[CUWiN-Dev] notes on TDV

[David Young]

On Sun, Oct 29, 2006 at 09:38:39PM -0600, David Young wrote:
> Some routers at TDV are spending about 50% of their CPU time in the
> operating system, leaving very little CPU headroom for forwarding, HSLS,
> etc.  I believe we owe the system overhead to the density of the network;
> every node can hear every other, so every node is bombarded by HSLS
> packets.  There are a few things we can try to get the CPU usage down:
> 
>         1 Turn off IPv6 (easily halves the number of packets).

Turned off in the TDV build.

>         2 Scale transmit power (sysctl -w hw.ath0.tpscale=4) to control
>           nodal degree and interference.

I set tpscale to 3 on the TDV build.  I hope that isn't too much.

>         3 Figure out how to adjust receive sensitivity to filter
>           out transmissions from distant nodes.

Looks to me like the HAL does not provide an API for that.

> Matt and I noticed that the diversity sysctl is turning back on
> (hw.ath0.diversity = 0 -> 1) when the ath0 is brought up.  I.e., we
> need to put '!/sbin/sysctl -w hw.$int.diversity=0' at the bottom of
> ifconfig.backhaul.tmpl.  I don't know if this is making any practical
> difference, since we have forced the interfaces to use just one antenna
> for transmit and receive, and those settings are not reset when we bring
> the interface up.

Done.

> Matt tells me that dhcpselect is not working right on gateways.  If the
> DHCP server is not available when the node boots, dhcpselect may or
> may not detect an Internet connection when the DHCP server starts.
> Sounds like a regression in dhcpselect.

I haven't investigated this, yet.

Dave

-- 
David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933