Subject: [rbridge] VLANs

From: sgai at nuovasystems.com (Silvano Gai)
Date: Mon, 30 Oct 2006 09:28:55 -0800

The second biggest issue I have with the four documents (first one being
broadcast/multicast storm) is the definition of VLANs.

I don't think the term VLAN is used consistently in the documents.

1) Sometimes VLAN refers to the VLANs present on the untagged frames,
which must be propagated by ISIS, VLAN pruning must be performed and so
on. They all share the same core instance of ISIS.

2) Sometimes VLANs refers to the fact that a CRED can be encapsulated
into a VLAN (present as a 1Q tag in the outer header) and therefore ISIS
will run per VLAN, i.e. there will be a core instance of ISIS per each
VLAN. This seems to be the case in some part of the architectural
document.

I propose to name the former IVLAN (inner VLAN) and the latter OVLAN
(Outer VLAN), with reference to the position of the 1Q tag in the frame.

This is also very relevant for the discussion that we need to complete
on the FTAG: it is my understanding that some folks think that the FTAG
is not needed, since there may be an OVLAN.

Comments?

-- Silvano