if you configure an RR to retain routes with a defined set of route target extended communities, and a specific
set of VPNs to service.
Another reason to use this attach point is for an ASBR. ASBRs do not require that VRFs be configured, but
need this configuration to retain the IPv4 VPN prefix information.
The following example shows how to configure the route policy retainer and apply it to the retain route target
attach point. The route is accepted if the route contains route target extended communities 10:615, 10:6150,
and 15.15.15.15.15:15. All other non-matching routes are dropped.
extcommunity-set rt rtset1
0:615,
10:6150,
15.15.15.15.15:15
end-set
route-policy retainer
if extcommunity rt matches-any rtset1 then
pass
endif
end-policy
router bgp 2
address-family vpnv4 unicast
retain route-target route-policy retainer
.
.
.
Neighbor-ORF
The neighbor-orf attach point provides the filtering of incoming BGP route updates using only prefix-based
matching. In addition to using this as an inbound filter, the prefixes and disposition (drop or pass) are sent to
upstream neighbors as an Outbound Route Filter (ORF) to allow them to perform filtering.
The following example shows how to configure a route policy orf-preset and apply it to the neighbor ORF
attach point. The prefix of the route is dropped if it matches any prefix specified in orf-preset (172.16.1.0/24,
172.16.5.0/24, 172.16.11.0/24). In addition to this inbound filtering, BGP also sends these prefix entries to
the upstream neighbor with a permit or deny so that the neighbor can filter updates before sending them on
to their destination.
prefix-set orf-preset
172.16.1.0/24,
172.16.5.0/24,
172.16.11.0/24
end-set
route-policy policy-orf
if orf prefix in orf-preset then
drop
endif
if orf prefix in (172.16.3.0/24, 172.16.7.0/24, 172.16.13.0/24) then
pass
endif
router bgp 2
neighbor 1.1.1.1
remote-as 3
address-family ipv4 unicast
Routing Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
414
Implementing Routing Policy
Neighbor-ORF