[rbridge] RBridge: a case of study

Wed Oct 31 10:33:07 PDT 2007

Hern,

That's one of the problems that we're trying to avoid
by forcing all RBridges on a bridged LAN to be configured
such that they are all reachable and see one another on
a single VLAN.

Anoop 

> -----Original Message-----
> From: rbridge-bounces at postel.org 
> [mailto:rbridge-bounces at postel.org] On Behalf Of Zhi-Hern Loh
> Sent: Wednesday, October 31, 2007 10:17 AM
> To: Eric Gray
> Cc: Developing a hybrid router/bridge.
> Subject: Re: [rbridge] RBridge: a case of study
> 
> Donald,
> 
> In addition to Eric's questions, could you (or anyone else) 
> explain what would happen in the following scenario?
> 
> Toplogy:
> 
>                 RBa
>                 /
>               VID a
>                /
>    RBn-link X-----VID b------RBb
> 
> Problem:
> 
>   RBn is connected to 2 VLANs on link/port X. Connectivity to 
> RBa is via VLAN a, and connectivity to RBb is via VLAN b.
> 
>   Suppose that RBa and RBb are in the multi-destination 
> distribution tree from RBn. For a multi-destination frame 
> going out link/port X on RBn to RBa and RBb, what is the VID 
> on the outer VLAN tag? Or could there be need to send 2 
> frames, one with VID a and another with VID b?
> 
> 
> 
> Thanks,
> Hern
> Fulcrum Microsystems
> 
> 
> ----- Original Message -----
> From: "Eric Gray" <eric.gray at ericsson.com>
> To: "Eastlake III Donald-LDE008" 
> <Donald.Eastlake at motorola.com>, "Zhi-Hern Loh" <zloh at fulcrummicro.com>
> Cc: "Developing a hybrid router/bridge." <rbridge at postel.org>
> Sent: Wednesday, October 31, 2007 4:16:33 AM (GMT-0800) 
> America/Los_Angeles
> Subject: RE: [rbridge] RBridge: a case of study
> 
> Donald,
> 
> 	When you say "would all have the same Outer [VID]"
> - do you mean:
> 
> 1) all frames MUST have the same VID within the an RBridge 
>    campus,
> 2) all frames forwarded from a (physical) port on one RBridge 
>    to a (physical) port on another RBridge MUST have the same
>    VID, or
> 3) something else?
> 
> --
> Eric Gray
> Principal Engineer
> Ericsson  
> 
> > -----Original Message-----
> > From: rbridge-bounces at postel.org
> > [mailto:rbridge-bounces at postel.org] On Behalf Of Eastlake III
> > Donald-LDE008
> > Sent: Wednesday, October 31, 2007 12:22 AM
> > To: Zhi-Hern Loh
> > Cc: Developing a hybrid router/bridge.
> > Subject: Re: [rbridge] RBridge: a case of study
> > 
> > Hi,
> > 
> > Yes, as noted in protocol draft -05, the pseudo code was unchanged 
> > from
> > -04 and is out of date.
> > 
> > As currently being discussed, the TRILL encapsulated data being 
> > forwarded out a particular physical port would all have the 
> same Outer 
> > VLAN ID.
> > 
> > Thanks,
> > Donald
> > 
> > -----Original Message-----
> > From: rbridge-bounces at postel.org
> > [mailto:rbridge-bounces at postel.org] On Behalf Of Zhi-Hern Loh
> > Sent: Tuesday, October 30, 2007 10:54 PM
> > To: Anoop Ghanwani
> > Cc: Developing a hybrid router/bridge.; Radia Perlman; James Carlson
> > Subject: Re: [rbridge] RBridge: a case of study
> > 
> > 
> > ----- "Anoop Ghanwani" <anoop at brocade.com> wrote:
> > > > -----Original Message-----
> > > > From: rbridge-bounces at postel.org 
> > > > [mailto:rbridge-bounces at postel.org] On Behalf Of James Carlson
> > > > Sent: Tuesday, October 30, 2007 2:37 PM
> > > > To: Silvano Gai
> > > > Cc: Developing a hybrid router/bridge.; Radia.Perlman at Sun.COM
> > > > Subject: Re: [rbridge] RBridge: a case of study
> > > > 
> > > > Silvano Gai writes:
> > > > > Radia,
> > > > > 
> > > > > I have added few slides to the example and I suggest that 
> > > > we use it as 
> > > > > a possible case of study for TRILL (of course, not the 
> > only one).
> > > > > 
> > > > > Let's see if the solutions we have discussed work on this
> > > example.
> > > > > 
> > > > > The complete case of study is at:
> > > > > 
> > > > > http://www.ip6.com/acme-example-v1.ppt
> > > > 
> > > > I have a few narrow questions that I think might help me 
> > > > understand this picture a bit better.  (I probably have more 
> > > > questions once I know the narrow answers.  ;-})
> > > 
> > > Let me take a shot at answering these.
> > > 
> > > >   1.  After the proposed fix, should VLAN 3 on Cloud L 
> be bridged
> > > >       together with VLAN 3 on Cloud R, even though the backbone
> > > itself
> > > >       doesn't directly carry VLAN 3?  (I.e., are TRILL 
> > packets with
> > > >       outer VLAN ID 7 or 8 and with inner VLAN 3 present on the
> > > >       backbone?)
> > > 
> > > Yes, that's pretty much what ends up happening.  
> > > We have effectively extended the bridged LAN.
> > > 
> > 
> > Anoop, I'm reading the RBridge protocol specification 
> version 5 and it
> > seems to me that your comment is inconsistent with the spec. 
> > In section,
> > 5.2.2.3, the spec says that the outer VLAN tag of TRILL data 
> > frames has
> > the same VID as the inner tag. Is this section going to be changed?
> > 
> > Futhermore, if we were to use different VIDs on outer VLAN 
> > tags then we
> > would need to handle the multi-destination case where one 
> > would need to
> > send a multi-destination frame per outer VID to communicate 
> > with the RBs
> > in the distribution tree which are using different VIDs. Is this
> > correct?
> > 
> > Thanks,
> > Hern
> > Fulcrum Microsystems
> > 
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> 
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