interface Output drops. Lan users complain about latency.

[Marc_AMI1]

Hello Guys,

 Linux Users connected to my Access user switch are complaining about latency.

I Checked the sw interfaces : Does any one now why do I have output drops pleaaase ?

	User int speed configuration on PC		sw Interfaces
127 input errors, 120 CRC, output drops: 6560435	1Gb		G4/0/35
65 input errors, 59 CRC, output drops: 4118716	1Gb		G4/0/31
53 input errors, 49 CRC, output drops 2072336	1Gb		G4/0/28
output drops 94122	1Gb		G3/0/15
output drops: 2539	1Gb		G4/0/30
148 input errors, 137 CRC, output drops 29049107	1Gb		G3/0/21
output drops: 3923988	1Gb		G2/0/24
output drops: 302659	1Gb		G1/0/9
Disabled	1Gb		G3/0/44
output drops: 2536	1Gb		G3/0/14
output drops: 1350036	1Gb		G1/0/22
output drops: 9428	1Gb		G2/0/7
output drops: 74435	1Gb		G2/0/22
output drops: 54846	1Gb		G3/0/9
output drops: 5092185	1Gb		G1/0/2
output drops: 159657	1Gb		G2/0/15
output drops: 630711	1Gb		G2/0/34
Not connected	1Gb		G4/0/38
72 input errors, 56 CRC, output drops: 10383796	1Gb		G4/0/37
output drops: 1413181	1Gb		G4/0/39
output drops: 58514	1Gb		G1/0/26
output drops: 237431	1Gb		G2/0/33
9162 input errors, 8676 CRC, output drops 82234343	1Gb		G1/0/39
925 input errors, 862 CRC, output drops 1846412	1Gb		G1/0/35

[Mark Malone]

Not really in logs for something like that you would need to check it with show int status

you could do it in prime in compliance but it would need to run and check and then report on it , standard cisco logs wouldn't pick something like that up when its set to auto negotiate

if someone is changing it on the router itself you could do it by archiving to see how and when and what they changed it and were logged in

[Marc_AMI1]

Hello Mark, I hope you are doing fine. I was hoping getting some help about this situation :

I want to prouve if my users latencies are coming from the output drops on users interfaces.

Below a sh int  of a user interface  :

GigabitEthernet4/0/34 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is e05f.b9f3.a322 (bia e05f.b9f3.a322)
  Description: *** STATION LINUX ***
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 8/255, 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 00:00:12, output hang never
  Last clearing of "show interface" counters 1d16h
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 275254
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1786000 bits/sec, 1896 packets/sec
  5 minute output rate 32018000 bits/sec, 3073 packets/sec
     28232562 packets input, 6897462495 bytes, 0 no buffer
     Received 0 broadcasts (0 multicasts)
     0 runts, 0 giants, 0 throttles
     6 input errors, 6 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     43043836 packets output, 56759910462 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     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

we see 275254 drops in 1d16h up time.

QOS is configured on my user interface. Could we now from which queue these drops are comming.

Here is a sh run int of the interface.

interface GigabitEthernet4/0/34
 description *** STATION LINUX ***
 switchport access vlan 50
 switchport mode access
 ip arp inspection trust
 ip arp inspection limit rate 100
 speed auto 1000
 srr-queue bandwidth share 12 8 30 50
 queue-set 2
 priority-queue out
 no snmp trap link-status
 storm-control broadcast level 5.00
 spanning-tree portfast
 spanning-tree bpduguard enable
 ip dhcp snooping limit rate 100
 ip dhcp snooping trust
end

Many thanks for your help.

[Mark Malone]

Hi

this command alone can be known to introduce slight latency as your telling router to wait service them 1st then when its empty service other queues ------ priority-queue out

to see queues in mls use the show mls qos interface gx/x statistics

Have you checked the path as well that they are taking src - dst ran a tracert or traceroute or mtr to see where the delay/latency is  to make sure its not qos ?

Have you tried removing qos off the switch to see if the latency is better , qos splits the buffers and can cause issues as well on certain platforms like 3750s or alter teh srr queues as well for the drops