[rbridge] Some comments on RBridge

[Radia Perlman]

It seemed like at the meeting some people were saying if we don't use 
the same Ethertype to specify "MPLS
encoding", that there isn't any advantage to using this format, and 
others were saying that using the same Ethertype
is asking for trouble because the label space would be overlapping. I 
suspect this is very implementation
dependent, and there might be some implementations that would benefit 
from this encodings, and others it wouldn't
help.

So the advantages of the MPLS-like format (with new Ethertype) is:

a) shorter (less overhead) than 8 bytes (which is probably what we'd use 
for an RBridge ID, a hop count, and
perhaps a priority field)
b) perhaps it would make some implementations easier
c) as long as we have to come up with a shim format, might as well use 
this encoding, since it has everything we want

The disadvantages are:
a) more complicated (because of the nickname acquisition protocol)...I 
don't think the nickname acquisition
protocol is all that complicated, but admittedly, with enough "let's do 
this one extra thing because it's not that hard"
can add up

I can't think of any other disadvantages. People can feel free to add to 
either list. But at any rate I don't think
it matters a lot, and we should just pick one and not waste much time on 
this.

Radia

Eastlake III Donald-LDE008 wrote:

> Yes, RBridge forwarding is completely different from MPLS forwarding. 
> But the argument has been that a lot of effort has been invested in 
> hardware to efficiently process the MPLS header at high speed. 
> Therefore, it will be helpful to more rapid deployment and the more 
> widespread attainment of the prospective advantages of TRILL to re-use 
> the MPLS header format.
>  
> Donald
>
> ------------------------------------------------------------------------
> *From:* rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org] 
> *On Behalf Of *Yang Yang
> *Sent:* Monday, July 10, 2006 8:15 PM
> *To:* rbridge at postel.org
> *Subject:* [rbridge] Some comments on RBridge
>
> Hello,
>    RBridge tries to adopt MPLS header. Are there any benefit to do so? 
> IMO, the forwarding behavior of RBridge is totally different from 
> MPLS. It's not possible to use the same forwarding componments.
>  
>    Best Regards!
>        Yang
>
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