[rbridge] How to deal with RBridge-Rbridge link metrics ?

[Pierre Francois]

Radia,

On Thu, 13 Jul 2006, Radia Perlman wrote:

> I don't think it's a problem to have two RBridges, R1, and R2, have
> different costs for
> the two directions of the R1-R2 link.

I agree it's not a problem, in general, to have asym. link metrics.
However, in our case here, we give a link A->B a default metric
for a 1Gbps link, although a "part a the link" is a 100Mbps one.

> I think what we're all agreeing on is that link costs should be tunable,
> but that there should be
> reasonable defaults.

Agreed, but if we say we refer to 802.1D defaults, we must remember that
it will not always match the link speed in TRILL, as illustrated
by Guillermo's case.


Pierre.


> Then the question is, should we specify the defaults for different types
> of links, and if so, in
> which document?
>
> One potential answer to "which document" is "not in TRILL", since we
> might be able to assume
> that any metrics used by IS-IS for layer 3 will work just fine for layer
> 2 TRILL.