[c-nsp] ASR9000 vlan rewrite

[Adam Vitkovsky]

> interface TenGigE0/1/0/0.22001 l2transport encapsulation dot1q 100-399
exact rewrite ingress tag pop 1 symmetric
What the heck. I have just tried to configure this in the lab and it did not
complain. 
When the box removes the tag form the incoming frame how does it know what
tag to apply on the outgoing frames? 
I'm not aware of any mac to tag mapping table in XR. 
This type of configuration would be rejected on regular IOS. 

adam