02-23-2009 11:21 PM - edited 03-06-2019 04:12 AM
Hi,guys,
I have a switch one of whose interface shows this:
FastEthernet0/14 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 1011.1134.30ce (bia 1011.1134.30ce)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 100BaseFX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:04, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 134000 bits/sec, 52 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
805589598 packets input, 992002446 bytes, 52309736 no buffer
Received 599136096 broadcasts (0 multicast)
1338 runts, 0 giants, 0 throttles
1338 input errors, 0 CRC, 0 frame, 0 overrun, 52309736 ignored
0 watchdog, 88848603 multicast, 0 pause input
0 input packets with dribble condition detected
1612338 packets output, 186867143 bytes, 0 underruns
0 output errors, 0 collisions, 2 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
There is a "52309736 no buffer" in above output. What's its impact to the switch? Sometimes I ping this swith, the icmp delay went to 500-600 ms. Is it buffer insufficient problem that causes this problem? How to solve it? Anyone help.
Thanks.
02-24-2009 01:10 AM
Hello Donghai,
Let's focus on the following lines
805589598 packets input, 992002446 bytes, 52309736 no buffer
Received 599136096 broadcasts (0 multicast)
1338 runts, 0 giants, 0 throttles
1338 input errors, 0 CRC, 0 frame, 0 overrun, 52309736 ignored
Usually the number of input errors is the sum of all types of errors.
So this is the first note input errors should show 1338+52309736
You are also receiving quite a lot of broadcast traffic :
599136096 that needs to be processed but the switch management TCP/IP stack.
Being 52309736 less then total broadcast 599136096 the ratio being 11.45.
I think that the real problem can be the amount of broadcast frames:
if you compare total input frames and received broadcast :
805589598
599136096 broadcast
it looks like that most of traffic is broadcast.
Hope to help
Giuseppe
02-24-2009 06:08 AM
"What's its impact to the switch?"
If I remember correctly, the packets are dropped.
Giuseppe's post should have you investigate the high broadcast rate. In the meantime, does the switch have an IP address on this port's subnet? Does it need to? If it has an IP address on the subnet, the switch, as an IP host, also needs to process broadcasts. If the switch doesn't have an IP address on the subnet, it should avoid such processing. Avoiding unnecessary broacast processing might decrease the no buffer errors.
03-11-2009 07:39 AM
Thanks. Suppose that the broadcast is the key to this problem, does it mean that this 2955 have buffer defect which leads to not being able to deal with too many broadcast? Anyhow, other switches in the LAN don't have such problem. And, if IP is moved, althougt maybe less broadcasts, but also arises another issue of lossing management of the device itself.
03-11-2009 05:20 PM
". . . does it mean that this 2955 have buffer defect which leads to not being able to deal with too many broadcast?"
A question best anwered by TAC (if you have maintenance).
If you also have maintenance, you might also try the latest software.
04-16-2009 03:15 PM
Hello,
I work with many kind of Cisco switches, and I have observed the sames errors on the series C2950-24, but only in models based on Rev A0 and Rev B0.
I don't found any technical information about differences between the hardware revisions. May be a different amount of memory at ASIC's port level ?
What's your version ?
Best regards
José Sanchez, network engineer, SIEN, Switzerland
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