Subject: Re: Question regarding MAC Withdrawal in H-VPLS Dual-homed MTU-s

From: [email-masked]
Date: Wed, 4 Oct 2006 09:51:16 -0400

I would think (A), since MAC Withdraw is used by a member of the VPLS mesh
to notify its neighbors of a change in topology -- except that the MW
should be sent only after switching over to the standby VC. The PE-rs
should be just as aware of the switchover as the MTU-s.

The larger ambiguity here (in my opinion) is the lack of specification
around just how H-VPLS dual homing works, i.e, how the failure is detected
and what the time limits are for that detection and subsequent recovery.
That part is currently implementation-dependent.

Regards,
Anil

                    "Asaf Henig"                                                                                   
                    <[email-masked]       To:     <[email-masked]>, <[email-masked]>, <[email-masked]>          
                    m>                   cc:                                                                       
                                         Subject:     Question regarding MAC Withdrawal in H-VPLS Dual-homed MTU-s 
                    09/26/2006                                                                                     
                    04:11 AM                                                                                       

It is yet unclear from draft
http://www.ietf.org/internet-drafts/draft-ietf-l2vpn-vpls-ldp-09.txt who is
responsible to send the MAC Withdrawal message to the secondary PE-rs when
fail-over occures in an H-VPLS dual homed MTU-s scenario.

It is known that when a primary VC fails in a dual-homing scenario the
PE-rs connected to the secondary VC should relearn the MAC addresses behind
the MTU-s. In order to make this process faster this "secondary" PE-rs
should flush the relevant previously learned MAC addresses. For that to
happen we have two options:

A) The primary PE-rs would send the MAC Withdrawal message to the secondary
PE-rs (and all other PE-s) the minute it recognizes that its VC has failed.
B) The MTU-s itself would send the MAC Withdrawal to the secondary PE-rs
the minute it switches from primary to secondary VC. The secondary PE-rs
would be responsible to propegate this message to all other PEs in the VPLS
domain (this option is recommended by
draft-pdutta-l2vpn-vpls-ldp-mac-opt-00.txt).

Which option is preferred  ?

Thanks for any help.
Asaf Henig
MRV communications

---

From: "Max Ng" <[email-masked]>
Date: Wed, 4 Oct 2006 22:46:29 +0800

All,

I do agree that the current draft should address this to avoid ambiguity
especially for implementation between vendors.

On another note, the mechanism used to do dual-homing is also not specified
and is currently left to individual vendor implementation. Again, what I see
is vendor equipment interop issue. I'm not sure if it is the jurisdiction of
IETF to state implementation mechanism or leaving it to vendor innovation,
but it does certainly lead to interop issues.

With the draft being progressed to the current state of "proposed standard",
is it too late to address both issue? Perhaps someone familiar with the
process can comment.

Regards,
Max

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Wednesday, October 04, 2006 9:51 PM
To: Asaf Henig
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: Question regarding MAC Withdrawal in H-VPLS Dual-homed MTU-s

Regards,
Anil

                    "Asaf Henig"
                    <[email-masked]       To:     <[email-masked]>,
<[email-masked]>, <[email-masked]>
                    m>                   cc:
                                         Subject:     Question regarding MAC
Withdrawal in H-VPLS Dual-homed MTU-s
                    09/26/2006
                    04:11 AM

Thanks for any help.
Asaf Henig
MRV communications

---

From: "Marc Lasserre" <[email-masked]>
Date: Wed, 4 Oct 2006 18:25:52 +0200

Thanks to both Ali and Pranjal for clarifying how and when MAC withdrawal 
messages should be generated.
I will check with the RFC editor if the draft can be updated on this topic.

As far as dual homing is concerned, it is covered in section 10.2 of the 
draft. What is not specified is which failure detection mechanism to use 
since it depends on the underlying technology and/or protocols being used.
An example of LDP adjacency status is given, but a variety of other 
mechanisms can be used (e.g. STP, BFD, 802.1ag, etc) and hence are left out 
of scope.

Cheers,
Marc

---

From: "Marc Lasserre" <[email-masked]>
Date: Wed, 4 Oct 2006 18:30:06 +0200

It is option B as already mentioned by Ali and Pranjal.
See my answer in my previous email regarding dual homing & failure 
detection.

Cheers,

Marc
----- Original Message ----- 
From: <[email-masked]>
To: "Asaf Henig" <[email-masked]>
Cc: <[email-masked]>; <[email-masked]>; <[email-masked]>
Sent: Wednesday, October 04, 2006 3:51 PM
Subject: Re: Question regarding MAC Withdrawal in H-VPLS Dual-homed MTU-s

>                                         Subject:     Question regarding 
> MAC Withdrawal in H-VPLS Dual-homed MTU-s
>                    09/26/2006
>                    04:11 AM
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