veying these values defined by the customer as represented by the network to the voice endpoints. This page intentionally left blank Chapter 3.3 VolP Technology Juanita Ellis, Charles Pursell and Joy Rahman In this chapter, we will discuss the unique issues that differing business needs. A small company may choose to need to be considered when deploying voice across an IP- implement IP telephony with acceptable sound instead based network infrastructure. We will discuss the special of buying newer networking equipment to support needs that voice traffic has, such as minimal delay, jitter, excellent voice sound. A large call center company may and packet loss. Also, we will discuss the network want excellent voice sound as part of its corporate protocols that can help support those needs, including strategy, regardless of the cost of implementation. 802.1p, Diffserv, and Priority Queuing. Finally we will The voice network has traditionally been separate provide some insight into some recommendations for the from the data network because of the protocols used as design of a converged network infrastructure. well as the fact that the characteristics of voice applica- tions are very different from those of data applications. Voice calls have had their own dedicated bandwidth Voice traffic needs in an IP network throughout the circuit-switched network. This provided an environment where extremely high levels of reliability Voice quality is always a subjective topic. Defining "good" became the standard. Interactive voice traffic is sensitive voice quality varies with business needs, cultural differ- to delay and jitter but can tolerate some packet ences, customer expectations, and hardware/software. loss, problems that were rarely an issue with circuit The final determination of acceptable voice quality lies switching. within the user's definition of quality and design, imple- The data network, on the other hand, is packet mentation and monitoring of the end-to-end data network. switched. Data is less sensitive to dela