[OLSR-users] Strange routing depending on netmask

[Ignacio García Pérez]

Hi,

I have found a strange behaviour of olsrd. I'm using version 0.4.8. My setup
is a little unusual:

Each node has four serial SLIP interfaces an a dummy interface. The dummy
interface is there and participates in the OLSR protocolo solely to provide
the main address This is the setup for, say, node 13:

dummy0	10.1.13.1
sl0		10.1.13.20
sl1		10.1.13.21
sl2		10.1.13.22
sl3		10.1.13.23

As you see, there are 256 addresses reserved for each node, and they are
assigned to different interfaces. The ".1" address is always assigned to the
dummy0 interface, so other nodes wanting to communicate with node 13 will
just connect to address 10.1.13.1.

For this example, the setup for node 15 is obviously:

dummy0	10.1.15.1
sl0		10.1.15.20
sl1		10.1.15.21
sl2		10.1.15.22
sl3		10.1.15.23

Let us assume that interface sl1 in node 13 is connected to interface sl2 in
node 15.

10.1.13.21 <-----> 10.1.15.22

IMPORTANT: In the olsrd.conf file I set the broadcast address for all
participating interfaces to 255.255.255.255.

Now, if I configure all interfaces with network mask 255.0.0.0, the routes
look, AS EXPECTED, like this:

In node 13:

Destination	Gateway	Intefrace
10.1.15.1	10.1.15.22	sl1
10.1.15.20	10.1.15.22	sl1
10.1.15.21	10.1.15.22	sl1
10.1.15.22	*		sl1
10.1.15.23	10.1.15.22	sl1

In node 15:

Destination	Gateway	Intefrace
10.1.13.1	10.1.13.21	sl2
10.1.13.20	10.1.13.21	sl2
10.1.13.21	*		sl2
10.1.13.22	10.1.13.21	sl2
10.1.13.23	10.1.13.21	sl2

But if I configure the all interfaces with network mask 255.255.255.0:

In node 13:

Destination	Gateway	Intefrace
10.1.15.1	10.1.15.22	sl1
10.1.15.20	10.1.15.22	sl1
10.1.15.21	10.1.15.22	sl1
10.1.15.22	*		sl1

In node 15:

Destination	Gateway	Intefrace
10.1.13.1	10.1.13.21	sl2
10.1.13.20	10.1.13.21	sl2
10.1.13.21	*		sl2

That is, routes are inserted in the routing table up to, and including, the
address of the network interface in the remote node with which we have a
link.

As far as I know, network interface mask should be meaningless to olsrd,
right?

Does anyone know this this happens?

Thanks.

Nacho.


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