TCP/IP Model
Posted by Harisinh | Posted in | Posted on 10:39 AM
A protocol is a set of rules governing the way data will be transmitted and received over data communication networks. Protocols are then the rules that determine everything about the way a network operates. Protocols must provide reliable, error-free communication of user data as well as a network management function. Therefore, protocols govern how applications access the network, the way that data from an application is divided into packets for transmission through cable, and which electrical signals represent data on a network cable.
The OSI model, defined by a seven-layer architecture, is partitioned into a vertical set of layers, as illustrated in Figure 1.2. The OSI model is based on open systems and peer-to-peer communications. Each layer performs a related subset of the functions required to communicate with another system. Each system contains seven layers. If a user or application entity A wishes to send a message to another user or application entity B, it invokes the application layer (layer7). Layer 7 (corresponding to application A) establishes a peer relationship with layer 7 of the target machine (application B), using a layer 7 protocol. In an effort to standardise a way of looking at network protocols, the TCP/IP four-layer model is created with reference to the seven-layer OSI model, as shown in Figure 1.3. The protocol suite is designed in distinct layers to make it easier to substitute one protocol for another. The protocol suite governs how data is exchanged above and below each protocol layer. When protocols are desiged, specifications se out how a protocol exchanges data with a protocol layered above it.
Both the OSI model and the TCP/IP layered model are based on many similarities, but there are philosophical and practical differences between the two models. However, they both deal with communications among heterogeneous computers.
Since TCP was developed before the OSI model, the layers in the TCP/IP protocol model do not exactly match those in the OSI model. The important fact is the hierarchical ordering of protocols. The TCP/IP model is made up of four layers : application layer, transport layer, Internet layer and network access layer. These will be discussed in the next post.
The OSI model, defined by a seven-layer architecture, is partitioned into a vertical set of layers, as illustrated in Figure 1.2. The OSI model is based on open systems and peer-to-peer communications. Each layer performs a related subset of the functions required to communicate with another system. Each system contains seven layers. If a user or application entity A wishes to send a message to another user or application entity B, it invokes the application layer (layer7). Layer 7 (corresponding to application A) establishes a peer relationship with layer 7 of the target machine (application B), using a layer 7 protocol. In an effort to standardise a way of looking at network protocols, the TCP/IP four-layer model is created with reference to the seven-layer OSI model, as shown in Figure 1.3. The protocol suite is designed in distinct layers to make it easier to substitute one protocol for another. The protocol suite governs how data is exchanged above and below each protocol layer. When protocols are desiged, specifications se out how a protocol exchanges data with a protocol layered above it.
Both the OSI model and the TCP/IP layered model are based on many similarities, but there are philosophical and practical differences between the two models. However, they both deal with communications among heterogeneous computers.
Since TCP was developed before the OSI model, the layers in the TCP/IP protocol model do not exactly match those in the OSI model. The important fact is the hierarchical ordering of protocols. The TCP/IP model is made up of four layers : application layer, transport layer, Internet layer and network access layer. These will be discussed in the next post.
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