[PLUG] Broadband speed monitoring software

Steve Bonds 1s7k8uhcd001 at sneakemail.com
Mon Aug 5 08:09:03 UTC 2002


On Mon, 5 Aug 2002, Stephen Liu satimis at writeme.com wrote:

> Is there open source software to monitor the broadband speed?  The
> story is :
> 
> I am subscribing a broadband of 10MB sharing dynamic IP.  From time to time 
> the download or browsing speed is quite slow.  My ISP claims that it is 
> caused by the traffic of the site I am browsing/downloading.  I expect to 
> find a software which can clear my doubt whether the responsibility falls 
> on my ISP's shoulder or otherwise because of too many users sharing one 
> line at the same time.
> 
> I browsed "goolge".  There are many suggestions, spectrum, web monitoring, 
> etc.  I am not sure which one shall be appropriate to my application.
> 
> Could any guy throw me some light.  Thanks in advance.

I usually take a packet cpature using "tcpdump" (http://www.tcpdump.org)
and run it through "tcptrace"
(http://irg.cs.ohiou.edu/software/tcptrace/tcptrace.html) to get TCP
statistics on retries, throughput, round-trip time, etc.  Unfortunately,
if you don't have a firm grasp on the internals of TCP this low-level
information won't help much.

My favorite book on TCP internals is "Troubleshooting TCP/IP" by Mark
Miller.  I've heard good things about the O'Reilly "Network
Troubleshooting Tools" by Joseph Sloan, but I have not read it.

If you want to take a more "active" role and have a remote server you can
use, check out Netperf (http://www.netperf.org/netperf/NetperfPage.html)/

The quick version from my experience:

Often remote systems get congested.  When this happens you will see TCP
retries start to creep up, as packets get discarded on the back
end.  Sometimes the round trip time is very high as well, but the retries
are what really kills performance.

When your local system gets congested you will notice degraded interactive
performance to remote sites (i.e. telnet/ssh) regardless of which site you
go to.  If this is happening, you probably have a local problem.  If your
interactive response is good, but that stubborn FTP session won't go over
5k/s, odds are it's a remote problem.

Slowness on the initial connection is almost always due to lousy DNS
servers.  Try running your own caching DNS to solve that little problem.  
;-)

Many remote sites won't do more than 10-20k/s.  I see this all the time.  
All that 10Mbit connection does for them is let you wait faster. :-(

  -- Steve






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