configuring DHCP on only one VLAN on 4500 switch

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Nov 5th, 2009
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I have created a DHCP pool on our 4500 switch. I only want our VLAN 6 to use the pool, and no other vlans.

How do I configure so that only VLAN 6 gets the addresses?

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Overall Rating: 4.5 (2 ratings)
Jagdeep Gambhir Thu, 11/05/2009 - 11:37
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Do not set IP helper command on rest of the vlans.

The ip helper-address interface subcommand tells the router to forward UDP broadcasts, including BootP, received on this interface.



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Kevin Melton Fri, 11/06/2009 - 07:13
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Actually this worked without having to configure ip helper address. The switch must be smart enough to only pull from pools that correspond to the ip configured on that interface.

Example: Interface VLAN 6 address is Ip dhcp pool /network /24 with some exclusions. Ports assigned to VLAN 6 started pulling from the beginning of the pool.

Richard Burts Fri, 11/06/2009 - 08:23
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You are correct that the switch is smart about the DHCP pools. If you configure a single DHCP pool then when the switch receives a DHCP request from a client, then the switch looks at the layer 3 interface on which the request was received. If the subnet of the receiving interface matches to the DHCP pool then the switch will assign an address from the pool to the client. And if the subnet of the receiving interface does not match the DHCP pool then the switch does not assign an address.




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