Deploying IP telephony in the enterprise campus requires the implementation
of various features particular to each submodule.

Building Access Submodule
Within the Building Access submodule,
these features support IP telephony:
- Voice VLANs
- 802.1p/Q
- Hardware support for multiple output queues
- Hardware support for in-line power to IP phones
- PortFast
- Root Guard
- Unidirectional Link Detection (UDLD)
- UplinkFast
Building Distribution Submodule
Within the Building
Distribution submodule, these features support IP telephony:
- Passive interfaces
- Layer 3 redundancy with Hot Standby Router Protocol (HSRP), HSRP track, and
HSRP preempt
- OSPF or Enhanced Interior Gateway Routing Protocol (EIGRP) routing with
adjusted timers, summary addresses, and path costs