Re: [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL - draft-ietf-trill-cmt-00

Hi Sunny,

The scenarios that links fail or CE switches are interconnected are interesting and make sense. The expensive (may lead to nickname exhaustion) solution you had pointed out is also the right direction I can think of right now. The only issue with this solution is its scalability.

Having said that, I think the failure recovery issue for an RBridge Aggregation is not that simple. It at least needs a control plane coordination among the aggregated members. Think about that a member joins/leaves the aggregation. A fast failure recovery mechanism for the RBridge Aggregation can be developed based on that coordination. When I suggested to  purchase this topic in a separate ID, I am on behalf of myself. I’d like to hear opinions from other guys.

Thanks,
Mingui

From: Sunny Rajagopalan [mailto:sunny.rajagopalan@us.ibm.com]
Sent: Thursday, August 16, 2012 9:36 AM
To: Mingui Zhang
Cc: Erik Nordmark; trill-bounces@ietf.org; trill@ietf.org
Subject: Re: [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL - draft-ietf-trill-cmt-00

Mingui,
This solution cannot be evaluated or deployed without knowing it's approach towards link failures.
IMO, the draft is incomplete without it, and a solution should not be deferred to another draft.
--
Sunny

On Aug 15, 2012, at 5:54 PM, "Mingui Zhang" <zhangmingui@huawei.com<mailto:zhangmingui@huawei.com>> wrote:

I had read this draft.

IMO, the updated version focus on the specific RPFC issue in active-active multi-homing. The failure recovery from links fails  can be regarded as another common issue of active-active multi-homing, which may  be handled in a separate ID.

Thanks,
Mingui

From: trill-bounces@ietf.org<mailto:trill-bounces@ietf.org> [mailto:trill-bounces@ietf.org] On Behalf Of Sunny Rajagopalan
Sent: Thursday, August 16, 2012 6:28 AM
To: Erik Nordmark
Cc: trill-bounces@ietf.org<mailto:trill-bounces@ietf.org>; trill@ietf.org<mailto:trill@ietf.org>
Subject: Re: [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL - draft-ietf-trill-cmt-00

I had sent out comments on this a while back, and none of them have been addressed.
To summarize the issues:
1) What happens when one of the CE-rbridge links fails? The draft doesn't talk about this scenario. I listed the possible solutions in my earlier email; are the authors planning to adopt one of them, or do they have another fix in mind?

2) The solution doesn't work if the CE switches are interconnected, but this is but this is not documented in the draft. What happens if they get interconnected accidentally? What is the process for recovery? This needs to be discussed in the draft.
More details here:
http://www.ietf.org/mail-archive/web/trill/current/msg04984.html

From:        Erik Nordmark <nordmark@acm.org<mailto:nordmark@acm.org>>
To:        "trill@ietf.org<mailto:trill@ietf.org>" <trill@ietf.org<mailto:trill@ietf.org>>
Date:        08/15/2012 03:14 PM
Subject:        [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL        - draft-ietf-trill-cmt-00
Sent by:        trill-bounces@ietf.org<mailto:trill-bounces@ietf.org>
________________________________

We are trying to understand if this document is getting close to WG last
call, but we don't know how many have read the document.

If you have reviewed the document, please let us know.
If not, this might be a good time to review the document and provide
comments.

Thanks,
   Erik and Donald
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