Questions about DHCP

[HWangLoyalty_2]

Currently we use core switch 6509 to provide DHCP function for use VLAN and Voice Vlan with "ip dhcp pool" command.

Right now we will build the new DHCP server for them. Obveriously we will configure "ip helper ...." for their VLAN interface.

Is it possible clinet could pick up address from new DHCP server if we did not remove ip dhcp pool...command?

I know we could configure new VLAN to run a quick test, but I would like to run it in the current environment because of some limitions.

Thanks for your answer!

[jonathanaxford]

Hi there,

Once you have the new DHCP server up and running and the IP helper command on the interfaces, then the new server will respond to DHCP queries as far as I know.

As the DHCP discover packet is a broadcast, it will be receicved by all DHCP servers, including the new one and the Cisco 6509. Generally, a client will use the first DHCP offer it receives, so there is a possibility that if both are configured, then both could be used.

Many thanks

Jonathan

[HWangLoyalty_2]

Thanks for your quick response.

Do you know is it possible client get IPs only from new DHCP server?

configure ACL for the switch port connected to client laptop, is it good idea? Please let me know