02-05-2009 03:24 PM - edited 03-06-2019 03:53 AM
Hi all,
I am having lot of output packet drops. I just want to know what kind of traffic it is dropping and what is causing it. For your information the interface f1/30 is connected to a 3rd party QOS box. I have tried all the troubleshooting steps, changing cables, checking mls stats. If you need more information I can provide it to u.
Statistics for Earl in Module 5
L2 Forwarding Engine
Total packets Switched : 6265369
L3 Forwarding Engine
Total packets L3 Switched : 6245992 @ 6666 pps
Total Packets Bridged : 3846350
Total Packets FIB Switched : 152
Total Packets ACL Routed : 0
Total Packets Netflow Switched : 0
Total Mcast Packets Switched/Routed : 16665
Total ip packets with TOS changed : 26816
Total ip packets with COS changed : 612329
Total non ip packets COS changed : 0
Total packets dropped by ACL : 8037
Total packets dropped by Policing : 0
Total packets exceeding CIR : 0
Total packets exceeding PIR : 0
Errors
MAC/IP length inconsistencies : 0
Short IP packets received : 0
IP header checksum errors : 0
TTL failures : 0
MTU failures : 0
Total packets L3 Switched by all Modules: 6245992 @ 6666 pps
sh int f1/30
FastEthernet1/30 is up, line protocol is up (connected)
Hardware is C6k 100Mb 802.3, address is 0019.e8d7.9ed5 (bia 0019.e8d7.9ed5)
Description:
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 12/255, rxload 25/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:20, output hang never
Last clearing of "show interface" counters 00:15:19
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 1307
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 9905000 bits/sec, 1841 packets/sec
30 second output rate 5022000 bits/sec, 1806 packets/sec
1572849 packets input, 892467909 bytes, 0 no buffer
Received 277 broadcasts (201 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
1546539 packets output, 492746040 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
FastEthernet1/30
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 15 7155
Route cache 0 0 0 0
Distributed cache 0 0 0 0
Total 0 0 15 7155
Tks
02-05-2009 04:55 PM
Total output drops: 1307
1546539 packets output
= 0.084%
Normally, such a drop percentage shouldn't be an issue. Some drops are normal due to TCP flows attempting to utilize full bandwidth.
02-05-2009 06:31 PM
Hi there,
Tks for the information. I know this time the packet drop is very less but some times it is between 3-5% ( in less than 5 minutes) not sure why.
02-06-2009 04:25 AM
Well, that could still be TCP flow(s) trying to use all the bandwidth. It could also be a heavy, relative to bandwidth, non-TCP flow(s), or a combination of both. If traffic offers more than link capacity, interfaces, at first, often queues bursts. If traffic continues to offer more than link capacity, queue overflows and packets are discarded and recorded as drops.
If you really want to see what's going on, you could tap into NetFlow stats (if available on your platform) or span the the port (if available on the platform) and capture traffic for examination.
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