[Olsr-dev] OLSR Multicast

[Erik Tromp]

I'm afraid the bmf version shipped with olsrd-0.5.6-r2 doesn't work.

I've tested it in a simple 2-node network. First started the olsr daemon
with debug level 9:

# ./olsrd -d 9 | grep -i bmf
        Name: "/olsr/olsrd-0.5.6-r2/lib/bmf/olsrd_bmf.so.1.5.3"
---------- LOADING LIBRARY /olsr/olsrd-0.5.6-r2/lib/bmf/olsrd_bmf.so.1.5.3
----------
OLSRD Basic Multicast Forwarding (BMF) plugin 1.5.3 (Nov 22 2008 17:32:36)
OLSRD BMF: opened 1 socket on OLSR interface "eth1"
OLSRD BMF: opened 1 socket on OLSR interface "eth2"
OLSRD BMF: opened 1 socket on OLSR interface "eth3"
OLSRD BMF: opened 1 socket on non-OLSR interface "eth4"
OLSRD BMF: opened 1 socket on "bmf0"
OLSRD Basic Multicast Forwarding (BMF) plugin: opened 5 sockets
---------- LIBRARY /olsr/olsrd-0.5.6-r2/lib/bmf/olsrd_bmf.so.1.5.3 LOADED
----------



In another console, started the ping session:

# ping 224.0.0.1

Now the problem shows up in the OLSRD debug output:

OLSRD BMF: outgoing pkt of 84 bytes captured on tuntap interface "bmf0":
10.0.4.3->224.0.0.1
OLSRD BMF: ----> Considering forwarding pkt on "eth3" to 10.0.6.5
OLSRD BMF: ----> Not forwarding to 10.0.6.5: link is timing out
OLSRD BMF: ----> No suitable neighbor found to forward to on "eth3"
OLSRD BMF: --> not encap-forwarding on "eth3": there is no neighbor that
needs my retransmission
OLSRD BMF: ----> No suitable neighbor found to forward to on "eth2"
OLSRD BMF: --> not encap-forwarding on "eth2": there is no neighbor that
needs my retransmission
OLSRD BMF: ----> No suitable neighbor found to forward to on "eth1"
OLSRD BMF: --> not encap-forwarding on "eth1": there is no neighbor that
needs my retransmission
OLSRD BMF: --> forwarded from non-OLSR to non-OLSR "eth4"

The ping packet is seen outgoing by the bmf process, but bmf cannot find a
suitable link to
forward the packet to. (In my specific test case, bmf should forward the
packet to 10.0.6.5,
which is a suitable link.)

The debug message originates from lib\bmf\src\NetworkInterfaces.c line 797
and onwards:

      if (currEtx < LINK_COST_BROKEN)
      {
        OLSR_PRINTF(
          9,
          "%s: ----> Not forwarding to %s: link is timing out\n",
          PLUGIN_NAME_SHORT,
          olsr_ip_to_string(&buf, &walker->neighbor_iface_addr));

        continue; /* for */
      }

The if-statement should read (of course):

      if (currEtx >= LINK_COST_BROKEN)

since we want to rule out links that are broken, instead of ruling out links
that are OK.

After I fixed this everything works fine.

I will put a special version of bmf for olsrd-0.5.6-r2 on
http://sourceforge.net/projects/olsr-bmf .

Henning, could you include this one-line-fix (or better, two-character-fix
:-) asap in your repo?

Best regards,
Erik




________________________________

	Van: (spam-protected)
[mailto:(spam-protected)] Namens shahab shiran
	Verzonden: vrijdag 21 november 2008 12:18
	Aan: (spam-protected); Henning Rogge
	Onderwerp: Re: [Olsr-dev] OLSR Multicast
	
	
		yes i see ICMP Echo request on the receiver's bmf0
interface,
	as you say,so everything must be fine.
	 
	many thanks for your help,
	Sh
	
	--- On Fri, 11/21/08, Henning Rogge <(spam-protected)> wrote:
	

		From: Henning Rogge <(spam-protected)>
		Subject: Re: [Olsr-dev] OLSR Multicast
		To: (spam-protected), (spam-protected)
		Date: Friday, November 21, 2008, 2:32 AM
		
		
		Am Friday 21 November 2008 11:22:42 schrieb shahab shiran:
		> /dev/net/tun exists, and i see bmf0-00 (by ifconfig)
		> and route 224.0.0.0 for bmf0.
		> but when i do ping 224.0.0.1, nothing comes back...
		I think the multicast itself works, but the ICMP-Reply does
not come back (you 
		are doing some kind of broadcast ping).
		
		Just check it with a tcpdump on the receiver side if you see
the ICMP-Request. 
		If yes, everything is fine.
		
		Henning
		
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