28.06.2014 Views

Discussion

Discussion

Discussion

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Router R3’s record route for the primary R1-to-R5 LSP shows:<br />

Record route: 10.1.13.1 10.1.36.2 10.1.56.1<br />

This matches the record route on the ingress router:<br />

Record route: 10.1.13.2 10.1.36.2 10.1.56.1<br />

The only difference here is that for R3, is between 10.1.13.1 and 10.1.36.2,<br />

while for R1, is at the beginning of the path, before 10.1.13.2. Next, look at<br />

the detour that R3 has set up:<br />

Detour Record route: 10.1.13.1 10.1.34.2 10.1.45.2<br />

This detour protects the downstream link from R3, which is the connection to R5. If<br />

this link fails, the detour goes to R4 (10.1.34.2), then to R5, the egress router.<br />

The next transit router to check is R2, which is not in the primary LSP but is part of<br />

the protection LSP that R1 has set up if its link to R3 goes down:<br />

aviva@R2> show rsvp session transit detail<br />

Transit RSVP: 1 sessions<br />

10.0.0.5<br />

From: 10.0.0.1, LSPstate: Up, ActiveRoute: 1<br />

LSPname: R1-to-R5, LSPpath: Primary<br />

Suggested label received: -, Suggested label sent: -<br />

Recovery label received: -, Recovery label sent: 100464<br />

Resv style: 1 FF, Label in: 100432, Label out: 100464<br />

Time left: 158, Since: Wed Oct 12 15:24:45 2005<br />

Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500<br />

Port number: sender 5 receiver 39275 protocol 0<br />

Detour branch from 10.1.12.1, to skip 10.0.0.3, Up<br />

Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500<br />

Adspec: received MTU 1500<br />

Path MTU: received 0<br />

PATH rcvfrom: 10.1.12.1 (so-0/0/0.0) 8 pkts<br />

Adspec: received MTU 1500 sent MTU 1500<br />

PATH sentto: 10.1.24.2 (so-0/0/3.0) 4 pkts<br />

RESV rcvfrom: 10.1.24.2 (so-0/0/3.0) 4 pkts<br />

Explct route: 10.1.24.2 10.1.45.2<br />

Record route: 10.1.12.1 10.1.24.2 10.1.45.2<br />

Label in: 100432, Label out: 100464<br />

Total 1 displayed, Up 1, Down 0<br />

The first few lines of the output confirm that this is LSP R1-to-R5, from 10.0.0.1 to<br />

10.0.0.5. The Detour branch line indicates that this router is a fast-reroute detour<br />

that will be used if R3 (10.0.0.3) fails.<br />

What happens when the link on one of the transit routers goes down? When R3 goes<br />

down, R1 can no longer direct the primary LSP out the so-0/0/2 interface to R3:<br />

aviva@R1> show rsvp interface<br />

RSVP interface: 2 active<br />

Active Subscr- Static Available Reserved Highwater<br />

Interface State resv iption BW BW BW mark<br />

so-0/0/0.0 Up 2 100% 155.52Mbps 155.52Mbps 0bps 50Mbps<br />

so-0/0/2.0 Down 0 100% 155.52Mbps 155.52Mbps 0bps 100Mbps<br />

532 | Chapter 14: MPLS<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!