Re: [trill] WG Last Call: draft-ietf-trill-fine-labeling-02.txt

[Thomas Narten <[e-mail]>]

Hi.

Donald Eastlake <[e-mail]> writes:

> Yes, an FGL RBridge must support Fine Grained Labeling (FGL) and
> support VLAN Labeling (VL) as the inner data label. In other words, an
> FGL RBridge must be able to ingress a native frame to an FGL TRILL
> data frame, handle an FGL TRILL data frame as a transit switch, and
> egress an FGL TRILL data frame to a native frame. In addition, an FGL
> RBridge must be able to ingress a native frame to a VL TRILL data
> frame, handle a VL TRILL data frame as a transit switch, and egress a
> VL TRILL data frame as a native frame, all this VL stuff as described
> in the TRILL base protocol RFC 6325.

I'm still a bit confused by this discussion.

My understanding (from reading the draft earlier today) was that an RB
either operates in FGL mode or VL mode. It doesn't mix and
match. I.e., you don't have an RB with some ports understanding FGL
and others VL.  (To do that, you'd an RB would have to convert between
the the two formats which could result in loss of information...)

And the way to look at VL mode, is that it is the fallback for the
case where not all of the RBs in the compus are FGL capable.

Is my understanding correct?

Skimming the document again, this could perhaps be clearer.

I.e., what is supposed o happen in a campus where some RBs say they do
FGL and others do not? Is the intention that one TRILL campus gets
formed with all nodes falling back to VL mode?

Thomas