My internet provider upgraded our system. I went from 450 kbps to 4500 kbps. Woo hoo! At no extra cost to me. My question is, before, my IP was static but, according to the installer, my IP now is dynamic.
Why the change?
Dynamic IP allocation lets your ISP get better use out of the limited number of IP addresses they own, since customers who rarely use the internet won’t tie up an address. If you need to access your computer remotely, try DynDNS.
But all cable modems are always on. Unless you turn the modem itself off. Is that not right? Many turn their puters off but few turn their modems off. I would think anyway.
You might find your IP is “sticky” rather than truly dynamic - mine’s not changed in six months.
With my ISP, at least, true static IPs are available, but at roughly twice the cost of dynamic service. My previous ISP used IPs that transcended dynamic and were *volatile * - the line would go down for a DHCP re-assign every three to four hours, and static IPs were reserved for business accounts at far higher rates.
Unless you’re hosting servers, there’s generally not a need for a home DSL line to be on static IP, anyway, and services like DynDNS alleviate that issue.
Right, but the cable modem isn’t what the IP address gets assigned to. (It does have one, but it’s on a private subnet using reserved addresses, which can be reused on every private network and therefore aren’t as scarce as the public addresses your computer gets).
At least if your ISP is anything like mine (Comcast), you don’t get a publically routable IP address until you turn on the computer/router that’s connected to the cable modem. That address is leased to you for several days, and renewed automatically if your computer stays on. I’ve only had about 4 different IP addresses in the two years I’ve had my cable modem.
Mr2001 got it. The computer has the IP address not the cable modem. The exception to this is if you have a Firewall between you and your cable modem. They will be assigned the IP address from the ISP, and your computer will get an IP address from the Firewall. If you never turn your system off there is a good chance your IP address will never change.
However a few ISPs do use a forced change DHCP that forces your computer to get assigned a new address every x hours/days. Mainly they do that to keep people from running servers on a DHCP address instead of paying extra for the static address. Services like DynDNS and others have made that tactic outdated. Now ISPs usually filter incoming connections to common server ports (80, 23, 20, 21, etc) unless you pay extra for their web server plan.
Note that they only block incoming ports not outgoing. So you can still connect to web servers because the outgoing traffic to the webserver is on port 80, but the traffic coming back to your computer is on a randomly assigned port (over 1024 IIRC).
I have also seen ISPs that block DNS resolution for domains they don’t control from IPs outside their network. Not sure if that was a big problem for ISPs, or if it is just a security measure following the if it isn’t required don’t allow it configuration.
And you now know more about ISP DHCP, and IP addressing than you wanted.
-Otanx
-Otanx
Cable modems aren’t the only way in which broadband is delivered; ADSL modems have to dial a connection and are often USB-powered, switching off when the computer is powered off (which lots of people do).
Even with cable modems that are always on, there are benefits for the ISP in being able to allocate addresses dynamically; if, for example, they wish to perform maintenance on part of their routing systems, or if circumstances result in them having a new range of addresses to play with.
It is possible that your IP address was never static, just sticky.
False, DSL service does not even have to have a dial tone (called naked DSL). It opperates totally independent of the dial tone service. Just like the cable modem service operates totally independent of your cable TV service.
Now some DSL services use a protocol, iirc PPPoE, that may appear to some to be a dialup sequence, but it has nothing to do with it. Most broadband firewall - switches can be set up to enter the PPPoE info and keep the connection alive 24/7.
Also most seem to have both a USB and eithernet connection, and the user decides which to use.
Who said anything about a dial tone? I’m aware of the separation of voice and data bands in DSL.
I’ve just returned from troubleshooting a DSL connection at a client’s office; it is configured as a dialup connection and a box pops up saying "dialling…connected… verifying username and password, etc, just the same as it would on an analogue modem); maybe something other than dialling is going on beneath the surface, but it’s close enough for me to call it dialling.
In my experience, most DSL modems that are supplied free with the package are USB only.
…but anyway, to avoid ambiguity and nitpicks, how about I amend my previous statement to:
Cable modems aren’t the only way in which broadband is delivered; ADSL modems are often USB-powered, switching off when the computer is powered off (which lots of people do), and these have to reconnect each time they are switched on, typically being assigned a new IP address.