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Posted by Agent_C on April 16, 2006, 12:46 pm
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>Elmo Wrote: "DOCSIS is DOCSIS.
>
>I've called my cable company a couple times as I've switched out cable
>modems, and all they ask for is the MAC address. Period. They don't
>care about brand name or model number.
>
>DOCSIS is DOCSIS, period."
>
>Well, sort of. Yes, there are minimum standard things that all DOCSIS
>ceritified modems have to do. And, yes, most cable companies have a
>generic provisioning file that can be used by any modem. However, there
>are a whole slew of vendor-specific options that can be implemented
>(anyone remember the RCA DCM105 e-mail light? It could be activiated by
>the .cm file and an SNMP trap). Most of the time, it has to do with
>port blocking and snmp traps, but just about anything can be done and
>labeled "vendor specific." We once had a problem that only affected 1
>brand of modem, because someone at corporate added a bunch of blocked
>ports to the config files and all 2000+ of this model decided to quit
>working one Saturday morning. The modems in question could only handle
>blocking a few ports, so they just locked up.
>
>The other big problem is when there is a firmware upgrade. This is a
>flag set in the .cm file telling the modem that a new version is
>available, and the release ID. The ID is compared to the firmware in
>the modem, and if they don't match, the modem will retrieve the new
>file. If you got the wrong type of modem, even a different make from
>the same vendor, you stand a very high likelyhood of trashing your
>modem.
>
>Now, there are a few other ways to determine the manufacturer of a
>cablemodem. One is to use the MAC address
>(http://coffer.com/mac_find/). Theoretically, one could determine the
>manufacturer and product by decoding the assigned MAC address and
>passing that info on to the provisioning system.
>
>It is also possible to read the make and model number from an SNMP
>browser, and pass it along to the provisioning system. While this would
>be very cool, it would require another server to be maintained, and
>there is the very real possibility of having a MIB report back an OEM
>instead of the real manufacturer (I recall this happening with Zyxel
>modem/routers, which reported a totally different modem and would have
>made them useless as a modem/router had we provisioned them using the
>other modem's config).
>
>But, why bother? It is much more accurate and reliable to get a human
>in the loop to read off the model number on the box and get it to the
>billing system, which then will pass it on to the provisioning system.
>
>Agent_C Wrote: "The reason I'm asking, is that I'm planning to
>replace the RCA modem
>Roadrunner provided with a Linksys WCG200."
>
>I can't speak for TW Roadrunner, but with Comcast, this modem will not
>work without Comcast's firmware (which is not available unless you go
>with the home networking option). The reason is because the retail
>version of the software will not pass on a second DHCP request for the
>router, and will attempt to route using the CM's internal address. They
>do say " While Comcast will support this modem's connectivity to the
>Internet, please direct any issues with the router or wireless Internet
>functionality to the vendor." It will provision, but that's all you'll
>be able to do (at least as of last summer). Again, this is on Comcast's
>network. You should really check with TW before you buy it, unless you
>know you can return it.
Thanks, that was extremely helpful.
A_C
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