The Digital Fact Book - Quantel

IPInternet Protocol is the de facto standard for networking and is the widest used of the networkprotocols that carry the data and lie on top of physical networks and connections. Besidesits Internet use it is also the main open network protocol that is supported by all majorcomputer operating systems. IP, or specifically IPv4, describes the packet format for sendingdata using a 32-bit address to identify each device on the network with four eight-bitnumbers separated by dots e.g. 192.96.64.1. Each IP data packet contains a source anddestination address. There is now a move toward IPv6 which brings, among many otherenhancements, 128-bit addressing – enough for over 6,000 billion devices and relievingIPv4’s address shortage.Above IP are two transport layers. TCP (Transmission Control Protocol) provides reliabledata delivery, efficient flow control, full duplex operation and multiplexing (simultaneousoperation with many sources and destinations). It establishes a connection and detectscorrupt or lost packets at the receiver and re-sends them. Thus TCP/IP, the most commonform of IP, is used for general data transport but is slow and not ideal for video.IUDP (User Datagram Protocol) uses a series of ‘ports’ to connect data to an application.Unlike the TCP, it adds no reliability, flow-control or error-recovery functions but it can detectand discard corrupt packets by using checksums. This simplicity means its headers containfewer bytes and consume less network overhead than TCP, making it useful for streamingvideo and audio where continuous flow is more important than replacing corrupt packets.There are other IP applications that live above these protocols such as File Transfer Protocol(FTP), Telnet for terminal sessions, Network File System (NFS), Simple Mail Transfer Protocol(SMTP) and many more.Website: www.ipv6forum.comIP Datacast Forum (IPDC)The IPDC Forum was launched in 2002 to promote and explore the capabilities of IP-basedservices over digital broadcast platforms (DVB and DAB). Participating companies includeservice providers, technology providers, terminal manufacturers and network operators.The Forum aims to address business, interoperability and regulatory issues and encouragepilot projects.See also: IP over DVBWebsite: www.ipdc-forum.org111