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high outdiscards on serial T1 interface on cisco 7513

Posted on 2004-10-28
Medium Priority
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
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LVL 79

Expert Comment

ID: 12437273
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?

Expert Comment

ID: 12443904
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

ID: 12446570
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
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Author Comment

ID: 12446584
oh yes and I thought about clearing the buffer too.  Thoughts/

LVL 79

Accepted Solution

lrmoore earned 1200 total points
ID: 12446948
>    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.

Assisted Solution

AutoSponge earned 800 total points
ID: 12447211
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.

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