[Babel-users] Next Hop TLV meaning

[Juliusz Chroboczek]

> so if I understand correctly, when A sends an Update to B, B needs to know
> address of A and, according to the proper circumstances, B gets address of A
> either from IPv6 packet's source address (case 1) or from The Next-hop TLV
> sent on purpose by A (case 2).

Correct.

>  x         y  z        w
> A  -------  B  -------  C

> with B that has, in its routing table, an entry for prefix of C with
> next-hop set to w.  I would like that by announcing this route,
> B includes the fact that its selected next-hop is w.

Note that if w is an IPv6 link-local address, it might in principle not be
globally unique, and hence announcing it to A might be ambiguous.  (In
practice, you'll find that your link-locals are unique, though.)

> If I understand correctly what I would call my "next-hop" TLV has a different
> meaning from the RFC one, therefore I should put the info I need into a subtlv
> right?

I'd call that the "second-hop", to avoid ambiguity, and dump it in a new
sub-TLV of the Update TLV.  Just grab a sub-TLV number in the experimental
range:

  https://www.iana.org/assignments/babel/babel.xhtml#sub-tlv-types

-- Juliusz