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aquilla
(knowledge is power) Fri 04-Jun-10 22:25:28

First day on 21CN and already seeing problems

[link to this post]

Today I got switched from the legacy 1Mbps product to the new Zen Pro 21CN product. The switchover happened around 10:00 this morning whilst I was at work. I logged into the router and saw a new sync speed of 12285 / 888. I got home this evening just before 8pm and ran a quick test - 100MB in 90 seconds (1.1MB/s). smile

However since then (aprox 2 hours) I have had to reboot my router at least three times because the connection appears to die and my SNR drops from around 5.0dB to -4.5dB (the lowest I've seen it go) according to my router. Of course each time I do reboot the router, the sync speed drops (currently at 11407 / 872) so I'm trying not to reboot if possible. When the SNR drops that low, web browsing / email / remote access all become impossible and pings become intermittent (via IP only - DNS fails completely).

My current stats:

Text

rtr-craw-01#sh dsl int atm 0
ATM0Alcatel 20190 chipset information
                ATU-R (DS)                      ATU-C (US)Modem Status:    Showtime (DMTDSL_SHOWTIME)
DSL Mode:        ITU G.992.5 (ADSL2+) Annex AITU STD NUM:     0x03                            0x3
Chip Vendor ID:  'STMI'                          'TSTC'Chip Vendor Specific:  0x0000                    0x0510
Chip Vendor Country:   0x0F                      0xB5Modem Vendor ID: 'CSCO'                          'TSTC'
Modem Vendor Specific: 0x0000                    0x5100Modem Vendor Country:  0xB5                      0xB5
Serial Number Near:    FCZ112250ZMSerial Number Far:     0000000000Chip ID:        C196 (0)
DFE BOM:         DFE3.0 Annex A (1)Capacity Used:   99%                             79%
Noise Margin:    -1.0 dB                          5.0 dBOutput Power:    20.0 dBm                        12.0 dBm
Attenuation:     33.0 dB                         14.0 dBFEC ES Errors:    0                               0
ES Errors:        1                              756SES Errors:       1                              35
LOSES Errors:     1                              1471742UES Errors:       0                              1471824
Defect Status:                       LOM     NoneLast Fail Code:  None
Watchdog Counter: 0x2AWatchdog Resets: 0
Selftest Result: 0x00Subfunction:     0x00
Interrupts:      8314 (0 spurious)PHY Access Err:  0
Activations:     1LED Status:      ON
LED On Time:     100LED Off Time:    100
Init FW:         init_AMR_4.0.018.binOperation FW:    AMR-E-4.0.018.bin
FW Source:       externalFW Version:      4.0.18
                  DS Channel1      DS Channel0   US Channel1       US Channel0
Speed (kbps):             0            11407             0               872Cells:                    0          1042178             0           4258194
Reed-Solomon EC:          0                0             0                 0CRC Errors:               0            38158             0              2333
Header Errors:            0            21013             0               539Total BER:                0E-0           7022E-7

I am also racking up a huge amount of CRC errors. When I was on the legacy product it was rock solid with virtually no CRC errors.

The router is a Cisco 877W running IOS 12.4.24.T2 with the ADSL firmware patch (v 4.0.018) from Cisco.

I'm also looking at getting some replacement ADSL Nation XF-1e microfilters but these won't be here before next week. I understand that these things take to settle.

Regards,

Stuart

Powered by ZeN 1Mbit Unlimited & Cisco 837

SNR: ▼ 30dB ▲ 23dB
Line Noise: ▼ 32dB ▲ 16dB
Latest Speed: ▼ 961Kbps ▲ 249Kbps

Latest Speed Test - [17 Mar 2006 @ 00:01 via Gandhi]

deleted
(deleted) Sat 05-Jun-10 13:12:22

Re: First day on 21CN and already seeing problems

[re: aquilla] [link to this post]

I'm sorry to be the bringer of bad news but that is exactly what happened with my line and Cisco 877.

I left it for two weeks but it never got any better, despite the BT DLM putting the SNR up (eventually maxed out at 15dB). In the end I put a Draytek Vigor 2820 on and it's been as good as gold. The DLM brought the SNR back down from 15 to 12 and eventually 9dB.

If you google you'll find others with similar issues with 877.

On the other hand I have seen people saying Draytek 2820s are rubbish on 21CN lines and yet others who say it depends on the match between chipset in the DSLAM and ADSL modem at the customer's end so your mileage as they say may vary. I suppose I was just lucky to hit on a combination that works well for my line.

Finally, there was one more reason for ditching the Cisco - it won't support Annex M (not even with a modem firmware upgrade) and BT will shortly be rolling out Annex M (according to a couple of ISPs I've asked, including A&A).

aquilla
(knowledge is power) Sat 05-Jun-10 14:18:47

Re: First day on 21CN and already seeing problems

[re: deleted] [link to this post]

Thanks. I knew I was going to possibly hit problems with Cisco and ADSL2+ but not like this.

I have managed to stabilise the connection by changing to DSL operating-mode to ADSL2 instead of ADSL2+.

My line is now sync'ing at 8939 / 880 instead of 11407. frown

On the upside I am seeing less CRC errors and the SNR is now stable at around 4.5dB.

Regards,

Stuart

deleted
(deleted) Sun 06-Jun-10 09:49:46

Re: First day on 21CN and already seeing problems

[re: aquilla] [link to this post]

Bit of info re Cisco routers on 21cn/ADSL2+ (courtesy of a customer).

Third party discussion:-

https://supportforums.cisco.com/docs/DOC-6183;jsessi...

http://www.dslreports.com/forum/r23241737-New-20190-...

https://supportforums.cisco.com/thread/2006514

http://blog.qsolved.com/2010/05/adsl-firmware-upgrad...

Problem:

Cisco routers 857 and 877 (dedicated ADSL2+ interface) and the HWIC-1ADSL card (1800, 2800, 3800 series add-in) are all based on the Alcatel 20190 chipset which has been having significant reliability and interoperability problems with the Hauwei MA5300 DSLAM and EADB line card as used by BT on the 21CN network.

The various problems are described in Cisco's defect tracking system under ids: CSCta54059, CSCta54040, and CSCtb31105.

Solution:

Upgrade the ADSL firmware in your Cisco device to 4.0.18. ADSL enabled IOS have a version of the ADSL firmware embedded in them which they download to the controller at power on. Upgrading IOS will get a newer release, but latest IOS may still not have latest ADSL firmware - the firmware can be downloaded and upgraded separately.

If you need the link for the new firwmare please PM Me.

aquilla
(knowledge is power) Sun 06-Jun-10 10:04:00

Re: First day on 21CN and already seeing problems DELETED

[re: deleted] [link to this post]

Post deleted by aquilla

aquilla
(knowledge is power) Fri 11-Jun-10 16:09:32

Re: First day on 21CN and already seeing problems

[re: deleted] [link to this post]

I have been working away from home this week, so the router has been on but has not been rebooted. I had a look at the router logs today and saw tons of disconnects / connects.

There are nearly 300 entries (292 to be precise) indicating the session went down. I also have a GRE tunnel configured and BGP (peered to filter out Bogons etc) and these have been bouncing something crazy.

The router log starts on 4th June just before 22:00 where the operating mode was auto (ADSL2+). At 22:24 I forced the operating mode to ADSL2 and the connection stayed up until I changed it back to ADSL2+ at 23:59 (to see how it coped overnight).

At 09:54 on the 5th June I changed it back to ADSL2 after discovering I was unable to use the internet. Sine then I have been away and no one has touched the router and it has not been rebooted.

The current sync speed is 9014 / 888 and the session has been up for 35 hours. When I get home later tonight, I will be replacing the microfilters and if that fails to stabilise the line, I will think about purchasing a Draytek 120 modem to sit between the ADSL and the Cisco.

Router log here: Router Log - 200KB

Regards,

Stuart

aquilla
(knowledge is power) Mon 14-Jun-10 00:39:01

Re: First day on 21CN and already seeing problems

[re: aquilla] [link to this post]

On Friday evening I installed the new filters, the SNR still dropped to -2.0dB, just at a slower rate. On Saturday I managed to obtain a Draytek Vigor 120 ADSL modem (which my boss recommened).

The modem now sits as a bridge between the ADSL and my Cisco 877 and so far the results look promising:

Draytek Stats smile

I may have scewed my stats with BT by forcing my connection to ADSL2 in the earlier days.

Regards,

Stuart

Zen Pro - "Up to 20Mbit Broadband"

rowter
(newbie) Mon 14-Jun-10 02:33:05

Re: First day on 21CN and already seeing problems

[re: aquilla] [link to this post]

I have seen something very much like this on ADSL where the SNR margin went in to a negative figure. This required G.Lite to be disabled on the cisco which resolved the issue.

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