[j-nsp] l2circuit between ASR9k and MX80

[Saku Ytti]

On (2015-08-05 00:13 +0000), Adam Vitkovsky wrote:

Hey Adam,

> Also how good is to preserve the SVLAN if the B side pops the SVLAN(s) leaving the frame with just CVLAN tag(s) or no VLAN tag.

The reason in this scenario is, so that you can always configure port same
way, regardless what is in the far-end port. This makes provisioning easier
and less error-prone. Either side can have 0 or arbitrary number of SVLANs,
and you don't have to know other side's config.

> In my mind the SVLAN CoS is equivalent of MPLS EXP though I'm aware there might be setups where unique QOS scheme might be required for the L2 Agg network.

It's indeed just for the CoS bits. Yes typically CoS would be same as EXP, so
you could copy EXP bit back to CoS. This is why you might want to standardize
on 0 SVLANs in MPLS transit.
But then again, if you happen for any reason to need the CoS bits, it's very
hard later on to change your standardization (change config of every port),
sacrificing 4 bytes isn't gonna make or break the product, but will let you
rest easily, that if you ever need them, you have them.

-- 
  ++ytti