[Olsr-dev] Same-IP on multiple interfaces problem replication

Jernej Kos (spam-protected)
Tue Sep 15 22:42:59 CEST 2009


Hi,

after this "same-IP on multiple interfaces discussion" I was trying to 
replicate these problems in my test setup but was unable to do so. Two nodes 
(each has same IP on both wired ethernet and wifi) connected by wired 
ethernet and visible via wifi.

By using the netem qdisc I simulated different packet losses so to simulate 
different LQs. In each case both nodes correctly detected the better link and 
properly set up the routes. Since olsrd binds to interfaces and not IPs this 
is understandable as the incoming interface can be uniquely identified 
regardless of its IP address.

So how can I replicate this problem here in order to better understand what 
the problem is exactly ? I understand that 2-hop neighbours (and more distant 
nodes) will not be able to see which interface exactly is the better one 
(because there is no interface identifier in olsr packet format), but I don't 
see why this information is relevant as nodes will simply emit "aggregated" 
information (in this case the ETX of the best link between the two). I assume 
that this latter issue is the real problem here ? In what case will this 
information cause problems for routing and how can I replicate this in my 
setup ?

-- 
Jernej Kos <(spam-protected)>
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