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I am starting to "polish" the LAN here at my new work and since it's the 1st time I face sommething that big (almost 300 clients a switches, proxy) I would like to understand easily where I get weak points (read: 10mbit hubs hidden under desks) before starting to deploy important services like dhcp, dns and AD. I remember about a tool called ipers (or similar, can't remember well) who has a server and client part. I could put the server on our proxy and the client on a laptop anche check how the various floors and rooms are working.

Any hints on how to achieve this?


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up vote 5 down vote accepted

If you haven't done it yet (and you're referencing...if you're serious...10 mbit hubs that may be on your network...) you need to set aside time to actually physically trace and document your network cabling and equipment. Map everything.

Get documented what you have and what needs to be replaced. Check wiring for stretches, cuts, other damage. Start planning to get switches that allow for management. Walking around with a laptop doing monitoring with various software solutions can wait until you have a good map of your network and a handle on what is actually where and working, plus getting other good equipment in will cut down on the number of band-aid solutions you will implement later.

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I'm sadly serious, my friend... And you're right about what to do, I think. – Pitto Nov 18 '10 at 16:49

There are many ways to define a weakpoint, I assume you are referring to bandwidth due to those 10mb hubs.

if you are running linux / osx you will want iperf (sudo port install needed on osx) setting up a a "listener" on the server and a client on the client machine

  • iperf -s on server
  • iperf -c on client

Outputs will look similar to:

[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   111 MBytes  93.2 Mbits/sec
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If you have managed client access switches, you can usually enter a command that will show what MAC addresses are reachable by specific ports. Armed with this data, you can fairly trivially find where to focus your attention first (multiple MACs on a port).

For example:

  • Cisco: show mac address-table dynamic
  • 3Com: display mac-address dynamic

This would be a good first step in starting a comprehensive network documentation

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while your on the switches, check if they are operating at top performance, i,e full duplex at full bit rate. Also take a note of any error counters, ports with high error's rates may have faulty equipment attached to them. – The Unix Janitor Nov 19 '10 at 0:38
user37899 has a great point and I'll add to it; ensure that ports are set to auto speed and auto duplex. If the link won't come up with the auto settings it is very likely there are wiring issues that need addressing. In 2011 it would be a slim chance indeed if the end device wouldn't properly support auto speed and duplex. – JGurtz Mar 29 '11 at 15:26

Some advice to start with ( without knowing what is there )

Plan to Vlan each floor seperately ( preferably by department if you can )

i think is what you are looking for ( which will give you network throughput )

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NetCPS is a similar tool for Windows.

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