Leak VRF Routes to GRT

[techno.it]

Hey Folks,

I was working on a route leaking on Fusion switch in SDA deployment where I need to leak specific routes from a VRF to the Global Routing Table.

I’ve used import ipv4 unicast map and export ipv4 unicast map under the VRF configuration.

Prefix-lists and route-maps are correctly matching the required prefixes

The route was not appearing in the GRT until I added a static route

After adding the static route, the GRT subnets were able to reach VRF subnets.

Just curious to understand why is that so. Why adding static route was important.

Appreciate any advice

[MHM Cisco World]

Import/export is only use as filter the real work of leaking is done by 

Bgp or static route (set global)

MHM

[M02@rt37]

Hello @techno.it 

In your case, adding the static route likely resolved the issue because it provided the necessary reachability between the GRT and the VRF...

When using import and export map commands to leak routes from a VRF to the GRT, the GRT might not automatically have a path to reach the VRF's prefixes, even if the prefix-list and route-map are correctly configured. The static route explicitly provided a next-hop for the GRT to reach those VRF-leaked subnets. Without it, the GRT may not have had a valid route to the VRF, which is necessary for traffic to flow between them. Additionally, the static route could have helped resolve any recursive route resolution issues, where the GRT needed to find a valid path to reach the VRF subnets.

[techno.it]

Thanks M02@rt37 

Is there a better and efficient alternative way instead creating multiple static routes.

[Andrii Oliinyk]

wouldnt be this of help?
Configure Route Leak Between Global and VRF Routing Table without Next-Hop - Cisco

UPD. other way around u could have separate "shared services" VRF & have there whatever resources needed in other VRFs. it would be then classic inter-VRF routing w/o need to have PBR/static etc kludges.
keep in mind that GRT in SDA world is associated with INFRA_VN. Some customers are willing to allow communications between SDA GRT & other VRFs to happen via central FWs instead of Fabric-site level route leaks.
Otherwise u could even take a look at Extranet Feature allowing inter-VRF communications just on BNs:
Cisco DNA Center User Guide, Release 2.3.4 - Provision Fabric Networks [Cisco Catalyst Center] - Cisco

[techno.it]

Thanks @Andrii Oliinyk 

Understood so that's kind of GRT limitation.