[Olsr-users] olsr.org olsrd and nrlsmf

[Joerg Pommnitz]

> Message: 3
> Date: Mon, 18 Aug 2008 16:49:12 +0200
> From: Bernd Petrovitsch <(spam-protected)>
> 
> Of the original sender of the packet: Not if another router
> is
> inbetween. You will then see the MAC address of the last
> router which
> resent the packet.

Both, hosts for which the current host is MPR and one-hop-neighbours are by definition just one hop away, so this is not a problem.

> From: "Erik Tromp" <(spam-protected)>
> I don't think so. I would think there are other media
> than Ethernet
> to transport IP packets.

Sure, but for a 802.11 network there are MAC addresses.

> From: Charles Wyble <(spam-protected)>
> On a cisco one would do show neighbors. On a Linux box you
> could
> 
> 1) Run some logic to get IP addresses of 1 hop neighbors
> 2) arp <ip of 1 hop neighbor> in a for loop.
> 
> I haven't deployed OLSR yet so don't know how to do
> step 1 but I'm 
> guessing it's trivial.

olsrd knows the one-hop neighbors.

> From: "Henning Rogge"
> From: Charles Wyble <(spam-protected)>
> Um. Ok. Well this could be done via arp. Or an API call I
> suppose. You 
> didn't exactly spell out your requirements, so I
> provided
> an answer based on the data I had. :)

ARP was my first thought as well. There are other ways:
1) capture the raw packets with libpcap
2) use raw sockets

None of this is a nice way to do it.

> From: Bernd Petrovitsch <(spam-protected)>
> strace'ing "arp" suggests looking into
> /proc/net/arp

IMHO the stack adds addresses to the ARP cache only when it tries to actually send to this very address. In OLSR you never send to anything but the broadcast address, so you will need a realy ARP lookup to get the mapping.

Regards
  Joerg

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