Administrator Guide

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. Configure the import target in the source VRF for reverse communnication with the destination VRF.
ip route-import 2:2
The show run output for the above configuration is as follows:
ip vrf vrf-Red
ip route-export 1:1 export_ospfbgp_protocol
ip route-import 2:2
! this action exports only the OSPF and BGP routes to other VRFs
!
ip vrf vrf-Blue
ip route-export 2:2
ip route-import 1:1 import_ospf_protocol
!this action accepts only OSPF routes from VRF-red even though both OSPF as well as BGP
routes are shared
The show VRF commands displays the following output:
Important Points to Remember
● Only Active routes are eligible for leaking. For example, if VRF-A has two routes from BGP and OSPF, in which the BGP
route is not active. In this scenario, the OSPF route takes precedence over BGP. Even though the Target VRF-B has
specified filtering options to match BGP, the BGP route is not leaked as that route is not active in the Source VRF.
● The export-target and import-target support only the match protocol and match prefix-list options. Other options that are
configured in the route-maps are ignored.
● You can expose a unique set of routes from the Source VRF for Leaking to other VRFs. For example, in VRF-red there is no
option for exporting one set of routes (for example, OSPF) to VRF- blue and another set of routes (for example, BGP
routes) to some other VRF. Similarly, when two VRFs leak or export routes, there is no option to discretely filter leaked
routes from each source VRF. Meaning, you cannot import one set of routes from VRF-red and another set of routes from
VRF-blue.
Configuring Route Leaking without Filtering Criteria
You can use the ip route-export tag command to export all the IPv4 routes corresponding to a source VRF. For leaking
IPv6 routes, use the ipv6 route-export tag command. This action exposes source VRF's routes (IPv4 or IPv6 depending
on the command that you use) to various other VRFs. The destinations or target VRFs then import these IPv4 or IPv6 routes
using the ip route-import tag or the ipv6 route-import tag command respectively.
NOTE:
In Dell Networking OS, you can configure at most one route-export per VRF as only one set of routes can be
exposed for leaking. However, you can configure multiple route-import targets because a VRF can accept routes from
multiple VRFs.
After the target VRF learns routes that are leaked by the source VRF, the source VRF in turn can leak the export target
corresponding to the destination VRFs that have imported its routes. The source VRF learns the export target corresponding to
the destinations VRF using the ip route-import tag or ipv6 route-import tag command. This mechanism enables
reverse communication between destination VRF and the source VRF.
If the target VRF contains the same prefix (either sourced or Leaked route from some other VRF), then the Leak for that
particular prefix will fail and an error-log will be thrown. Manual intervention is required to clear the unneeded prefixes. The
source route will take priority over the leaked route and the leaked route is deleted.
Consider a scenario where you have created four VRF tables VRF-red, VRF-blue, VRF-Green, and VRF-shared. The VRF-shared
table belongs to a particular service that should be made available only to VRF-Red and VRF-Blue but not VRF-Green. For this
purpose, routes corresponding VRF-Shared routes are leaked to only VRF-Red and VRF-Blue. And for reply, routes
corresponding to VRF-Red and VRF-Blue are leaked to VRF-Shared.
For leaking the routes from VRF-Shared to VRF-Red and VRF-Blue, you can configure route-export tag on VRF-shared (source
VRF, who is exporting the routes); the same route-export tag value should be configured on VRF-Red and VRF-blue as route-
import tag (target VRF, that is importing the routes). For a reply communication, VRF-red and VRF-blue are configured with
two different route-export tags, one for each, and those two values are configured as route-import tags on VRF-shared.
To configure route leaking, perform the following steps:
1020
Virtual Routing and Forwarding (VRF)