dslreports logo
    All Forums Hot Topics Gallery


how-to block ads

Search Topic:
share rss forum feed

·TekSavvy Cable
·WIND Mobile
reply to TwiztedZero

Re: [Cable] Modem is not part of the Continuum. Intermittant SB6

OK, It's hard to tell exactly what's going on here.

There are apparently more detailed logs available through a telnet interface ... maybe through Haxorware if that doesn't violate your modem's firmware.

From what I am reading, I think it goes like this ...

After an original boot up, when the modem does its initial ranging, it can do what is called maintenance ranging. Ranging is the ability of the modem to adjust its power output (upstream) to compensate for changing line conditions.

The modem will send the modem a RNG-REQ packet saying it wants to do maintenance ranging. The CMTS replies with an RNG-RSP packet saying got it, and then proceeds and follows that with a packet called a RNG-REQ Grant Map which tells the modem to increase or decrease power or "we're good".

A T4 timeout occurs when a cable modem fails to receive the RNG-REQ Grant Map from the CMTS within 35 sec. The modem may receive the Abort response in the meantime which means that the CMTS can't get a good signal from the modem.

So, there are many things that can cause this problem.

If lots of customers on the same CMTS are getting it, the usual reason is an overloaded CMTS.

If a single customer is getting it, it's more likely to be a line condition (temporary) such as a noise burst caused by a fault on the plant. It would be interesting to see if there is a TV problem around the same time.

Basically when this happens, the modem assumes the line/CMTS has gone crap and the only way to get online again is a reboot.