[Soekris] net4801 slow network speeds

Andy Michaels lego at therac25.net
Thu Mar 8 15:16:44 UTC 2007



On Thu, 8 Mar 2007, Mail Lists wrote:

> Thanks a lot for your suggestion - I tried iperf and it gives me about
> 24Mbit/s
>
> This is better - but maybe still not what I was expecting - I mean this is
> running without pf and I think there's difference between raw and compressed
> data, no?
>
not sure what you're referring to.  What part is doing the compression? 
iperf isn't compressed.  It just fills a TCP segment with 0-9 repeating 
until it fills the segment, and shoves it over the pipe as fast as 
possible.  There are options for UDP as well.

> I guess the bottleneck in this regard is the CPU (it goes to 100% usage when
> running iperf).
> Is there a way to tune packet handling in OpenBSD that anyone is aware of?
>

Can you clarify your configuration?  I'm assuming the following:

PC1 --\
        >--|Net4801|
PC2 --/

and you're running iperf on PC1 and PC2.  This should give you the best 
results, since the Net4801 will be doing nothing but routing packets.

If, instead, you're running iperf on the Net4801, you're taxing the 
machine pretty heavily.  I'm assuming that most things on your network 
won't be running off of your Net4801.  Things like tftp, DHCP, DNS(like 
dnsmasq, not BIND), etc should be okay.  File sharing off the net4801 
doesn't sound like a good idea. also if you're trying to test transfers 
*to* the Net4801, then you'll run into limitations of CF write speeds 
(Slow), and the fact that the Net4801 is a pentium class machine.  Dig up 
an old Pentium 266 and see how well it fares ;)

> Here's a rather simplistic comparison  - how does my piece of crap belkin
> router handle at > 70Mbit/s?
>

Well, it depends on what you're looking at.  the switch performance on the 
Belkin should be >70Mbit/s, actually, that's kinda crappy, a good switch 
should yeild you 90Mbit/s or more..  Your Net4801 
OTOH isn't a switch, unless you configured it in bridge mode (I think). 
It's actually doing routing.  Routing is more resource intensive.  Plus 
the Belkin has an ASIC to do the switching in hardware vs. software.

I bet if you plug PC1 into the WAN port on the Belkin and PC2 into a 
switch port on the Belkin you'd see about 10Mbps max.  It's not so common 
to put a 100BT PHY as a WAN port on those consumer grade routers.  So 
there's your apples-to-apples comparison.

Hope this helps, and again, some more detail about your setup will be 
helpful.

-Andy


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