[c-nsp] Unexplainable Output drops on serial interfaces

Todd Shipway todd at newfrontierssolutions.com
Thu Feb 19 15:22:52 EST 2009


No. I don't graph each card VIP usage. But that is actually my weekend  
project.

Card 9 (channelized ds3) has the most int with drops and I've got more  
VIP memory to put in it. But average usage is low. Other cards have  
128mb memory and low amount of interfaces being used but still show  
drops. I'll check CPU usage once again when I get back to the office.



On Feb 19, 2009, at 3:15 PM, "David Freedman" <david.freedman at uk.clara.net 
 > wrote:

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> What about the VIP CPU load on these VIPs? do you graph it?
>
> Todd Shipway wrote:
>> 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
>>>>
>>>>
>>>>
>>>> --- 
>>>> --- 
>>>> ------------------------------------------------------------------
>>>>
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>>>
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