[rbridge] Final outcome of outer VLAN tags onRBridge-RBridgepackets?

[Anoop Ghanwani]

Silvano,

If we require the database synchronization step in Radia's
other email (#e) then we don't really need per VLAN messages.

Even if we have per-VLAN messages there will still be
scenarios that will break and we can at best only
detect them.

The only case where I think the per-VLAN scheme has an
advantage over the database synchronization approach
is when you have 2 ports that come up _simultaneously_
on a LAN and those have the misconfiguration problem
of not being able to see each other on the "RBridge
control VLAN".  In that case, depending on the
size of the network and how long it takes an LSP
to propagate, the per VLAN messages may detect the
problem a bit quicker.

Anoop

> -----Original Message-----
> From: Silvano Gai [mailto:sgai at nuovasystems.com] 
> Sent: Tuesday, October 23, 2007 3:21 AM
> To: Anoop Ghanwani; Radia Perlman; Developing a hybrid router/bridge.
> Subject: RE: [rbridge] Final outcome of outer VLAN tags 
> onRBridge-RBridgepackets?
> 
> 
> 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 supervisor.
> 
> 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]
> On
> > 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
> > > _______________________________________________
> > > rbridge mailing list
> > > rbridge at postel.org
> > > http://mailman.postel.org/mailman/listinfo/rbridge
> > >
> > 
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