[c-nsp] Unexplainable Output drops on serial interfaces

[Todd Shipway]

The multilink interface had qos setup but not on the individual serial  
interfaces.  However I am seeing these drops on interfaces with no qos  
or shaping on them as well.


On Feb 19, 2009, at 3:03 PM, "David Freedman" <david.freedman at uk.clara.net 
 > wrote:

> Todd, do you have any kind of shaping / QoS on these circuits?
>
> Drops by traffic management configurations are frequently shown as
> interface drops.
>
> Dave.
>
>
> Todd Shipway wrote:
>> Hi,
>>
>> We have multiple T1 interfaces across different cards and different  
>> type
>> of cards in a 7513.  Many interfaces are showing output drops and I
>> can't pinpoint why.  The interfaces are spread throughout the  
>> system and
>> I can't pinpoint a single point that could be causing the drops.   
>> Below
>> is 2 interfaces showing the drops.
>>
>> The bandwidth is very low when the drops are occurring, these 2
>> interfaces are part of a multilink interface which shows no drops.   
>> Any
>> ideas as to what I should look for that could be causing this?
>>
>> Serial9/0/0:12 is up, line protocol is up
>>  Hardware is cyBus T3
>>  Description: Bonded T1
>>  MTU 1500 bytes, BW 1540 Kbit, DLY 20000 usec,
>>     reliability 255/255, txload 11/255, rxload 5/255
>>  Encapsulation PPP, LCP Open, multilink Open
>>  Link is a member of Multilink bundle Multilink66, crc 16, loopback  
>> not
>> set
>>  Keepalive set (10 sec)
>>  Last input 00:00:00, output 00:00:00, output hang never
>>  Last clearing of "show interface" counters 6d03h
>>  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops:
>> 4050
>>  Queueing strategy: fifo
>>  Output queue: 0/100 (size/max)
>>  5 minute input rate 33000 bits/sec, 19 packets/sec
>>  5 minute output rate 68000 bits/sec, 18 packets/sec
>>     3121597 packets input, 667733893 bytes, 0 no buffer
>>     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
>>     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
>>     2929740 packets output, 1363133541 bytes, 0 underruns
>>     0 output errors, 0 collisions, 0 interface resets
>>     0 output buffer failures, 0 output buffers swapped out
>>     0 carrier transitions no alarm present
>>  Timeslot(s) Used: 1-24, Transmitter delay is 0 flags
>>  non-inverted data
>>
>> Serial9/0/0:11 is up, line protocol is up
>>  Hardware is cyBus T3
>>  Description: Bonded T1
>>  MTU 1500 bytes, BW 1540 Kbit, DLY 20000 usec,
>>     reliability 255/255, txload 10/255, rxload 5/255
>>  Encapsulation PPP, LCP Open, multilink Open
>>  Link is a member of Multilink bundle Multilink66, crc 16, loopback  
>> not
>> set
>>  Keepalive set (10 sec)
>>  Last input 00:00:00, output 00:00:00, output hang never
>>  Last clearing of "show interface" counters 6d03h
>>  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops:
>> 4085
>>  Queueing strategy: fifo
>>  Output queue: 0/100 (size/max)
>>  5 minute input rate 31000 bits/sec, 19 packets/sec
>>  5 minute output rate 65000 bits/sec, 17 packets/sec
>>     3122847 packets input, 668516220 bytes, 0 no buffer
>>     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
>>     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
>>     2930011 packets output, 1364226428 bytes, 0 underruns
>>     0 output errors, 0 collisions, 0 interface resets
>>     0 output buffer failures, 0 output buffers swapped out
>>     0 carrier transitions no alarm present
>>  Timeslot(s) Used: 1-24, Transmitter delay is 0 flags
>>  non-inverted data
>>
>> Multilink interface for the T1's above:
>> Multilink66 is up, line protocol is up
>>  Hardware is multilink group interface
>>  Description: Bonded T1
>>  Internet address is 10.10.56.1/30
>>  MTU 1500 bytes, BW 3080 Kbit, DLY 100000 usec,
>>     reliability 255/255, txload 11/255, rxload 4/255
>>  Encapsulation PPP, LCP Open, multilink Open
>>  Open: IPCP, loopback not set
>>  Keepalive set (10 sec)
>>  DTR is pulsed for 2 seconds on reset
>>  Last input 00:00:30, output never, output hang never
>>  Last clearing of "show interface" counters 1w0d
>>  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output  
>> drops: 0
>>  Queueing strategy: Class-based queueing
>>  Output queue: 0/40 (size/max)
>>  5 minute input rate 58000 bits/sec, 47 packets/sec
>>  5 minute output rate 139000 bits/sec, 49 packets/sec
>>     7075294 packets input, 1705142684 bytes, 0 no buffer
>>     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
>>     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
>>     7483773 packets output, 3524642362 bytes, 0 underruns
>>     0 output errors, 0 collisions, 0 interface resets
>>     0 output buffer failures, 0 output buffers swapped out
>>     0 carrier transitions
>>
>> Any help would be appreciated.  As I said earlier, this scenario is
>> happening on multiple interfaces throughout the system.  A  
>> Channelized
>> DS3 card has been swapped out as a test as well as the output queue
>> raised from 40 to 100 with no change in drops.
>>
>> -Todd
>>
>>
>>
>> --- 
>> ---------------------------------------------------------------------
>>
>> _______________________________________________
>> cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/cisco-nsp
>> archive at http://puck.nether.net/pipermail/cisco-nsp/
>