[c-nsp] Output drops mysteriously appear/disappear on 3750X
Tóth András
diosbejgli at gmail.com
Wed Aug 22 14:42:45 EDT 2012
Hi Eric,
This seems to be caused by the below software bug.
CSCtq86186 - Switch stack shows incorrect values for output drops on
show interfaces
http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtq86186
I've verified that this affects 15.0(1)SE3 and it'll be fixed in 15.0(2)SE.
You can use the 'show platform port-asic stats drop' command to check
hardware drop counters.
Best regards,
Andras
On Wed, Aug 22, 2012 at 12:38 AM, Eric Van Tol <eric at atlantech.net> wrote:
> Hi all,
> I've got a pair of stacked 3750X switches running 15.0(1)SE3 and I'm noticing something funky. On a pair of mirror destination ports, I'm seeing output drops appear and disappear in the CLI output of 'show interface' at random intervals. What I mean by this is, after clearing counters on all interfaces, I can do a 'show int gi1/0/16' and see 'output drops 0' re-run the command one second later and see 'output drops 39428200', then re-run the command another second later and see 'output drops 0' again. I see it on four monitor session destination ports. The problem started somewhat randomly one day last week, after having working fine for two days prior after being put into production use.
>
> Anyone ever seen this before? I'm pretty sure it's not just a cosmetic issue, as the analyzer attached to these ports is seeing "packet loss" on the traffic its analyzing, but I don't believe the source ports are actually seeing any loss.
>
> Output is below - take note of the 'Last clearing of counters' times.
>
> -evt
>
> ~~~~~~~~~~~~~~
> vsw1-1213c.ss.sls.md#sh int gi2/0/17
> GigabitEthernet2/0/17 is up, line protocol is down (monitoring)
> Hardware is Gigabit Ethernet, address is d48c.b549.4511 (bia d48c.b549.4511)
> Description: VL Mirror Port
> MTU 9198 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
> reliability 255/255, txload 1/255, rxload 1/255
> Encapsulation ARPA, loopback not set
> Keepalive set (10 sec)
> Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
> input flow-control is off, output flow-control is unsupported
> ARP type: ARPA, ARP Timeout 04:00:00
> Last input never, output never, output hang never
> Last clearing of "show interface" counters 01:23:22
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
> Queueing strategy: fifo
> Output queue: 0/40 (size/max)
> 30 second input rate 0 bits/sec, 0 packets/sec
> 30 second output rate 3868000 bits/sec, 2243 packets/sec
> 0 packets input, 0 bytes, 0 no buffer
> Received 0 broadcasts (0 multicasts)
> 0 runts, 0 giants, 0 throttles
> 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
> 0 watchdog, 0 multicast, 0 pause input
> 0 input packets with dribble condition detected
> 24027518 packets output, 5217538085 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 babbles, 0 late collision, 0 deferred
> 0 lost carrier, 0 no carrier, 0 pause output
> 0 output buffer failures, 0 output buffers swapped out
> vsw1-1213c.ss.sls.md#sh int gi2/0/17
> GigabitEthernet2/0/17 is up, line protocol is down (monitoring)
> Hardware is Gigabit Ethernet, address is d48c.b549.4511 (bia d48c.b549.4511)
> Description: VL Mirror Port
> MTU 9198 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
> reliability 255/255, txload 1/255, rxload 1/255
> Encapsulation ARPA, loopback not set
> Keepalive set (10 sec)
> Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
> input flow-control is off, output flow-control is unsupported
> ARP type: ARPA, ARP Timeout 04:00:00
> Last input never, output never, output hang never
> Last clearing of "show interface" counters 01:23:23
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 39428034
> Queueing strategy: fifo
> Output queue: 0/40 (size/max)
> 30 second input rate 0 bits/sec, 0 packets/sec
> 30 second output rate 3868000 bits/sec, 2243 packets/sec
> 0 packets input, 0 bytes, 0 no buffer
> Received 0 broadcasts (0 multicasts)
> 0 runts, 0 giants, 0 throttles
> 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
> 0 watchdog, 0 multicast, 0 pause input
> 0 input packets with dribble condition detected
> 24027518 packets output, 5217538085 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 babbles, 0 late collision, 0 deferred
> 0 lost carrier, 0 no carrier, 0 pause output
> 0 output buffer failures, 0 output buffers swapped out
> vsw1-1213c.ss.sls.md#sh int gi2/0/17
> GigabitEthernet2/0/17 is up, line protocol is down (monitoring)
> Hardware is Gigabit Ethernet, address is d48c.b549.4511 (bia d48c.b549.4511)
> Description: VL Mirror Port
> MTU 9198 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
> reliability 255/255, txload 1/255, rxload 1/255
> Encapsulation ARPA, loopback not set
> Keepalive set (10 sec)
> Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
> input flow-control is off, output flow-control is unsupported
> ARP type: ARPA, ARP Timeout 04:00:00
> Last input never, output never, output hang never
> Last clearing of "show interface" counters 01:23:23
> Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
> Queueing strategy: fifo
> Output queue: 0/40 (size/max)
> 30 second input rate 0 bits/sec, 0 packets/sec
> 30 second output rate 3868000 bits/sec, 2243 packets/sec
> 0 packets input, 0 bytes, 0 no buffer
> Received 0 broadcasts (0 multicasts)
> 0 runts, 0 giants, 0 throttles
> 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
> 0 watchdog, 0 multicast, 0 pause input
> 0 input packets with dribble condition detected
> 24048581 packets output, 5222039119 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 unknown protocol drops
> 0 babbles, 0 late collision, 0 deferred
> 0 lost carrier, 0 no carrier, 0 pause output
> 0 output buffer failures, 0 output buffers swapped out
>
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