I am having problems with my Windows 7 computers. It seems to be reelated to Windows 7 and my Cisco routers DHCP. I recently installed Windows 7 on approximately 130 computers that were previously Winodws XP machines. I have another 50 or so still on Windows XP. We are using a Cisco 2921 router with a few VLAN's setup. The DHCP pools are set up on the router for each VLAN on our network.
DHCP has been set up on this router for a year and we have never had a problem with it and our XP machines. Now the newly reloaded Windows 7 computers are having issues. They worked fine for the first couple of weeks. The other night I had several of them that when woken up from sleep mode or turned on could not pick up an IP address. This was only a problem for the Windows 7 machines.
I verified that the DHCP service was running on the Windows 7 computers. The computers had the exclaimation point over the network icon and had a default 169.*.*.* address. Releasing and renewing did not pick up the correct IP adress. Restarting also did nothing. Resetting the TCP/IP protocal did not work.
After an hour of troubleshooting I cleared the ARP cahce on our main 2921 router which did not work. I then restarted the router and this seemed to solve the problem. The Windows 7 machines began to pick up a correct IP address. Everything has been working fine for about 32 hours now. I am concerned the problem will return. Are there any Windows 7 Cisco DHCP issues related to the address lesases? Ideas?
Note: We have one core switch and several IDF switches. The Windows 7 computers are all part of our largest VLAN, approximately 130 computers. The computers are mixed model Dell machines. The probelm seems to be isolated to these Windows 7 computers.
This is the router DHCP entry for VLAN20, for the problem computers..
ip dhcp pool VLAN20-PC
network 10.17.20.0 255.255.255.0
dns-server 10.17.10.10 10.17.10.11
lease 0 6
Are you using Active Directory?
With that many desktop clients, I highly recommend using a Windows DHCP server and "ip helper-address <ip>" command on the router interfaces.
It simply works better because it is the DHCP server's job to update DNS records, in particular the PTR records and IOS-based DHCP just can't do that.