ipBalance

Why 3 MAC addresses required for Cisco port-security with VoIP phone?

In general, port-security is turned on, the default number of allowed mac-addresses is 1. for the daisy chain topology with an IP phone , we need 3 MAC addresses - one for PC, one for the VoIP phone on the voice VLAN and one for the phone on the native VLAN for CDP(or built-in mini switch on the in phone). If you are using other vendor's phone... still you might need extra MAC for LLDP.

Good luck~