The MPLS WG Archive

[Toby Smith <tob@laurelnetworks.com>]

Narasimha Swamy <NarasimhaS@netbrahma.com> writes:

> 1. In martini draft, it says, vc-id together with vc-type uniquely
> identifies a particular VC. does this mean two VCs can have same vc-id but
> different vc-type?

Yes.


> I don't think this should be the case, because group-id
> exists for higher hierarchy and vc-id should be different for each l2vpn
> circuit.

Group ID has nothing to do with uniquely identifying a VC at signaling
time; it exists only as a convenient way in which one LSR may signal
the withdrawal of many VCs at once.


> 2. In case of vc-label withdraw, 4 messages have to be exchanged between 2
> peers(first one being label withdraw for label corr. to this vc-id, then
> label release from its peer. Then label withdraw from its peer for vc-label
> at its end for this vc-id and lastly label release for this withdrawl).

Reception of a withdraw from one LSR does not instigate the generation
of a withdraw by the receiving LSR.  The LSR receiving the withdraw
will continue to advertise the VC information it has already sent
(unless there's been a local change to the VC configuration of
interface oper status).


> 3. what should be done if tunnel path doesn't exist, any notification msg to
> be sent?

No; the signaling of the VCs is independent of the availability of an
underlying data path.  There was some churn on this topic on the
martini draft list some time back, and this was the conclusion
reached.

Regards,
Tob