[rbridge] Two "shared VLAN" alternative proposals

[Eric Gray (LO/EUS)]

I agree with Anoop.  The assumption that someone might only do 
ECMP in the core is simply that - as assumption.  Further - as 
Anoop directly states - the assumption that topology can be 
cleanly segregated into "core" and "edge" is also JUST an 
assumption.

--
Eric Gray
Principal Engineer
Ericsson  

> -----Original Message-----
> From: Anoop Ghanwani [mailto:anoop at brocade.com] 
> Sent: Tuesday, May 08, 2007 7:29 PM
> To: Silvano Gai; Eric Gray (LO/EUS); Radia Perlman
> Cc: J. R. Rivers; Caitlin Bestler; rbridge at postel.org
> Subject: RE: [rbridge] Two "shared VLAN" alternative proposals
> Importance: High
> 
> 
> That's assumes that one restricts the topology
> to a clean edge-core-edge design where bridges
> are present only at the edges (if at all).  
> 
> The general case where you have a random mix
> of bridges and rbridges is where the problem lies.
> 
> Anoop 
> 
> > -----Original Message-----
> > From: Silvano Gai [mailto:sgai at nuovasystems.com] 
> > Sent: Tuesday, May 08, 2007 1:23 PM
> > To: Eric Gray (LO/EUS); Radia Perlman; Anoop Ghanwani
> > Cc: J. R. Rivers; Caitlin Bestler; rbridge at postel.org
> > Subject: RE: [rbridge] Two "shared VLAN" alternative proposals
> > 
> > 
> > We do ECMP only in the core, but we don't learn in the core, 
> > so I don't see the problem.
> > 
> > -- Silvano
> > 
> > > -----Original Message-----
> > > From: Eric Gray (LO/EUS) [mailto:eric.gray at ericsson.com]
> > > Sent: Tuesday, May 08, 2007 8:23 AM
> > > To: Silvano Gai; Radia Perlman; Anoop Ghanwani
> > > Cc: J. R. Rivers; Caitlin Bestler; rbridge at postel.org
> > > Subject: RE: [rbridge] Two "shared VLAN" alternative proposals
> > > 
> > > Silvano,
> > > 
> > > 	The possibility of frame re-ordering using ECMP is not the only 
> > > concern.  A more significant issue is that schemes that exist for 
> > > trying to avoid re-ordering may not guarantee symmetric frame 
> > > delivery.
> > > 
> > > --
> > > Eric Gray
> > > Principal Engineer
> > > Ericsson
> > > 
> > > > -----Original Message-----
> > > > From: Silvano Gai [mailto:sgai at nuovasystems.com]
> > > > Sent: Tuesday, May 08, 2007 12:18 AM
> > > > To: Radia Perlman; Anoop Ghanwani
> > > > Cc: Eric Gray (LO/EUS); J. R. Rivers; Caitlin Bestler; 
> > > > rbridge at postel.org
> > > > Subject: RE: [rbridge] Two "shared VLAN" alternative proposals
> > > >
> > > >
> > > > The protocol specs states:
> > > >
> > > >    The main idea is to have RBridges run a link state protocol 
> > > > amongst
> > > >    themselves. This enables them to have enough information to 
> > > > compute
> > > >    pairwise optimal paths for unicast, and to calculate 
> > distribution
> > > >    trees for delivery of frames either to unknown 
> destinations, or
> > to
> > > >    multicast/broadcast groups.
> > > >
> > > >    ECMP (Equal Cost MultiPath) may be supported, but it may
> > introduce
> > > >    frame reordering.
> > > >
> > > >
> > > > I think this is correct.
> > > >
> > > > -- Silvano
> > > >
> > > > > -----Original Message-----
> > > > > From: Radia Perlman [mailto:Radia.Perlman at sun.com]
> > > > > Sent: Monday, May 07, 2007 8:28 PM
> > > > > To: Anoop Ghanwani
> > > > > Cc: Eric Gray (LO/EUS); J. R. Rivers; Caitlin Bestler; Silvano
> > Gai;
> > > > > rbridge at postel.org
> > > > > Subject: Re: [rbridge] Two "shared VLAN" alternative proposals
> > > > >
> > > > > Which draft says that multipathing (allowing more than 
> > one path to
> > a
> > > > > destination)
> > > > > is a nongoal? The architecture document, problem statement, or
> > > > protocol
> > > > > spec?
> > > > >
> > > > > Radia
> > > > >
> > > > >
> > > > > Anoop Ghanwani wrote:
> > > > > >
> > > > > > According to Radia's response, she thinks 
> > multipathing is being 
> > > > > > addressed and yet the draft explicitly  mentions it as a 
> > > > > > non-goal so there seems to be a bit of a disconnect.
> > > > > >
> > > > > >
> > > >
> > > >
> > 
>