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Posted by Bill Crocker on September 23, 2006, 10:15 am
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Is Comcast assigning everyone static I/P addresses these days? I live in
Macomb, Michigan and I've had the same I/P address for a very long time now.
Powering the cable modem off, and on does not force a change...even if I
leave it off for several hours. Is there a way to force a new I/P address?
Thanks,
Bill Crocker
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Posted by Bit Twister on September 23, 2006, 11:42 am
On Sat, 23 Sep 2006 10:15:55 -0400, Bill Crocker wrote:
> Is Comcast assigning everyone static I/P addresses these days?
Yep, not likely to change unless your cable segment gets congested and
they decide to split your segment. You address might change if you
wind up on the new split side.
> I live in
> Macomb, Michigan and I've had the same I/P address for a very long time now.
Why would you want to change it. I like the almost static address so
I can use it to kill file morons in Usenet posts.
> Powering the cable modem off, and on does not force a change...even if I
> leave it off for several hours.
Yep, looking at my dhcp lease from comcast here in Dallas.
Obtained Fri Sep 22 22:41:58 CDT 2006
Renewal 2006/9/24 19:29:26;
Rebind 2006/9/26 15:41:56;
Expires 2006/9/27 03:41:56;
I would have to leave it off past the expiration date to have a ghost
of a chance of loosing it. Then several other people would have to
leave theirs off for the same period or a bunch of new customers would
have to get added to my segment to force the dhcp server to re-use my
expired address. Not much chance of that.
> Is there a way to force a new I/P address?
Buy a new interface card and connect it to the cablem modem.
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Posted by Eric on September 30, 2006, 11:11 am
Bit Twister wrote:
> On Sat, 23 Sep 2006 10:15:55 -0400, Bill Crocker wrote:
> > Is Comcast assigning everyone static I/P addresses these days?
>
> Yep, not likely to change unless your cable segment gets congested and
> they decide to split your segment. You address might change if you
> wind up on the new split side.
>
And, if you stay on the same CMTS, it is unlikely to change either, due
to interface bundling. Normally, a CMTS (or any router, for that
matter), segments subnets via hard interfaces. However, this tends to
be inefficient and eats up a lot of IP address space or requires a lot
of administration (this happened all the time in the bad old days with
@home. They ALWAYS underestimated subnet requirements and we ran out of
addresses every few weeks). Cisco introdced interface bundling to help
combat this problem, basically turning the CMTS into a switch instead
of a router. Works like a champ, makes everyone happy. Of course if you
are in a major metro area, you will likely see new devices added and
nodes moved to the new device, not a reshuffle.
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Posted by John Gray on September 23, 2006, 1:30 pm
> Is Comcast assigning everyone static I/P addresses these days? I
> live in Macomb, Michigan and I've had the same I/P address for a very
> long time now. Powering the cable modem off, and on does not force a
> change...even if I leave it off for several hours. Is there a way to
> force a new I/P address?
>
> Thanks,
> Bill Crocker
>
>
If you have a NAT router, change the internet(WAN) MAC address of it.
That always changed the IP I was assigned by RR. If I changed it back a
week later, I got the previous one that I had for 5+ years. I liked the
"static" IP. However, recently RR reconfigured this area and I now have
a new IP in a different range, and so far it's holding static. Comcast
may do the same.?? You will probably have to power down the cable modem
for a couple of minutes for the new IP to be acquired.
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Posted by Warren on September 23, 2006, 2:16 pm
Bill Crocker wrote:
> Is Comcast assigning everyone static I/P addresses these days? I live
> in Macomb, Michigan and I've had the same I/P address for a very long
> time now. Powering the cable modem off, and on does not force a
> change...even if I leave it off for several hours. Is there a way to
> force a new I/P address?
You're describing the very nature of any fixed network, whether it uses
static IP's or DHCP. IP addresses will not change unless there is a need
for them to change.
The difference is that when using DHCP, the changes that need to occur
happen automatically. With static IP's, when changes have to be made,
someone has to manually make them, and make them during the right time
window. That's not practical when so many pieces of equipment are located
inside thousands of private residences.
Even with DHCP, your IP address does not change unless it has to. The DHCP
server will continue to give out the same IP addresses to the same
equipment as long as it's possible. Disconnect and reconnect as many times
as you want, but you'll continue to get the same IP address. It won't
change until there is a network reconfiguration that requires a
renumbering.
This differs from dial-up. With dial-up, if you disconnect, and reconnect
you are, depending on how busy things are, likely to get a different IP.
That's because the fixed part of the network ends at the modem rack. At
the PoP there will be a rack with, let's say, 64 modems on it. The first
call to the access phone number goes to the first modem in the rack, the
second call to the second modem, etc. And when someone disconnects, the
next person to call in fills that empty space. So at a busy PoP, each time
you dial-in, you'll get a different modem. In a network like this, they
only have enough IP addresses to give each modem an IP address, not each
possible user who might connect to the modems. So the IP address you'll
get will depend on which modem you connect to.
With a cable internet system, theoretically everyone is always connected,
so there must be enough IP addresses for each user. All IP addresses will
always be in use. There's absolutely no reason to vary from normal
networking practices of the DHCP server always giving the same IP address
to the same equipment. That's the way DHCP normally works, and there's no
need to confuse things by randomly juggling IP addresses around.
Essentially, whether you configure things by DHCP or manually, IP
addresses should not change unless they need to. Using DHCP just means
someone doesn't have to make a manual change to each piece of equipment.
DHCP allows any change to be transparent to the end user. That's it. It
does not mean your IP address will change. It only means that if it has to
change, you won't be required to make the change manually on your end at a
prescribed time.
--
Warren H.
==========
Disclaimer: My views reflect those of myself, and not my
employer, my friends, nor (as she often tells me) my wife.
Any resemblance to the views of anybody living or dead is
coincidental. No animals were hurt in the writing of this
response -- unless you count my dog who desperately wants
to go outside now.
Power Lawncare Tools for Spring Clean-up:
http://www.holzemville.com/mall/blackanddecker/
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