[Olsr-dev] IPv6 Unique Local Addresses

Alina Friedrichsen (spam-protected)
Sat Nov 29 00:40:56 CET 2008

Hi John!

> > In OLSRv1 (that is what we are using today) this would work, but ipv6
> itself 
> > is a problem with OLSRv1 because the address fields are getting HUGE.

4 Bytes <---> 16 Bytes?

I think using a FPU on devises, that don't have a FPU was a much bigger problem. Jumping into the kernel space for every calculation costs much more then 3 instructions more for every IP address.

> > In OLSRv2 (which can use address compression for address blocks) even
> with 
> > "autoconfig" it would be better to use a real subnet so that you
> compress the 
> > blocks (common header/suffix-compression).
> > 
> > But the IPv6 autoconfig might be a good step to get a "permanent"
> adderss in 
> > an OLSRv2 IPv6 network. :)

The plan is to use the unique local address only for bootstrapping. I think to write a autoconf algorithm for it is a little bit oversized. A 64 bit random number does the same, with less problems. If now the node is in the mesh it searches for the nearest Internet gateway. If found, it takes his/her 64 bit random number in the unique local prefix and put it after the global prefix which the Internet gateway routes into the mesh. So the node has now a real public IP address with which is now reachable from the Internet without NAT, a centralized or other suck.

With the unique local address of the node address / routing table compression should work not so good but with the public global address in the Internet it should work fine.

> Something that should be considered is to use link-local addresses for
> the olsr packets. The ipv6 addresses that are exchanged should still
> be global or the unique local rfc4193 style. What I'm talking about is
> the address of the packet itself. There are two advantages that I can
> see.

I don't know what from-addresses packages to multicast addresses have or should have. :/

> 1 - It is closer to how other routing daemons work.

Which daemon?

> 2 - You automatically have the interface info because it is part of the
> link-local address.

Do you mean the MAC address?


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