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DS3 or ATM? Which is better?

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by rhantson 1 view

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A client of ours were talked into a 20Meg ATM instead of the 45Meg DS3 that we suggested to them. They are now being told by thier provider that they are utilizing 60% of the ATM (our monitoring says about 25%), and they have been experiencing packet losses and slowdowns ever since.

The link is used SOLELY for Website and Database. No Phone over IP or any of that.

Am I off base here in pointing my finger at the ATM as being the problem? What's the difference between the two and what can I do/say to get our client convinced that they made the wrong decision? White Papers would be great... This is a dire problem...

2 replies

by nico baggus

regarding the capacity 60% or 25%, you may both
be right. At what interval are you looking
once per second, once per 5 minutes.

f.e. Cisco equipment keeps a five-minute
average. So if you have traffic that peaks and
than collapses waits a while and then starts
again it might be on average using the line for
only part of it's capacity.

My guess would be to have some traffic
monitoring done .

You dont mention the OS involved,
try prtg for windows.
iptraf, ethereal, tcpdump et al to listen on
your network.

iplog ipaudit passively look at a network link
and will tell you what happening there, at least
for a part.

Als you have to check if your network is
configured correctly... sometimes
autonegotiating speeds & duplex on ethernet
ports just doesn't work or doesn't work
reliably.

Verifing everything is effectively the same
(both side of a cable are both 10Mbit/Half or
100Mbit/Full. a 10/100 differece obviously
won't work, but a 100/Full against a 100/Half
port will work when NOT stressed or when traffic
is realy going oneway only otherwise the
halfduplex side will stop tranmitting when the
full duplex side starts (it will do that at
will) and the full duplex side will notice a lot
of short packets and a lot of CRC errors.

A tool like netio should be able to tell you
more if you cannot examine the states of a port.
http://freshmeat.net/projects/netio/

To solve this you need to know more what is
happening on that cable.....

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