C9500-48Y4C - Total output drops high

[jds5]

Hello,

I ask you to understand where the high drops come from on a channel port of two 10G interfaces

Port-channel105 is up, line protocol is up (connected)
Hardware is EtherChannel, address is cc7f.7603.8527 (bia cc7f.7603.8527)
Description: XXX
MTU 9216 bytes, BW 20000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 40/255, rxload 35/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Gb/s, link type is auto, media type is N/A
input flow-control is on, output flow-control is unsupported
Members in this channel: Twe1/0/40 Twe2/0/39
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 4d15h
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 5612117
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2821620000 bits/sec, 394376 packets/sec
5 minute output rate 3178132000 bits/sec, 414382 packets/sec
98690421302 packets input, 105115497472331 bytes, 0 no buffer
Received 207151115 broadcasts (161787918 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 161787918 multicast, 0 pause input
0 input packets with dribble condition detected
97981939555 packets output, 109840443234791 bytes, 0 underruns
Output 51896934 broadcasts (0 multicasts)
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

TwentyFiveGigE1/0/39 is up, line protocol is up (connected)
Hardware is Twenty Five Gigabit Ethernet, address is cc7f.7603.8ac7 (bia cc7f.7603.8ac7)
Description: XXX
MTU 9216 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 25/255, rxload 39/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Gb/s, link type is auto, media type is SFP-10GBase-SR
input flow-control is on, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:02, output 00:00:02, output hang never
Last clearing of "show interface" counters 4d15h
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 20864
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 1535676000 bits/sec, 199750 packets/sec
5 minute output rate 1001890000 bits/sec, 146813 packets/sec
24818977575 packets input, 32032374681116 bytes, 0 no buffer
Received 66707572 broadcasts (41378969 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 41378969 multicast, 0 pause input
0 input packets with dribble condition detected
23917974631 packets output, 25857355405979 bytes, 0 underruns
Output 11208791 broadcasts (0 multicasts)
0 output errors, 0 collisions, 0 interface resets
13380 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

TwentyFiveGigE2/0/39 is up, line protocol is up (connected)
Hardware is Twenty Five Gigabit Ethernet, address is cc7f.7603.8527 (bia cc7f.7603.8527)
Description: XXX
MTU 9216 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 35/255, rxload 48/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Gb/s, link type is auto, media type is SFP-10GBase-SR
input flow-control is on, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:02, output 00:00:04, output hang never
Last clearing of "show interface" counters 4d15h
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 4728059
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 1914794000 bits/sec, 288508 packets/sec
5 minute output rate 1391619000 bits/sec, 218012 packets/sec
66823007212 packets input, 66681704291914 bytes, 0 no buffer
Received 119094590 broadcasts (80963207 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 80963207 multicast, 0 pause input
0 input packets with dribble condition detected
60931781287 packets output, 61734517917483 bytes, 0 underruns
Output 22618560 broadcasts (0 multicasts)
0 output errors, 0 collisions, 0 interface resets
13380 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

This is a switch: C9500-48Y4C
 Version 17.3.3, RELEASE SOFTWARE (fc7)

Best Regards,

[balaji.bandi]

check the troubleshooting guide :

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-switch/216236-troubleshoot-output-drops-on-catalyst-90.html

[MHM Cisco World]

change the Queue Size and problem will solved.
fast solution here is increase the Soft Queue size by multiply it with 12  times.
do command bellow and  monitor the drop count 

9300(config)#qos queue-softmax-multiplier 1200

[jds5]

Hello,

Thank you for your feedback.

is there any risk in implementing this type of filtering?

BR,

[MHM Cisco World]

NO at all, 
apply it and monitor the drop
note:- it not filtering it multiplying of Queue size 

[balaji.bandi]

is there any risk in implementing this type of filtering?

what filtering ? you are increase qos config ( as suggested the document)

this will not effect your environment.

Once you added softlimit, reset the counters of interface and monitor.