Subject: Extensions to GMPLS RSVP-TE for Bidirectional Lightpath with the Same Wavelength Draft

From: Sugang XU <[email-masked]>
Date: Tue, 13 Nov 2007 09:22:32 +0900

Dear CCAMPers,

We have published an individual draft -Extensions to GMPLS RSVP-TE for 
Bidirectional Lightpath with the Same Wavelength

http://www.ietf.org/internet-drafts/draft-xu-rsvpte-bidir-wave-01.txt

[WSON-FRAME]
(http://www.ietf.org/internet-drafts/draft-bernstein-ccamp-wavelength-switched-02.txt)
provides control plane models for wavelength switched optical network. 
In section 4, routing and wavelength assignment issue, and in section 
5.2.3, relationship to link bundling and layering have been described.

In this draft, in addition to the description of a bidirectional 
lightpath provisioning mechanism, we would highlight some features on 
this signaling approach.

1. Simple extension
It uses one bit in LSP_ATTRIBUTES obj [RFC4420] to identify the 
bidirectional provisioning and only issue a labels update process on 
both directions.

2. A unified and fast signaling solution
This signaling approach can be used for both combined routing and 
wavelength assignment and separate routing and wavelength assignment 
approaches, with and without Path Computation Element (PCE) support. 
This signaling provides a unified and fast signaling solution for 
different scenarios.

3. Link bundling issue
PCE path computation problems may occur when computing bidirectional 
lightpaths. In a GMPLS network where multiple component links are 
aggregated into a link bundle and advertised as a single bidirectional 
TE link, the Traffic Engineering Database (TED) may indicate the 
availability of a particular wavelength in both directions on the TE 
link. However, it may actually be the case that the wavelength is only 
available in one direction on one component link, and the other 
direction is only available on a different component link. In this 
scenario, creating an end-to-end path that uses the same wavelengths and 
the same component links in both directions presents a PCE path 
computation problem. This signaling can be used to verify the solution 
received from PCE.

We appreciate your comments and suggestions!

Best regards,

Sugang