Subject: [manet] Packet looping issue in MANET routing protocol

From: "Yasunori Owada" <[email-masked]>
Date: Mon, 26 Nov 2007 14:04:22 +0900

Hello all,

We have implemented OLSRv2 routing protocol that can run on Linux
platform as daemon prosess and also run on QualNet simulator, and have
been checking the protocol operation and performance.
Through the real world experiments and simulation, we've found that
MANET routing protocol cannot solve the looping path issue completely.
The looping issue is acceralated when the Link Layer Notification is
enabled, and
much Looping occured with the proactive routing protocol such as OLSR
and OLSRv2 compare to the reactive routing protocol such as AODV. This
issue is caused form the node's network topology information
inconsistency (usually more than 2 hop information inconsistency) for
the proactive routing protocols.
Once the looping occures, the traffic load jump up localy, and total
network load incleases up to 20% in our simulation (50 nodes, random
way-point movement, 1500m squared area).
Unicast packet looping causes much traffic overhead because usually the
unicast frame is retransmitted by the MAC layer when the ack frame
doesn't come. This also leads large packet-delivery delay.
In addition, we found that most looping is formed between two nodes
(ping-poing looping).
Very few triangle loops are fouded, but more larger loops are not
found in our simulation.

Loop privention or avoidance is difficult issue considering unstable
wireless environment with multi-path fading and shadowing, but loop
detection is possible. It is expanding DPD technique to the unicast
packet. In this background we have submitted the initial I-D.
The draft can be found at:
http://www.ietf.org/internet-drafts/draft-mase-manet-loopdetect-00.txt

I think this looping issue should be widely discussed in the MANET WG.
Thanks,
-- 
Assistant Professor of Natural Hazard and Disaster Recovery, Niigata
University, Japan.
Yasunori Owada <[email-masked]>
TEL: +81-25-262-7429

_______________________________________________
manet mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/manet