[Olsr-dev] broadcast packet filtering

[Erik Tromp]

> This is where you take the big CPU hit. The gateworks board 
> runnning 54M b/sin 802.11g mode we are using tops the CPU at 
> 100% at about 13mbps when user space handles the packets, 
> while it can handle much when using pure kernel forwarding.

13 Mbps multicast?? Wow! A few months ago I visited a company
involved in video distribution. They considered using IP multicast
but refrained from that because their (commercial) routers,
(not mentioning the brand name but it begins with a 'C') couldn't
cope with more than a few hundred Kbps of multicast traffic.
They were using some version of PIM.

I also think that 13 Mbps over 11g ad-hoc mode is quite ambitious,
at the least. As far as I know, the maximum theoretical bit rate of
11g is 27 Mbps, in a network of 2 nodes. Having 50 nodes, the
bit rate may drops to 7 Mbps and lower (see also
http://ieeexplore.ieee.org/iel5/4299640/4299641/04299680.pdf )
This bit rate will drop even more if multi-hop traffic is
present (as would be expected in OLSR networks).

Erik