Why in the hell ..

[lihan161051]

.. do unprovisioned cable modems hand out unrouted 192.168.100.xx IP's instead of just not answering DHCP like they used to? Is there any logical reason?

("Because people scream at us when their computers get self assigned IP addresses and this makes them think it's their platform so they'll call their platform support" is not a reason I consider

Comments

[alohawolf]

Yes, frequently.

[notthebuddha]

It's just the ones that are also their own single port router/gateways.

This is very occasionally useful in that it lets the tech instruct the user over the phone to configure the modem via the internal web interface, but I agree it hardly makes up for all the rest of the false positives it inflicts during troubleshooting.

[reynardo]

At least you can tell from the lights on the front what the status is. "I'm sorry, Mr Jones, but our system isn't broken. You were removed from our network when your six-month-overdue bill still hadn't been paid. See that flashing light at the top? Pay the bill now, by credit card, with me, and I'll make it go solid within a minute."

[tregare]

many of the cable modems that function as routers live at 192.168.100.1 ( a fairly safe non routing IP block to use) it would hand out that class C so you can configure it from the computer end of things, and also to run diagnostics if the connection won't come up.

[ptomblin_lj]

Ok, that's very weird - at that address, I get a "About your Modem" page with a "WebSTAR Scientific Atlanta" logo. The only problem with that is that my modem has a Cisco logo on the outside. I don't have anything on this network made by Scientific Atlanta - no cable tv box or anything.

[mouser]

The label on the outside isn't the same as the label on the inside?

I'm shocked!

(Now if I could only find the real/equivalent model for my Dell Mono Laser MFP 1125 so I can find a driver that will work with a Mac...)

[geekgrrl_ca]

Last I knew (it's been a while since i've been cursed with dell equipment) dell were rebranded lexmark. hope that helps.

[geekgrrl_ca]

in addition to the reasons listed above it firewalls the customer's computers from the rest of the internet cutting down on incoming vulnerability attacks which helps keeps spam/bots/etc down. it also prevents customer's from running their own web/mail/whatever servers, the isps want you to pay business rates for that (and as much as we all want those features for free the isps are in business to make $$$$$). For the average user having your router being a firewall is great, though it would be nice if the user could turn off this feature to have their own router connect to the internet directly.

[lihan161051]

Well, a NAT router will normally firewall the customer's LAN just as an artifact of how it works. I wasn't griping about that.

It's that there's a rash of cable modems out there that will give out a single public IP on DHCP to the device they're provisioned to, but *also* give out an IP to other devices, which breaks a lot of device-side detection that the connection is in fact down. Any frontline tech can tell if the platform isn't getting an IP from the router with minimal training. But if the customer is trying to use their own external router and the only error they get is double NAT, and they escalate up to my level because the "NAT" is an unrouted 192.168.100.xx .. that's just pure rectal pain. It'd be simpler if they just only gave DHCP to the device they've registered, and answered HTTP at 192.168.100.1 just for config. The false positives from the former are a serious training problem.

[travisd]

I believe that some systems will allow an unprovisioned modem to connect to their "walled garden" which permits people to self-service provision and change modems (tie a new modem to their account, etc).