why do you need VRFs for VXLAN

[carl_townshend]

Hi Guys

I recently built a layer 2 vxlan in my test environment between 2 routers, the same vlan was presented at each end and it works fine.

I have default anycast gateway on each end to allow them to route out of this vlan.

Can someone tell me why we need layer 3 vni's and vrf's?

Could I just not replicate the same for each vlan that I have done already, would this not allow them to route out of the vlan like a normal SVI would do inter vlan routing?

cheers

[MHM Cisco World]

It not mandatory.

MHM

[carl_townshend]

Hi, so why do they recommend this so called transit vrf? What if I don’t have it? 

so if I don’t have this it would just route using the normal vlan gateway ?

[MHM Cisco World]

Transit VRF? Can you more elaborate?

Now for vxlan there is underlying which is global 

And overlying which is ONE vrf for one vlan svi for route type 5 or multi vlan in same vrf.

Engineer recommend using one vrf for each vlan to separate the L3/L2 of traffic between different VLAN. 

MHM

[Pavel Tarakanov]

It's needed for routing between vlans/l2vnis in the same tenant/vrf.

It's called Symmetric IRB.

https://www.cisco.com/c/en/us/td/docs/dcn/nx-os/nexus9000/102x/configuration/vxlan/cisco-nexus-9000-series-nx-os-vxlan-configuration-guide-release-102x/m-evpn-hybrid-irb-mode.html