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Unformatted text preview: nd 11). The reports are in a different order this time, as expected, since the time between
receiving the query and sending the report should be randomized.
The final query that we show occurs about 2 minutes after the previous query, and again we have the
expected responses. 13.5 Summary
Multicasting is a way to send a message to multiple recipients. In many applications it is better than
broadcasting, since multicasting imposes less overhead on hosts that are not participating in the
communication. The simple host membership reporting protocol (IGMP) is the basic building block for
Multicasting on a LAN or across closely connected LANs uses the techniques we've described in this chapter.
Since broadcasting is often restricted to a single LAN, multicasting could be used instead of broadcasting for
many applications that use broadcasting today
A problem that has not been completely solved, however, is multicasting across wide area networks. [Deering
and Cheriton 1990] propose extensions to common routing protocols to support multicasting. Section 9.13 of
[Periman 1992] discusses some of the problems with multicasting across WANs.
[Casner and Deering 1992] describe the delivery of audio for an IETF meeting across the Internet using
multicasting and a virtual network called the MBONE (multicasting backbone).
13.1 We said that hosts schedule IGMP reports with random delays. How can the hosts on a LAN try to
ensure that no two hosts generate the same random delay?
13.2 In [Casner and Deering 1992] they mention that UDP lacks two features needed for sending audio
samples across the MBONE: detection of packet reordering and detection of duplicate packets. How could
you add these capabilities above UDP? file:///D|/Documents%20and%20Settings/bigini/Docum.../homenet2run/tcpip/tcp-ip-illustrated/igmp_int.htm (7 of 7) [12/09/2001 14.47.02] Chapter 14. DNS: The Domain Name System DNS: The Domain Name System
The Domain Name System, or DNS, is a distributed database that is used by TCP/IP applications to map between
hostnames and IP addresses, and to provide elec...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12