Download Computer Networks Lecture Handout: Multicast Protocols and Client-Server Interaction and more Lecture notes Computer Networks in PDF only on Docsity! Lecture Handout Computer Networks Lecture No. 43 MULTICAST PROTOCOLS: Several multicast protocols exist. Some of the proposed protocols are: DISTANCE VECTOR MULTICAST ROUTING PROTOCOL (DVMRP): This protocol is used by the Unix program mrouted and the Internet Multicast backBONE (MBONE). DVMRP performs local multicast and uses IP-in-IP encapsulation to send multicast datagrams from one site on the Internet to another. CORE BASED TREES (CBT): A multicast routing scheme in which the protocol software builds a delivery tree from a central point. When a user joins a group, routers send a message toward the central point (i.e., the core) to search for the nearest participating router. PROTOCOL INDEPENDENT MULTICAST -— SPARSE MODE (PIM-SM): This is a protocol that uses the same approach as CBT to form a multicast routing tree. The designers chose the term protocol independent to emphasize that although unicast datagrams are used to contact remote destinations when establishing multicast forwarding. PIM-SM does not depend on any particular unicast routing protocol. HANDOUTS COMPUTER NETWORKS PROTOCOL INDEPENDENT MULTICAST — DENSE MODE (PIM-DM): A protocol designed for use within an organization. Routers that use PIM-DM broadcast (i.e. flood) multicast packets to all locations within the organization. Each router that has no member of a particular group sends back a message to prune the multicast routing tree ((i.e., a request to stop the flow of packets). The scheme works well for short-lived multicast sessions (e.g., a few minutes) because it does not require setup before transmission begins. MULTICAST EXTENSIONS TO THE OPEN SHORTEST PATH FIRST PROTOCOL (MOSPF): A protocol designed for use within an organization. MOSPF builds on OSPF and reuses many of the same basic concepts and facilities. None of the above mentioned protocols is best in all circumstances. CHAPTER 28 (Not Included in the Exams) CLIENT-SERVER INTERACTION: Although an internet system provides basic communication service, the protocol software cannot initiate contact with, or accept contact from, a remote computer. Instead two application programs must participate in any communication i.e. one application initiates communication and the other accepts it. HOW TWO APPLICATION PROGRAMS MAKE CONTACT? The two application programs make contact in the following way: One application actively begins execution first and another application waits passively at prearranged location. This process is called client-server interaction.
