[rbridge] Access-only link
james.d.carlson at Sun.COM
Wed Jul 9 12:08:05 PDT 2008
Radia Perlman writes:
> I'm a little less clear on why access-only links are as important, since
> it doesn't seem as though the traffic of
> LSP propagation would be that much. But again, I think it's simple and
> safe, so if people think it's useful, I wouldn't
> oppose it.
The case I remember discussing (Silvano, maybe?) was with a wiring
closet. There's a set of "backbone" links interconnecting the
RBridges, but there are a pair of RBridges that are incidentally
connected through a local access-side wiring closet. The owner of the
wiring closet doesn't want any backbone traffic traversing it, no
matter how attractive it might look as a path.
> The idea is for the DRB to signal in its Hello "this is access-only".
> And in the LSP for the pseudonode, the DRB
> can set the "database overflow" flag, which is a flag already in IS-IS
> for the purpose of dealing with a router that
> can't hold the LSP database. That flag means "don't go through this node
> unless absolutely no other path exists".
> If the "overflow" flag is set in the pseudonode's LSP, that would mean
> that that pseudonode would not be computed
> in a path as a transit link.
I think the desire was for "no way, no how." Not "go ahead and use
this to patch together the rest of the network if necessary."
Perhaps that's too strict a requirement, but that's what I *thought* I
understood from the lunch table discussion. Perhaps the others
involved could pipe up and clarify whether overflow would be
James Carlson, Solaris Networking <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677
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