalh...@cisco.com]
Sent: Tuesday, August 17, 2021 10:15 PM
To: Dikshit, Saumya <saumya.diks...@hpe.com>; 
draft-ietf-bess-evpn-irb-extended-mobil...@ietf.org
Cc: bess-cha...@ietf.org; bess@ietf.org
Subject: Re: Few queries on draft-ietf-bess-evpn-irb-extended-mobility


Hi Saumya,

Thanks for your comments/questions. Will respond by end of this week.

Thanks,
Neeraj

From: "Dikshit, Saumya" <saumya.diks...@hpe.com<mailto:saumya.diks...@hpe.com>>
Date: Tuesday, August 17, 2021 at 12:25 AM
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Resent-Date: Tuesday, August 17, 2021 at 12:25 AM

Hello Authors of draft-ietf-bess-evpn-irb-extended-mobility,

Please help me with below queries.

Thanks
Saumya.

From: BESS [mailto:bess-boun...@ietf.org] On Behalf Of Dikshit, Saumya
Sent: Saturday, August 14, 2021 11:30 AM
To: 
draft-ietf-bess-evpn-irb-extended-mobil...@ietf.org<mailto:draft-ietf-bess-evpn-irb-extended-mobil...@ietf.org>
Cc: bess-cha...@ietf.org<mailto:bess-cha...@ietf.org>; 
bess@ietf.org<mailto:bess@ietf.org>
Subject: [bess] Few queries on draft-ietf-bess-evpn-irb-extended-mobility

Changing the subject line and resending, Please ignore the previous email. 
Apology for mixing up things]

Hello Authors of  draft-ietf-bess-evpn-irb-extended-mobility:

I have following queries and comments about this draft 
“draft-ietf-bess-evpn-inter-subnet-forwarding”.
Please help clarify.

>>>>Section 
>>>>https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.1<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.1>

MUST be at least equal to corresponding SYNC MAC sequence number
      if one is present.
Can we formally define what a “SYNC MAC sequence number” ?

>>>>Section 
>>>>https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.3<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.3>

“MAC Mx with a sequence number that is higher than or equal to
   sequence number assigned to a LOCAL route for MAC Mx:
   o  PE MUST trigger probe and deletion procedure for all LOCAL IPs
      associated with MAC Mx.
   o  PE MUST trigger deletion procedure for LOCAL MAC route for Mx.

”
As per rfc7423, if equal sequence number is received, then the one published 
with lower vtep-ip is retained, and the other one is withdrawn.
While this section talks about probing it again.
This should be called out in the Interop section as well, for the co-existence 
of old rule and newly defined

Quoting from  
https://datatracker.ietf.org/doc/html/rfc7432#section-15<https://datatracker.ietf.org/doc/html/rfc7432#section-15>:

“If two (or more) PEs advertise the same MAC

   address with the same sequence number but different Ethernet segment

   identifiers, a PE that receives these routes selects the route

   advertised by the PE with the lowest IP address as the best route”


>>>> Section 
>>>> https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.6<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.6>

“   an inter-op scenario with a different implementation could arise,

   where a PE implementation non-compliant with this document or with

   RFC 7432<https://datatracker.ietf.org/doc/html/rfc7432> assigns and 
advertises independent sequence numbers to MAC

   and MAC+IP routes”
How do we expect this implementation to inter-op, as it may expect two 
different MAC-only and MAC-IP advertisement from remote peers as well.?
Can we paraphrase this ?


>>>> Section 
>>>> https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.8<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-8.8>

“Following a host move from PE1 to PE2, the host's MAC is

      discovered at PE2 as a local MAC via a data frames received from

      the host.”

Do we need to call out the misconfiguration case, where a probe may lead to DUP 
responses,

one from the (local learning) access side and other one across the fabric 
(overlay tunnel).


>>>> Section 
>>>> https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-10.4.1<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-10.4.1>

“unfreezing the

      route at the FROZEN location will result in the route being

      advertised with a higher sequence number.”
Why are we tying probing with “unfreezing” ? FROZEN will typically indicate 
dropping of flows. Probing can still go on in parallel ?
Can this be called out explicitly.

>>>> Section " 
>>>> https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-4.3.1<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-extended-mobility-05#section-4.3.1>"
>>>>  :
" [IP7, M1] is learnt as a new route at
   [PE3, PE4] and advertised to remote PEs with a sequence number of 0.
   As a result, L3 reachability to IP7 would be established across the
   overlay, however, MAC mobility procedure for MAC1 will not trigger as
   a result of this MAC-IP route advertisement"

If a host is moved with the same MAC, the following is still being following in 
current implementation(s):
- Either "MAC-only-route" or "MAC-IP-route" advertisement, the sequence number 
is bumped in both cases
- On receiving side,
      -  the sequence-number is picked up from "MAC-only-route" or 
"MAC-IP-route" and applied to MAC learnings
      - the bumped up sequence number leads a withdraw of "MAC-only" or 
"MAC-IP-route" from the inferior (earlier) publisher

Kindly help explain, if the text mentioned in “section 4.3.1” is creating some 
doubts regarding the way things operate with current standards.
Though I definitely believe that this literature does away with lot of existing 
ambiguities.
I think we need to paraphrase this section atleast.

Thanks
Saumya.


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