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New Member

DHCP Primary/Secondary

Hi Group,

Kindly check this setup,

- 2*4500 are working in primary/secondary setup.

- Voice VLAN is 12 and DHCP pool for IP Phones is Same DHCP pool is configured on both primary & seconadry switch.

- HSRP is running, Primary 4500 is 'Active' Router.

- Primary 4500 is root switch for VLAN 12.

- All edge switches are connected with primary and secondary 4500 except 2 switches which are cascaded with each other and one of them is only connected with secondary 4500 so root port is going towards secondary 4500. As per my understanding when IP phones which are connected with this edge switch will require IP Address from DHCP then they will broadcast the request. In the result broadcast traffic will actually flow through secondary 4500 to reach root switch but secondary switch is also running DHCP service with same DHCP pool so it will provide the IP Addresses to specific IP Phones. This setup could result in DHCP IP conflicts ??

Thanks & Reagrds,


Hall of Fame Super Silver

Re: DHCP Primary/Secondary


If both switches are configured with exactly the same pool for DHCP then conflicts may result. It would be better to split the current DHCP pool, perhaps giving a larger part of the pool to the primary 4500 and a smaller part of the pool to the secondary 4500.



New Member

Re: DHCP Primary/Secondary


Thanks for your response. From above scenario what I concluded that it does not matter what is your HSRP 'Active Router' but it matters what is the root path or root switch for a particular VLAN which is trying to get IP Address from DHCP, kindly correct me if this is wrong.

Should I run 'no ip conflict logging' for above scenario.