[Olsr-users] Functionality of HNA when no OLSR link is established

(spam-protected) (spam-protected)
Tue Dec 1 10:02:34 CET 2009

We are using OLSR in a wireless network with nodes having both an air interface and a LAN interface.
The OLSR routing is used for the air interfaces.

In order to inform the other nodes of the relation between each node's air interface IP address and LAN IP address, we use the HNA function.

What we experience is that a node will transmit UDP/IP unicast packets with a LAN IP address as long as the validity time of the HNA message from that particular node is not exceeded even when the OLSR link is broken. Our assumption was that packets addressed to such HNA given addresses would not be transmitted unless there exists a valid link between the related air interface IP addresses established by the HELLO and TC messages.

As it functions there are two drawbacks;
1. The air interface capacity is wasted with packet transmissions getting nowhere - and not stopped before the HNA validity time is past after a link is broken.
2. After the HNA validity time is past, it takes a long time to reestablish the link to the HNA given address (depending on the HNA interval time) after the air interface link is reestablished by the HELLO and TC messages. Short HNA interval times is not a solution due to more OLSR overhead traffic.

Have we implemented OLSR correctly or is this how OLSR functions?

Hans Jonassen
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