01-03-2008 04:40 PM
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
01-04-2008 12:38 AM
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.
01-06-2008 06:12 PM
Thanks Andrew!
I am going to try increasing the output queue to 128.
01-07-2008 08:03 AM
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.
01-09-2008 09:51 AM
Thanks for the link Andrew.
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