Re: Question on GMPLS contentions resolution

[Eric Gray <eric.gray@sandburst.com>]

Guangzhi,

    The thing I can't figure out, is where you're getting all of this from.
I can't help you with your issues, because - from where I sit - it looks
like you pulled them out of thin air.

    Could you provide more specific information about where you see the
these issues of contention being defined?

--
Eric Gray

You wrote:

> Dear GMPLS authors and all experts:
>
> During GMPLS last call, I posted the same question on the mailing list
> without response. Please somebody spend a little time and check with the
> following example? Something seems not clear when the current GMPLS
> contention resution schemes are applied on a framework with both
> bi-directional and uni-directional LSPs. Your clarification is very much
> appreciated.
>
> Sincerely,
>
> Guangzhi
>
> --------------------------------------------------------------------------------------------------
>
> The issue arises because contention is resolved between bi-directional
> LSPs by the node with the higher node index while for uni-directional
> LSPs, contention is resolved by the downstream node. Consider the
> following example of two nodes with paired, bi-directional interfaces
> (i.e., a transmitter/receiver pair of ports).  Node 1 with ID=100 and
> node 2 with ID = 50.  Node 1 uses label 1 for the transmitter port and
> label 2 for the receiver port; node 2 uses label 4 for the transmitter
> port and label 3 for the receiver port.   We assume that a
> bi-directional LSP requires a single I/O interface.
>
> We consider two LSPs - a uni-directional LSP (LSP A) and a
> bi-directional LSP (LSP B). Both LSPs are going from node 1 to node 2,
> with the uni-directional LSP setup request arriving marginally before
> the bi-directional LSP.  LSP A does not use a suggested label, and thus
> is assigned a label (port) by node 2.  Label 3 is assigned,
> corresponding to label 1 at node 1.  At the same time, for LSP B (the
> bi-directional LSP) node 1 assigns label 2, with suggested label 1.
> Because node 1 has the higher node ID, node 2 will assume (due to the
> contention resolution rule for bi-directional LSPs) that LSP B wins the
> contention and thus label 3 is assigned to LSP B.  Thus label 1 at node
> 1 (label 3 at node 2) has been assigned to two different LSPs.  Both
> LSPs have ?won? the contention.