Problems on a VSAT link (Stupid-subject-was: I NEED HELP

[Stephane Bortzmeyer <bortzmeyer at gitoyen.net>]

On Wed, Feb 26, 2003 at 12:37:15AM -0800,
 Ademola Ajayi <ademolaajayi72 at yahoo.com> wrote 
 a message of 55 lines which said:

> pls I need help on my serial link that is misbehaving badly. my VSAT
> link is always timing out everyday and the request time when ping my
> provider is very high about 1325 to 1456ms.

When the link is loaded by actual traffic? If you suspect that the
link may be faulty, you need to test on an unloaded link, for instance
by disconnecting it from the network (just leave one machine to run
the tests).

> so someone told me that my link is choked up or there is a collusion
> on my VSAT link or my providers are not giving me the requested
> bandwidth we ask for from them.

Bandwidth (throughput would be a more correct word) and latency are
two separate (but not *completely* separate) issues. ping measures
latency. You use bing or Netpipe or treno or pathchar to measure the
throughput.

> Now, I want you to help on how to check on my cisco 2600 router how
> to check for collusion 

'show interface serial 0' will show a lot of interesting
statistics. Cisco gurus on that list could certainly make sense of
it. (My routers are PC so I cannot help more.)

> and check the actual bandwidth we are getting from our provider.

It is not obvious to do it right. A statistics program can be useful
(if you see that the link never transmits more than 64 kb/s, it
probably means that your throughput is limited to that
amount). Otherwise, two cases:

1) You have access to a machine on the remote side (close from the
remote side). Use Netpipe <URL:ftp://ftp.scl.ameslab.gov/pub/netpipe>
which is the only reliable tool.

2) You do not: use bing
<URL:http://www.freenix.org/reseau/outils.html>, pathchar
<URL:http://www.employees.org/~bmah/Software/pchar/> and treno
<URL:http://www.psc.edu/networking/treno_info.html> and mix in some
creative way their results, none is perfect. Use these resultats with
care before sueing your provider.

> secondly, how can I know from my router or on the network if my link
> is choked up by my client.

You use a statistics tool. MRTG <URL:http://www.mrtg.org/> is the most
popular.





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