high outdiscards on serial T1 interface on cisco 7513

Posted on 2004-10-28
Last Modified: 2008-01-09
I have racked my brain.  Outbound utilization is only 26% in 95th percentile.  Inbound only 7%.  Showing fairly high outdiscards in the 2% to 3% range for low utilization.   Short of calling in an outage and swapping out the interface for bad hardware.  Do any of you folks have soloutions that I might try.

Thanks in advance

Question by:tnystuen
    LVL 79

    Expert Comment

    What type of connection is it? Frame-relay? Leased line point-to-point?
    Can you post output of "show interface serial x/x/x so we can see what type errors your aare seeing that would cause the discards?
    Do you have external CSU/DSU, or is the DSU on the router module itself?
    LVL 5

    Expert Comment

    Do all that stuff and also do a "show buff fail" so I can see if your output drops are connected to buffer overruns.

    Author Comment

    It is a serial point to point, no csu/dsu and when I did a show buff fail nothing came up.  Of course it could mean I do not have access to that command.

    Here is the output from ho int s10/1/1

    I have removed the router name and ips due to security.
    sho int s10/1/1
    Serial10/1/1 is up, line protocol is up
      Hardware is cyBus Serial
      Description: : serial link to
      Internet address is
      MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, rely 255/255, load 66/255
      Encapsulation HDLC, crc 16, loopback not set
      Keepalive set (10 sec)
      Last input 00:00:03, output 00:00:01, output hang never
      Last clearing of "show interface" counters never
      Queueing strategy: VIP-based fair queuing
      Output queue 0/40, 106631 drops; input queue 0/75, 0 drops, 0 flushes
      5 minute input rate 108000 bits/sec, 89 packets/sec
      5 minute output rate 398000 bits/sec, 75 packets/sec
         131408271 packets input, 3885956237 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         600598 input errors, 536863 CRC, 0 frame, 55994 overrun, 7936 ignored, 7741
         116960014 packets output, 905622066 bytes, 0 underruns
         0 output errors, 0 collisions, 10 interface resets
         0 output buffer failures, 0 output buffers swapped out
         45 carrier transitions
         RTS up, CTS up, DTR up, DCD up, DSR up

    Author Comment

    oh yes and I thought about clearing the buffer too.  Thoughts/

    LVL 79

    Accepted Solution

    >    600598 input errors, 536863 CRC, 0 frame, 55994 overrun, 7936 ignored, 7741 abort
    >     45 carrier transitions

    This amount of errors is unacceptible.
    I would call the telco and make sure they clean up this circuit. 90% of the time, these errors are telco related - bad dax somewhere, bad wire pairs in the street, cross-ixc timing issues, etc. The other 10% is if you have bad wiring between the router and the telco's smart jack.
    LVL 5

    Assisted Solution

    Counters were never cleared, so it sort of depends on how long this has been up, but yes, that's a lot of errors.  It would be very helpful to have a CSU on this to help determine the nature of the errors, but telco is certainly is your starting point unless you have a T1 loopback plug that you can place on one end or the other.  If you do that and see the errors go away (while continuously pinging to an address you won't succeed on) then the problem has been isolated to a wire/interface beyond that.  It could also be a clocking problem, since it's p2p and all, telco probably isn't providing a clock.  If you're taking errors quickly then you reboot the router and it runs error free for a while, you've probably got  a clocking problem.

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone. Privacy Policy Terms of Use

    Featured Post

    Anonabox PRO Tor & VPN Router

    PRO is the most advanced way to fortify your privacy and online anonymity by layering the Tor network with VPN services. Use both together or separately, and without needing to download software onto your devices.

    The DSL Parameters part of this article is valid and can be considered with any brand of internet router and modem (Dlink, 3com, Alcatel, Usrobotics, Parks), by accessing the configuration interface available by the manufacturer eg: …
    Article by: IanTh
    Hi Guys After a whole weekend getting wake on lan over the internet working, I thought I would share the experience. Your firewall has to have a port forward for port 9 udp to your local broadcast x.x.x.255 but if that doesnt work, do it to a …
    Viewers will learn how to connect to a wireless network using the network security key. They will also learn how to access the IP address and DNS server for connections that must be done manually. After setting up a router, find the network security…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

    875 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    14 Experts available now in Live!

    Get 1:1 Help Now