the interface tries to negotiate ifid with the other end by using IPv6CP.
other changes:
- do not share ppp sequence number across protocols.
- if LCP proto-rej is received, drop the protocol mentioned by the message.
this is to be friendly with non-IPv6 peer (if the peer complains due to
lack of IPv6CP, drop IPv6CP). this basically implements "RXJ+" state
transition in the RFC.
- cleanup debugging message. always print blank just before message.
CAVEAT:
- if the peer uses the same MAC address as our side (pretty unlikely)
the code may go into req-rej loop.
- even though we negotiate ifid, we don't configure destination address
onto the interface. it is not really necessary to do so (IMHO).
- I've tested this code on a NetBSD 1.4.2 node, which was with fair amount
of modifications. not sure if the committed code does it right... (please
test and send reports)
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.
The old timeout()/untimeout() API has been removed from the kernel.
