Data packet in the context of Header (computing)

Internet Protocol television (IPTV), also called TV over broadband, is the service delivery of television over Internet Protocol (IP) networks. Usually sold and run by a telecom provider, it consists of broadcast live television that is streamed over the Internet (multicast) — in contrast to delivery through traditional terrestrial, satellite, and cable transmission formats — as well as video on demand services for watching or replaying content (unicast).

IPTV broadcasts started gaining usage during the 2000s alongside the rising use of broadband-based internet connections. It is often provided bundled with internet access services by ISPs to subscribers and runs in a closed network. IPTV normally requires the use of a set-top box, which receives the encoded television content in the MPEG transport stream via IP multicast, and converts the packets to be watched on a TV set or other kind of display. It is distinct from over-the-top (OTT) services, which are based on a direct one-to-one transmission mechanism.

Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit.

Circuit switching originated in analog telephone networks where the network created a dedicated circuit between two telephones for the duration of a telephone call. It contrasts with message switching and packet switching used in modern digital networks in which the trunklines between switching centres carry data between many different nodes in the form of data packets without dedicated circuits.

A router is a computer and networking device that forwards data packets between computer networks, including internetworks such as the global Internet.

Routers perform the "traffic directing" functions on the Internet. A router is connected to two or more data lines from different IP networks. When a data packet comes in on a line, the router reads the network address information in the packet header to determine the ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Data packets are forwarded from one router to another through an internetwork until it reaches its destination node.

In computer networking, a link-local address is a network address that is valid only for communications on a local link, i.e. within a subnetwork that a host is connected to. Link-local addresses are typically assigned automatically through a process known as link-local address autoconfiguration, also known as auto-IP, automatic private IP addressing (APIPA, specific to IPv4), and stateless address autoconfiguration (SLAAC, specific to IPv6). While most link-local addresses are unicast, this is not necessarily the case; e.g. IPv6 addresses beginning with ff02: (ff02::/16), and IPv4 addresses beginning with 224.0.0. (224.0.0.0/24) are multicast addresses that are link-local.

Link-local addresses are not guaranteed to be unique beyond their network segment. Therefore, routers do not forward packets with link-local source or destination addresses.