[Bier] About bierin6 and signalling of encapsulation

[Juliusz Chroboczek <[e-mail]>]

Hi,

Crossposted between BIER and Babel.

Thanks a lot to Sandy for presenting bierin6 this morning at the Babel
meeting.  I asked a question about how encapsulation is signalled, and
Tony answered it doesn't matter.  He's probably right, but I need an
explanation.

Suppose a BIER router A has a neighbour B.  From the routing protocol, it
has learnt that frames with a given bit index set are to be forwarded to
B.  How does it know which among the different BIER encapsulations to use
in order to send its BIER frames to B?

I'm probably missing something, but I only see three solutions:

  1. statically configured (e.g. a given BIER domain is statically
     configured to use a given encapsulation);

  2. carried by a specific signalling protocol (call it the BIER Hello
     Protocol for now);

  3. carried by the routing protocol (e.g. carried by a sub-TLV of the IHU
     TLV in Babel, or using RFC 5613 signalling in OSPF).

So what's the vision here?

-- Juliusz