[quagga-dev 3948] Re: point-to-point interfaces on linux/ospf

J.J. Krabbendam jkrabbendam at aimsys.nl
Tue Feb 14 09:08:27 GMT 2006

J.J. Krabbendam wrote:

> Hi,
> I already asked the quagga-users list about this issue, but now I 
> dived into the code and therefore I want to pose the question here as 
> well.
> I want to connect two linux ospf routers using (unnumbered) 
> point-to-point interfaces. All point-to-point interfaces on a router 
> should have the same ip-address assigned. Eg I have three 
> point-to-point connections (using pppd)  from R1 to R2. The p2p 
> interfaces on R1 have address and on R2 they have the 
> address
> At first I saw only ospf enabled on the first p2p interface. I made a 
> kludge (using ifindex) and saw hello's be sent out on all three p2p 
> interfaces. However, as soon as the system starts sending  database 
> description packets, they are only sent on ppp0 and not on ppp1 and 
> ppp2. I have been looking at ospf_write() in ospf_packet.c. For 
> multicast addresses, each time a call to ospf_if_ipmulticast() is done 
> that ends in doing a setsockopt() with IP_MULTICAST_IF using the 
> ifindex. But it seens to only work for multicast addresses, not for 
> unicast.
> I tried also the call setsockopt_ifindex() but it does not seem to 
> accept an ifindex. So I more or less ran out of options.
> Question: how do I send a unicast packet to a specific network 
> interface using my setup or is it not possible?
> Thanks,
> Jaap Krabbendam.
Sorry for sending two messages, but I had trouble with my mail and I 
thought that I lost the first one.
Anyway, I was able to have full adjacencies over the point to point 
links now.
I use setsockop_ifindex() and pktinfo code based on 


Jaap Krabbendam

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