I have a certain number of packets dropped on my port channel interface with 3gbps bundled speed, on Cisco 6500 with Sup 720. You can see underneath the number of dropped packet within a minute, after I cleared the counters.
I'm wondering why packets don't enter in the queue at all before being dropped. Please help me resolve the problem with queue drops.
Will adding another interface in to the bundle resolve help reduce the drops?
CORESW01#show interfaces port-channel 50
Port-channel50 is up, line protocol is up (connected)
Hardware is EtherChannel, address is XXXXXXXXXX (bia XXXXXXXX)
Description: [***Etherchannel Connected to DELL-ENCLOSURE-B1 Ports 17,18,19,20***]
MTU 1500 bytes, BW 3000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s
input flow-control is off, output flow-control is off
Members in this channel: Gi2/33 Gi2/34 Gi2/35
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters 17:30:41
--THIS LINE--> Input queue: 0/2000/73599/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 7422000 bits/sec, 1105 packets/sec
5 minute output rate 6306000 bits/sec, 1329 packets/sec
77713779 packets input, 87465246992 bytes, 0 no buffer
Received 530784 broadcasts (258881 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 5 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
46002614 packets output, 24633769164 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
11-18-2016
CORESW01#show interfaces gigabitEthernet 2/33
GigabitEthernet2/33 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is XX
Description: [***Uplink Connected to DELL-ENCL1-B2***]
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 2/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:29, output hang never
Last clearing of "show interface" counters 04:47:46
Input queue: 0/2000/359/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 3744000 bits/sec, 820 packets/sec
5 minute output rate 10958000 bits/sec, 1649 packets/sec
7916371 packets input, 4017248800 bytes, 0 no buffer
Received 32074 broadcasts (24595 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
13081762 packets output, 4307087164 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
CORESW01#show interfaces gigabitEthernet 2/34
GigabitEthernet2/34 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is XX
Description: [***Uplink Connected to DELL-ENCL1-B2***]
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:36, output hang never
Last clearing of "show interface" counters 04:47:49
Input queue: 0/2000/136/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 6338000 bits/sec, 647 packets/sec
5 minute output rate 821000 bits/sec, 298 packets/sec
7605420 packets input, 6914668706 bytes, 0 no buffer
Received 79343 broadcasts (26075 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
11489585 packets output, 5625019559 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
CORESW01#show interfaces gigabitEthernet 2/35
GigabitEthernet2/35 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is XX
Description: [***Uplink Connected to DELL-ENCL1-B2***]
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:44, output hang never
Last clearing of "show interface" counters 04:48:08
Input queue: 0/2000/193/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 4163000 bits/sec, 515 packets/sec
5 minute output rate 2445000 bits/sec, 373 packets/sec
25776481 packets input, 32767081104 bytes, 0 no buffer
Received 37253 broadcasts (29829 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
14263612 packets output, 13067998250 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
CORESW01#show module
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 24 CEF720 24 port 1000mb SFP WS-X6724-SFP XX
2 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-45AF Xx
5 2 Supervisor Engine 720 (Active) WS-SUP720-3B SX
Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
1 0016.XXXX.7ad6 to 0016.XXXX.7aed 2.3 12.2(14r)S5 12.2(18)SXF3 Ok
2 0016.XXXX.f2e0 to 0016.XXXX.f30f 2.0 8.4(1) 8.5(0.46)RFW Ok
5 0014.XXXX.d988 to 0014.XXXX.d98b 4.5 8.1(3) 12.2(18)SXF3 Ok
Mod Sub-Module Model Serial Hw Status
---- --------------------------- ------------------ ----------- ------- -------
1 Centralized Forwarding Card WS-F6700-CFC XX 2.0 Ok
2 IEEE Voice Daughter Card WS-F6K-48-AF XX 2.0 Ok
5 Policy Feature Card 3 WS-F6K-PFC3B XX 2.2 Ok
5 MSFC3 Daughterboard WS-SUP720 XX 2.4 Ok
Mod Online Diag Status
---- -------------------
1 Pass
2 Pass
5 Pass
CORE-SW01#
Group: 50
----------
Port-channels in the group:
----------------------
Port-channel: Po50 (Primary Aggregator)
------------
Age of the Port-channel = 389d:22h:28m:24s
Logical slot/port = 14/2 Number of ports = 3
Port state = Port-channel Ag-Inuse
Protocol = LACP
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 49 Gi2/33 Active 3
1 92 Gi2/34 Active 3
2 24 Gi2/35 Active 2
Time since last port bundled: 389d:22h:27m:19s Gi2/35
Since I am not seeing the queue count jump, I think this could be because of bursts of traffic.
Best Answer
You get a high number of input drops if your device cannot service the input queue fast enough. There can be many reasons for this. For instance, routing policies or other services which cause process switching will slow your CPU and increase the number of input drops.
Cisco has a document, Troubleshooting Input Queue Drops and Output Queue Drops, which discusses the problem: