Specifications

mpls traffic-eng fast-reroute backup-prot-preemption
MP-318
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
The backup tunnel currently is protecting LSP1 through LSP5, which have the following bandwidth, and
do not have backup bandwidth protection (that is, the “bandwidth protection desired” bit was not set via
the tunnel mpls traffic-eng fast-reroute command):
• LSP1: 10 units
• LSP2: 20 units
• LSP3: 30 units
• LSP4: 60 units
• LSP5: 100 units
As shown, LSP1 through LSP5 use 220 units of bandwidth.
LSP6 has backup bandwidth protection and needs 95 units of bandwidth. Twenty units of bandwidth are
a
vailable, so 75 more units of bandwidth are needed.
In the following example, backup bandwidth protection is enabled and the amount of wasted bandwidth
is m
inimized:
Router(config)# mpls traffic-eng fast-reroute backup-prot-preemption optimize-bw
LSP2 and LS4 are preempted so that the least amount of bandwidth is wasted.
In the following example, backup protection preemption is enabled and the number of preempted LSPs
is m
inimized:
Router(config)# no mpls traffic-eng fast-reroute backup-prot-preemption
The router selects the LSP whose bandwidth is next-greater than the required bandwidth. Therefore, the
router picks LSP5 because it has the next larger amount of bandwidth over 75. One LSP is demoted. and
25 units of bandwidth are wasted.
Related Commands Command Description
show ip rsvp fast bw-protect Displays information about whether backup bandwidth
pro
tection is enabled and the status of backup tunnels
that may be used to provide that protection.