Hi guys, I'm writing a short report about the actual behaviour of b.a.t.m.a.n. in case of client roaming between bat-nodes.
I was wondering what could happen in a particular (but not so unusual) situation:
take a network made up of several nodes, and 2 IP gateways, say X and Y. These 2 gws are advertising themself as gw (via the gw-mode). Now we have two nodes A and B which respectively recognize as gw X and Y (A recognizes X and B recognizes Y, where recognize means "to have such gw as best gw"). Each gw runs a dhcp server which assigns itsself as default ip route.
Now, what would it happen if a client roams from A to B and sends a new dhcp request (cause the lease time has expired) so changing the default gw from X to Y? The established connections will stop to work.
I think that this is a classical level 3 issue in the hand-off procedure. What do you think about this problem? Am I missing something?
Thank you all :)
On Friday 20 August 2010 14:22:52 Antonio Quartulli wrote:
Now, what would it happen if a client roams from A to B and sends a new dhcp request (cause the lease time has expired) so changing the default gw from X to Y? The established connections will stop to work.
I think that this is a classical level 3 issue in the hand-off procedure.
This is not entirely correct. When the lease expires the client will try to renew its lease. If it still can reach its original gateway it should not switch.
However, this might not be desired. The connection towards the old gateway might just be good enough to let the DHCP request through but is horrible when used for real data. In that case it would be smarter if batman dropped the renewal attempt to make sure the client switches.
We have to find the right balance between breaking the established connections and having a usable connection.
Cheers, Marek
b.a.t.m.a.n@lists.open-mesh.org
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Antonio Quartulli -
Marek Lindner