Dynamic Route LeakingRoute Leaking is a powerful feature that enables communication between isolated (virtual) routing domains by segregating and sharing aset of services such as VOIP, Video, and so on that are available on one routing domain with other virtual domains. Inter-VRF Route Leakingenables a VRF to leak or export routes that are present in its RTM to one or more VRFs.Dynamic Route Leaking enables a source VRF to share both its connected routes as well as dynamically learnt routes from variousprotocols, such as ISIS, OSPF, BGP, and so on, with other default or non-default VRFs.You can also leak global routes to be made available to VRFs. As the global RTM usually contains a large pool of routes, when thedestination VRF imports global routes, these routes will be duplicated into the VRF's RTM. As a result, it is mandatory to use route-maps tofilter out leaked routes while sharing global routes with VRFs.Configuring Route Leaking without Filtering CriteriaYou 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 thatyou use) to various other VRFs. The destinations or target VRFs then import these IPv4 or IPv6 routes using the ip route-importtag 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 forleaking. 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 tothe destination VRFs that have imported its routes. The source VRF learns the export target corresponding to the destinations VRF usingthe ip route-import tag or ipv6 route-import tag command. This mechanism enables reverse communication betweendestination 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 prefixwill fail and an error-log will be thrown. Manual intervention is required to clear the unneeded prefixes. The source route will take priorityover 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 tablebelongs to a particular service that should be made available only to VRF-Red and VRF-Blue but not VRF-Green. For this purpose, routescorresponding 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, whois 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, onefor each, and those two values are configured as route-import tags on VRF-shared.To configure route leaking, perform the following steps:1 Configure VRF-shared using the following command:ip vrf vrf-sharedinterface interface-type slot/port[/subport]ip vrf forwarding vrf-sharedip address ip—address maskA non-default VRF named VRF-Shared is created and the interface 1/4 is assigned to this VRF.2 Configure the export target in the source VRF:.1018 Virtual Routing and Forwarding (VRF)
