No need for L3 Domain for an L3 External connection?

[dodgerfan78]

In my lab I have an L3 out doing OSPF and everything works. My VMs in my VMM domain can reach the network in the external OSPF domain. However, I do not have an L3 domain connected to my L3 out. I was expecting to have to create one, as I did when I was testing an L2/Bridged external network.

Why do I need a "Domain" connector for L2, but not L3? This kind of threw me for a loop as I understood an AEP was required for externally connectivity, but without the Domain, there is obviously no AEP for this port.

Thanks,

-Bryan

[lpember]

Hi Bryan,

If you don't have an L3 Domain associated to your L3Out, then you should have an "Invalid Path" fault under the L3Out as a result. Can you confirm you don't have that fault?

Leigh

[dodgerfan78]

Hey Leigh,

Yep, I do. In fact I noticed that while troubleshooting but the fault is still there and everything is working now.

[dodgerfan78]

Could it be because I am connecting it to a Bridge domain directly and not doing an L3 EPG association? 

[lpember]

Are you using SVI, sub-interface or routed interface for the L3Out?

The reason why it still works is likely because having a completely valid path is not a hard requirement at this time. There are certain portions of the path that are required for certain configurations, like a VLAN pool for an EPG static path. But you may be able to get things to work without having a complete path (and will have an invalid path fault as a result) but that would not be a best practice moving forward.

[dodgerfan78]

I am using routed interface. Thanks for the info!