here's a FECN question for the network techs in the room...

Discussion in 'Computer Security' started by Dood, Dec 21, 2004.

  1. Dood

    Dood Guest

    I've got a router with a full T-1 plugged in. I've configured traffic
    shaping and FULL CIR. I've confirmed with Bell South that they are set
    to FULL CIR on there side also. So supposedly both sides are set for
    full T-1 CIR. My problem is the fact that my router is seeing approx
    5000 FECNs per hour, even when I show 30 to 40 percent utilization on
    my line. I've configured my router to throttle back when it recieves
    FECNs instead of shutdown. I have a WAN Sniffer inline on my serial
    link inbetween my CSU and my router. I've run captures and history
    samples and benchmark utilization. I've tasked Bell South to tell me
    which frame switch is sending my router the FECN's, but so far no
    luck. Has anyone else experienced anything like this? I could be
    wrong, but if both sides are set to FULL CIR, I don't think I should
    see FECNs even if I oversubsribe my circuit. Both sides should be
    transmitting and recieving at the same speed.

    Any input is greatly appriciated, Peace.

    Network Dood.
    Dood, Dec 21, 2004
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  2. Dood

    donnie Guest

    What router are you using? Athough it appears to be a telco problem,
    you might want to hear what the router manufacturer has to say.
    donnie, Dec 21, 2004
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  3. First a couple of things. If you are using Frame Relay on a T1 (physical)
    you can NOT over subscribe (over 1.54 Mbs). Remember you can only go as
    fast as the physical layer permits. In other words try to get more than
    1.54 Mbs on a T1 is NOT possible.

    Second, you should look at the stats on the physical (T1) and data link
    (Frame Relay) layers. Look for errors on both. It is posssible that you
    have some sort of error that is causing packet loss.

    Michael J. Pelletier, Dec 21, 2004
  4. Dood

    Dood Guest

    Thanks for the input guys. I've had the router vendor, Nortel,
    conferenced with Bell South, and according to Nortel, my router is
    configured correctly for full CIR on a T-1. According to Bellsouth I'm
    not oversubscribing my circuit. Most of the day the router sits at 30
    to 40 percent utilization. I'm not seeing errors increment anywhere I
    look. I'm using Sniffer and Ethereal to look, and both are reporting
    the same data as far as utilization on the pipe goes. I just keep
    seeing FECNs from the cloud which tells my router to throttle back.
    Bell South has run stress tests and found "nothing wrong". One
    Bellsouth guy even told me the FECNs must be coming from my router. I
    had to very calmly explain to him that I don't own a piece of hardware
    capable of generating FECNs, Frame switches generate FECNs. Sometimes
    you wonder where they get there techs from. I wonder how much they
    pay? I'm gonna swap the router out as soon as I can to rule out that
    possibilty, even though I really don't think my routers the issue. I
    think there is congestion somewhere in the frame cloud that Bell south
    needs to fix.
    Dood, Dec 22, 2004
  5. Dood

    donnie Guest

    You're probably right, but I thought I would mention the router anway.
    Swaping the router is a good test.
    donnie, Dec 22, 2004
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