[rbridge] Final outcome of outer VLAN tags onRBridge-RBridgepackets?
Dinesh G Dutt
ddutt at cisco.com
Tue Oct 23 07:20:57 PDT 2007
I agree that using a single VLAN solution for IS-IS DRB is weak.
However, I'm skeptical that another protocol that also just sends Hellos
is much more scalabale or better than IS-IS sending only Hellos on all
On Tue, 2007-10-23 at 03:20 -0700, Silvano Gai wrote:
> I want to restate that IMHO a design that sends messages on a single
> VLAN is so week to be completely useless.
> I met Anoop on a plane back from a T11 meeting and we discussed the
> issue of sending messages on all the configured VLANs. Anoop pointed out
> that, if these messages are ISIS messages, this can overload the RBrige
> We identified a possible solution based on two different message types:
> - ISIS used on a single VLAN to compute adjacency
> - simple per-VLAN checking on all the VLANs to verify reachability.
> The second kind of messages is much simpler and therefore they load less
> the RBrige supervisor. In the future, per-VLAN checking can be
> implemented by the port ASIC. This seems a viable solution that requires
> design effort, but it is promising.
> Without the per-VLAN checking, running ISIS on a single VLAN holds water
> like a pasta-strainer.
> -- Silvano
> > -----Original Message-----
> > From: rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org]
> > Behalf Of Anoop Ghanwani
> > Sent: Monday, October 22, 2007 11:01 AM
> > To: Radia Perlman; Developing a hybrid router/bridge.
> > Subject: Re: [rbridge] Final outcome of outer VLAN tags onRBridge-
> > RBridgepackets?
> > If we want to make implementations work with
> > only a single Hello for all VLANs than the
> > option is (a). I think that is what it should be.
> > Basically, as a part of RBridge configuration
> > there should be a "RBridge Control VLAN" configuration
> > that applies to the whole device. It should default
> > to VLAN 1, but an operator can choose to change it.
> > A RBridge only emits Hellos on that VLAN. If it
> > receives Hellos on any other VLAN that should
> > be detected as an error condition and reported.
> > There have been some problem corner cases that
> > have been pointed out previously on the list
> > that may result in temporary duplication of
> > traffic when there is misconfiguration. Those
> > should be documented.
> > Anoop
> > > -----Original Message-----
> > > From: rbridge-bounces at postel.org
> > > [mailto:rbridge-bounces at postel.org] On Behalf Of Radia Perlman
> > > Sent: Saturday, October 20, 2007 9:47 PM
> > > To: Developing a hybrid router/bridge.
> > > Subject: [rbridge] Final outcome of outer VLAN tags on
> > > RBridge-RBridgepackets?
> > >
> > > I'm not sure I understood the final consensus on what we
> > > should do for outer VLAN tags on inter-RBridge packets.
> > >
> > > The possibilities I think the consensus might have been are:
> > >
> > > a) only use VLAN 1, explicit tag, no configuration possible.
> > > b) default is VLAN 1, explicit tag, configuration is possible
> > > to change sending with VLAN tag(s) something other than 1. If
> > > this is what was decided, I don't believe we've worked out
> > > the design details. I'd assume this would mean RBridges
> > > should be willing to receive packets from other RBridges
> > > regardless of outer VLAN tag. Would we then mark in the
> > > Hellos what VLAN tag(s) you've heard from what other RBridges
> > > with? What do we do with multicast if there isn't a single
> > > VLAN tag that seems to work to send to everyone? Would we
> > > allow configuration to send on a set of VLAN tags, or just on
> > > one at a time (and we allow configuration to say which one it is)?
> > >
> > > Certainly a) is simpler. If the consensus was b), we'd better
> > > work out the details.
> > >
> > > Radia
> > > _______________________________________________
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> > > rbridge at postel.org
> > > http://mailman.postel.org/mailman/listinfo/rbridge
> > >
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