[c-nsp] N5k provider backbone bridging

[Curtis Piehler]

I know Nexus 5ks do not support straight up provider backbone bridging but
is there any way to emulate such a thing?

Scenario is thus:

Two N5596 uplink to two ASR9000 "Core routers".  Any VLAN in this VDC is
considered infrastructure.  A couple of hosts connect to the N5596 which
are VPC'd into 10G ports.  I am wanting to light up an additional two links
to another ASR9000 "PE".  This Port-Channel I would like to do some type of
provider back bone bridging between the ports on the hosts.  The "outer
tag" if you will would dictate each customer instance on the server and the
inner tag would be passed to the "PE" for L2VPN functionality and the VM.
In a perfect world I would do QinQ with service instances but that is only
support on N7ks and above.  Is there any way to accomplish this via MAC
Address functions/features?  I am not able to find any.

I also notice VXLAN is only supported on N5600 and above.

Thanks