[OLSR-users] WLAN and Broadcasts (e.g. OLSR)

Sven-Ola Tuecke (spam-protected)
Tue Apr 25 14:10:13 CEST 2006


some Wifi cards have 2 settings for speed and mode. Unicast rate and 
multi(broad)cast Rate. If may have for example a multicast rate of 54g while 
using unicast 1b. Look out for iwprivs on that issue.


"Joerg Pommnitz" <(spam-protected)> schrieb im Newsbeitrag 
> Hello all,
> I have stumbled accross a problem with olsrd. It seems that HELLO-Messages 
> are only visible over a very short distance. Other protocols (ICMP-Echo, 
> ssh, iperf) work fine, however. The difference is, that these protocols 
> are unicast while olsr HELLO-messages are sent to the broadcast address of 
> the subnet. I have verified that a broadcast ping has the same problems, 
> so its not really OLSR-specific.
> This got me thinking. My understanding is, that 802.11 modifies the 
> over-the-air coding of the data packets according to the error rate when 
> talking to the peer. It trades bandwidth for reliability when the error 
> rate goes up. However, this is a point-to-point concept. In AdHoc-Mode 
> where you talk to all the nodes in a cell, this is not applicable. My 
> suspiction is, that the 802.11 card sends the broadcast packets in 
> whatever coding is the default for the current mode which might not be 
> optimal for nodes that are further away. Has anybody seen something like 
> this? Am I on the right track? Is there a solution? Something I could try?
> --  Thanks in advance
>       Joerg
> _______________________________________________
> olsr-users mailing list
> (spam-protected)
> https://www.olsr.org/mailman/listinfo/olsr-users 

More information about the Olsr-users mailing list