09-23-2008 01:38 AM - edited 03-01-2019 02:08 PM
DOH-GSR-PE2#sh int g2/0/1 controller
GigabitEthernet2/0/1 is up, line protocol is up
Hardware is GigabitEthernet, address is 0019.55e9.f4cd (bia 0019.55e9.f4cd)
Description: ***Connected to OLD_4500-Gig4/47***
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, rely 255/255, load 34/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full Duplex, 1000Mbps, link type is force-up, media type is LX
output flow-control is on, input flow-control is on
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 00:22:24
Queueing strategy: fifo
Output queue 0/40, 58350 drops; input queue 1/75, 33 drops
Available Bandwidth 1000000 kilobits/sec
5 minute input rate 115415000 bits/sec, 28397 packets/sec
5 minute output rate 134713000 bits/sec, 27906 packets/sec
35908851 packets input, 17612788274 bytes, 0 no buffer
Received 28758 broadcasts, 0 runts, 4518126 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 67269 multicast, 0 pause input
35645315 packets output, 21985400017 bytes, 0 underruns
Transmitted 2596 broadcasts
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
Above is the output of show interface command. In the output we see some output queue drops with very less queue.
Output queue 0/40, 58350 drops; input queue 1/75, 33 drops
What could be the reason for this act?
10-21-2008 09:22 AM
Hi Senthilkumar,
The reason for these output queue drops is that there were several congestions earlier on the output queue.
The default queueing strategy for Gig interfaces is FIFO, which means First In First Out.
Output queue 0/40 means that the FIFO queue size is 40 packets (40 packets can be stored in the FIFO queue). If there is congestion and more than 40 packets try to go out of interface Gig2/0/1, then the packets above 40 cannot be stored as there is no memory allocated for them.
Depending on your traffic patterns there can be several solutions to this.
One solution may be to increase the FIFO queue size using the hold-queue x interface config command, where x is the number of packets. But this cannot always solve the problem.
Another solution could be to use some other queuing strategy like Weighted Round Robin with priority queueing.
You should look at QoS possibilities in the product documentation of your switch on cisco.com.
Each type has some specifics for configuring QoS.
Cheers:
Istvan
10-29-2008 01:29 AM
I have a same problem for this case.
So, I was using the hold-queue x command to change from 40 to 200 packets. But it's still have drop on the output queue.
I will to configuration other QoS on the Gigaethernet.
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