Incredibly frsutrating issue with PPP over ATM - HELP!!

[colinkiely1]

Hi All

I have been seeing some crazy stuff happening on a Cisco 887W Router since I brought it online. I am seeing the txload on the Dialer interface running at 255/255 the whole time, even with all LAN interfaces shut. Upon further investigation, I can see this is all ppp over atm traffic

show interfaces d0 accounting  

Dialer0

                Protocol    Pkts In   Chars In   Pkts Out  Chars Out

                      IP       8481     686517      10750    4189699

           PPP over ATM          0          0 13282269238568943991 2542327207066529655

#show int atm0

ATM0 is up, line protocol is up

  Hardware is MPC/AOE ATMSAR, address is c464.1356.0e80 (bia c464.1356.0e80)

  MTU 1600 bytes, sub MTU 1600, BW 1080 Kbit/sec, DLY 340 usec,

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

  Encapsulation ATM, loopback not set

  Keepalive not supported

  Encapsulation(s): AAL5

  4 maximum active VCs, 1024 VCs per VP, 1 current VCCs

  VC Auto Creation Disabled.

  VC idle disconnect time: 300 seconds

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

  Last clearing of "show interface" counters 01:03:15

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

  Queueing strategy: Per VC Queueing

5 minute input rate 170535433000 bits/sec, 256 packets/sec

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

    45540 packets input, 81762853542480 bytes, 0 no buffer

     Received 0 broadcasts (0 IP multicasts)

     0 runts, 0 giants, 0 throttles

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

     11515 packets output, 4218437 bytes, 0 underruns

     0 output errors, 0 collisions, 0 interface resets

     0 unknown protocol drops

     0 output buffer failures, 0 output buffers swapped out

Dialer0 is up, line protocol is up (spoofing)

  Hardware is Unknown

  Internet address is 81.x.x.x/31

  MTU 1500 bytes, BW 56 Kbit/sec, DLY 20000 usec,

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

  Encapsulation PPP, LCP Closed, loopback not set

  Keepalive set (10 sec)

  DTR is pulsed for 1 seconds on reset

  Interface is bound to Vi2

  Last input never, output never, output hang never

  Last clearing of "show interface" counters 01:04:42

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

  Queueing strategy: weighted fair

  Output queue: 0/1000/64/0 (size/max total/threshold/drops)

     Conversations  0/0/16 (active/max active/max total)

     Reserved Conversations 0/0 (allocated/max allocated)

     Available Bandwidth 42 kilobits/sec

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

5 minute output rate 146764428340145000 bits/sec, 149752568416638 packets/sec

     8545 packets input, 693891 bytes

     16817699949415247146 packets output, 11384292129267460273 bytes

Bound to:

Virtual-Access2 is up, line protocol is up

  Hardware is Virtual Access interface

  MTU 1500 bytes, BW 1080 Kbit/sec, DLY 20000 usec,

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

  Encapsulation PPP, LCP Open

  Open: IPCP

  PPPoATM vaccess, cloned from Dialer0

  Vaccess status 0x44

  Bound to ATM0 VCD: 1, VPI: 0, VCI: 38, loopback not set

  Keepalive set (10 sec)

  DTR is pulsed for 5 seconds on reset

  Interface is bound to Di0 (Encapsulation PPP)

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

  Last clearing of "show interface" counters 01:04:42

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

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

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

  5 minute output rate 433094867621755000 bits/sec, 1701864893368117 packets/sec

     9321 packets input, 740451 bytes, 0 no buffer

     Received 0 broadcasts (0 IP multicasts)

     0 runts, 0 giants, 0 throttles

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

    16192178438524644640 packets output, 9344773238850528397 bytes, 0 underruns

     0 output errors, 0 collisions, 0 interface resets

     0 unknown protocol drops

     0 output buffer failures, 0 output buffers swapped out

     0 carrier transitions

#show int atm0

I see nothing in any debugs but I am wondering if this is an IOS bug?

Cisco IOS Software, C800 Software (C800-UNIVERSALK9-M), Version 15.1(4)M3

Any idea's at all guys? I have a few of these routers with this issue, but yet on a slightly older model with same config everything is fine

Many thanks

[Giuseppe Larosa]

Hello Colin,

the counters of virtual-access2  are clearly wrong  it is not possible to achieve those speeds even on 10GE link !

1701864893368117  packets/sec

seventeen decimal digits of packet rate is not possible anywhere in current internet.

This is a SW bug.

by the way, is the router working?

virtual-access2 has IPCP state open so it looks like PPPoA has negotiated successfully.

Hopefully only counters are broken.

Hope to help

Giuseppe

[colinkiely1]

Hi Giuseppe

This is exactly my thoughts! I had to bring the figures into excel just read them!

The router is working fine, but what concerned me was the txload on the dialer interface. With this number of pakcets, it will putting an unnecessary load on the outbound interface and cause some performance issue

What do you think would be the best next step?

[Giuseppe Larosa]

Hello Colin,

I would open a service request with TAC tell them that you cannot perfom IP accounting with so bad counters and so on,

I don't think the load on dialer is an issue if you have flat rate DSL lines.

There is no configuration error that can cause this. It is clearly a SW bug.

Hope to help

Giuseppe

[Ivan Shirshin]

Hi Colin,

This seems to be very similar to the following bug, only for output counter:

CSCty39815    C887VAW, PPPoA ATM Interface input rate counter NOK

Symptom:

ATM interface counters misreporting . ATM interface input rate show abnormally large values .

Conditions:

during nomal traffic conditions .

Workaround:

None

15.1 is affected by it. Bug is fixed in 15.2(03)T1 and 15.2(02)T2, you could try any of those or later releases.

Kind Regards,
Ivan

**Please grade this post if you find it useful.

Сообщение отредактировал: Ivan Shirshin

[Ivan Shirshin · Accepted solution]

Hi Colin,

I also did some research about the bug, it is exact match, affects both output and input counters and does not have functional impact.

Note the following 2 duplicates of the same issue - 2nd is describing your issue by all symptoms:

CSCtr94703

Packet counters and rate are displayed in correctly for dialer

CSCtk02920

ADSL:L2TPv3:very large traffic counts values seen w/o traffic

You should upgrade the IOS to have it fixed. Note that it is quite new DDTS, so there are not many IOS releases with fix integrated.

Kind Regards,
Ivan

**Please grade this post if you find it useful.

[colinkiely1]

Thanks a lot for all the assistance guys, much appeciated