[Olsr-users] Heads-up: AHCP redesign

[John Hay]

On Fri, Dec 12, 2008 at 08:00:03AM +0100, Henning Rogge wrote:
> Am Thursday 11 December 2008 22:13:12 schrieb Jacques _:
> > No intend to troll, but doesn't ipv6 solve the need for ahcp by just having
> > prefix-mac
> Prefix-mac addresses will make address compression of PacketBB difficult.
> 
> > (even cooler would be olsrd on link local) ? Therefore ipv6 is
> > auto-configuring by itself.
> I don't think link-local addresses will work well, because we need the 
> addresses be valid for the whole network, not only for the one-hop 
> neighborhood.

The way I think it should be used, is that you use link-local addresses
to distribute the global ones. That is in line with other routing
protocols. So you use a link-local address to multicast your olsr
packets from. The routes inside the packets are still global. But when
you add the route to the kernel, you add it to the link-local address.
Something like this:

#####################
netstat -rnf inet6
...
2001:4200:7000:102::/64           fe80::2d0:12ff:fe03:2488%sis1 UG         sis1
2001:4200:7000:103::/64           fe80::202:6fff:fe34:21b5%ath0 UG         ath0
2001:4200:7000:104::/64           fe80::202:6fff:fe34:21b5%ath0 UG         ath0
2001:4200:7000:105::/64           fe80::202:6fff:fe34:21b5%ath0 UG         ath0
2001:4200:7000:106::/64           fe80::202:6fff:fe34:21b5%ath0 UG         ath0
...
fd9c:6829:597c:4:200:24ff:fec3:cf95 fe80::202:6fff:fe34:21b5%ath0 UGH      ath0
fd9c:6829:597c:6:200:24ff:fec3:cf94 fe80::202:6fff:fe34:21b5%ath0 UGH      ath0
fd9c:6829:597c:6:20d:b9ff:fe02:feb0 fe80::202:6fff:fe34:21b5%ath0 UGH      ath0
fd9c:6829:597c:10:202:6fff:fe41:192b fe80::2d0:12ff:fe03:2334%sis2 UGH     sis2
...
#####################

Two advantages that I can think of immediately:

A box does not need to have global addresses to be a router, so it can
route other's traffic even if it has not been configured yet.

Just looking at the source address of the received packet, already tells
you from which interface you received it. So it is not necesary to do
fancy trick to find out from which interface you received the packet.

John

-- 
John Hay -- (spam-protected) / (spam-protected)