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The second step is to configure autobandwidth on the LSP itself. In this recipe, we<br />

set autobandwidth on the R1-to-R5 LSP, specifying that RSVP always allocates a minimum<br />

of 50 Mbps for the LSP.<br />

To verify the autobandwidth configuration, look at the LSP on the ingress router:<br />

aviva@R1> show mpls lsp detail ingress<br />

Ingress LSP: 1 sessions<br />

10.0.0.5<br />

From: 10.0.0.1, State: Up, ActiveRoute: 0, LSPname: R1-to-R5<br />

ActivePath: (primary)<br />

LoadBalance: Random<br />

Autobandwidth<br />

MinBW: 50Mbps<br />

AdjustTimer: 86400 secs<br />

Max AvgBW util: 0bps, Bandwidth Adjustment in 86368 second(s).<br />

Encoding type: Packet, Switching type: Packet, GPID: IPv4<br />

*Primary<br />

State: Up<br />

SmartOptimizeTimer: 180<br />

Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 30)<br />

10.1.12.2 S 10.1.26.2 S 10.1.56.1 S<br />

Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):<br />

10.1.12.2 10.1.26.2 10.1.56.1<br />

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

The first highlighted line shows that autobandwidth is operational, and the second<br />

line reflects the configured minimum bandwidth of 50 Mbps. The AdjustTimer line is<br />

how often MPLS automatically recalculates the LSP’s bandwidth. Here, the default<br />

time is 86,400 seconds (24 hours). Use the following command to change the interval:<br />

[edit protocols mpls]<br />

aviva@R1# set label-switched-path R1-to-R5 auto-bandwidth adjust-interval 28800<br />

This configuration changes the recalculation interval to 12 hours.<br />

Next, verify that RSVP has reserved bandwidth for the LSP:<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 1 100% 155.52Mbps 155.52Mbps 0bps 0bps<br />

so-0/0/2.0 Up 1 100% 155.52Mbps 105.52Mbps 50Mbps 80Mbps<br />

RSVP has reserved 50 Mbps for the LSP in interface so-0/0/2.<br />

You might wonder whether the LSP goes down each time RSVP recalculates the<br />

bandwidth requirements. The answer here is no. The whole point of autobandwidth<br />

is that the LSP stays up during the entire process and RSVP makes the bandwidth<br />

changes without dropping any traffic traveling along the LSP. This occurs because<br />

RSPV sets up the new LSP before tearing down the existing one—make-beforebreak.<br />

You can confirm this by forcing RSVP to recompute the allocated bandwidth:<br />

aviva@R1> request mpls lsp adjust-autobandwidth<br />

536 | Chapter 14: MPLS<br />

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

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

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