Multicast in the context of Live support software

Online chat is any direct text-, audio- or video-based (webcams), one-on-one or one-to-many (group) chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat (IRC), talkers and possibly MUDs or other online games. Online chat includes web-based applications that allow communication – often directly addressed, but anonymous between users in a multi-user environment. Web conferencing is a more specific online service, that is often sold as a service, hosted on a web server controlled by the vendor. Online chat may address point-to-point communications as well as multicast communications from one sender to multiple receivers and voice and video chat, or may be a feature of a web conferencing service.

Online chat in a narrower sense is any kind of communication over the Internet that offers a real-time transmission of text messages from sender to receiver. Chat messages are generally short in order to enable other participants to respond quickly. Thereby, a feeling similar to a spoken conversation is created, which distinguishes chatting from other text-based online communication forms such as Internet forums and email. The expression online chat comes from the word chat which means "informal conversation".

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.

In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compression techniques to reduce the size of each individual program stream, and multiplexing to combine them into a single signal. The practice is sometimes called "multicasting".

UPnP (originally Universal Plug and Play) is a set of Internet Protocol-based networking protocols that permits networked devices, such as personal computers, printers, Internet gateways, Wi-Fi access points and mobile devices, to seamlessly discover each other's presence on the network and establish functional network services. UPnP is intended primarily for residential networks without enterprise-class devices. Officially, only the abbrevations UPnP and UPnP+ are trademarked.

UPnP assumes the network runs IP, and then uses HTTP on top of IP to provide device/service description, actions, data transfer and event notification. Device search requests and advertisements are supported by running HTTP on top of UDP (port 1900) using multicast (known as HTTPMU). Responses to search requests are also sent over UDP, but are instead sent using unicast (known as HTTPU).

Web conferencing is used as an umbrella term for various types of online conferencing and collaborative services including webinars (web seminars), webcasts, and web meetings. Sometimes it may be used also in the more narrow sense of the peer-level web meeting context, in an attempt to disambiguate it from the other types known as collaborative sessions.

In general, web conferencing is made possible by Internet technologies, particularly on TCP/IP connections. Services may allow real-time point-to-point communications as well as multicast communications from one sender to many receivers. It offers data streams of text-based messages, voice and video chat to be shared simultaneously, across geographically dispersed locations. Applications for web conferencing include meetings, training events, lectures, or presentations from a web-connected computer to other web-connected computers.

In packet switching networks, traffic flow, packet flow or network flow is a sequence of packets from a source computer to a destination, which may be another host, a multicast group, or a broadcast domain. RFC 2722 defines traffic flow as "an artificial logical equivalent to a call or connection." RFC 3697 defines traffic flow as "a sequence of packets sent from a particular source to a particular unicast, anycast, or multicast destination that the source desires to label as a flow. A flow could consist of all packets in a specific transport connection or a media stream. However, a flow is not necessarily 1:1 mapped to a transport connection." Flow is also defined in RFC 3917 as "a set of IP packets passing an observation point in the network during a certain time interval."Packet flow temporal efficiency can be affected by one-way delay (OWD) that is described as a combination of the following components:

• Processing delay (the time taken to process a packet in a network node)
• Queuing delay (the time a packet waits in a queue until it can be transmitted)
• Transmission delay (the amount of time necessary to push all the packet into the wire)
• Propagation delay (amount of time it takes the signal’s header to travel from the sender to the receiver)

In computer networking, unicast is a one-to-one transmission from one point in the network to another point; that is, one sender and one receiver, each identified by a network address.

Unicast is in contrast to multicast and broadcast which are one-to-many transmissions.

IP multicast is a method of sending Internet Protocol (IP) datagrams to a group of interested receivers in a single transmission. It is the IP-specific form of multicast and is used for streaming media and other network applications. It uses specially reserved multicast address blocks in IPv4 and IPv6.

Protocols associated with IP multicast include Internet Group Management Protocol, Protocol Independent Multicast and Multicast VLAN Registration. IGMP snooping is used to manage IP multicast traffic on layer-2 networks.

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.

A multicast address is a logical identifier for a group of hosts in a computer network that are available to process datagrams or frames intended to be multicast for a designated network service. Multicast addressing can be used in the link layer (layer 2 in the OSI model), such as Ethernet multicast, and at the internet layer (layer 3 for OSI) for Internet Protocol Version 4 (IPv4) or Version 6 (IPv6) multicast.

Inter-domain routing is data flow control and interaction between Primary Domain Controller (PDC) computers. This type of computer uses various computer protocols and services to operate. It is most commonly used to multicast between internet domains.