CCNP ONT Exam Certification Guide

Upon completion of this section, you will know the primary advantages and benefits of packet telephony networks, the main components of packet telephony networks, the definition of analog and digital interfaces, and the stages of a phone call. The final part of this section helps you understand the meaning of distributed and centralized call control […]

Digitizing and Packetizing Voice (Cisco VoIP Implementations)

Upon completion of this section, you will be able to identify the steps involved in converting an analog voice signal to a digital voice signal, explain the Nyquist theorem, the reason for taking 8000 voice samples per second; and explain the method for quantization of voice samples. Furthermore, you will be familiar with standard voice […]

Encapsulating Voice Packets (Cisco VoIP Implementations)

This section explains the protocols and processes involved in delivering VoIP packets as opposed to delivering digitized voice over circuit-switched networks. It also explains the RTP as the transport protocol of choice for voice and discusses the benefits of RTP header compression (cRTP). End-to-End Delivery of Voice To review the traditional model of voice communication […]

Bandwidth Calculation (Cisco VoIP Implementations)

Computing the exact amount of bandwidth needed for each VoIP call is necessary for planning and provisioning sufficient bandwidth in LANs and WANs. The previous section referenced parts of this computation, but this section thoroughly covers the subject of VoIP bandwidth calculation. The impact of packet size, Layer 2 overhead, tunneling, security, and voice activity […]

Implementing VoIP Support in an Enterprise Network (Cisco VoIP Implementations)

This section is intended to give you an overview of telephony deployment models and their necessary elements and components in an enterprise network. It briefly introduces Cisco Unified CallManager, and it discusses a few different implementation options for CallManager clusters. The last part of this section includes a simple configuration for a Cisco voice gateway […]

Introduction to QoS (IP Quality of Service)

This section introduces the concept of QoS and discusses the four main issues in a converged network that have QoS implications, as well as the Cisco IP QoS mechanisms and best practices to deal with those issues. This section also introduces the three steps in implementing a QoS policy on a network. Converged Network Issues […]

Identifying and Comparing QoS Models (IP Quality of Service)

This section discusses the three main QoS models, namely best-effort, Integrated Services, and Differentiated Services. The key features, and the benefits and drawbacks of each of these QoS models, are explained in turn. Best-Effort Model The best-effort model means that no QoS policy is implemented. It is natural to wonder why this model was not […]

QoS Implementation Methods (IP Quality of Service)

This section explores the four main QoS implementation methods, namely CLI, MQC, Cisco AutoQoS, and SDM QoS Wizard. A high-level explanation of each QoS implementation method and the advantages and disadvantages of each are provided in turn. Legacy Command-Line Interface (CLI) Legacy CLI was the method used up to about six years ago to implement […]

Classification and Marking (Classification, Marking, and NBAR)

With QoS, you intend to provide different treatments to different classes of network traffic. Therefore, it is necessary to define traffic classes by identifying and grouping network traffic. Classification does just that; it is the process or mechanism that identifies traffic and categorizes it into classes. This categorization is done using traffic descriptors. Common traffic […]

The DiffServ Model, Differentiated Services Code Point (DSCP), and Per-Hop Behavior (PHB) (Classification, Marking, and NBAR)

Within the DiffServ architecture, traffic is preferred to be classified and marked as soon (as close to the source) as possible. Marking of the IP packet was traditionally done on the three IP precedence bits, but now, marking (setting) the six DSCP bits on the IP header is considered the standard method of IP packet […]