Identifying Bottlenecks in Busy Network

Tony Giangreco
Tony Giangreco used Ask the Experts™
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I manage a 45 user Windows 2003 network/Domain. There are 30 local users and 15 remote Terminal Service users.

Two T1's bonded into 3Meg for internet.

Sonicwall TX210W firewall

Two Netgear 24 port gig switches and Cat5E throughout the network.

All servers have atleast 30 gigs of free space on all drives
All server drives are defragged and restarted every two weeks.
All boxes run Symantec Endpoint Protection 12.1
 
One Dell PE1950 sevrer (dc) running Win 2003 Std with 4 gigs of ram, Exchange 2003. and terminal Services.  

One Dell Pe1900 Win2k3 Ent server (dc) and file share.

One Dell PE 2650 Win2k3 Ent server running Blackberry Enterprise Server Express.

30 Dell Pc's (less than 18 months old) with Win7 and Office 2007, 4 Gigs ram.

3 Win XP/Vista Pc's with 2 Gigs of ram slated for replacement this year.

I know it would help if I could replace the server but there isn't a budget for that right now.

All Pc's are operating, but many of them appear slow.
How do I identify the hot spots of the network to eliminate bottlenecks?
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Top Expert 2012

Commented:
Good info so far but need more details...

What is slow? Browsing? Accessing file server? Need to be more specific to help to narrow this down...

Author

Commented:
Browsing and file server response from workstations appear slow at times. it's sporatic.

I'm looking at replacing the T1's with a faster line, but that won't happen overnight.
Commented:
Setting a port to mirroring on your switch and attaching a packet sniffer might give you some clues...

You may want to make sure you have the server plugged into a gigabit port.  Possibly switch it from autodetect the duplex to FULL.

Run some ping tests and see if you are getting any kind of packet loss...

Just a few thoughts and suggestions.
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Author

Commented:
The Dell 1950 server has two Broadband Gig nics teamed together plugged into a Netgear 24 port Gig switch.

The switches are not managed so I don't know how I can set a port to mirror.

Is thee a free packet sniffer I can use to identify and rule out areas of the network?

Commented:
Wireshark is a very popular one.  Maybe you have a ton of broadcast traffic or something happening.

It sounds like it is mainly between users and that server.  You don't find the interenet sluggish?

Author

Commented:
I will look into wireshart tutorials.

Internet access is sporatic also from Pc to Pc - new and old. It's real hard to get a handle on where the problem is.

Commented:
Have you tried powercycling the switch ever?  I've seen when they have some power fluctuations/browning that lowerend ones get sort of stupid...

You may want to disable the antivirus as well on a system and see if performance improves...  Finding bottlenecks can be tough, but AV would be something common among all the systems.

Author

Commented:
Also, all servers, switches and the firewall are hooked up to a APC 3000 UPS with network powerchute active.

We have about one power outage a year.
Top Expert 2012
Commented:
What are your ping times like on local LAN?

ping <serverbyIPaddress>
ping <serverbyDNS>

If they are over 1ms then it may be a network issue

Do this at 'slow' times just to see as well it might narrow things down...
If you have 2 switches its hard to see both having issues but I assume the 'slowness' is on all pc's? Not a subset?

Commented:
Do you notice it more with opening Office documents?  There is an update I know of that is known to slow down opening those files:

http://social.technet.microsoft.com/Forums/en/officeitpro/thread/214b4ff1-f908-496f-bafa-87b8d73775b1

Author

Commented:
I run Windows Update on the servers every two to three weeks followed by a restart to keep them patched. I don't have no idea if one specific update is causing the bottleneck.

Author

Commented:
I just pinged 15 of the pc's from the main server with response times from 1 to 12 ms and ttl of 128.
Top Expert 2012

Commented:
What was the average ms? Look at bottom after finishing the ping(note run a longer ping test with the -t option like so)

ping -t <serverbyIP>

Will run a continuous ping, let it run for a couple minutes and note the average
Unless the server itself is overloaded its rare for the ms to be above 1ms in most cases, so if the average is on the high side you have some sort of network issue

On the server load task manager and select the network tab - what the network utilization % reading? Does the graph it builds show a lot of traffic, or just in spurts?
Commented:
You mentioned that the nic's are teamed. Are the just in failover or otherwise. If they are otherwise than you should trunk the ports on the switch, but if I've read your comments correctly you're using unmanaged switches so trunking won't be possible. Therefore I suggest you remove the teaming and disconnect the second nic. On the first nic you'll be assigning the current ip addresses of the server.

Also "mmicha's" suggestion on setting it to manual speed in full duplex corresponding the speed of the switch is good advice here.

I would try this with just one server and see if it brings any improvement. If not switch back to the way it originally was configured.
Commented:
I just read some info on another case here on EE and there it is stated:

-Do not set speed or duplex to a fixed option, they must match the switch, and with a non-managed switch, the only option is auto-negotiate.

My experiance is only with managed switches so I can't vouch for unmanaged switches.

Author

Commented:
I haven't had a chace to install and try Wireshark, but I will this week.

Author

Commented:
Great suggestions. Thanks

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