IP and network conflict?

[catalin_toth]

At the office we have 3 computers linked to each other and internet with a swich. Every mornig there is a network problem. 2 PC use windows XP SP 2 and one uses Win 7. when i start the win7 the network says the lan conection is working but no internet acces if i reboot the swich i get lan and internet connection but one xp loses lan connection. For the xp to gain lan connection i have to unplug the internet cable from the PC wait 2 sec and reconnect. the PC obtain ip automatic if i set an ip it wont work

[tumbleweed_biff]

There are a couple of different possibilities.

Windows handles networking in a rather pain in the ass means. When a Windows computer connects, a browse master is appointed which keeps track of the networked Windows computers. This browse master list is only updated every 20 minutes, so computers which come on after the browse master is appointed don't show on the network for up to 20 minutes. When a more powerful Windows computer (say a Windows 7 machine when the browse master is an XP machine) the more advanced Windows version becomes the browse master.

I don't think this is what is going on here, but it could be a factor.

More likely it is a problem with whatever is assigning your DHCP addresses. You should make certain that you are set up as follows:
Internet modem -> router/dhcp server -> switch (may or may not be part of the router) -> separate ethernet cable direct to each computer. The internet modem may be the router/dhcp server, depending upon the hardware from your ISP.

You need to check your router to make sure that it has a DHCP pool of addresses large enough for all the machines on your network. Something you can do to help eliminate IP address issues is to make a list of the MAC address of each computer, log into the router and find the DHCP reservation list. Here you enter each MAC address and specify the IP address which is to be assigned to that MAC address each and every time the computer connects. The computer continues to use DHCP to get its IP, but the DHCP server always assigns the specified IP to that computer and never assigns it to another MAC address.