‫The TCP IP model is a model with four layers, which is for both modeling current internet architecture,
‫as well as providing a set of rules that govern all forms of transmission over a network.
‫DARPA, an agency of the United States Department of Defense, created it in the 1970s.
‫This model was being made at the same time the Osai model was created.
‫The TCP IP model is not the same as high model, however, it was influenced by the model, which is
‫why many of the names of the different layers are the same.
‫So we can simply say that the TCP IP reference model represents reality in the real world, whereas
‫the OSAI reference model represents an ideal.
‫OK.
‫So these are the main differences of the TCP IP reference model.
‫The three top players in the U.S. model that is the application layer, the presentation layer and the
‫session layer are not distinguished separately in the TCP IP model, which only has an application layer
‫above the transport layer.
‫TCP corresponds to Osai layer for the transport layer.
‫IP corresponds to a subset of Osai layer three, the network layer.
‫TCP IP makes no prescriptions as to the link layers below IP, while OCI specifies two layers.
‫The physical address, commonly the Mac address, which is located in a special field in the data link
‫layer header changes as the packet passes from one device to another.
‫For example, from the source PC to a switch to a router to another switch and then finally to the destination
‫PC.
‫However, the original IP source and destination addresses do not change when transiting the network
‫because the packet is stripped of its layer three header only when it goes beyond a router.
‫When it stays within the same land, it only passes through switches, which de capsule8 it at the layer
‫to header containing the Mac address.
‫So as a result, the header changes as the packet is re encapsulated, as does the Mac address fields.