Retain Route-Target; Label-Mode - Cisco ASR 9000 Series Configuration Manual

Attach Points
if destination in (0.0.0.0/0) then
pass
endif
end-policy
router bgp 2
vrf vrf1
rd auto
address-family ipv4 unicast
allocate-label route-policy label-policy
.
.
.

Retain Route-Target

The retain route target attach point within BGP allows the specification of match criteria based only on route
target extended community. The attach point is useful at the route reflector (RR) or at the Autonomous System
Boundary Router (ASBR).
Typically, an RR has to retain all IPv4 VPN routes to peer with its PE routers. These PEs might require routers
tagged with different route target IPv4 VPN routes resulting in non-scalable RRs. You can achieve scalability
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
.
.
.

Label-Mode

The label-mode attachpoint provides facility to choose label mode based on arbitrary match criteria such as
prefix value, community. This attach point is typically used to set the type of label mode to per-ce or per-vrf
or per-prefix based on deployment preferences. The attribute setting actions supported are for pass and drop.
This example shows label mode selection at VPNv4 AF (address family) level and at VRF IPv4 AF level:
route-policy set_label_mode
set label-mode per-prefix
end-policy
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
498
Implementing Routing Policy
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