"A case could be made either way. First, look at the functions performed at the network layer to deal with the communications network (hiding the details from the upper layers). The network layer is responsible for routing data through the network, but with a broadcast network, routing is not needed. Other functions, such as sequencing, flow control, error control between end systems, can be accomplished at layer 2, because the link layer will be a protocol directly between the two end systems, with no intervening switches. So it would seem that a network layer is not needed. Second, consider the network layer from the point of view of the upper layer using it. The upper layer sees itself attached to an access point into a network supporting communication with multiple devices. The layer for assuring that data sent across a network is delivered to one of a number of other end systems is the network layer. This argues for inclusion of a network layer. In fact, the OSI layer 2 is split into two sublayers. The lower sublayer is concerned with medium access control (MAC), assuring that only one end system at a time transmits; the MAC sublayer is also responsible for addressing other end systems across the LAN. The upper sublayer is called Logical Link Control (LLC). LLC performs traditional link control functions. With the MAC/LLC combination, no network layer is needed (but an internet layer may be needed)."
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"Your system layer is responsible for dealing with nodes inside a realistic technique. It is also liable for doing selections with routing a new bundle derived from one of community completely to another. Inside a send out multilevel, direction-finding is not necessary. The transmittal from just about any affixed train station is definitely received aside other fastened channels. Various other operates,such as sequencing, flow control, error control, can be carried out on level 3. The actual Apple pc sublayer is answerable to dealing with throughout the LAN. While using Data link coating and it is sublayers (Apple pc & LLC), simply no network covering is needed."
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