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Data loss on 2MB line (help needed)

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  • Data loss on 2MB line (help needed)


    We have a 2MB backup line to a small satellite site that has recently had problems connecting to our main site. The router at the small site end is a HP router (model unknown but I can't find any errors on it). THe router at the main end and the one I think is causing the problem is a Cisco 3725. I have included below the information about the line.

    Serial0/2 is up, line protocol is up
    Hardware is GT96K Serial
    Description: *** 2Mb/s Circuit to Eastgate ***
    Internet address is
    MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
    reliability 152/255, txload 1/255, rxload 1/255
    Encapsulation PPP, LCP Open
    Listen: CDPCP
    Open: IPCP, loopback not set
    Keepalive set (10 sec)
    Last input 02:09:10, output 00:00:04, output hang never
    Last clearing of "show interface" counters 03:49:22
    Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
    Queueing strategy: weighted fair
    Output queue: 0/1000/64/0 (size/max total/threshold/drops)
    Conversations 0/1/256 (active/max active/max total)
    Reserved Conversations 0/0 (allocated/max allocated)
    Available Bandwidth 1158 kilobits/sec
    5 minute input rate 0 bits/sec, 0 packets/sec
    5 minute output rate 0 bits/sec, 1 packets/sec
    5631 packets input, 367593 bytes, 0 no buffer
    Received 0 broadcasts, 0 runts, 3156 giants, 0 throttles
    2402732 input errors, 2402707 CRC, 2094479 frame, 1146765 overrun, 0 ignored, 1218379 abort
    12713 packets output, 1291833 bytes, 0 underruns
    0 output errors, 0 collisions, 6 interface resets
    0 output buffer failures, 0 output buffers swapped out
    0 carrier transitions

    My main concern is the reliability. It shows on average 150/255 and this is reflected when
    trying to ping the router at the far end. If I leave ping running for 15 minutes I will
    have approximatly 40-60% sucess rate. Basically I can get a reply half the time and
    for the rest of the time I get a timeout error. I have called BT who have checked the line
    and they report that there are no faults on it.

    As I don't know much about Cisco (previous team member was our Cisco guy) I'm at a loss as
    to what to do. I belive the reliability counter is trying to tell me what the problem is
    but I don't know enough about it to be able to diagnose.

    Can anyone help me please?

    DCD=up DSR=up DTR=up RTS=up CTS=up

  • #2
    Re: Data loss on 2MB line (help needed)

    What type of line are you using? Cable modem? DSL?
    MCITP:SA, MCSA 2003, MCP, CCNA, A+, Net+, Security+


    • #3
      Re: Data loss on 2MB line (help needed)

      It's a leased line in the UK, so DSL.

      Thanks for a quick response!


      • #4
        Re: Data loss on 2MB line (help needed)

        I had a similar issue with this at a site once. It would continually drop the connection and became unreliable.

        To resolve my situtation I had to lower the size of the MTU packets being transmitted by the routers to avoid blackhole issues that occur with some ISPs. The issues can be remedied on the comptuer, but can also be satisfied at the routers as well. My recommendation would be on the router.

        Here's a link with more information:

        MCITP:SA, MCSA 2003, MCP, CCNA, A+, Net+, Security+


        • #5
          Re: Data loss on 2MB line (help needed)

          Thankyou Boondock, I'll be implementing this today and will report back with how it goes!


          • #6
            Re: Data loss on 2MB line (help needed)


            No luck with that. Regardless of how low I set the thresehold it still drops packets. Any other ideas?

            Appericiate the help so far.


            • #7
              Re: Data loss on 2MB line (help needed)

              Can you post the configs of both routers?
              CCNA, Network+