Re: ARP relay

> On Sun, 2005-05-01 at 13:18, Freek Dijkstra wrote:
 >
>> since some 
>> things have to be fixed in the kernel (for example, ARP replies must be 
>> broadcasted, 

Andreas Hofmeister replied:

> I assume that you want to avoid duplicate IP addresses in adjacent
> networks. But blindly broadcasting ARP replies will lead to a number of
> serious problems.

No, ARP replies are needed to avoid duplicate IP addresses when joining 
two network segments on layer 1 or layer 2. I don't think I'm refering 
to bridging like you are, and I certainly did not refer to ARP relaying 
(whatever that might be ;-) ).

I just mentioned ARP reply broadcasting just like ARP requests are 
broadcasted (and only for those with a link-local sender IP address), as 
is mentioned in the last paragraph of section 2.5 of the internet-draft, 
and illustrated in section 4.

Maybe it helps if I explain a bit further what exactly I'm using 
link-local IP addressing for. I'll do in a later mail (sorry, bit busy 
now). In short, I'm looking if it is possible to apply link-local 
addressing on so-called "optical networks", which are (for the most part 
at least) just link-local networks, with a few thousand km between the 
nodes, and no routers in between.

By the way -- you are right that multi-homed hosts (hosts with multiple 
physical interfaces) are a problem. The internet-draft unfortunately 
does not present a good solution for that problem.

By the way -- I haven't checked if modern kernels do broadcast ARP 
replies. MacOS X does, a 2.4 kernel does not, but I haven't found the 
time to test a 2.6 kernel.

> As it is impossible to add a "ttl" to relayed ARP replies

Thankfully. I surely don't see a reason to want that kind of such a 
solution.

Regards,
Freek


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