too many collisions -- slow network?

[ka]

Hello --

ok, we have about 70+ NT workstations, couple of print servers, and some jet direct cards patched through to our computer room, linked to 4 D-link 10BaseT hubs attached to our router. We're running a novell 4.11 server for file and print services. 3 days ago, users begin to routinely complain of network slowness. the collision lights on the hubs are going a bit crazier than usual, one imparticular. (we suspect a dodgy NIC card somewhere.)

When each port is disconnected from this one hub, nothing changes. So i guess we'll try each hub and look for changes. Any other suggestions on what you first look for when collisions seem high and network is slow? also, is there any software out there to help monitor collisions? i've been looking and looking without success.

any help or advice is much appreciated!

 

[Nostradamus]

Using 70+ workstation on a 10baseT network that only use hubs... that´s gotta be slow. Since you have problems already, try talk the boss into buying switches with support of 100/10 mbit full duplex.
a switch is a lot faster then a hub, especially when you reach as many users (workstations) as you do.

I once had a problem with a hub. Collision lamp went crazy whenever I ran IP or IPX through it (Bay Networks). Netbeu worked fine. Isn´t that strange?

Have you had an increase of workstations lately?

Nostradamus

 

[PhilipSmith]

Ka,

Why not try the opposite approach. Early in the morning or late at night, unplug everything. Then plug each device in one at a time until lights go crazy. This should help you find the problem system.


I hope this helps,
Philip Smith/University of Windsor

 

[ka]

1. Nostradamus:

cheers for the quick reply! unfortunately, a fully switched network isn't in the budget. we are moving to a new floor which will be fitted out in cat5 100Mbs ethernet and getting 1 switch and some smart hubs. so if it is a cable problem, or a problem with one of our old hubs, hopefully it will go away. it's just very odd b/c everything was running fine (maybe not optimal, but usable) for a long time then bang! sluggishness.

2. PhilipSmith:

yes, i too thought of doing this but, (and please correct me if i'm misunderstanding this), when no one's logged in then there are virtually no packets coursing through the veins of our network and therefore no packets to collide. now, if i could disconnect users one by one during the working day this would be ideal. unfortunately it's our busiest time. do you know of any good detection software for finding faults on the network? anything that could help diagnose packet collisions would be of interest.

anyway, thanks for your input --

k.a.

 

[Nostradamus]

with that many users, some collisions is nothing you can avoid. The sudden increase of collisions is perhaps a faulty network card. It is however hard to find since traffic is much higher during working hours, and you don´t want to unplug users. It is however always a little traffic in the network in form of broadcasts, A router, especially, won´t shut up. Probably nothing that causes those collisions but anyway.

I don´t know of any good program, but I know there are lots of them. Search for network tools/sniffers on

http://www.tucows.com

If I were you I would take this problem with calm. I think much (most likely all) of it will dissapear with a faster and smarter network as the one you´re getting.

Nostradamus

 

[kjonnnnn]

There's a trial program (14 days), that you can download for free. It will at least tell you who is sending and receiving a lot of traffic. Its called netboy

Ndgsoftware.com

 

[Guest_imported]

If you are uplinking hubs with cable then take a carefull look at the uplink switch on your hub and as to which ports you are utilising for the uplink. Here too whether you are using cross cable or an uplink MDIX you should carefully check the ports and settings on the hub. If these are configured badly then expect the worst from your network.

 

[ka]

xact --

thanks for the info. this past weekend, we were finally able to methodologically diagnose where the slowness and over abundance of collisions were occurring. it seems to have been a dodgy hub -- we believe it was at the bnc connector in the back which daisy chains the hubs together. when the server was on the bad hub and an active workstation was on a good hub, performance was low. when they were on the same faulty hub, performance was fine (which is why we guess it's the bnc connector). when the server was on a good hub and the workstation was on another good hub (and the bad hub turned off), things worked fine. we replaced the hub in question and our collisions are back to a "normal" amount.

thanks for all the replies -- at least the users aren't complaining anymore! (they aren't saying thank you, exactly, but they're not complaining.)

cheers --- ka