Hi @interfacedy ,
My understanding to it is that one VRF in ACI defines an IP address range, the range can consist of multiple subnets.
That's NOT what a VRF is, unless you accept that the IP address range that is defined by a VRF is the range 0.0.0.0 through to 255.255.255.255. EVERY VRF, whether it is ACI or anything else can potentially have knowledge of the entire IPv4 address range.
but a VRF should define one subnet or one ip address.
No - but each subnet and each IP address in that range can only exist once in the VRF (although we do sometimes cheat and allow the same IP address to exist in multiple places which is OK so long as it doesn't matter which instance of the IP gets it - like the Pervasive Default Gateway in ACI)
Is this VRF in ACI different with original one? thanks
The VRF concept in ACI is consistent with all other vendors and all other Cisco supported VRFs.
The reference you quoted (and the v5.0 equivalent) tells it quite well when it says
"a VRF defines a unique IP address space"
That's it. A hunk of memory on your devices that describes all of the IP addresses from 0.0.0.0 to 255.255.255.255. Now it is quite possible that many of those addresses are not reachable and therefore will NOT appear in the forwarding information for that VRF for a particular device.
Remember that one device's view of a particular VRF may not be the same as the next device either. The whole idea of the VRF is about how to handle packets that arrive on an interface that is part of that VRF.
RedNectar aka Chris Welsh.
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