Slowing LAN

Posted on 2007-11-13
Last Modified: 2010-04-12
Hi, I have two 3Com switches one in the server room and one in a CAD office both with 4 fibre ports, they are linked via a fibre cable in port 1 of each switch and this has been fine up to now but the operators are telling me that it is slowing down.
This office has around 25 CAD operators designing houses with files stored on a server in the server room, all work is done across the network via a mapped drive and this cannot change.
My question is if I run a second fibre cable between the two switches will this increase the speed or create bottlenecks?
Or should I get another fibre switch in the CAD office and split the users over the two using two fibres?
Are there any network testing tools to see which user is using the most bandwidth? Are there any other ways to get around this?

Any assistance is appreciated.
Question by:Brum07
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Accepted Solution

Sahmeepee earned 250 total points
ID: 20278276
You can put another fibre in and aggregate the link, yes. It should (roughly) double your bandwidth. If you install the free 3com network supervisor from the 3com website you can do some basic troubleshooting, analysis and admin on the switches. You may need to set them up with IP addresses first though.

Also, as far as monitoring them goes, on most 3com switches you can check via the web administration interface on the switches which ports have passed the most data since the last switch reboot (or in the last 10 seconds). Again the switches will need IP addresses set up for this to work.

If you don't mind paying a little for monitoring I can recommend PRTG - that will show you the throughput on individual ports on each switch, including the fibre ports. You can try out the free version with 3 ports I think. The paid-for version is very reasonable though.
LVL 13

Author Comment

ID: 20278323
Would I need to Aggregate both switches?

Expert Comment

ID: 20278360
I would advise you to do some analysis before jump into conclusion.  As you mention you have 25 CAD user span over 2 room?  Each room have their dedicated switch?
So which room user are facing slowness?
How many user are there in each room?
What are the average file size the user are pulling from the server?
What is the Serve4r bandwidth for this setup?
Could it be the server slow?

Need more details before I can advise...
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Expert Comment

ID: 20278369
 If you have 4 core fibers, you do not need to have pull additional fiber. Patch the remaining 2 cores to your second fiber port on both of your switches. But, before adding fiber, you can use NMS like MRTG to sniff your network port utilizations. Analyze your network before you make any changes.

LVL 13

Author Comment

ID: 20278386
There is only 1 cad room with 25 users and 1 3Com switch then a fibre switch in the server room.
The Server is a DL380 with 6 146GB in a RAID 5 giving 700GB with over 200Gb free it has 2GB RAM and 2 Xeon 3.4's the network is teamed to give a 2GPS connection stright to the fibre switch via CAT6.

The average file size is approx 10MB

Expert Comment

ID: 20279004
Installed anything suspiciously lately? Like a firewall?
LVL 13

Author Comment

ID: 20279122
Nothing on the network has changed over the past 6 months.

Expert Comment

ID: 20282701
I should probably add that you can use Windows's own built in performance monitor to monitor multiple remote hosts' bandwidth usage remotely. It is a tad fiddly to set up, but certainly doable:

Start>Run>Perfmon (you'll need to run this as an administrator)
Delete 3 default counters with the delete key
Click the + to add a counter

Select counters from: \\CAD-PC01 (say)
Performance object: Network interface
Select counters from list: Bytes total/sec (for now anyway)
Select instances from list: Intel PRO100 Ethernet Card (or whatever their network card is called)
Click Add

Select counters from: \\CAD-PC02

When you've added them all, click Close and you will be able to see the traffic each PC is generating. You may need to mess with the scale on the graph to get it displaying nicely.


Expert Comment

ID: 20286180
There on sourceforge has some network protocol analysising tools for free. You can check them out. Maybe try something like wireshark something along this lines.
LVL 13

Author Comment

ID: 20287858
OK, I think I may of found an issue after running loads of tests, the main Switch in the server accessed via HTTP to manage shows all of the ports in use as Port enabled, link present, reduced speed instead of Port enabled, link present, maximum speed except for the fibre link which is at Maximum speed.
All of the cables are CAT6 and the servers all have gigabit ports so the should be at Maximum speed!
I am going to replace this switch (as it is 2 years old anyway) and aggregate the CAD office with a 2nd fibre as per Sahmeepee.

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