Users Guide

Configuring Route Leaking with Filtering
When you initalize route leaking from one VRF to another, all the routes are exposed to the target VRF. If the
size of the source VRF's RTM is considerablly large, an import operation results in the duplication of the target
VRF's RTM with the source RTM entries. To mitigate this issue, you can use route-maps to filter the routes that
are exported and imported into the route targets based on certain matching criteria. These match criteria
include, prefix matches and portocol matches.
You can use the match source-protocol or match ip-address commands to specify matching criteria
for importing or exporting routes between VRFs.
NOTE: You must use the match source-protocol or match ip-address commands in conjunction with the
route-map command to be able to define the match criteria for route leaking.
Consider a scenario where you have created two VRF tables VRF-red and VRF-blue. VRF-red exports routes
with the export_ospfbgp_protocol route-map to VRF-blue. VRF-blue imports these routes into its RTM.
For leaking these routes from VRF-red to VRF-blue, you can use the ip route-export route-map command on
VRF-red (source VRF, that is exporting the routes); you must also specify a match criteria for these routes
using the match source-protocol command. When you leak these routes into VRF-blue, only the routes
(OSPF and BGP) that satisfy the matching criteria defined in route-map export_ospfbgp_protocol are exposed
to VRF-blue.
While importing these routes into VRF-blue, you can further specify match conditions at the import end to
define the filtering criteria based on which the routes are imported into VRF-blue. You can define a route-
map import_ospf_protocol and then specify the match criteria as OSPF using the match source-protocol
ospf command.
You can then use the ip route-import route-map command to import routes matching the filtering criteria
defined in the import_ospf_protocol route-map. For a reply communication, VRF-blue is configured with a
route-export tag. This value is then configured as route-import tag on the VRF-Red.
To configure route leaking using filtering criteria, perform the following steps:
1 Configure VRF-red:
ip vrf vrf-red
interface-type slot/port
ip vrf forwarding VRF-red
ip address ip—address mask
A non-default VRF named VRF-red is created and the interface is assigned to this VRF.
2 Define a route-map export_ospfbgp_protocol.
Dell(config)route-map export_ospfbgp_protocol permit 10
3 Define the matching criteria for the exported routes.
Dell(config-route-map)match source-protocol ospf
Dell(config-route-map)match source-protocol bgp
Virtual Routing and Forwarding (VRF) 1107