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Webcast-Catalyst9k
New Member

interface buffer problem

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.

5 REPLIES
Hall of Fame Super Silver

Re: interface buffer problem

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

Super Bronze

Re: interface buffer problem

"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.

New Member

Re: interface buffer problem

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.

Super Bronze

Re: interface buffer problem

". . . 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.

New Member

Re: interface buffer problem

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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