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Default class drops

Hi Everyone,

 

I'm seeing total drops in default class which (Summation) is not matching with total drops in different dscp values.

 

Output :-

 

Class-map: class-default (match-any)
155834394 packets, 125586331940 bytes
5 minute offered rate 12559000 bps, drop rate 2000 bps
Match: any
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/184494/0 >>>>>>>>>>>>>>>
(pkts output/bytes output) 155649900/125362734518
bandwidth 7236 kbps
Exp-weight-constant: 8 (1/256)
Mean queue depth: 0 packets
dscp Transmitted Random drop Tail drop Minimum Maximum Mark
pkts/bytes pkts/bytes pkts/bytes thresh thresh prob

default154672390/124851578978 0/0 0/0 51 136 1/5
1 0/0 0/0 0/0 51 136 1/5
2 0/0 0/0 0/0 51 136 1/5
3 0/0 0/0 0/0 51 136 1/5
4 17329/4118330 0/0 0/0 51 136 1/5
5 0/0 0/0 0/0 51 136 1/5
6 0/0 0/0 0/0 170 272 1/10
7 0/0 0/0 0/0 51 136 1/5
cs2 6553/836144 0/0 0/0 20 32 1/10
cs4 43451/22518406 0/0 16/12069 24 32 1/10
af41 442529/408177474 0/0 88/84544 28 32 1/10
ef 1024/113576 0/0 1/94 30 32 1/10
cs6 466009/75329192 5/502 102/11415 28 32 1/10
cs7 615/62418 0/0 0/0 30 32 1/10

 

Config :-

class class-default
bandwidth 7236
random-detect dscp-based
random-detect exponential-weighting-constant 8
random-detect dscp 0 51 136 5
random-detect dscp 1 51 136 5
random-detect dscp 2 51 136 5
random-detect dscp 3 51 136 5
random-detect dscp 4 51 136 5
random-detect dscp 5 51 136 5
random-detect dscp 6 170 272 10
random-detect dscp 7 51 136 5


12069+84544+94+11415+502 = 108624 = Sum of tail and random drops in default.

But there is a huge difference (75870) in total drops and sum of tail & random drops.
Need help to know how can i find reason of remaining drops in default.
Or I'm missing something in calculation.

 

Thanks in adavnce for your response.

 

Ankit

 

6 Replies 6

Hello,

 

post the output of:

 

show interfaces interface
show queue interface
show queueing
show queueing random-detect

Hello Georg,

 

Please find below O/P.

 

#sh int gig0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
Hardware is ISR4331-3x1GE, address is 247e.1253.84b0 (bia 247e.1253.84b0)
MTU 1500 bytes, BW 40960 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 81/255, rxload 36/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set
Keepalive not supported
Full Duplex, 100Mbps, link type is force-up, media type is RJ45
output flow-control is on, input flow-control is on
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:07:43, output hang never
Last clearing of "show interface" counters 1d01h
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 199360
Queueing strategy: Class-based queueing
Output queue: 0/40 (size/max)
5 minute input rate 5837000 bits/sec, 1640 packets/sec
5 minute output rate 13068000 bits/sec, 2559 packets/sec
118627558 packets input, 42862792335 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 45796 multicast, 0 pause input
171303405 packets output, 134330297312 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

 

Rest commands are not recognised -

 

#show queue?
% Unrecognized command

 

#show queue
^
% Invalid input detected at '^' marker

 

#show queueing?
% Unrecognized command

 

 

Thanks 

 

Ankit

Joseph W. Doherty
Hall of Fame
Hall of Fame
It might be due to the global queue limit only being 64.

btw, were do these numbers, "12069+84544+94+11415+502", come from?

Hello Joseph,

 

it was calculated from attached O/P.

 

Thanks 

 

Ankit

Ok, but I still don't see the numbers you're using. On your attachment, I see 5 random drops and about 200 WRED tail drops.

Hi,

I think it's very difficult to match with this single output.

 

The Total drops accounts for several other reasons as well apart from WRED/Tail drops in the output. It also depends upon the platform.

Eg: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_mqc/configuration/xe-16-8/qos-mqc-xe-16-8-book/qos-limits-wred.html#GUID-88B6CDEC-E039-484B-9C1B-BEB238EE5C7A

 

In fact, it's only 212 packets dropped w.r.t WRED/Tail drops vs what's shown in 184494 total drops (Queue depth/ total drops talks about packets, not bytes).

 

Regards...

Ashok.

 


With best regards...
Ashok
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