how can i check route-target value by auto generated

[fly]

 I config vxlan evpn，but i forgot typing vni 50999 under vrf context Tenant1

so router report route-target auto generate problem

and I can see bgp learn far end vxlan routes , but can't install in vrf routing table.

so I add static route target on two nexus 9k, it worked.

but how can i check route-target value(import export) but auto generate.

  thank you

Tom

[JohnJoseph]

Easy way to check is to capture the bgp update message on the spine switch and look at the path attribute >> MP_REACH_NLRI >>Network layer reachability information >>EVPN NLRI and look for route distinguishes  configured is matching with what you have it in the switch, then look at the  path attribute  >> Extended community >> Carried extended community  >> Route target value. 

According to RFC it should be the ASN: VNI. For eg ASN = 64512 VLAN = 22 VNI = 5022

auto RT value should be 64512:5022

NX OS is doing this right except that the Cisco don't care about the 2 indicative bits before the start of VNI value, as per rfc if it's VNI it should be 00 and for vlan it should be 01 NXOS always keep 00 as the indicative bits. 

For IOS XE it never uses VNI value always takes VLAN value, for the same reason auto RT on IOS XE and NXOS won't inter-operate.