Testing network stability?

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
Are there any tools for testing network stability and such for a LOCAL network? Ie, a network that has nothing to do with the internet whatsoever.

I suspect me skimping on cables (UTP in cable lists ..) had a quite negative impact on my network performance, but I can't really find a good tool to verify this...
Sure, I can ftp files back and forth all day, or try to ping a machine and hope I get lucky with the packetloss, but there has got to be a better way?

I'm looking for something where I can set up for example a listener on one machine, tell it to expect 30038328 UDP packets and 320439 TCP packets, then set up the sender on another machine and let it rip... And obviously generate some sort of report on how many packets got through okay, how many were damaged (UDP) and how many times they were resent (TCP)...

Any ideas? (except "code one yourself!")
 

StarTrek4U

Gawd
Joined
Jan 8, 2003
Messages
1,011
Why not just buy a decent cable or two and see if you notice any improvement? Is this just for a home workstation or two or for something larger?
 

LittleMe

2[H]4U
Joined
Feb 20, 2001
Messages
2,977
Buy a really nice Fluke. It's not the cheapest route and you may have to sell a few organs but they're dang nice.
 

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
I am going to buy a decent cable... but..

I still want a test utility like the one i described - in software, not hardware.
There has to be one somewhere.........right?
 

atomiser

Gawd
Joined
Jun 12, 2004
Messages
619
theres no substitute for decent cabling, it's arguably the most important part of the network!!!

if you can't afford to buy some decent cable testing equipment, another route might be to strike a deal with a local cabling company where they come and test it for you...they might look after you if you can agree a deal whereby they get the work to resolve any issues that they find. be careful they don't take you for a ride though!

on the software side of things, what about running something like iperf? another route is, if your hardware is manageable, look at interface statistics - these will often give you tell tale signs of cable issues.

hope this helps! :)
 

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
Well, if there's nothing available I guess I'll have to write it myself... :(

Seems it should exist somewhere though.... easy way to test cables and switches (but obviously not as good as hardware tests)..
 

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
Ah, thank you. Missed that one.

I'll try it as soon as I get home from work..
 
Joined
Jan 31, 2008
Messages
59
If you have a cabling problem, it will manifest itself in late collisions and framing errors.

Since you're already in the business of moving FTPs around, which I think is a fair test, you can check the interface statistics of the interface that all the traffic is coming in on / going out of, by running this command from the prompt (if it's a windows box)

netstat -s 1 | find "Segments Retransmitted"

This command will reflect any changes in this stat column every 1 second. You can also replace the "Segments Retransmitted" with any other stat field to get those results as well.

This is a poor man's technique, but it comes in handy. NOTE: a few retransmissions are normal. If you end up seeing more then 10/second, then you have a problem.
 

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
Mmmm, I ran iperf, and it seemed to work just fine using cheap cables (the ones that are already in lists on the wall), both with TCP and like 500mbit of UDP data...

But when i use my tvix (media box, uses NFS over UDP) it craps out immediately due to dropped packets and corrupt packets when using the cheap cables, but not using the good ones (across the floor).

Bit weird that iperf doesn't crap out the same way, but I'll keep at it...
 

Faldaani

Limp Gawd
Joined
Mar 25, 2007
Messages
195
Ya, I guess I'll do that...

Have to wait though, server fried a stick of ram yesterday and got stuck in an infinite reboot loop (bsod -> dump -> reboot) for 8 hours...

Bad ram might have affected transmissions....
 
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