LAN connection slow

55 pts.
Tags:
Networking
Performance management
Hello, We are running a LAN of around 45 nodes connected using two dlink 100Mbps switches. The network is connected to the internet via a CISCO router. My problem is with the LAN performance where I am not getting anything above 10-20Mbps speed while doing file transfers from node to node. All are running Redhat Linux. Please advise.
ASKED: June 15, 2006  10:40 AM
UPDATED: June 16, 2006  7:34 AM

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Make sure the port speed and duplex match between the PCs and the switches. You may want to manually set the speed/duplex on the NICs and switch if you can. ‘Auto’ is a nice idea, but doesn’t work very well when you mix vendors.

—JRE—

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  • Jrerickson
    Make sure the port speed and duplex match between the PCs and the switches. You may want to manually set the speed/duplex on the NICs and switch if you can. 'Auto' is a nice idea, but doesn't work very well when you mix vendors. ---JRE---
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  • Kerrwj
    There are many reasons for slow network performance. JRE is right on with one of the more common causes. Q - how did you measure 10-20 Mbps? Is this bits or bytes per sec? 10-20M bytes/sec = 80-160M bits/sec, so may be normal performance depending on how you measured the throughput. What machines did you measure between? Was the performance ever good? When did it slow down? Other possibilities: - Check for link/interface errors on your switches if your dlink is manageable. Check for errors on your pc nics. If your testing happened to be between several nodes and the server, it may be speed/duplex settings to the server or a bad cable to the server. You may want to reset the counters/reboot the pcs before checking the error counters. - If you're not doing anything on the network, what is the traffic level? Could be chattering nics, a loop, a misbehaving application (including infections) causing a high background traffic level. Do you have adequate virus/spyware protection?
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  • Aromalrajagopal
    Hi guys, I am measuring the traffic IN/OUT of the individual machines and the NIC settings too. It was set for auto negotiation where the speed was autonegotiated to 100Mbps and I have turned that off and set to 100Mbps without negotiation. Couldnt see any collisions also. I am going to read the router traffic via snmp and shall get back to you guys on the traffic. Already monitoring the traffic from our main internal servers. Thanks for your help so far.
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  • Jwilkins
    Just locking the nics to 100/Full doesn't always cut it. The switch ports and the nics should have the same settings. Make sure your node types are not broadcast as well. ipconfig /all I have seen several systems around our site that display broadcast node. If this is the case start checking DNS suffix settings, subnet mask, etc.
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