Subject: Re: [pim] WGLC pim-rpf-vector

From: Yakov Rekhter <[email-masked]>
Date: Wed, 26 Sep 2007 07:09:26 -0700

Mike,

> Today begins a two week wglc for draft-ietf-pim-rpf-vector-04. Please
> review this draft and respond.
>
> http://ietf.org/internet-drafts/draft-ietf-pim-rpf-vector-04.txt

>From  2.3.2:

   Note that a router which
   receives a Vector Attribute must use it, even if that router happens
   to have a route to the source. 

What happen when some of the routers on the path from the router
that inserts the Vector attribute to the router whose address
is carried in the Vector attribute do not support the Vector attribute ?

Yakov.

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From: IJsbrand Wijnands <[email-masked]>
Date: Wed, 26 Sep 2007 16:41:24 +0200

Yakov,

> is carried in the Vector attribute do not support the Vector  

If an upstream router in the path does not support attributes, the  
downstream router will know this via the Hello option and send a PIM  
join without any attribute.

Thx,

Ice.

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From: Yakov Rekhter <[email-masked]>
Date: Wed, 26 Sep 2007 07:52:47 -0700

Ice,

> join without any attribute.

Does that mean that the RPF vector would operate correctly in an
environment where only some, but not all the routers support it 
(the routers that do not support it are assumed to have a route
to the source) ?

Yakov.

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From: IJsbrand Wijnands <[email-masked]>
Date: Wed, 26 Sep 2007 17:02:08 +0200

Yakov,

> (the routers that do not support it are assumed to have a route

For the RPF vector to work well, all routers in the path need to  
support it. If there is a router in the path that does not, the only  
thing you can do is send the PIM join without the vector and hope for  
the best. If the upstream router does not have a route to the source,  
RPF will fail.

Thx,

Ice.

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From: Yakov Rekhter <[email-masked]>
Date: Wed, 26 Sep 2007 09:40:05 -0700

Ice,

> the best. If the upstream router does not have a route to the source,  

Please add the above paragraph to the draft. Please also add
to this paragraph that the draft provides no mechanisms to determine
whether all routers in the path support the RPF vector.

Yakov.

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From: Yakov Rekhter <[email-masked]>
Date: Wed, 26 Sep 2007 09:50:52 -0700

Ice,

> join without any attribute.

Does the Hello option allow to indicate support for a *particular* attribute 
type (e.g., RPF Vector) ?

Yakov.

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From: Jean-Jacques Pansiot <[email-masked]>
Date: Wed, 26 Sep 2007 18:55:09 +0200

> whether all routers in the path support the RPF vector.
One such mechanism could be the PIM tree unreachable message we proposed 
some time ago:

<draft-hilt-pim-tree-unreachability-00.txt>

Jean-Jacques

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From: IJsbrand Wijnands <[email-masked]>
Date: Wed, 26 Sep 2007 19:19:17 +0200

> whether all routers in the path support the RPF vector.

Ok, sounds good.

Thx,

Ice.

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From: IJsbrand Wijnands <[email-masked]>
Date: Wed, 26 Sep 2007 19:18:34 +0200

Yakov,

> type (e.g., RPF Vector) ?

No.

Thx,

Ice.

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From: Yakov Rekhter <[email-masked]>
Date: Wed, 26 Sep 2007 10:30:19 -0700

Ice,

> > Does the Hello option allow to indicate support for a *particular*  
> > attribute type (e.g., RPF Vector) ?
> 
> No.

With this in mind I do not think the above answers my original question.

But you answer my question in your other e-mail. Namely,

Yakov.