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Community Member

output drop

Hi all,

I've my 3845 with a giga interface configured 100M/Full Duplex.

I've applied an Hierarchical Policy with a policy parent that shape traffic at 20M and the child that manage 3 different classes with CBWFQ.

With show interface I see different output drops:

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 347

but with show policy-map interface I haven't any drop in any class even in default class..

For me output drops on phisical interface should be the amount of drops of all the classes? I'm confused..I've no crc,error...

Many thanks in advance for your support

6 REPLIES
Hall of Fame Super Gold

Re: output drop

Do the drops increase while traffic is flowing ? Do the packet counters in show policy-map appears to be correct ?

Community Member

Re: output drop

Thanks for your answer.

Here you are the show on my router:

sh policy-map interface gi0/0

GigabitEthernet0/0

Service-policy output: SHAPING-OUT

Class-map: class-default (match-any)

231065 packets, 95744568 bytes

30 second offered rate 2939000 bps, drop rate 0 bps

Match: any

Traffic Shaping

Target/Average Byte Sustain Excess Interval Increment

Rate Limit bits/int bits/int (ms) (bytes)

20000000/20000000 125000 500000 500000 25 62500

Adapt Queue Packets Bytes Packets Bytes Shaping

Active Depth Delayed Delayed Active

- 0 231577 96095374 2445 1565883 no

Service-policy : LLQ

Class-map: TRANSAZIONI (match-any)

182374 packets, 75496969 bytes

30 second offered rate 2358000 bps, drop rate 0 bps

Match: access-group name TRANSAZIONI

182374 packets, 75496969 bytes

30 second rate 2358000 bps

QoS Set

precedence 4

Packets marked 182374

Queueing

Output Queue: Conversation 267

Bandwidth 8000 (kbps)Max Threshold 3000 (packets)

(pkts matched/bytes matched) 419/199692

(depth/total drops/no-buffer drops) 0/0/0

Class-map: MULTICAST (match-any)

9919 packets, 1709230 bytes

30 second offered rate 18000 bps, drop rate 0 bps

Match: access-group name MULTICAST

9919 packets, 1709230 bytes

30 second rate 18000 bps

QoS Set

precedence 2

Packets marked 9916

Queueing

Output Queue: Conversation 265

Bandwidth 11500 (kbps)Max Threshold 4000 (packets)

(pkts matched/bytes matched) 1479/1007435

(depth/total drops/no-buffer drops) 0/0/0

Class-map: NETWORK-CONTROL (match-all)

66 packets, 4337 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: ip dscp cs6 (48)

Queueing

Output Queue: Conversation 266

Bandwidth 100 (kbps)Max Threshold 64 (packets)

(pkts matched/bytes matched) 0/0

(depth/total drops/no-buffer drops) 0/0/0

Class-map: class-default (match-any)

38706 packets, 18534032 bytes

30 second offered rate 564000 bps, drop rate 0 bps

Match: any

Queueing

Flow Based Fair Queueing

Maximum Number of Hashed Queues 256

(total queued/total drops/no-buffer drops) 0/0/0

sh int gi0/0

GigabitEthernet0/0 is up, line protocol is up

. . .

reliability 255/255, txload 40/255, rxload 6/255

Encapsulation ARPA, loopback not set

Keepalive not set

Full-duplex, 100Mb/s, media type is RJ45

output flow-control is XON, input flow-control is XON

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 00:04:46

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 482000 bits/sec, 495 packets/sec

30 second output rate 3167000 bits/sec, 2002 packets/sec

152371 packets input, 17211008 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 watchdog, 145 multicast, 0 pause input

0 input packets with dribble condition detected

229956 packets output, 95137103 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

Gianluca

Community Member

Re: output drop

Now you see Total output drops 0 since i have done a clear counter...

Regards

Gianluca

Hall of Fame Super Gold

Re: output drop

All seems good. Perhaps a transient situation caused the drops.

Community Member

Re: output drop

ok...but the question is: why I see output drops on phisical interface and no drops on the show policy map?

I mean..if the policy seems no drop traffic..why theese packet are dropped on phisical interface?

Many thanks for your support...

Super Bronze

Re: output drop

What might be happening is the drops happened within the shaper's queues.

Yes, one assumes the parent shaper kicks over rate traffic into the child queues, and it does, but it's unclear how the two queues, parent's and child's, interact.

On some routers using hierarchal policy maps, I recall I've seen traffic queued in both the parent shaper's queues, which appears to use FQ, and the child's class defined queues.

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