In article <200106261522.f5QFMGt13957@smtp.gwi.net>, Fletcher E Kittredge <fkittred@gwi.net> wrote:
I tend to agree because: The mac addresses of the computers in my house may change quite a bit, but my external IP addresses will remain the same (and have to, since only those IPs are being routed to me).
Do you have any actual experience with designing or operating such a public access network? If so, please explain how to get the "port and switch number" for a user's PC on a cable network as I was unaware of this functionality.
I have a bit of experience in designing and operating such a network. We are an ADSL provider, and we use RC1483 bridging. The modem at the customer has an ether over ATM over ADSL connection to the DSLAM and then that connection is forwarded to a central BRAS - a Redback in our case. When the BRAS requests config info when the circuit goes up (using radius) or when it acts as a DHCP relay, it includes the VPI/VCI of the ATM channel in the request. That means that you can assign IP addresses based on the physical connection rather than the MAC address, and this is what we do [well, will do soon anyway ;)] The ATM-based COM21 modems operate in much the same way (ethernet over ATM over cable using a BRAS to terminate the connection) so if you're designing a new network it's very well possible to get the "port and switch number". I'm not sure about the DOCSIS system, if the modems have a unique identifier that cannot be changed by the enduser and the headend somehow puts this info in a DHCP option when it acts as a DHCP relay you can probably do something similar. This is pure speculation though.
We haven't had a problem explaining to users how to get their MAC addresses.
Well, we have, and what's more if you're doing your accounting purely based on the mac addresses in the DHCP logs how do you ever know for sure who was using a certain IP address on a certain time? That's important, did customer A send out spam or was it his neighbor spoofing A's MAC address when A was asleep ?
3) ARIN has sent the strong message that they expect IP over E public network providers to use dynamic IP allocation in order to conserve IPv4 addresses.
And the intelligent public has sent an equally strong message that dynamic IPs are not acceptible. Most people I know with DSL or similar service make sure to use static IPs that are usable for server purposes. Wether static or dynamic IPs are used, the same _number_ of IPs is required, we aren't talking about dial-up here where most of the users will be offline most of the time.
I disagree with all of the above. Since it nothing more than your opinion and anecdotal evidence, mere contradiction suffices.
It's true though. With a cable or DSL network you must assume the worst, that is all users online at the same time. It will happen. And then your dynamic pool needs to be just as big as the number of subscribers. Mike.