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1041
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6
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Too many output drops

joel
Level 1
Level 1

I notice too many output drops on my router's multilink interface. What does this mean and what could be causing this?

Software Version: c3745-ipvoicek9-mz.124-10b.bin

Problem Details: 3745#sh int multilink 1

Multilink1 is up, line protocol is up

Hardware is multilink group interface

MTU 1500 bytes, BW 3072 Kbit, DLY 100000 usec,

reliability 255/255, txload 31/255, rxload 8/255

Encapsulation PPP, LCP Open, multilink Open

Listen: CDPCP

Open: IPCP, loopback not set

Keepalive set (10 sec)

DTR is pulsed for 2 seconds on reset

Last input 00:00:08, output never, output hang never

Last clearing of "show interface" counters 3w0d

---------------------------------

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 510015

---------------------------------

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 97000 bits/sec, 128 packets/sec

5 minute output rate 384000 bits/sec, 144 packets/sec

97055282 packets input, 2198805340 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

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

100573061 packets output, 2464703235 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

4 Replies 4

andrew.burns
Level 7
Level 7

Hi,

In the absence of any other errors it looks like a simple case of over-subscription. The number doesn't mean much by itself, you need to look at it as a percentage, and in your case it's 0.5%

This may be OK, or it may be causing you issues already but without more context it's hard to say.

HTH

Andrew.

Thanks Andrew!

I am going to try increasing the output queue to 128.

Hi,

Before you do that you might want to read the following doc which gives some more detailed info on troubleshooting output drops:

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a0080094791.shtml#topic4

Enabling WRED on the interface could give you a better solution, but bear in mind that you probably won't be able to eliminate the drops, only manage them better.

HTH

Andrew.

Thanks for the link Andrew.

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