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Ian Cowley

Cisco 877 ADSL2+ Annex A - What is Going On!"

I understand why there are issues with Annex M deployements in UK, however I believe the Annex A should be compatable.

In every case teh router is either doesn't sync or is unstable and collapse after a certain period depenedent on the amount of data.

The problem is characterised by middle and big buffer failures. ICMP and SSH to the box are fine, but normal data traffic stops.

A reboot is the only option to clear the buffers

Here is example info:-

Ian Cowley

IFP-C877-ADSL#sh ver

Cisco IOS Software, C870 Software (C870-ADVIPSERVICESK9-M), Version 12.4(24)T1, RELEASE SOFTWARE (fc3)

Technical Support:

Copyright (c) 1986-2009 by Cisco Systems, Inc.

Compiled Sat 20-Jun-09 02:20 by prod_rel_team

ROM: System Bootstrap, Version 12.3(8r)YI3, RELEASE SOFTWARE

IFP-C877-ADSL uptime is 21 hours, 25 minutes

System returned to ROM by power-on

System restarted at 15:45:02 UTC Tue Oct 6 2009

System image file is "flash:c870-advipservicesk9-mz.124-24.T1.bin"

Cisco 877W (MPC8272) processor (revision 0x200) with 118784K/12288K bytes of memory.

Processor board ID FCZ1113236K

MPC8272 CPU Rev: Part Number 0xC, Mask Number 0x10

4 FastEthernet interfaces

1 ATM interface

1 802.11 Radio

128K bytes of non-volatile configuration memory.

24576K bytes of processor board System flash (Intel Strataflash)

Configuration register is 0x2102

IFP-C877-ADSL#sh dsl int a0


Alcatel 20190 chipset information


Modem Status: Showtime (DMTDSL_SHOWTIME)

DSL Mode: ITU G.992.5 (ADSL2+) Annex A

ITU STD NUM: 0x03 0x2

Chip Vendor ID: 'STMI' 'IFTN'

Chip Vendor Specific: 0x0000 0x71B9

Chip Vendor Country: 0x0F 0xB5

Modem Vendor ID: 'CSCO' ' '

Modem Vendor Specific: 0x0000 0x0000

Modem Vendor Country: 0xB5 0x00

Serial Number Near: FCZ1113236K

Serial Number Far:

Modem VerChip ID: C196 (0)

DFE BOM: DFE3.0 Annex A (1)

Capacity Used: 52% 99%

Noise Margin: 10.0 dB 6.0 dB

Output Power: 20.5 dBm 12.0 dBm

Attenuation: 30.5 dB 14.0 dB

FEC ES Errors: 51 2

ES Errors: 8 1

SES Errors: 8 0

LOSES Errors: 8 0

UES Errors: 0 86

Defect Status: None None

Last Fail Code: None

Watchdog Counter: 0xE7

Watchdog Resets: 0

Selftest Result: 0x00

Subfunction: 0x00

Interrupts: 21767 (0 spurious)

PHY Access Err: 0

Activations: 2

LED Status: ON

LED On Time: 100

LED Off Time: 100

Init FW: init_3.0.33_nobist.bin

Operation FW: AMR-3.0.033.bin

FW Source: external

FW Version: 3.0.33

DS Channel1 DS Channel0 US Channel1 US Channel0

Speed (kbps): 0 9728 0 1194

Cells: 0 24577129 0 174136395

Reed-Solomon EC: 0 1564 0 350

CRC Errors: 0 5 0 32

Header Errors: 0 3 0 30

Total BER: 0E-0 4804E-13

Leakage Average BER: 0E-0 7728E-19

Interleave Delay: 0 17 0 11


Bitswap: enabled enabled

Bitswap success: 0 0

Bitswap failure: 0 0

LOM Monitoring : Disabled

IFP-C877-ADSL#sh int a0

ATM0 is up, line protocol is up

Hardware is MPC ATMSAR (with Alcatel ADSL Module)

MTU 4470 bytes, sub MTU 4470, BW 1194 Kbit/sec, DLY 300 usec,

reliability 255/255, txload 28/255, rxload 151/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 AAL2, PVC mode

10 maximum active VCs, 64 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 never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 26

Queueing strategy: Per VC Queueing

5 minute input rate 708000 bits/sec, 146 packets/sec

5 minute output rate 135000 bits/sec, 130 packets/sec

3550095 packets input, 1252801794 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

3427796 packets output, 462411711 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 unknown protocol drops

0 output buffer failures, 0 output buffers swapped out

sh buffer

Buffer elements:

1027 in free list (1119 max allowed)

14311492 hits, 0 misses, 619 created

Public buffer pools:

Small buffers, 104 bytes (total 40, permanent 50, peak 56 @ 21:25:46):

38 in free list (20 min, 150 max allowed)

1143702 hits, 75 misses, 144 trims, 134 created

0 failures (0 no memory)

Middle buffers, 600 bytes (total 89, permanent 25, peak 89 @ 00:58:52):

82 in free list (10 min, 150 max allowed)

4330623 hits, 198 misses, 80 trims, 144 created

58 failures (0 no memory)

Big buffers, 1536 bytes (total 56, permanent 50, peak 79 @ 04:47:38):

40 in free list (5 min, 150 max allowed)

854620 hits, 93 misses, 119 trims, 125 created

12 failures (0 no memory)

VeryBig buffers, 4520 bytes (total 10, permanent 10):

10 in free list (0 min, 100 max allowed)

12 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Large buffers, 5024 bytes (total 0, permanent 0):

0 in free list (0 min, 10 max allowed)

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Huge buffers, 18024 bytes (total 3, permanent 0, peak 3 @ 00:54:44):

3 in free list (0 min, 4 max allowed)

509 hits, 2 misses, 1 trims, 4 created

0 failures (0 no memory)

Interface buffer pools:

Raw Cell Private Pool buffers, 100 bytes (total 32, permanent 32):

0 in free list (0 min, 32 max allowed)

32 hits, 0 fallbacks

16 max cache size, 0 in cache

16 hits in cache, 16 misses in cache

Syslog ED Pool buffers, 600 bytes (total 132, permanent 132):

100 in free list (132 min, 132 max allowed)

5186 hits, 0 misses

Dot11Radio0Psp buffers, 1676 bytes (total 80, permanent 80):

80 in free list (0 min, 80 max allowed)

0 hits, 0 fallbacks

SEC Eng Packet buffers, 1700 bytes (total 256, permanent 256):

0 in free list (0 min, 256 max allowed)

256 hits, 0 fallbacks

256 max cache size, 256 in cache

0 hits in cache, 0 misses in cache

Dot11Radio0 buffers, 2400 bytes (total 96, permanent 96):

32 in free list (0 min, 96 max allowed)

64 hits, 0 fallbacks

Particle Clones:

1024 clones, 37144 hits, 0 misses

This unit is running but will be expected to fail soon.

The ATM drops are at 86 8hrs after these traces.

Hi Ian,

Did you get anywhere with this? I am experiencing the same issues. Firmware 4.0.15 is a stable enough, but not perfect.

I tried the latest version 9, which made the problem worse!

I have changed the dsl noise-margin to 1.5 which has helped a little too (need to enable service internal for this command to be available).

The ISP we have is Demon, and they have said they have no end of problems with Cisco routers on their ADSL2+ lines.


You use 4.0.15 but on which platform ?

Supposedly not the 877.


Its on the 877-M.

Cisco TAC told me to use this version.


version 8 that is!

Correct, I had not read completely the release notes.



I have been pushing this through major resellers and ISPs. No one seems to be interested.

I am using almost every feature on the router including an IPSEC VPN which may be contributing.

One ISP who uses these routers on private DSL/MPLS services has no issues at all.

I'll look into your noise margin settings too.

Other posts suggests 877-M thats applicable in UK to my knowledge.

Hi Ian,

Im having the same issues with no-one knowing the problem and wanting to help!

We are going to get a new line with a different ISP who uses the 877's regulary.

The link is still fairly stable with 4.0.15 and 1.5 noise margin - the only users who are affected are connected via VPN. If you are trying the noise marging, work from 3 down, with .5 decrements. I would also advise doing it while consoled in as sometimes the link can be virtually unusable.

Let me know if you get any answers, but next week we'll have the new line in.

Good luck!



   Did you guys ever resolve this issue. Got the same problem with a 877 dropping off dsl connection. Error logs show:

000086: *Jan  9 21:00:12.013 NZST: %LINK-3-UPDOWN: Interface Virtual-Access2, ch
anged state to down
000087: *Jan  9 21:00:12.013 NZST: %DIALER-6-UNBIND: Interface Vi2 unbound from
profile Di0
000088: *Jan  9 21:00:13.013 NZST: %LINEPROTO-5-UPDOWN: Line protocol on Interfa
ce Virtual-Access2, changed state to down
000089: *Jan  9 21:00:13.101 NZST: %LINK-3-UPDOWN: Interface ATM0, changed state
to down
000090: *Jan  9 21:00:14.101 NZST: %LINEPROTO-5-UPDOWN: Line protocol on Interfa
ce ATM0, changed state to down

Is this the same problem? and what are your margins now for noise if you found a better figure. I see from the output there are two figures.

Any help appreciated



Please check and state your current ADSL firmware level.