Slow network how to diagnose?

[tj2419]

Hi

 

I have been told by a couple of our teachers that the network keeps running slow for them and their class leading to software crashing. I have asked them each a list of questions to try help diagnose the problem. But i was wondering if any one has any software that can scan the network for bottle necks? Or scan a list of IP's or specific switch to help see whats happening.

 

Cheers

[ADMaster]

Hi tj,

There are a few tools out there to monitor your whole network and give you nice bandwidth graphs. Nagios, cacti, the dude, opsview, mrtg just to name a few free ones.

 

These tools should also be able to monitor for packet loss and interface errors.

 

Depending on what switches you have you can log in and check all of these stats in the switch interface. Some switches also allow you to do a cable diagnostics from the switch, you may have a faulty cable in the path.

 

Cheers

[tj2419]

We have HP 1910's do you know if they have that cable diagnostics? Cheers

[ADMaster]

Sorry I'm Cisco here.

[elsiegee40]

Are these machines on wifi?

[Dos_Box]

Moving to correct forum.

[Chris_Cook]

1910s have cable diagnostics. Its hidden under VCT (virtual cable test) under the device menu on the left hand side of the web interface. It should be noted that the port you are testing will go down for 5 seconds.

 

There are also interface statistics under the device menu.

[tj2419]

Are these machines on wifi?

 

No all cabled. It is apparently when they are using applications like flash, serif web plus etc. the machines are about 24 months old with 4gb ram and i5's so can't see it being the machines.

[SpuffMonkey]

First thing I'd do is go down to a class that's complained and see for yourself - just in case its a user "misinterpretation" of the facts

[FN-GM]

What is the network speed to your end network devices?

What is the speed of your network back bone?

What is your core network switch?

Are you daisy chaining switches? or they stacked? How do they eventually get to the core?

What is your server specs, in particular disk speed and network connection speed? In particular your file server.

 

Are you noticing speed issues on your computer? If not what is different between them?

[seawolf]

I recommend PRTG for monitoring bandwidth usage (and everything else) on your network. The "Top 10" reports will show you if you have a network issue.

 

But, as suggested in a previous comment, I would hedge a bet that it's not a network issue at all, but similar to a teacher saying "the internet is down" when in fact it is a single website that is down...

[tj2419]

Yer i've asked them to call me next time it happens so i can see it for myself but its an area i'm a bit vague in so thought it might be a useful exercise to learn how to troubleshoot it.

 

What is the network speed to your end network devices?

1GB connection to the machines.

 

What is the speed of your network back bone?

We have fibre connection in between all cabs but these machines are connected directly to our main cabinet.

 

What is your core network switch?

3Com 4800G 48-port

 

Are you daisy chaining switches? or they stacked? How do they eventually get to the core?

Switches are all stacked. connected to core via ethernet.

 

What is your server specs, in particular disk speed and network connection speed? In particular your file server.

We are on 3 physical servers ML350 G6's E5530's @ 2.40 Ghz (16CPU), 16GB RAM, 300GB 15k SAS drives, 5 in each server.

 

Are you noticing speed issues on your computer? If not what is different between them?

Not that i had noticed. Mine is a slightly newer machine with i5 and SSD and 4GB. But they are all connected to switches in the main cab.

[FN-GM]

What speed is the backbone? 10GB I assume?

 

How many devices do you have? Have you separated them with VLANS?

[psydii]

Quick check on the file servers.

 

Run rammap for sysinternals and post the result...

 

Also do you redirect AppData?

[Homer]

Make sure the links to the core from the switches in question aren't saturated... could cause it. Have you deployed any network intensive applications recently (eg video editing)?

[lmgtfy]

Seeing that you have HP and 3COM switches I would use HP's very good management and monitoring software IMC. You can download a free 60 day trial and if you whack it on a VM it should only take 30 minutes or so to setup from scratch. It will show you the load of all your switches, draw you a pretty network diagram which can be helpful, show you any config problems and should help you identify any network slowness if that is the problem.

 

https://ssl.www8.hp.com/us/en/campaigns/imc-60-day-free-trial/registration.html

 

Cheers

[tj2419]

Right some time has passed and made a little progress.

 

We have a RM CC4 network with 3 DC's with our users spread across the three servers. The only users being affected by this slow down are all stored on server 3. I have also noticed in the server log that in the security event log it is constantly having security audit success and audit failures all day and night! Requests like every few seconds.

 

What could be causing this?

 

The other thing i have noticed is there are hundred of errors for RM printer credits in the event logs. We don't use RM printer credits. Has anyone come across this before?

 

Any thoughts on whether this could be linked to the slow down?

 

Thanks

[tj2419]

Quick check on the file servers.

 

Run rammap for sysinternals and post the result...

 

Also do you redirect AppData?

 

We are on server 2003 so cannot run RAMMap. We're a RM CC4 network so not sure on AppData. Is there a quick way for me to check?

 

Cheers

[Duke5A]

I cannot stress enough for the need to setup some kind of network monitoring software; aside from alerts and the peace of mind that comes from it, it'll help out immensely with troubleshooting. There is no need to spend money on this either as there are plenty of good, free alternatives. I'm using The Dude in my district and have every single network device and server across seven buildings setup in it with reporting on UPS units, core/edge switches and even temperature in data center. Included is a map of one of my smaller buildings. Traffic is logged and graphed between all switch links and has already aided me a couple of times in diagnosing issues with a few being broadcast storms. I get the occasional staff member that decides to bring a dumb switch into their classroom where they promptly introduce a switching loop causing a broadcast storm. Trying to find the source in a large building without a monitoring setup would be a lesson in futility. Just glancing at the map I was able to see what switch it was coming in off of, and opening the switches properties allowed me to see the exact port. This is just one time this has made my job a lot easier.

 

[tj2419]

I cannot stress enough for the need to setup some kind of network monitoring software; aside from alerts and the peace of mind that comes from it, it'll help out immensely with troubleshooting. There is no need to spend money on this either as there are plenty of good, free alternatives. I'm using The Dude in my district and have every single network device and server across seven buildings setup in it with reporting on UPS units, core/edge switches and even temperature in data center. Included is a map of one of my smaller buildings. Traffic is logged and graphed between all switch links and has already aided me a couple of times in diagnosing issues with a few being broadcast storms. I get the occasional staff member that decides to bring a dumb switch into their classroom where they promptly introduce a switching loop causing a broadcast storm. Trying to find the source in a large building without a monitoring setup would be a lesson in futility. Just glancing at the map I was able to see what switch it was coming in off of, and opening the switches properties allowed me to see the exact port. This is just one time this has made my job a lot easier.

 

[ATTACH=CONFIG]23151[/ATTACH]

 

Yes i am looking into this now as we have always used RM Event Master but that notifies our LEA support and not us. Just got a lot of devices to drag around the screen on the dude to clean it up a bit

 

Would you say the Dude is the best free monitoring software available?

[Duke5A]

Yes i am looking into this now as we have always used RM Event Master but that notifies our LEA support and not us. Just got a lot of devices to drag around the screen on the dude to clean it up a bit

 

Would you say the Dude is the best free monitoring software available?

 

That I've found yes, but The Dude doesn't look like it is being actively developed anymore. Mikrotik has been silent in the forums regarding it's development for a couple of years now. It still works though and I see no reason to look for a replacement.