White Papers

Table Of Contents
DellEMC# show ip route vrf VRF-Blue
O 22.2.2.2/32 via 122.2.2.2 110/0 00:00:11
C 122.2.2.0/24 Direct, Te 1/1/2/1 0/0 22:39:61
O 44.4.4.4/32 via vrf-shared:144.4.4.4 0/0 00:32:36
C 144.4.4.0/24 Direct, vrf-shared:Te 1/1/4/1 0/0 00:32:36
DellEMC# show ip route vrf VRF-Green
O 33.3.3.3/32 via 133.3.3.3 110/0 00:00:11
C 133.3.3.0/24 Direct, Te 1/1/3/1 0/0 22:39:61
DellEMC# show ip route vrf VRF-Shared
O 11.1.1.1/32 via VRF-Red:111.1.1.1 110/0 00:00:10
C 111.1.1.0/24 Direct, VRF-Red:Te 1/1/1/1 0/0 22:39:59
O 22.2.2.2/32 via VRF-Blue:122.2.2.2 110/0 00:00:11
C 122.2.2.0/24 Direct, VRF-Blue:Te 1/1/2/1 0/0 22:39:61
O 44.4.4.4/32 via 144.4.4.4 110/0 00:00:11
C 144.4.4.0/24 Direct, Te 1/1/4/1 0/0 00:32:36
Important Points to Remember
If the target VRF conatins the same prefix as either the sourced or Leaked route from some other VRF, then route Leaking
for that particular prefix fails and the following error-log is thrown.
SYSLOG (Duplicate prefix found %s in the target VRF %d, address, import_vrf_id)
with
The type/level is EVT_LOGWARNING.
The source routes always take precedence over leaked routes. The leaked routes are deleted as soon as routes are locally
learnt by the VRF using other means.
For recovery, you must take appropriate action either by deleting the unwanted prefixes or issuing clear command or both.
In the target VRF, you cannot leak routes that are imported through the route leaking feature.
The leaked route points to the next-hop of the source routes. You cannot do any modifications to the next-hop of the leaked
route in the destination VRF.
IPv6 link local routes will never be leaked from one VRF to another.
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.
1054
Virtual Routing and Forwarding (VRF)