What is the meaning of "output buffers swapped out" in serial interface ?

[godfreyma]

When I show interface in serail interface, the counter of "output buffers swapped out" is increasing, but the counter of "output buffers failure" is zero. I have serached in CCO and could not find the related doc to explain. So what cause the counter of "output buffers swapped out" increase?

Thanks!

[milan.kulik · Accepted solution]

Hi,

I've found output buffers swapped out = Number of packets swapped to DRAM

It seems like some packets are forced to process switching ( http://www.cisco.com/warp/public/121/inputdrops.pdf) for some reason.

See http://www.cisco.com/warp/public/63/queue_drops.pdf.

I'd also try to paste the complete sh int serial ... output

to the TAC Command Interpreter Tool (https://www.cisco.com/cgi-bin/Support/OutputInterpreter/home.pl).

Regards,

Milan

[godfreyma]

I have captured the sh interface :

Serial1/2 is up, line protocol is up

Hardware is cxBus Serial

Internet address is 168.12.1.10/16

MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, rely 255/255, load 6/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 2w0d

Input queue: 0/75/0 (size/max/drops); Total output drops: 597

Queueing strategy: weighted fair

Output queue: 0/64/597 (size/threshold/drops)

Conversations 0/23 (active/max active)

Reserved Conversations 0/0 (allocated/max allocated)

5 minute input rate 413000 bits/sec, 141 packets/sec

5 minute output rate 42000 bits/sec, 26 packets/sec

70862231 packets input, 1791884212 bytes, 0 no buffer

Received 157180 broadcasts, 0 runts, 0 giants

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

20227734 packets output, 3248376574 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 827305 output buffers swapped out

0 carrier transitions

RTS up, CTS up, DTR up, DCD up, DSR up

What cause the packets are forced to process switching ?

Thanks!

[milan.kulik]

Is there anything special configured on the interface (policy routing, route map, NAT, tunnel, e.g.)?

Verify if CEF is running on the interface (see http://www.cisco.com/warp/customer/105/cef_whichpath.html)

Regards,

Milan

[godfreyma]

"Fast Switching" has been enabled in the serial interface.