Routing in the context of Network packet

The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

IP has the task of delivering packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this purpose, IP defines packet structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram with source and destination information.IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974, which was complemented by a connection-oriented service that became the basis for the Transmission Control Protocol (TCP). The Internet protocol suite is therefore often referred to as TCP/IP.

Reverse geocoding is the process of converting a location as described by geographic coordinates (latitude, longitude) to a human-readable address or place name. It is the opposite of forward geocoding (often referred to as address geocoding or simply "geocoding"), hence the term reverse. Reverse geocoding permits the identification of nearby street addresses, places, and/or areal subdivisions such as neighbourhoods, county, state, or country. Combined with geocoding and routing services, reverse geocoding is a critical component of mobile location-based services and Enhanced 911 to convert a coordinate obtained by GPS to a readable street address which is easier to understand by the end user, but not necessarily with a better accuracy.

Reverse geocoding can be carried out systematically by services which process a coordinate similarly to the geocoding process. For example, when a GPS coordinate is entered the street address is interpolated from a range assigned to the road segment in a reference dataset that the point is nearest to. If the user provides a coordinate near the midpoint of a segment that starts with address 1 and ends with 100, the returned street address will be somewhere near 50. This approach to reverse geocoding does not return actual addresses, only estimates of what should be there based on the predetermined range. Alternatively, coordinates for reverse geocoding can also be selected on an interactive map, or extracted from static maps by georeferencing them in a GIS with predefined spatial layers to determine the coordinates of a displayed point. Many of the same limitations of geocoding are similar with reverse geocoding.

In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers.

The internet layer is a group of internetworking methods, protocols, and specifications in the Internet protocol suite that are used to transport network packets from the originating host across network boundaries; if necessary, to the destination host specified by an IP address. The internet layer derives its name from its function facilitating internetworking, which is the concept of connecting multiple networks with each other through gateways.

The internet layer does not include the protocols that fulfill the purpose of maintaining link states between the local nodes and that usually use protocols that are based on the framing of packets specific to the link types. Such protocols belong to the link layer. Internet-layer protocols use IP-based packets.

Internet transit is the service of allowing network traffic to cross or "transit" a computer network, usually used to connect a smaller Internet service provider (ISP) to the larger Internet. Technically, it consists of two bundled services:

• The advertisement of customer routes to other ISPs, thereby soliciting inbound traffic toward the customer from them
• The advertisement of other ISPs' routes (usually but not necessarily in the form of a default route or a full set of routes to all of the destinations on the Internet) to the ISP's customer, thereby soliciting outbound traffic from the customer towards these networks.

In the 1970s and early 1980s-era Internet, the assumption was made that all networks would provide full transit for one another. In the modern private-sector Internet, two forms of interconnect agreements exist between Internet networks: transit, and peering. Transit is distinct from peering, in which only traffic between the two ISPs and their downstream customers is exchanged and neither ISP can see upstream routes over the peering connection. A transit free network uses only peering; a network that uses only unpaid peering and connects to the whole Internet is considered a Tier 1 network. In the 1990s, the network access point concept provided one form of transit.

An ad hoc routing protocol is a convention, or standard, that controls how nodes decide which way to route packets between computing devices in a mobile ad hoc network.

In ad hoc networks, nodes are not familiar with the topology of their networks. Instead, they have to discover it: typically, a new node announces its presence and listens for announcements broadcast by its neighbors. Each node learns about others nearby and how to reach them, and may announce that it too can reach them.

A network switch (also called switching hub, bridging hub, Ethernet switch, and—by the IEEE—MAC bridge) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.

A network switch is a multiport network bridge that uses MAC addresses to forward data at the data link layer (layer 2) of the OSI model. Some switches can also forward data at the network layer (layer 3) by additionally incorporating routing functionality. Such switches are commonly known as layer-3 switches or multilayer switches.

A network bridge is a computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called network bridging. Bridging is distinct from routing. Routing allows multiple networks to communicate independently and yet remain separate, whereas bridging connects two separate networks as if they were a single network. In the OSI model, bridging is performed in the data link layer (layer 2). If one or more segments of the bridged network are wireless, the device is known as a wireless bridge.

The main types of network bridging technologies are simple bridging, multiport bridging, and learning or transparent bridging.