Subject: Re: WGLC completed on draft-ietf-rtgwg-cl-requirement-03

From: Curtis Villamizar <[email-masked]>
Date: Wed, 02 Mar 2011 14:18:12 -0500

In message <[email-masked]>
Lucy yong writes:
>  
>  
> Hi Curtis,
>  
>  
> > I suggest that we go down a path which allows the following options:
> > 
> >   1.  list existing min-bw, max-bw summary with attached extended
> >       attributes per aggregate, with no other information.
>  
> [LY] Does "min-bw" mean the largest LSP that composite link can take?
> If yes, I agree this is the right direction. 

We do need to extend the semantics on min-bw and I had indicated that.
The existing min-bw applies to LSP that must take only one component.

With existing hash based multipath techniques a larger LSP can be
accommodated as long as no microflow within the LSP is larger than
min-bw.

Currently there is no way to determine which case applies.  Both cases
should be supported (must be?) with the LSR indicating which flavor it
supports.

> >   2.  add to #1, for all or a subset of components a sub-aggregation
> >       that is characterized by min-bw, max-bw and attached extended
> >       attributes,
>  
> [LY] Yes, we had this in mind. In addition, it is valuable to allow a
> composite link containing some component links that just use recovery
> purpose so their BW does not need to be advertised. A good example is
> that when a composite link contains a 10G component link with 30ms
> transmission delay and 1G component link with 500ms transmission
> delay. The composite link can just advertise 10BW with 30ms. 1G link
> can be used for recovery purpose. This gives operator flexibility to
> use the composite link. This does not require protocol changes, just
> need to describe the usage.

Yes and this too would have the semantics of min-bw listed above with
a needed extension to disambiguate the current "standard" meansing of
min-bw and a common interpretation or not force deployments that need
the "all ones" behaviour to configure min-bw to be equal to max-bw
regardless of component sizes (to get the desired ingress behaviour).

The sub-aggregation must be in addition rather than a replacement for
backwards compatibility.

> >   3.  add to #1 or #1 plus #2, advertisements for individual
> >       components.
> > 
> > #1 is just extended attributes added to link bundle.  #2 and #3 are
> >  sub-tlvs added to the link bundle.

Yes.

> [LY] Agree. 
> Lucy

Regards,

Curtis