Re: [bess] [pim] WGLC: draft-ietf-bier-mvpn-05

[Eric C Rosen <[e-mail]>]

On 6/21/2017 2:22 PM, Swadesh Agrawal (swaagraw) wrote:
> It can be achieved by having ipv6 explicit NULL in data path. We may not need different label to identify AFI.

We could have a rule saying that if MVPN payload packet is an IPv6 
packet, then v6 explicit null must be pushed before the 
upstream-assigned label is pushed.

But hen someone would claim that we're favoring v4 over v6, and the rule 
should be that if the MVPN payload is a v4 packet, v4 explicit null must 
be pushed before the upstream-assigned label is pushed.

If we don't have one rule or the other, we risk multi-vendor interop 
problems.

People will disagree about which rule is best, so someone will claim 
that we need a configuration item to say which payload type is the 
default and which requires explicit null.

Then someone would say that we need to add to the signaling an 
indication of which payload type is the default and which requires 
explicit null.

Then someone would say that the root cause of the problem is the lack of 
a protocol type field in MPLS, and we should fix the root cause instead 
of using explicit null.

So although your observation is absolutely correct, I think it's simpler 
if we just use different upstream-assigned labels for the different AFIs.