Understanding Show Int- output queue

Answered Question
May 17th, 2007
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I'm having trouble understanding the output queue information following. Is there a good document for understanding all this information? Specifically what is the Available Bandwidth statement telling me in this sho command?

Thanks,

Andy


Dupont_2801Router#sho int ser 0/1/0

Serial0/1/0 is up, line protocol is up

Hardware is GT96K with integrated T1 CSU/DSU

Description: $FW_OUTSIDE$$ES_WAN$

Internet address is 172.20.201.98/30

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 16/255, rxload 13/255

Encapsulation HDLC, loopback not set

Keepalive set (10 sec)

Last input 00:00:01, output 00:00:01, output hang never

Last clearing of "show interface" counters 00:22:45

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

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/55/256 (active/max active/max total)

Reserved Conversations 1/1 (allocated/max allocated)

Available Bandwidth 541 kilobits/sec

5 minute input rate 84000 bits/sec, 50 packets/sec

5 minute output rate 98000 bits/sec, 48 packets/sec

54469 packets input, 11952629 bytes, 0 no buffer

Received 136 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

53426 packets output, 13689288 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

Correct Answer by Manoj Wadhwa about 10 years 1 month ago

Input and output queues are used in a router to temporarily hold packets if there is any congestion on the Lan/ Wan links. If the interface is busy sending out packets and a new packet arrives, the packet is kept in queue unless the interface sends out the previous packet. There are various QoS queuing tools available (CQ, PQ, FIFO, WFQ, CBWFQ, LLQ) which decide the manner in which packets need to be sent out the interface. The default queuing techique is Weighted Fair queueing (WFQ), hence the output shows "Queueing strategy: weighted fair".

Output queue: 0/1000/64/0 (size/max total/threshold/drops. The above line indicates there are no packets in the queue, the total size of the queue is 1000, each queue size is 64 and there are no drops so far. In regards to Available Bandwidth, I would say that your config would have QoS configured with BW allocated to different classes. Since the total BW is 1544, you can subtract the BW configured for individual classes to get the BW of 541. Thanks!


- Manoj

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Correct Answer
Manoj Wadhwa Thu, 05/17/2007 - 09:36
User Badges:

Input and output queues are used in a router to temporarily hold packets if there is any congestion on the Lan/ Wan links. If the interface is busy sending out packets and a new packet arrives, the packet is kept in queue unless the interface sends out the previous packet. There are various QoS queuing tools available (CQ, PQ, FIFO, WFQ, CBWFQ, LLQ) which decide the manner in which packets need to be sent out the interface. The default queuing techique is Weighted Fair queueing (WFQ), hence the output shows "Queueing strategy: weighted fair".

Output queue: 0/1000/64/0 (size/max total/threshold/drops. The above line indicates there are no packets in the queue, the total size of the queue is 1000, each queue size is 64 and there are no drops so far. In regards to Available Bandwidth, I would say that your config would have QoS configured with BW allocated to different classes. Since the total BW is 1544, you can subtract the BW configured for individual classes to get the BW of 541. Thanks!


- Manoj

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