Direct Router To Reduce Route Preference - Cisco ASR 9000 Series Routing Configuration Manual

Implementing BGP

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
Note
been applied to it.
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
Command or Action
Step 1
configure
Step 2 router bgp as-number
Example:
RP/0/RSP0/CPU0:router(config)# router
bgp 120
Step 3 neighbor ip-address
Example:
RP/0/RSP0/CPU0:router(config-bgp)#
neighbor 172.168.40.24
Step 4 remote-as as-number
Example:
RP/0/RSP0/CPU0:router(config-bgp-nbr)#
remote-as 2002
Step 5 graceful-maintenance as-prepends value|
local-preference value
Example:
RP/0/RSP0/CPU0:router(config-bgp-nbr)#
graceful-maintenance
local-preference 4
Purpose
Specifies the BGP AS number and enters the BGP configuration mode,
allowing you to configure the BGP routing process.
Places the router in neighbor configuration mode for BGP routing and
configures the neighbor IP address as a BGP peer.
Creates a neighbor and assigns a remote autonomous system number to
it.
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
local preference value specified for the routes. When the router adds the
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
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
BGP Graceful Maintenance
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