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Vpns vs explicit null label

  • From: francis.arts@alcatel.be
  • Date: Wed, 29 Jan 2003 13:06:41 +0100
  • X-MIMETrack: Serialize by Router on BEMAIL06/BE/ALCATEL(Release 5.0.11 |July 24, 2002) at01/29/2003 13:06:42,Serialize complete at 01/29/2003 13:06:42


Hello,

I have a question on the explicit null label.

Issue
=====
Consider a 2-step approach:
1) Step-1: Setup of an LSP between 2 PE routers (say PE-1 and PE-2).
==> During LSP setup PE-2 indicates the use of the explicit null label.
2) Step-2: Send VPN packets through the LSP from PE-1 to PE-2.

In this configuration the VPN packets arrive at PE-2 with the VPN label beneath the explicit null label. PE-2 drops the VPN packets since RFC 3032 indicates that the explicit null label can only occur at the bottom of a label stack.

Question
========
Then the question is:
* How can during the LSP setup between PE-1 and PE-2 be made known to PE-2 that it should not use the explicit null label?
OR
Should the statement that <the explicit null label only occurs at the bottom of the stack> be relaxed?

Thanks for any help you can provide.

        Francis.