[rbridge] MAC aggregation in rbridge?

[Guillermo Ibáñez]

Sakku, Steven,

Just for  information on MAC aggregation, you can find here a link to a 
proposal  originated by Jose  Morales, based on private MAC  addresses 
assignment by ISPs (and the like), that allows aggregation.  I have no 
defined position on this proposal, but there are interesting aspects on 
it to analyze. Regarding upper layers the proposal is quite radical.
Guillermo

 http://www.lmdata.es/uets/uets-cm1.pdf

Steven Bakker wrote:

>On Wed, 2005-12-07 at 12:32 +0200, Saku Ytti wrote:
>
>  
>
>> I was thinking about the feasibility of supporting MAC address aggregation
>>in rbridges. How I think it could work in most simple way is that each rbridge
>>has it's own MAC 'prefix' and it then performs MAC rewrite on it's 'edge'
>>port, effectively changing the original MAC to rbridge prefix+ifindex. Then
>>you'd have aggregated MAC TLV with mask to propagate the information.
>>    
>>
>
>Mmmh, sounds like a L2 NAT? Just as in L3 (IPv4) NAT, L2 NAT has the
>potential to break many things. Right off the bat, I can tell you it
>will break ARP since ARP packets carry MAC address information in their
>payload. This means that for L2 NAT to work, your rbridges need to know
>about possible protocol and rewrite payloads, recalculate checksums,
>etc. This is not going to work. And even if it could, would that scale
>to 10GE and higher speeds? That's an awful lot of rewriting...
>
>  
>
>> Is this feasible? Is this needed or is it more sane to just grow
>>TCAM sizes?
>>    
>>
>
>IMO, it is unfeasible, unnecessary, and very undesired. Wearing the hat
>of my current employer (large scale Internet exchange), I like the idea
>of rbridge for its potential to better utilise the available links and
>efficiently route traffic. I pretty much have all the TCAM I need.
>
>MAC aggregation might make sense if there were some kind of structure on
>the allocation of addresses (as in IPv4/v6), but there is not.
>
>Regards,
>Steven
>
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>  
>