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Question About Running Multiple Devices On One Modem - Printable Version

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Question About Running Multiple Devices On One Modem - [fr31ns]Karrde - 12-12-2009

Something I've always wondered about and figured I'd ask you guys (HeK ;P ).  Why is it that I need to reboot my modem whenever I switch between a different computer/device?  IE I'm plugged into my laptop and need to reboot the modem before it works on the desktop.

Re: Question About Running Multiple Devices On One Modem - CaffeinePowered - 12-12-2009

Why not just use a router?

Re: Question About Running Multiple Devices On One Modem - zaneyard - 12-12-2009

(12-12-2009, 04:19 PM)Caffeine link Wrote: Get a router
with a built in switch

Re: Question About Running Multiple Devices On One Modem - HeK - 12-12-2009

ooooh, I know the answer to this!!

If you are using a DOCSIS (ie, Motorola Surfboard) cable modem, it has an internal DHCP server which only allows a certain number of leases. Lets say your ISP allows one IP address (with the option to add extras for lets say, $5/month each) and when a computer first requests an IP address, the DHCP server associates that address with the hardware MAC address of your network card. The DHCP server refuses to allocate additional IP addresses unless specified to do so.

When you reboot your modem to change computers, the DHCP allocations stored in memory are lost.

You are best off buying/building a router, especially wireless if you would like additional freedom with your laptop.

A weird alternative is to override the MAC address on one of the computers, and match it to the other. I would still advise a router, as it offers protection via a NAT separated firewall.

Re: Question About Running Multiple Devices On One Modem - [fr31ns]Karrde - 12-12-2009

(12-12-2009, 05:24 PM)zaneyard link Wrote: [quote author=Caffeine link=topic=3966.msg126429#msg126429 date=1260652796]
Get a router
with a built in switch
[/quote]

Yes I know I could do that.  I just wanted to know the technical reason for it.  Just curious Tongue  Thanks HeK.

Re: Question About Running Multiple Devices On One Modem - zaneyard - 12-12-2009

Quote:Karrde link=topic=3966.msg126491#msg126491 date=1260677594]
[quote author=zaneyard link=topic=3966.msg126442#msg126442 date=1260656696]
[quote author=Caffeine link=topic=3966.msg126429#msg126429 date=1260652796]
Get a router
with a built in switch
[/quote]

Yes I know I could do that.  I just wanted to know the technical reason for it.  Just curious Tongue  Thanks HeK.
[/quote]
well i could have told you the technical reason for that, but i wouldn't be very helpful to fix the problem though would i?

Re: Question About Running Multiple Devices On One Modem - [fr31ns]Karrde - 12-15-2009

There's no real problem though Tongue  I know I just need to get a reasonable router, I'm just lazy.