2

We just installed a new IP phone system. The phones get their configuration via DHCP, which includes an option to set the phone to a different VLAN. The phone then requests an address via DHCP on that VLAN.

So now I have two registrations for the phone in my DHCP database: one in the "computer" VLAN, and one in the "Phone" VLAN.

Is there a standard way of cleaning up the extra DHCP registrations for the phones?

longneck
  • 23,082
  • 4
  • 52
  • 86
  • Does the computer VLAN use globally routeable IPv4 addresses? If it does not use globally routeable IPv4 addresses, then you could just allocate enough addresses to the computer VLAN, such that you won't run out of addresses. The DHCP leases will expire eventually. – kasperd Aug 26 '14 at 16:05
  • 1
    Very short leases? Get the phones off the "computer" VLAN to begin with? – Michael Hampton Aug 26 '14 at 17:26

1 Answers1

2

In my case, the answer was LLDP. By enabling LLDP on my Cisco switches, the phones were able to learn of the Voice VLAN before they started the DHCP process.

longneck
  • 23,082
  • 4
  • 52
  • 86