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Discover the power and efficiency of IP Multicast for improved computer systems and new types of applications such as videoconferencing and live multimedia training. Learn how this technology solves the shortfalls of Unicast communication and enables seamless transmission to multiple destinations.
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Multicast Integrated Network Services Almerindo Graziano
Introduction • New applications • Type of communications • Shortfalls of Unicast • Multicast • IP Multicast • IP Multicast sessions • Example • Conclusions
New Applications • Improved computer systems • New types of applications: • Point-to-Multipoint • Multipoint-to-Multipoint • Computer networks do not keep the pace
Multiple-Destination Applications • Videoconferencing • Remote seminars • Transmission of corporate messages to employees • Live transmission of multimedia training • Communication of stock quotes to brokers • Transmission over networks of live TV or radio news
Unicast • Problems of using Unicast: • Lack of Bandwidth • Need more powerful workstations • Difficult to manage with multiple destinations • A possible solution: • Multicast
D1 D2 . . . . . BT = B BT = N x B S D S: Source D: Recipient BT: Total Bandwidth involved B: Bandwidth required by one recipient DN Unicast Transmission
IP Multicast • IP Multicast (Steve Deering 1989, RFC112) • Greatly reduces the used bandwidth • Reduces the load on the servers • It’s receiver initiated • Introduces the concept of Session
IP Multicast • Host groups (logical addressing) • Multicast Sessions • IGMP (Internet Group Management Protocol) • It works better on broadcast media
IP Multicast Addresses • Class D Internet Protocol addresses: • 224.0.0.0 to 239.255.255.255 • 224.0.0.0 to 224.0.0.255 are reserved: • 224.0.0.1 is all host groups • 224.0.13.0 to 224.0.13.255 for Net News
Receivers Sender R BT = B BT = B BT = B BT = B R R R Internetwork S: Source D: Recipient BT: Total Bandwidth involved B: Bandwidth required by one recipient Multicast Transmission
IP multicast over 802 LANs • IP unicast address MAC address • IP Multicast address multiple MAC addresses? • IEEE assigns 01-5E-00-00-00 to the IETF for Multicast • Low-order 23 bits of IP Multicast address low-order 23 bits of MAC address 01-5E-00-00-00 • Mapping is not unique
MAC address format 8 7 6 5 4 3 2 1 O U/L I/G Byte 1 U Byte 2 I Byte 3 Byte 4 Manufacturer Byte 5 Byte 6
Mbone (IP Multicast Backbone) • Virtual network layered on top of the Internet (IETF July 1992) • Is made of multicast island • Communication between islands is achieved via tunnels
Mbone Topology Multicast Router Tunnels LAN Multicast Island
LAN A LAN B MRA MRB Tunnelling
References • http://www.mbone.com • http://www.ipmulticast.com • http://www.video.ja.net/mice