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Community Member

Huawei DSLAM, Cisco SHDSL problem


we have a problem with Cisco 878 and Cisco 1803 connected to Huawei DSLAMs. In about 10 cases we have the problem, that the cisco is losing sync from time to time and there is no pattern. The line quality is good and we tried every IOS Version from 12.4(9)T to the newest 12.4(15)T3, but the problem is still there. There are times, when the Ciscos have sync for 4-6 days and other times they lost sync every 1-2 minutes. Is there maybe a known issue?

All Ciscos are configured as followed:

controller DSL 0

mode atm

line-term cpe

line-mode auto enhanced

dsl-mode shdsl symmetric annex B

interface ATM0

no ip address

no atm ilmi-keepalive

pvc 1/32

pppoe-client dial-pool-number 3

As for example one output of "sh controllers dsl 0":

DSL 0 controller UP

Globespan xDSL controller chipset

Line Mode: Two Wire

DSL mode: Trained with SHDSL Annex B

Frame mode: Utopia

Configured Line rate: 2304Kbps

Line Re-activated 7 times after system bootup

LOSW Defect alarm: ACTIVE

CRC per second alarm: ACTIVE

Line termination: CPE

Current 15 min counters

CRC : 0 LOSW Defect : 0 ES : 0 SES : 0 UAS : 0

Previous 15 min counters

CRC : 209 LOSW Defect : 0 ES : 6 SES : 1 UAS : 42

Current 24 hr counters

CRC : 1063 LOSW Defect : 0 ES : 58 SES : 3 UAS : 375

Previous 24 hr counters

CRC : 0 LOSW Defect : 0 ES : 0 SES : 0 UAS : 0

Line-0 status

Chipset Version: 0

Firmware Version: R4.2.1

Modem Status: Data, Status 1

Last Fail Mode: No Failure status:0x0

Line rate: 2312 Kbps

Framer Sync Status: In Sync

Rcv Clock Status: In the Range

Loop Attenuation: 9.9 dB

Transmit Power: 14.5 dB

Receiver Gain: 24.7420 dB

SNR Sampling: 38.9550 dB

Receive HEC Error Count: 0

Dying Gasp: Present

As you can see there are CRC errors, but this CRC errors show up from time to time and then the Cisco is losing sync very often. We have lines, that are terminated only 500 meters away of the DSLAM and have very good SNR and Loop Attenuation values and regardless of that, they still lose sync and we have lines that are far away from the DSLAM and have bad values, but they're working fine from the beginning so I don't think it's a line problem.

Community Member

Re: Huawei DSLAM, Cisco SHDSL problem

Hi gaarasama,

You mentioned that you're only seeing this issue in about 10 cases. Have you tried replacing the router, meaning using a working router to replace a non working router? Since all routers are using the same config, through this way you can verify if it's a router issue or a line issue.

Try using this config below and see if it will make any difference:

controller DSL 0

mode atm

line-term cpe

line-mode 2-wire line-zero

dsl-mode shdsl symmetric annex B

line-rate auto

Let me know how it goes.

Community Member

Re: Huawei DSLAM, Cisco SHDSL problem

Hi alvin_acar,

we tried to replace the routers with new ones and ones, we have already used and verified, that they're functioning. We're on about two months with this issue, so we tried a lot of things but didn't find any solution for this.

Thank you very much for the config. We try, if it helps and let you know the results.

Community Member

Re: Huawei DSLAM, Cisco SHDSL problem

You're welcome gaarasama. If the config does not help, post a capture of show dsl int atm0.

Community Member

Re: Huawei DSLAM, Cisco SHDSL problem

Hi alvin_acar,

unfortunately it didn't help to configure the line-mode to "2-wire line-zero". Here is the output you asked for:

ATM0 is up, line protocol is up

Hardware is MPC ATMSAR

Description: *** SHDSL interface (UR2) ***

MTU 4470 bytes, sub MTU 4470, BW 2304 Kbit, DLY 160 usec,

reliability 255/255, txload 38/255, rxload 2/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 , PVC mode

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

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input 00:18:41, 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: 0

Queueing strategy: Per VC Queueing

5 minute input rate 21000 bits/sec, 22 packets/sec

5 minute output rate 346000 bits/sec, 43 packets/sec

225423 packets input, 104564225 bytes, 0 no buffer

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

0 input errors, 153 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

242140 packets output, 116267610 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

Community Member

Re: Huawei DSLAM, Cisco SHDSL problem

i'm having similar problem in my network.

Dear Mr. Alvin, please verify your process utilization as i'm having my process utilization to 100%.


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