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RE: composite link - candidate for respin, maybe

Subject: RE: composite link - candidate for respin, maybe
From: John E Drake
Date: Mon, 29 Mar 2010 08:56:35 -0700
Comments inline

> -----Original Message-----
> From: rtgwg-bounces[email protected] [mailto:[email protected]] On Behalf Of
> Tony Li
> Sent: Sunday, March 28, 2010 10:38 PM
> To: [email protected]
> Cc: [email protected]
> Subject: Re: composite link - candidate for respin, maybe
> 
> 
> Hi Curtis,
> 
> > What we don't want to do (IMHO) is completely remove aggregation of
> > the bundle (aka CL) advertisement.  If there are a dozen identical
> > links and four that are differnt there is no need to pick exactly one,
> > just one from either set, or don't care.
> 
> My concern is that down the road, as resources get used, the links will no
> longer be identical.   Each will have its own unique usage levels.  Global
> planning and optimization can use this information to determine exactly
> how
> many LSPs and at what sizes can fit down the link.
[JD] 

Then why bother with link bundling?  This level of control has been part of TE 
since the beginning.  Link bundling was introduced to trade information hiding 
for scalability.

> 
> 
> > If we don't put a bound on the number of sets, in the limit each
> > component could be advertised with the added semantic that there is a
> > sharing option.  In that case the LSP may need to specify the set of
> > "groups" (as I have it above in the absense of a term) that are
> > acceptable.  This could make for a very big ERO.  It should be
> > adequate to indicate in the RRO that the bundle is being used with a
> > field indicating which member was currently in use (if nailed in
> > place).  This is beyond requirements, so if we are OK with the stated
> > requirement, let defer the details to later.
> 
> I'm fine with that, but we may also want to specify the component in the
> ERO.
[JD] 

See 
http://datatracker.ietf.org/doc/draft-ietf-mpls-explicit-resource-control-bundle/

> 
> > OK.  So what is your objection?  Are you suggesting that we need to
> > restrict the load balance to look down N labels from the top and no
> > further?
> 
> No, I'm suggesting that we need a bit in the RESV to say that this LSP
> should be demuxed by inner labels or kept atomic.
[JD] 

In current link bundling an LSP is either assigned to a specific component link 
or split across all of the component links.  In the latter case this 
effectively means all or a subset of the component links.

If an LSP is assigned to a specific component link, RFC 5150 
(http://datatracker.ietf.org/doc/rfc5150/) (a one hop LSP on the assigned 
component link) and MBB can be used to move the LSP non-disruptively to another 
component link  

> 
> > Good to be working with you again.
> 
> Likewise.  While we have a history of disagreeing, I find it far
> preferable
> to disagree intelligently with someone than some of the other discussions
> that I've been having lately.  ;-)
> 
> Tony
> 
> 
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