Network Address, Internet Protocol IP | Multi-Tech Systems FR2201

MultiFRAD II User Guide

different destination address, and in some cases, different sizes. A typical packet holds 512 bytes of information, so it takes many packets to transfer a large file over a network.

As packets traverse a network, the addressing information contained in them is used by bridges and routers to direct packets to their destination, or keep them off of networks where they don't belong. Routers direct packets along a specific path that has been predetermined as the best route to the packets' destination. Routers use algorithms to determine efficient paths in conjunction with other routers on the network. Administrators can also manually configure routers, based on the cost or speed of routes. Information can be transmitted to another system using either connection-oriented or connection-less methods. A connection-less session is more efficient for short, bursty transmissions since a session setup is not required, but the end system may need to perform more work to resequence packets that arrive out of order and check for lost packets.

Network Address

Every node on a network has an assigned address that other nodes use when communicating with it. For Ethernet and token ring network adapters, unique addresses are assigned at the factory. ARCNET networks have user-definable addresses. For example, the address of an Ethernet and token ring network adapter consists of a 6-byte address, half of which is a special number identifying the board's manufacturer. The last half of the address is a unique number for the board assigned at the factory. This strategy virtually guarantees that no two Ethernet or token ring network interface cards will ever have the same address and prevents conflicts.

When separate networks are connected into an internetwork, a new addressing scheme is required. On interconnected NetWare networks, each network segment has its own address, which is used for routing purposes and differentiate each segment from the others.

In TCP/IP networks such as the Internet, every node has a numeric address that identifies both a network and a local host or node on the network. This address is written as four numbers separated by dots, for example 148.1.9.1. The assignment of addresses is arbitrary within a company or organization, but if the company plans to connect with the Internet, it is important to obtain registered addresses from an outside agency to conform with international addressing standards. Applications running in computers also have addresses that other applications, either local or remote, use to communicate with the application. On TCP/IP networks, a socket is a combination of an Internet address plus an application address.

Internet Protocol (IP)

Internet Protocol is a connection-less communication protocol that by itself provides a datagram service. Datagrams are self-contained packets of information that are forwarded by routers based on their address and the routing table information contained in the routers. Datagrams can be addressed to a single node or to multiple nodes. There is no flow control, acknowledgment of receipt, error checking, and sequencing. Datagrams may traverse different paths to the destination and thus arrive out of sequence. The receiving station is responsible for resequencing and determining if packets are lost. IP handles congestion by simple discarding packets. Resequencing and error handling are taken care of by upper layer protocols.

IP works on a number of local and wide area networks. When IP runs in the LAN environment on an Ethernet network, for example, the data field in the Ethernet frame holds the IP packet and a specific field in the frame indicates that IP information is enclosed. IP uses an addressing scheme that works independently of the network addressing scheme. For example, every Ethernet adapter has a factory-assigned address for each node.