[OLSR-users] Multiple Internet Gateways?

[Thomas Lopatic]

Hey there.

Yes, you can have more than one gateway. The nodes will then chose the
gateway to which they have the path with the best total link quality
(ETX enabled) or which is the least number of hops away from them (ETX
disabled).

You may, however, run into problems. Let's assume that you establish a
TCP connection to an Internet host via gateway #1. Gateway #1 does NAT
and so the Internet host sees your TCP connection come from gateway #1's
IP address. Now the link qualities in your network change and your
default gateway switches over. You now use gateway #2 for Internet
access, as the path to this gateway now has the best total link quality.
Gateway #2 also performs NAT. Now the Internet host is suddently
confronted with TCP packets coming from gateway #2's IP address - which
it won't accept. The Internet host will then reset the TCP connection
and you'll have to re-establish it. This then works until the gateway
switches again.

You can work around this problem by establishing an IP-in-IP tunnel from
your node to one of the gateways. In this way, you can select the
gateway to be used for Internet access on your node.

-Thomas