[CUWiN-Dev] notes on TDV

[Matt Isaacs]

The tpscale isn't going to work as well as we had hoped, at least not at 3.
The node appears to see nothing but itself at 3.  If we slide up to a scale
of 2, we see more stuff but poorly.  We get ~75& packet failure rate to
nodes that are directly next to it.  (I've been testing from a gateway.)
I'm trying it now with 1.  What I've seen suggests ~50% packet failure rate
to neighboring nodes.  No scaling yeilds about a 30% failure rate to
neighboring nodes.

I'll try turning off IP6 and see what that does for us.

On 10/30/06, David Young <dyoung at pobox.com> wrote:
>
> 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
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>



-- 
Matthew Isaacs

CUWiN Network Engineer
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