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

liao.ting@zte.com.cn Fri, 17 August 2012 07:49 UTC

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To: Ayan Banerjee <ayabaner@gmail.com>
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Cc: Erik Nordmark <nordmark@acm.org>, trill-bounces@ietf.org, "trill@ietf.org" <trill@ietf.org>
Subject: Re: [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL - draft-ietf-trill-cmt-00
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Hi Ayan,

Thank you for your response.
The RFC 6325 doesn't care how to distribute the trees, but I think 
in a group as described in this draft, the ingress member RBridges 
should not use the same tree, so this draft should provide a solution 
on how to assign the trees among the member RBridges.IMO, the solution 
should take the cost between the tree roots and the ingress member 
RBridges into account.

Thanks,
Tina




Ayan Banerjee <ayabaner@gmail.com> 
发件人:  trill-bounces@ietf.org
2012-08-17 13:27

收件人
liao.ting@zte.com.cn
抄送
Erik Nordmark <nordmark@acm.org>rg>, trill-bounces@ietf.org, "trill@ietf.org" 
<trill@ietf.org>
主题
Re: [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL - 
draft-ietf-trill-cmt-00






Liao,

Just to get the entire context of the Section that you quote from the RFC:

   How an ingress RBridge chooses the distribution tree or trees that it
   uses for multi-destination frames is beyond the scope of this
   document.  However, for the reasons stated above, in the absence of
   other factors, a good choice is the tree whose root is least cost
   from the ingress RBridge and that is the default for an ingress
   RBridge that uses a single tree to distribute multi-destination
   frames.


The RFC clearly states that it is outside its scope and has a
suggestion regarding root choice. This draft provides the "other
factors" to influence the choice of trees.

Thanks,
Ayan




On Thu, Aug 16, 2012 at 1:40 AM, <liao.ting@zte.com.cn> wrote:
>
>
> I have read this draft and have a question about section 5.1,
> it describes how to distribute the trees among edge RB members of a 
group as follow:
>      Assign each tree to RBi such that tree number { (tree_number) %
>      k}+1 is assigned to RBridge i for tree_number from 1 to n. where n
>      is the number of trees and k is the number of RBridges considered
>      for tree allocation.
>
> And in RFC 6325 section 4.5 describes:
>    a good choice is the tree whose root is least cost
>    from the ingress RBridge and that is the default for an ingress
>    RBridge that uses a single tree to distribute multi-destination
>    frames.
>
> So, if a network has two trees, the first tree root is RBi and the 
second tree root is RBj,
> a group has two member RBridges RB1 and RB2, numerically ascending order 
by SystemID such that RB1<RB2,
> RBi is assigned to RB1 and RBj is assigned to RB2 as described in this 
draft,
> but maybe RB1 is closer to RBj and RB2 is closer to RBi, does the 
solution care about this?
>
>
>
> Erik Nordmark <nordmark@acm.org>
> 发件人:  trill-bounces@ietf.org
>
> 2012-08-16 06:11
>
> 收件人
> "trill@ietf.org" <trill@ietf.org>
> 抄送
> 主题
> [trill] Any comments on Coordinated Multicast Trees (CMT) for TRILL   - 
draft-ietf-trill-cmt-00
>
>
>
>
>
>
> 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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> trill@ietf.org
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>
>
>
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