Is there any extra configuration we need to take in consideration to mirror traffic from a VRF that belong to GRE Tunnel.
A=====GRE=======B------------>Wireshark ( GRE Tunnel is established between A and B)
when I ERSPAN the GRE tunnel i see the traffic but i can’t see the traffic goes through the VRF
Can you tell us a little bit more about the trouble you are having? When you say you can see the traffic but you cannot see the traffic that goes through the VRF, do you mean that you see it encapsulated but can’t read it? Or you don’t see it at all? Are you sure it is routed through the GRE tunnel?
For ERSPAN, a GRE tunnel interface can be used as the source of an ERSPAN session. This feature is supported. And VRFs are not a configuration that will affect the operation of ERSPAN since ERSPAN captures any frames going through that interface, no matter what upper layer characteristics they have. So I would suggest you troubleshoot not so much the ERSPAN, but your topology and ensure that the VRF in question is indeed going through the GRE tunnel.
It would be helpful if you shared a little bit more about your VRF and GRE config at A and B as well as a packet capture so that we can help you further.
I hope this has been helpful!