Fundamentals of Data Communication Networks

Chapter 9Transport Layer – SCTP and DCCP

9.1 Introduction

In this chapter, we continue our discussion on transport layer protocols. Transmission control protocol (TCP) and user datagram protocol (UDP) that we discussed in Chapter 8 were designed in the early days of the Internet when it was expected that the network would be used primarily for non-real-time traffic. With the increasing use of the Internet for different types of applications most of which generate traffic that needs to be delivered in real time, there is a need to design new transport protocols that can deal with these traffic types. Also, there are new applications that require the simplicity of UDP but they generate a large volume of traffic that needs to be controlled in order to avoid congestion collapse. In this chapter, we discuss two transport protocols that were specifically designed to meet these needs. The first of these protocols is the Stream Control Transmission Protocol (SCTP), which, like TCP, is a connection-oriented protocol that provides reliable end-to-end transfer. The second is the Datagram Congestion Control Protocol (DCCP), which was designed to inherit some of the features of TCP and some of the features of UDP.

9.2 Stream Control Transmission Protocol

SCTP, which is defined in RFC 3309, is designed to transport SS7 signaling messages over IP networks. As a transport layer protocol, it operates directly on top of IP, at the same level as TCP. Its basic service is the connection-oriented ...