Modem losing sync and lock errors?
Sean Simpson
morning - a Motorola SB4100i. Problems with the ISPs admin and DNS servers
aside I seem to be having strange problems with the network in the mornings.
Checking the modem logs has revealed a period in the mornings, usually from
about 6am to 10am when the modem repeatedly experiences drops and regains
sync to the network. The problem usually disappears by about 10:30am. Here
is a snapshot from the CM log:
010802083128 7-Information H501.6 HFC: TRC SYNC Recovery OK
010802083127 3-Critical H501.4 HFC: LOST TRC SYNC- trying to recover
010802083127 7-Information H501.12 HFC: FEC LOCK recovery OK
010802083127 7-Information H501.15 HFC:FEC LOCK recovery OK
010802083024 7-Information H501.6 HFC: TRC SYNC Recovery OK
010802083023 3-Critical H501.4 HFC: LOST TRC SYNC- trying to recover
010802083023 7-Information H501.12 HFC: FEC LOCK recovery OK
The error log is full of repeat entries such as those above. It appears the
CM loses TRC sync and FEC lock ranging from every couple of seconds up to 25
minutes between incidents. It got so bad yesterday that the CM was shutting
the downstream down and rebooting itself. This happened a couple of times
where the CM reset the LAN Ethernet connection. Subsequently I lost the DHCP
address on my PC and got the dummy 169.XX address or if the CM was
disconnected from the HFC the internal CM DHCP server gave me a 192.XX
address. At least I could point my browser to the CM to see what it was
doing. Doing a DHCP release/renew did not work (couldn't connect to the ISP
DHCP server?) and I had to reboot my laptop to get a real DHCP address. Oops
it just happened again. Here is the latest log snaphot:
010803090212 7-Information F502.1 Bridge Forwarding Enabled.
010803090212 7-Information F502.3 Bridge Learning Enabled.
010803090212 7-Information B518.0 Baseline Privacy is skipped
010803090212 7-Information I500.0 Registration Completed
010803090212 7-Information I0.0 REG-RSP Registration Response
010803090212 7-Information I0.0 REG-REQ Registration Request
010803090212 7-Information D509.0 Retrieved TFTP Config docsis.md5 SUCCESS
010803090212 7-Information D507.0 Retrieved Time....... SUCCESS
************ 7-Information D511.0 Retrieved DHCP .......... SUCCESS
************ 5-Warning D520.2 DHCP Attempt# 1 BkOff: 4s Tot DSC:1 OFF:1
REQ:1 ACK:1
************ 7-Information D0.0 DHCP CM Net Configuration download and Time
of Day
************ 7-Information T500.0 Acquired Upstream .......... SUCCESS
************ 8-Debug T503.1 Acquire US with status OK, powerLevel 39,
tempSid 996
************ 8-Debug T505.0 Acquired Upstream with status OK
************ 7-Information T501.0 Acquired Downstream (331000000 Hz)........
SUCCESS
************ 8-Debug T509.0 Acquired DS with status OK, DS Freq 331000000,
US Id 1
************ 7-Information I510.0 *** BOOTING *** SB4100-4.0.9-SCM07-NOSHELL
010803090143 7-Information H501.2 HFC: Shutting Downstream Down
010803090143 2-Alert T507.0 Received Async Error Range Failed
010803090143 3-Critical H501.8 HFC: T4 Timer Expired
010803090114 7-Information H501.6 HFC: TRC SYNC Recovery OK
010803090113 3-Critical H501.4 HFC: LOST TRC SYNC- trying to recover
The downstream signal level this morning was -1dBmV and the SNR ranges from
32 to 34 dB (dipped at one point to 17dB). I thought the problem might be
spurious noise on the HFC network in the mornings.
I've called in the problem with Blueyonder, they are yet to respond. Anyone
have any ideas?
Sean Simpson
sean.simp...@blueyonders.co.uk
To reply, remove "nospam" from the e-mail address
Robin Walker
Sean Simpson <sean.s...@blueyonder.co.uk> wrote:
>The downstream signal level this morning was -1dBmV and the SNR ranges from
>32 to 34 dB (dipped at one point to 17dB). I thought the problem might be
>spurious noise on the HFC network in the mornings.
>
>I've called in the problem with Blueyonder, they are yet to respond. Anyone
>have any ideas?
Your problems are all caused by the SNR dipping 30dB. Somewhere on
your local cable network there is noise ingress.
--
--
Robin Walker, (Junior Bursar), Queens' College, Cambridge, CB3 9ET, UK
rd...@cam.ac.uk http://www.quns.cam.ac.uk/ Tel:+44 1223 335528 Fax:335566
Bryan
The occasional drop to 17 dB is probably when the modem "breaks lock". The
HFC- Sync losses you see are a strong indicator of some type of RF problem.
This could be a misconfigured sweep. A sweep sends a "sweeping" pulse of RF
into the system for testing purposes. I've seen where someone at the cable
office will occasionally mess up and incorrectly set the sweep and it runs
into the digital signal causing momentary "glitches" that from time to time
will cause the modem to lose sync.
OR you might have a bad connector or piece of cable or.... there are a lot
of possibilities that really require a tech to check.
But this does indicate a downstream problem and not upstream. The level
39dBmV shows a desirable level...
Good luck let us know what they find.
Bryan
"Sean Simpson" <sean.s...@blueyonder.co.uk> wrote in message
news:eZta7.39662$_b4.3...@news1.cableinet.net...