Another unable to obtain ip address from dhcp server problem.

I have a computer that is connected to a sprint dsl modem (zyxel 645 prestige) that I can only connect to if I first assign an ip address. This modem is designed to release 1 address. This would not be an issue if I didn't need to connect other computers to the internet. I have been trying to place a linksys cable/dsl router in service and the computer also won't obtain an address from the router. I am sure that it is a software/setting issue because i can attach other computers that are set to obtain addresses automatically and they work and connect just fine.

I have checked all cables, reset and reinstalled tcpip, flushed cache, uninstalled and reinstalled the nic all to no avail.

System is running Winxp sp2, sygate firewall and symatec 9.01 corp.ed av with a 3com 10/100 pci nic. Note that condition existed before sp2 installation and the other computer are also running winxp sp2.

I might also note that I have tried disabling firewall and av and then tried to renew connection but that fails. Ipconfig shows 0.0.0.0 as an address the same w/ subnetmask. Can't ping or telnet into modem or router. Which I think??? would indicate duplicate addressing.

Other than a format and reinstall not sure where to go from here but sure could use some help.

Eprom

 

Can you please add a little more clarification? Mainly because the terms "modem" "router" are often incorrectly interchanged, and DSL can cover a multitude of different broadband types.

How do you connect from your "sprint dsl modem (zyxel 645 prestige)" to the PC? Directly via USB or Network cable? Or indirectly via a hub or switch? How many PC do you connect at once?

Are you using ADSL, or is this a cable connection?

Are you replacing the "modem" with the "linksys cable/dsl router" or are you installing the router between the modem and your computers?

 

Sorry...the pc is connected to the dsl modem (ADSL) through the nework card and a crossover cable. At present the "sprint dsl modem (zyxel 645 prestige)" is not set to bridge mode (yet) but it has the ability to assign an ip address (only 1) to the the network device connected to it. The addressing scheme is 192.168.1.1 w/ subnetmask 255.255.255.252 and thus allows only address 192.168.1.2 to be assigned. The account is a ppoe account that requires a un and a pswd to connect. Only 1 pc can be connected to this device at a time which is why I would like to hook up the router between the pc and the ADSL modem.

My problem really exists because this pc can not obtain an address from either the router or the ADSL modem.

 

That is not an arrangement I've seen before. However, there are some basic principles that I can use to suggest possible solutions.

DHCP servers usually give out addresses on a lease bases. That is a computer will be given the lease to use an IP address for 3 or 5 days on a LAN. An ISP will give a lease of a much shorter period so that once you disconnect, the address can be reassigned to another user. I wonder if the problem you have is that the lease for the single IP address that is being given out by the "modem" is too long and it is not being released. If this is the case, the DHCP will have the IP address assigned to the MAC address of your other computer for a given period (which could be a day or two), and will not let another computer use it until the lease expires. Have a look at the set up of the modem and see if there is a way to reduce the lease time.

The other solution is to assign the IP address statically. The modem will not care if the address you use was manually configured or statically configured - as long as the settings (IP, mask, gateway, DNS) are right.

I would strongly recommend that you invest in an ADSL router rather than try to get a DSL router talking to an ADSL modem. Seperating the ADSL connection from the router just makes thing more complicated. You can pick up some very cheap ADSL routers nowadays, and if you use personal firewalls, the cheap units are fine.

 

ReggieB,

Thanks for the response. Actually the ISP (Sprint/Earthlink) is sending this same linksys cable/dsl router out to business customers and having them set their "modem" to bride mode thus allowing the router to pass out ip addresses. The router is then set to establish the ppoe account.

I have reset both devices which should cause the DHCP server to renew the lease of the attached device. The other computers that I have used to connect to this "modem" are computers that I work on and it really does not seem to matter when I connect them thy just work. So....1. I will check the lease settings...2. ????

Eprom

 

After re-thinking ReggieB's last post (I must have missed your point) I guess there is no reason that this pc cannot be assigned a static ip while the others can obtian automatically from the router.

Thanks for the help.

Eprom