Chapter 11 -- Multicasting

Chapter 11

Multicasting is a relatively new technology that allows data to be sent from one member and then replicated to many others without creating a network traffic nightmare. This technology was developed as an alternative to broadcasting, which can negatively impact network bandwidth if used extensively. Multicast data is replicated to a network only if processes running on workstations in that network are interested in that data. Not all protocols support the notion of multicasting—on Win32 platforms, only two protocols accessible from Winsock are capable of supporting multicast traffic: IP and ATM. This chapter presents the information necessary to understand multicasting in general, as well as how multicasting specifically applies to these two protocols.

First we will cover the basic semantics of multipoint networking, which includes the various possible types of multicasting as well as the basic characteristics of IP and ATM multicasting. Following this, the specifics of IP and ATM will be presented in their own sections. Last we will cover the API calls for multicasting in Winsock 1 and Winsock 2. Winsock has supported IP multicasting for quite some time, starting with Winsock 1. In Winsock 2, the multicasting interface was extended to become protocol-independent.

The platforms that support multicasting are Windows CE 2.1, Windows 95, Windows 98, Windows NT 4, and Windows 2000. IP multicast support for Windows CE is new to version 2.1 and unavailable in earlier versions. All of the platforms supporting multicasting are capable of IP multicasting. However, since native ATM Winsock support is available only in Windows 98 and Windows 2000, only these two platforms support ATM multicasting natively. Note that this doesn't preclude you from developing IP multicasting applications that run on an ATM network. It only means that you cannot write native ATM multicasting code. We will discuss this in more detail in the IP multicasting section. Another multicasting support issue is that some older network cards are not capable of sending and receiving on the IP multicast addresses. Most NICs manufactured in the last couple of years do support IP multicasting, but this certainly isn't always true.



Network Programming for Microsoft Windows
Linux Server Hacks, Volume Two: Tips & Tools for Connecting, Monitoring, and Troubleshooting
ISBN: 735615799
EAN: 2147483647
Year: 1998
Pages: 159

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