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mepukin

join:2001-03-24
Englishtown, NJ

What is the T4 Timer and why does it expire?

My cable modem started losing it's connection several times a day, about 2 weeks ago, coincident with the 15/2 upgrade in 07726. I have an SB4200. Line tests are always clean and no packet loss. In fact, there are no other problems at all. When I looked at the modem logs, it appears that each reboot secuence begins with the T4 Timer expiring:

************ 7-Information I510.0 *** BOOTING *** SB4200-1.4.9.0-SCM00-NOSH
060507034200 7-Information H501.2 HFC: Shutting Downstream Down
060507034200 2-Alert T507.0 Received Async Error Range Failed
060507034200 3-Critical R4.0 Received Response to Broadcast Maintenance Request, but no Unicast Maint
060507034200 3-Critical H501.8 HFC: T4 Timer Expired

My question is what it the T4 timer in a surfboard, and why would it expire?

Thank You.

TheWiseGuy
Dog And Butterfly
Premium,MVM
join:2002-07-04
East Stroudsburg, PA
kudos:3
I guess there is some chance there is still work going on. Otherwise it may be an intermittent noise problem.

»www.cisco.com/univercd/cc/td/doc···errs.htm

said by Cisco Error page :

%UBR900-3-RESET_T4_EXPIRED: R04.0 Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received. T4 timeout.

Explanation The cable modem did not received a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). The cable modem is resetting its cable interface and restarting the registration process. Typically, this indicates an occasional, temporary loss of service, but if the problem persists, check for possible service outages or maintenance activity on this particular headend system. This error message is DOCSIS event message is R04.0, Ranging Request.

Recommended Action Check the configuration on the CMTS. Check the cable plant for RF connector or cabling issues that could be generating noise on the downstream and upstream. If using a Cisco CMTS, you can use the show cable flap-list command to determine if other cable modems on the upstream are having problems. You can also use the show interfaces cable upstream command and examine the noise, microreflection, and uncorrectable error counters to determine the level of noise on the upstream.

--
Warning, If you post nonsense and use misinformation and are here to argue based on those methods, you will be put on ignore.

mepukin

join:2001-03-24
Englishtown, NJ
Thanks for pointing me to that info. From the recommended action portion, it would appear as though this event is observable at the headend, at least on Cisco gear, and it can also be observed that multiple modems in an area are experiencing the problem, indicating a problem with the system rather than the client infrastructure.

Do you know if CV is using Cisco gear at the headend?

I would think that the RF freq had to increase when the bandwidth increased. Perhaps I have something here that's interfering with the RF.

BTW, I've searched the net and found people with the same problem dating back to 1999. Often enough back then it was linked to an increase to 10mbps on their system.

TheWiseGuy
Dog And Butterfly
Premium,MVM
join:2002-07-04
East Stroudsburg, PA
kudos:3

1 edit
Last I heard OOL only used Cisco. I guess they might have changed but I doubt it.

Edit
There would be no changes to the RF frequency. There probably was a change to the modulation used from 64QAM to 256QAM downstream and QPSK to 16QAM upstream. These require a better signal.