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How do I identify causes of a network sl

By dave ·
Running 3 Netware3.2 servers on one site, thru a 16-port 10/100 switch into 10Mb and 100Mb hubs. Approx 80 users. Mix of Cat5 UTP and BNC. Also some IP traffic for shared web browsing via proxy server.

Occasionally segments of the network slowright down (sometimes some software times out and falls over, sometimes the Client32 comes up with the "re-connect in background" message). The servers load % never goes above 20% and no significant network errors are reported at the server.Then some random time later all is back to normal and it doesn't happen again for weeks. Never been able to pin down whats happening.

We don't have network analysers.

What might it be?

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How do I identify causes of a network sl

by guy In reply to How do I identify causes ...

This is a job for Performance Monitor.
Monitor each server, not only for Processor, but also for Processes and Network Segment.

Finally if you have NT, you could install then Network Monitor Tools and Agent which comes with NT and is a very goodNetwork Protocol Analyser.

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How do I identify causes of a network sl

by dave In reply to How do I identify causes ...

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How do I identify causes of a network sl

by Haggis In reply to How do I identify causes ...

Firstly i suggest verifiying that all nodes are getting 100MB connections where possible, especially on the server. Is the switch perhaps not granting 100 MB connection for some reason ? Also check for error stats like dropped packets etc. Also check server that packet receive buffers are not maxed out and directory cache buffers are not maxed out. If so increase settings. BNC cabling can be a nightmare. Is there a pattern with PC's that are experiencing slowness ?

This sort of stuff is really prerequisite before protocol analysers should be used.

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How do I identify causes of a network sl

by dave In reply to How do I identify causes ...

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How do I identify causes of a network sl

by White Wolf In reply to How do I identify causes ...

Since I work at a service bureau I tend to deal with this alot. One possibility you need to examine is your *Network Bandwidth* becoming pulled down by a large file x-fer by one of the users/clients on the network. If you need something to do a quick network analysis - I suggest using Network instruments Observer (a demo is available at www.networkinstruments.com) to examine what's happening at the packet level. It's quick and relatively simple to bring up & scope out what's going on when a network slow is occuring. Armed with that info you can usually work out how deal with it from there. I usually pinpoint as being a user ripping down a big DL off the net, and ask that user to attempt the DownLoad in off hours.

- Good Luck!

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How do I identify causes of a network sl

by dave In reply to How do I identify causes ...

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How do I identify causes of a network sl

by Duster52 In reply to How do I identify causes ...

There are so many reasons....Obviously you need to determine what is happening during this slow down. Is one user 'hogging' the bandwidth? Does it happen to a particular subset of users? Can you correlate it to a time of month - such as end-of-month processing? When this does happen look at the disk activity on the servers, that might give you a clue. Do you have any way of looking at the utilization on your switch and hubs? Maybe the network hardware has dropped it's connections and is trying to reconnect and is having problems negotiating a connection speed and duplex. You may even have a NIC in one of your workstations that is chattering and flooding the wire.

The only true way to determine what is really happening is to put asniffer on the network and capture traffic.

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How do I identify causes of a network sl

by dave In reply to How do I identify causes ...

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How do I identify causes of a network sl

by isys In reply to How do I identify causes ...

Someone is moving big files or streaming video. If you run both IPX and IP, they both will transport data. IP isn't the problem; IPX is. Unless you can determine who is doing it (from the proxy logs), updating to Netware 5 to eliminate IPX is your only real solution. I had the same problem with a pure 100 Mbps network, so replacing hardware will not cure it.

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How do I identify causes of a network sl

by dave In reply to How do I identify causes ...

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