Implementing Routing Policy on Cisco IOS XR Software
Information About Implementing Routing Policy
RC-225
Cisco IOS XR Routing Configuration Guide
router bgp 2
address-family ipv4
aggregate-address 10.0.0.0/8 policy sample
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Dampening
The dampening attach point controls the default route-dampening behavior within BGP. Unless
overridden by a more specific policy on the associate peer, all routes in BGP apply the associated policy
to set their dampening attributes.
The following policy sets dampening values for BGP IPv4 unicast routes. Those routes that are more
specific than a /25 take longer to recover after they have been dampened than routes that are less specific
than /25.
route-policy sample_damp
if destination in (0.0.0.0/0 ge 25) then
set dampening halflife 30 others default
else
set dampening halflife 20 others default
endif
end-policy
router bgp 2
address-family ipv4 unicast
bgp dampening policy sample_damp
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Default Originate
The default originate attach point allows the default route (0.0.0.0/0) to be conditionally generated and
advertised to a peer, based on the presence of other routes. It accomplishes this configuration by
evaluating the associated policy against routes in the Routing Information Base (RIB). If any routes pass
the policy, the default route is generated and sent to the relevant peer.
The following policy generates and sends a default-route to the BGP neighbor 10.0.0.1 if any routes that
match 10.0.0.0/8 ge 8 le 32 are present in the RIB.
route-policy sample-originate
if rib-has-route in (10.0.0.0/8 ge 8 le 32) then
pass
endif
end-policy
router bgp 2
neighbor 10.0.0.1
remote-as 3
address-family ipv4 unicast
default-originate policy sample-originate
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Note The current implementation of default origination policy permits matching only on destination address.