Swicth Issues - Intranet
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Thread: Swicth Issues - Intranet

  1. #1
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    Exclamation Swicth Issues - Intranet

    Just a quick question....

    I was analyzing some bandwidth issues we are having here at work, in our help desk support area, and i have traced the problem back to the switch for that segment of the network. I have some questions though, considering i am not a networking guru.

    The switch is a Cisco3500(Xl-C3H2S-M) Version 12.0(5)Wcb3

    I walked the configuration of the switch, Via. SNMP, and found some things that i thought were unusual:

    A. The switch is only learning a few "MAC to Switch port" relationships.

    B. On the most active Ports there is a high amount of transmitting and receiving errors.

    C. There is an interface on the switch that appears and disappears.

    Also when connecting a five port linksys switch to a port in any cube, it does not detect that we are running at full duplex and shows numerous collisions through out the day.

    I am not apart of our networking group and of course they say everything is fine...

    I have come to 2 conclusions:

    A. The switch is not configured properly and my need a firmware upgrade.

    B. We are not operating on a truly switched network. The topology leads me to believe that some how, some where, the PCs are not isolated to their own collision domain?

    Any ideas?

    Last edited by encipher; May 8th, 2007 at 01:17 AM.

  2. #2
    Just Another Geek
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    Quote Originally Posted by encipher
    A. The switch is only learning a few "MAC to Switch port" relationships.
    As PC's and servers don't change that often this should be normal.
    B. On the most active Ports there is a high amount of transmitting and receiving errors.
    Check the cables. Also fixate the speed/duplex settings on the switch AND the NICs connected to it.
    C. There is an interface on the switch that appears and disappears.
    Which interface? Is it a GBIC? It may need to be replaced?
    Oliver's Law:
    Experience is something you don't get until just after you need it.

  3. #3
    Senior Member Aardpsymon's Avatar
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    sounds like a dodgy switch to me. but that could be as simple as a loose cable or even a damaged cable. One PC sends crappy data to a switch it can wreck everything else on that switch.
    If the world doesn't stop annoying me I will name my kids ";DROP DATABASE;" and get revenge.

  4. #4
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    Quote Originally Posted by SirDice
    As PC's and servers don't change that often this should be normal.

    Check the cables. Also fixate the speed/duplex settings on the switch AND the NICs connected to it.

    Which interface? Is it a GBIC? It may need to be replaced?
    That cant be normal... I think i should elaborate more.

    There are about 20+ PCs connected to the switch and out of those 20 only 3, if that, have been learned by the switch. When looking at the "look up" table, the MAC address' are listed as learned but the interface they are connected is UNKNOWN.

    Doesn't that degrade the performance of the switch...? If the switch has 20 PCs connected to it, and it only knows where 3 of them are, wont that increase the time it takes to locate what interface a PC, that has an UNKOWN interface listed, is connected to?

    Again im not apart of the networking group, but according to them, they have checked the cables and tried forced 100MB Full Duplex instead of auto-negotiating (settings were changed respectively on the PCs).

    The interface is fast ethernet...

    Im not expecting anyone to solve this but i just want some opinions

    Thanks for your responses so far... Im looking forward to some more



  5. #5
    Just Another Geek
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    Are there (other) switches or hubs connected to any of those ports?
    Oliver's Law:
    Experience is something you don't get until just after you need it.

  6. #6
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    I know there is not another switch connected... As far as i know there is not a hub either but i cannot be 100% sure of that...

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