05-14-2008 11:59 AM - edited 03-05-2019 10:59 PM
could the interfaces drop packets because the workstations connected to them are not processing the data fast enough?
05-14-2008 12:07 PM
There are number of factors:
- slow processing by receiver
- a congested link
- hardware queue or buffer size of interface may be full
- tcp flow control due to window size etc.
05-14-2008 12:10 PM
thanks for the quick reply. Switchports are configured to 100 full so are the workstations. Where would a congestion occurs? How do i increase the buffer size on a 6509?
05-14-2008 12:14 PM
The drops seem to on the transmit part according to this output:
Interface FastEthernet1/24 queueing strategy: Weighted Round-Robin
QoS is disabled globally
Trust state: trust DSCP
Extend trust state: not trusted [COS = 0]
Default COS is 0
Queueing Mode In Tx direction: mode-cos
Transmit queues [type = 2q2t]:
Queue Id Scheduling Num of thresholds
-----------------------------------------
1 WRR low 2
2 WRR high 2
WRR bandwidth ratios: 1[queue 1] 255[queue 2]
queue-limit ratios: 0[queue 1] 100[queue 2]
queue tail-drop-thresholds
--------------------------
1 100[1] 100[2]
2 100[1] 100[2]
queue thresh cos-map
---------------------------------------
1 1
1 2
2 1 0 1 2 3 4 5 6 7
2 2
Queueing Mode In Rx direction: mode-cos
Receive queues [type = 1q4t]:
Queue Id Scheduling Num of thresholds
-----------------------------------------
1 Standard 4
queue tail-drop-thresholds
--------------------------
1 100[1] 100[2] 100[3] 100[4]
queue thresh cos-map
---------------------------------------
1 1
1 2
1 3 0 1 2 3 4 5 6 7
1 4
Packets dropped on Transmit:
BPDU packets: 0
queue thresh dropped [cos-map]
---------------------------------------------------
2 1 29299 [0 1 2 3 4 5 6 7 ]
Packets dropped on Receive:
BPDU packets: 0
queue thresh dropped [cos-map]
---------------------------------------------------
1 3 0 [0 1 2 3 4 5 6 7 ]
05-14-2008 12:24 PM
It is good to understand the rate at which drops are occuring. Unless theres CRC on the link, drops are too less in rate.What is the output of sh int fa0/21. Buffer size can be increased with hold-queue command on the interface.
05-14-2008 12:27 PM
No CRCs on the link, please see the output below:
FastEthernet1/24 is up, line protocol is up (connected)
Hardware is C6k 100Mb 802.3, address is 000d.bd3c.e53b (bia 000d.bd3c.e53b)
Description: <<< 16B >>>
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 3/255, rxload 1/255
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 never, output hang never
Last clearing of "show interface" counters 05:50:38
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 29299
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1247000 bits/sec, 501 packets/sec
301113 packets input, 240285033 bytes, 0 no buffer
Received 207606 broadcasts (207500 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
89211777 packets output, 26794965996 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
05-14-2008 12:54 PM
Hello, output drops in your case as compared to the interface output is less than .1%. I dnt think this should be bothering, at such a low rate. Is there any impact on access to applications. are they observing any slowness or latency. Otherwise this is ok.
05-14-2008 01:16 PM
No, no one has yet to complain. I was just curious since other interfaces are not showing it. I'd rather have everything clean :-)
Thanks.
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