Cisco ASR 9000 Series Routing Configuration Guide

Direct Router to Reduce Route Preference
The BGP Graceful Maintenance feature works only with the availability of alternate paths. You must advertise
routes with a lower preference to allow alternate routes to take over before taking down a link or router. Use
the following steps to modify the route preference:
Attributes for graceful maintenance are added to a route update message after an outbound policy has
been applied to it.
Note
SUMMARY STEPS
1.
configure
2.
router bgp as-number
3.
neighbor ip-address
4.
remote-as as-number
5.
graceful-maintenance as-prepends value| local-preference value
DETAILED STEPS
PurposeCommand or Action
configure
Step 1
Specifies the BGP AS number and enters the BGP configuration mode,
allowing you to configure the BGP routing process.
router bgp as-number
Example:
RP/0/RSP0/CPU0:router(config)# router
bgp 120
Step 2
Places the router in neighbor configuration mode for BGP routing and
configures the neighbor IP address as a BGP peer.
neighbor ip-address
Example:
RP/0/RSP0/CPU0:router(config-bgp)#
neighbor 172.168.40.24
Step 3
Creates a neighbor and assigns a remote autonomous system number to
it.
remote-as as-number
Example:
RP/0/RSP0/CPU0:router(config-bgp-nbr)#
remote-as 2002
Step 4
Specifies the number of times the local AS number is to be to prepended
to the AS path of routes and advertises the GSHUT community with the
graceful-maintenance as-prepends value|
local-preference value
Step 5
local preference value specified for the routes. When the router adds the
Example:
RP/0/RSP0/CPU0:router(config-bgp-nbr)#
GSHUT community to a route as it advertises it, it also changes the
LOCAL_PREF attribute and prepends the local AS number as specified
in the commands. Sending GSHUT provides flexibility in the manner in
graceful-maintenance
local-preference 4
which neighboring routers handle the lower preference: they can match it
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
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Implementing BGP
BGP Graceful Maintenance

Cisco ASR 9000 Series Specifications

General

Brand	Cisco
Model	ASR 9000 Series
Category	Network Router
Language	English