MLPPP getting input errors after updateing to 12.3.23

Answered Question
Oct 9th, 2007

I have some routers that I just upgraded to 12.3.23 and now I am getting input errors when I do a "sh int". Plus I see them on my Network Monitor. Does anyone know of this issue?

Thanks.

I have this problem too.
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Correct Answer by Joseph W. Doherty about 9 years 2 months ago

The 12.4 I am using is the mainline version, although not GD yet. What's interesting is it was fine and got broken with a new patch release. Saw this happen before early in the 12.2 mainline, someone working and then a maintenance release broke it. (Fortunately, seems to happen rarely.)

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Overall Rating: 5 (2 ratings)
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ddevecka Tue, 10/09/2007 - 10:05

Here is a dump from what I see.

Multilink2, bundle name is Farm-Router

Bundle up for 1d01h, total bandwidth 3072, load 14/255

Receive buffer limit 24384 bytes, frag timeout 1000 ms

0/0 fragments/bytes in reassembly list

0 lost fragments, 840100 reordered

0/0 discarded fragments/bytes, 0 lost received

0x54A790 received sequence, 0x5EB6A6 sent sequence

Member links: 2 active, 0 inactive (max not set, min not set)

Se0/0:0, since 1d01h, 1920 weight, 1496 frag size

Se0/3:0, since 19:38:52, 1920 weight, 1496 frag size

Multilink2 is up, line protocol is up

Hardware is multilink group interface

Internet address is X.X.X.X/2XX

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

reliability 137/255, txload 18/255, rxload 8/255

Encapsulation PPP, LCP Open, multilink Open

Open: IPCP, CDPCP, loopback not set

Keepalive set (10 sec)

DTR is pulsed for 2 seconds on reset

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

Last clearing of "show interface" counters 1d01h

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 13033

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 107000 bits/sec, 67 packets/sec

5 minute output rate 227000 bits/sec, 71 packets/sec

5384323 packets input, 1709732669 bytes, 0 no buffer

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

5384323 input errors, 0 CRC, 5384323 frame, 0 overrun, 0 ignored, 0 abort

5647964 packets output, 2865553925 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

Joseph W. Doherty Tue, 10/09/2007 - 11:57

Don't know if they're related, but similar issue found within 12.4(16) but not 12.4(13d). Believe it's a known bug, at least with 12.4.

ddevecka Tue, 10/09/2007 - 12:07

Thanks, I will do some digging to see it this is the case. I stuck with GD to hopefully miss these issues. Guess not.

Correct Answer
Joseph W. Doherty Tue, 10/09/2007 - 15:16

The 12.4 I am using is the mainline version, although not GD yet. What's interesting is it was fine and got broken with a new patch release. Saw this happen before early in the 12.2 mainline, someone working and then a maintenance release broke it. (Fortunately, seems to happen rarely.)

ddevecka Wed, 10/10/2007 - 06:55

TAC said it is a bug. I will apply the lastest version and see what happens.

mdvzwp001 Mon, 11/05/2007 - 07:50

Do you have the bug id. I am seeing the same behaviour.

393257 input errors, 0 CRC, 393257 frame, 0 overrun, 0 ignored, 0 abort

mbell Fri, 02/01/2008 - 20:32

I would also be interested in knowing what the bug ID is. I am also seeing the same issue on a 2821 running 12.4(16). I searched on the Bug Toolkit but could not find it.

pcameron Fri, 02/01/2008 - 21:09

This looks like the following bug -

CSCsj26883

"SH INT" on MLPPP Bundle interface shows 100% input errors

It's a cosmetic bug that does not affect the actual router operation. Here is some more background -

Symptom: on a multilink bundle interface, the output from "show interface" will show an input error count which includes essentially 100% of the traffic being received. Other drop counters, usually the "bad frame" counter, are also incremented to match. For example:

# show interface Multilink1

Multilink1 is up, line protocol is up

Hardware is multilink group interface

Internet address is 10.20.0.1/30

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

reliability 181/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Open, multilink Open

...

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

6080 packets input, 1027997 bytes, 0 no buffer

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

6077 input errors, 0 CRC, 6077 frame, 0 overrun, 0 ignored, 0 abort

^^^^ ^^^^

Impact: Very Low. This is an accounting error; the counters are being accidentally incremented each time Multilink begins to receive a new datagram. This does not affect actual traffic flow or operation of the bundle, it is only the statistics that are in error.

Workaround: none.

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IOS's that have the fix: 12.3(24) 12.4(17) 12.4(15)T2 12.4(17)T 12.4(16a)

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