[Olsr-users] Route convergence time: a function of scale?

[Breno Jacinto]

Hello,

>>
>> # ping 192.168.10.15
>>
>>      Which, if my routing table is up-to-date *and* connectivity
>> (meaning, layer 1 and 2 conditions) is fine up to that node, then I'll
>> get a reply.
> OLSR.org sets an additional routing table entry for EACH other node of the
> network pointing towards the next hop.

     OK.
>
>> My point is: what if I get a Host Unreachable reply? Is
>> it because:
>>
>> 1) The node really isnt in the network - that IP is not used.
> If the node is not in the network you will have no local route to this node,
> so your node starts to send an ARP (tries to discover the unknown node in your
> neighborhood) and responds with an error

     Yes, if the node really isnt in the network, meaning: there's no
IP address 192.168.10.15 allocated to any host in the network.

>> 2) The node is in the network, but since it may have gotten too dense
>> (which is OLSR's supposed especialty), there's a route convergence
>> time for that route to get up-to-date.
> If you have not got a TC (topology control) packet mentioning the new node,
> your local node does not know about it, so you have no local route for it.

    OK, but that's exactly my point. If I got no TC messages *yet*,
doesnt mean the node is NOT in the network. I mean: the IP address may
be already allocated, but, for whatever reason, not every node in the
network is *aware* of it. Maybe the TC message is not reaching a given
node to inform it of a new joining node. So, this could be a problem
in cases of finding a duplicate / unused IP address, using a simple
ping.

     My question is how long would be this delay, and if there is any
study or practical experiments that demonstrating how long it takes
for everyone become aware of a joining node. In small scale networks,
of course this isnt much of an issue.


      Thanks for the answers.

regards,
-- 
-- 
:: Breno Jacinto ::
:: breno - at - gprt.ufpe.br ::
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