[rbridge] Consensus Check: Point to Point links

[Eastlake III Donald-LDE008]

Actually, although I'm not entirely sure, I believe that BPDUs, LLDP
PDUs, etc., all start with an Ethertype which identifies them so, in
principle, they could be made to work on a specially equipped point to
point link with no outer MAC addresses. However, I don't think anyone
has proposed that TRILL should consider omitting the outer MAC addresses
except when that suggestion appears as part of a question asking why, if
you want to do some optimization on a point-to-point link, you don't
want to do even more optimization.

Donald

-----Original Message-----
From: Anoop Ghanwani [mailto:anoop at brocade.com] 
Sent: Thursday, October 04, 2007 1:46 PM
To: Radia Perlman; Eastlake III Donald-LDE008
Cc: Rbridge at postel.org
Subject: RE: [rbridge] Consensus Check: Point to Point links

 

> -----Original Message-----
> From: rbridge-bounces at postel.org 
> [mailto:rbridge-bounces at postel.org] On Behalf Of Radia Perlman
> Sent: Thursday, October 04, 2007 8:51 AM
> To: Eastlake III Donald-LDE008
> Cc: Rbridge at postel.org
> Subject: Re: [rbridge] Consensus Check: Point to Point links
> 
> Personally, I need a reminder of what we are trying to 
> accomplish with this before I can have any opinion.
> 
> a) Is omitting the outer VLAN tag to save space?
> b) Why put in anything for destination address other than the 
> MAC address of the next hop RBridge, or put in anything into 
> the source address other than your own MAC address?
> It won't save space. So what does it gain?
> c) Is there any danger if an RBridge is confused about 
> whether this is a pt-to-pt link or not?
> 
> I can see the advantage of omitting the entire outer header 
> if it is somehow absolutely known this is a pt-to-pt link, 
> and both ends of the link understand this. 

That wouldn't work because there are other frames that will
have to have MAC addresses, e.g. LACP, LLDP.

> But that isn't 
> what's being proposed here. It seems to be only omitting the 
> VLAN tag, and allowing insertion of random addresses into the 
> source and destination fields in the outer header, if I'm 
> reading it correctly.

I don't like the idea of random addresses (is it that
a big a deal to set them correctly?), but as long as
it's completely optional, I don't really care. 
[By the way, even though the proposal says that it
can be random, it really can't because we have to
say that they cannot be from the BPDU address space
or things like LACP and LLDP will break.]

Anoop