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My school DHCP server(Win2008) runs out of IPs so I expanded the scope: original: 10.20.1.0 to 10.20.2.255 new: 10.20.1.0 to 10.20.3.255

But as soon as I finished it, all my workstations could not get outside connection any more while internal connection has no problem.

FYI: The DHCP has multiple scopes. We have multiple VLANs set up. School wide we have eight Cisco 2950 switches and two 3650 core switches. No Cisco routers but one ASA5510 firewall.

I guess other than simply expanding the scope we will have to do something related to the vLans, but I am just not so sure. Thanks for your help in advance.

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For the love of all things holy please call the internet "The Internet" and don't ever refer to it as the "cloud". –  Brent Pabst Dec 5 '12 at 20:32
    
What's your subnet mask? –  silmaril8n Dec 5 '12 at 20:35
    
Did you verify that the router you're assigning to the DHCP clients in your Scope (or Server) options is correct? –  joeqwerty Dec 5 '12 at 20:44
    
Subnet mask is 255.255.0.0 –  RabbitSF Dec 5 '12 at 21:23

1 Answer 1

Did you change the subnet to be larger (on all devices in this subnet, static and DHCP-defined), as well? If you didn't, that's most likely one of your many problems. You can't just expand a subnet without changing the netmask for all devices on the subnet.

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You also need to do so for all routes to the subnet on devices outside the subnet, all access rules that are supposed to match devices in the subnet on servers and routers, and so on. –  David Schwartz Dec 5 '12 at 20:40
    
Very good point. –  mfinni Dec 5 '12 at 20:48
    
My subnet mask is 255.255.0.0, so I guess it should be fine. I think David got the point. But all our switches have been configured well in terms of inter-vLAN connections or trucking because different vLANS can communicate with each other with out problem. I am not a Cisco pro, so I am not sure what else I am missing and where to start. –  RabbitSF Dec 5 '12 at 21:45
    
By the way, our switches all have 192.168.254.x IPs. –  RabbitSF Dec 5 '12 at 21:50
    
The IPs within the management VLAN have nothing to do with the IPs on the access VLANs. –  mfinni Dec 5 '12 at 23:41

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