Voice Over IP: Readiness Checklist
By Cameron Sturdevant
The IEEE 802.3af power-over-Ethernet specification is almost complete and will likely be ratified as a standard later this year. This means that IP telephones will potentially gain the always-on reliability that is a de facto requirement for practical deployment in the enterprise. eWEEK Labs is seeing switchlike network devices that add power to existing structured Ethernet cable. These 802.3af-compliant devices should make it less of a chore to add IP telephones to the network.
A host of concerns around quality of structured wiring, QOS (quality of service) and the requirements of voice applications are coming into focus for enterprise IT and telephony vendors. One area that remains in flux is the implementation of VOIP in a wireless LAN.
VOIP systems are only as good as the quality of the underlying network physical plant and logical layout. Network cabling that has been implemented according to official Ethernet specifications and is cabled with at least Category 5 wire should be a basic requirement for any VOIP project. This means testing the physical cable to ensure that cable runs dont exceed Ethernet-specified lengths.
It makes sense to have IP telephone clients (either handsets or soft phones installed on PCs) in a fully switched environment. This reduces bandwidth contention and should make it easier to implement QOS policies.
Implementing QOS is a network management action that requires a significant amount of planning in its own right. 802.1p/Q and Differentiated Services require that IT managers think about how network devices will be updated to accept the new policies. Almost more important, IT departments need to consider how the policies will be maintained. New and existing tools abound to assist IT managers with device configuration management, while network equipment vendors almost always make management software for their own tools. The trick is to make sure that the management tool used in the enterprise works with all the platforms that carry voice traffic.
Because VOIP is only as good as the weakest network link, it is essential that IT managers use network device tools that are capable of implementing policies on each device that carries data. As part of the VOIP budgeting process, it must be determined if funds are available to replace equipment that cant be managed from a central console or configured with QOS policies to support voice traffic.