[wplug] Measuring & optimizing broadband speed

Patrick Wagstrom patrick at wagstrom.net
Sun Feb 10 07:39:04 EST 2008


Zach wrote:
> I am looking for accurate methods of measuring broadband speed,
> particularly for a 728 kbps / 128 kbps DSL line.
> I want to see how close my real world throughput gets to the
> advertised bandwidth. Also what is the theoretical maximum and minimum
> ping (average return time) and lag (standard deviation of the ping)
> for such a DSL line? Is there any sort of MTU, routing table or TCP/IP
> stack changes I can make (if so please explain how) to increase my
> latency, lag and packet loss? I use Debian lenny with a 2.6.18 kernel.
> Oh yes I will have a static IP address.
> 
> Also I got some advice on how to setup my ADSL line I'm getting next
> week but no one mentioned using the "route" command and setting up the
> routing table (gateway, metrics, netmask). Is that not necessary in my
> case?

Use of the route command is completely unnecessary.  Your DHCP client -- 
the protocol which will most likely give you your IP address will also set 
these values for you.  Yes, most places use DHCP even for "static" IP 
addresses.

In terms of measuring bandwidth, try speedtest.net.  It's not perfect, but 
good enough.  However, remember that most tools only measure bytes received 
and don't take into account the overhead traffic for PPPoE and TCP. 
Usually, if I want to know the maximum number of usable bytes per second 
for a connection, I ballpark it by dividing the bits per second by 10. 
Works well enough.

Getting started, I would not worry about optimizing lag and packet loss. 
There are some tools, most notable OpenBSD through PF that can optimize 
ACKs to "increase" your bandwidth or maintain queues for different usages. 
  I've done that before when I've set up networks at conference with mixed 
success.

--Patrick


More information about the wplug mailing list