[rbridge] Final outcome of outer VLAN tags onRBridge-RBridgepackets?
Radia.Perlman at sun.com
Tue Oct 30 17:22:52 PDT 2007
Silvano Gai wrote:
> "VLAN 1--nonconfigurable" is a non-starter for me, I hope to have
> explained why.
> "single VLAN per layer 2 cloud" may be workable, but I need to see the
> details of the algorithm to see if there are corner cases.
> If we can agree to concentrate our focus on a "single VLAN per layer 2
> cloud" we have made some progress.
> -- Silvano
I can live with "single VLAN, configurable, default=1". I'd recommend
that regardless of
the VLAN you are configured to send a Hello on, you accept Hellos on any
are capable of receiving traffic on, and that each DRB tells all the
other RBridges on that cloud
what VLAN to send on, so that they all wind up sending RBridge traffic
on the same VLAN.
I think the only complexity/overhead it adds over "VLAN 1,
a) something configurable to document and present in the management
interface (the VLAN on
which to send Hellos)
b) until a DRB is elected, there might be lots of RBridges transmitting
on different VLANs because
each might be configured with a different VLAN
c) if there are multiple (say k) DRBs (because for load splitting each
of them is DRB for
a different (nonoverlapping) set
of VLANs), then there will be k times as many Hellos being sent
d) I think there might be a slightly higher probability that there will
be misconfiguration such
as telling each RBridge a different set of VLANs to talk on, but the
safeguards that I specified
in previous emails (listen to BPDUs, report root bridge in pseudonode
LSP, don't decapsulate
from an ingress RBridge that you haven't seen all the LSPs from, wait
until you've synchrornized
LSP databases with your neighbors when you first start up) will prevent
loops in these cases, and
at worst orphan parts of the layer 2 cloud from the rest of the campus.
So...can everyone live with this? (Silvano -- as you said above,
you promised to think about whether there
were any corner cases to worry about. You also said you wanted to see
"the whole algorithm
specified". I'll do that in a separate email.
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