The MPLS WG Archive

[Jean Philippe Vasseur <jvasseur@cisco.com>]

Hi,

At 09:43 AM 8/28/2003 +0800, lidefeng wrote:
>In Draft Recommendation Y.17fw (MPLS management framework) TD 26 Rev.1 (WP
>3/13) at the meeting of Geneva, 21 July - 1 August 2003,it described the FRR
>process procedure when a failure occurs along a protected LSP,but I am not
>very clear about it in detail.

For the details on FRR, please refer to 
draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt

>As to the Figure A2.1 (See attachment) in Appendix 2,it states that "When a
>failure occurs along a protected LSP, the Point of Local Repair (PLR)
>redirects traffic into the appropriate bypass LSP. For instance if node R3
>fails in figure 6.1, R2 will switch traffic received from R1 on the
>protected LSP onto the Bypass LSP1 toward link [R2-R6]; the label will be
>switched from one which will be understood by R4 to indicate the protected
>LSP and then the bypass LSP's label will be pushed onto the label stack of
>the redirected packets. "
>
>what is the detail label operation in R2 when R2 switch traffic received
>from R1 on the protected LSP onto the Bypass LSP1 toward link [R2-R6],in my
>understanding,R2 has the label L3(which R3 distributed to R2),but has no
>label which R4 distributed to R2,so R2 has no label which will understood by
>R4(as indicated in the above paragraph).

R2 learns the label expected by the MP R4 via the RRO object carried in the 
Resv message of the protected TE LSP.

>And R2 needn't switch the label in the packet received from upstream with
>the label L3( the label R3  distributed to R2), just need to switch the
>label in the packet received from upstream with the label L6(the label R6
>distributed to R2).

no, it needs to swap the label used between R1 and R2 to the label 
distributed by R4 to R3, push an additional label corresponding to the 
bypass tunnel and redirect the traffic to the R2-R6 intefrace.

Again see the draft above.

JP.

>Did I catch it?
>
>Sincerely Yours
>
>Defeng Li
>Huawei Technologies
>+86-10-82882343
>lidefeng@huawei.com