Service Manual

Conguring 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 lter the routes that are exported and imported into the route targets
based on certain matching criteria. These match criteria include, prex 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 dene 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 dened 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 dene the ltering criteria
based on which the routes are imported into VRF-blue. You can dene 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 ltering criteria dened in the
import_ospf_protocol route-map. For a reply communication, VRF-blue is congured with a route-export tag. This value is then
congured as route-import tag on the VRF-Red.
To congure route leaking using ltering criteria, perform the following steps:
1. Congure VRF-red using the following command:ip vrf vrf-redinterface gigabitethernet 1/11ip vrf
forwarding vrf-redip address x.x.x.x 255.x.x.x
A non-default VRF named VRF-red is created and the interface 1/11 is assigned to this VRF.
2. Dene a route-map export_ospfbgp_protocol.Dell(config)route-map export_ospfbgp_protocol permit 10
3. Dene the matching criteria for the exported routes.Dell(config-route-map)match source-protocol
ospfDell(config-route-map)match source-protocol bgp
This action species that the route-map contains OSPF and BGP as the matching criteria for exporting routes from vrf-red.
4. Congure the export target in the source VRF with route-map export_ospfbgp_protocol.ip route-export 1:1
export_ospfbgp_protocol
5. Congure VRF-blue.ip vrf vrf-blue interface gigabitethernet 1/22ip vrf forwarding VRF-blueip
address x.x.x.x 255.x.x.x
A non-default VRF named VRF-blue is created and the interface 1/22 is assigned to it.
6. Dene the route-map import_ospf_protocol.Dell(config)route-map import_ospf_protocol permit 10
7. Dene the matching criteria for importing routes into VRF-blue.Dell(config-route-map)match source-protocol
ospf
This action species that the route-map contains OSPF as the matching criteria for importing routes into vrf-blue.
8. Congure the import target in VRF-blue with route-map import_ospf_protociol.ip route-import 1:1
import_ospf_protocol
When you import routes into VRF-blue using the route-map import_ospf_protocol, only OSPF routes are imported into VRF-
blue. Even though VRF-red has leaked both OSPF as well as BGP routes to be shared with other VRFs, this command imports
only OSPF routes into VRF-blue.
9. Congure the import target in the source VRF for reverse communnication with the destination VRF.ip route-import
2:2
862
Virtual Routing and Forwarding (VRF)