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The network layer deals with logical addressing. A logical address is one that is assigned to an interface in software—as opposed to one that is burned onto an interface at the factory.
For two IP hosts to communicate, they must be in the same network. If they are in different networks, we need a router to connect the two networks. Finding the way between networks, potentially through hundreds of routers, is called path determination. This is the second function of the network layer. Path determination means routing, and routers are a Layer 3 device.
The last function of the network layer is to communicate with the layer above (transport) and the layer below (data link). This is achieved by attaching a header to the beginning of the segment that Layer 4 built. The addition of this header makes the segment into a packet. The packet header has a field that indicates the type of segment it is carrying—TCP or UDP, for example—so that the packet can be sent to the correct function at Layer 4. Communicating with Layer 2 in this case means that an IP packet can be sent to Layer 2 to become an Ethernet frame, Frame Relay, Point-to-Point Protocol, or almost any other Layer 2 technology..
One of the big advantages of a logical addressing scheme is that we can make it hierarchical. Hierarchical means "organized into a formal or ranked order." Because all the networks are numbered, and we have control over where those networks are set up, it's easy for us to build a really big system: Big networks are broken into smaller and smaller pieces, with the routers closer to the core knowing the big picture and no details, and the routers at the edge knowing their little set of detailed information but nothing about anyone else's. This makes it easier to organize and find all the millions of different networks, using routers. It's roughly equivalent to a postal address.
Posted by griffinLincoln
Its basically a Layer 3 (of seven) in the OSI model of computer networking. The Network Layer is responsible for end-to-end (source to destination) delivery of packets.
Posted by HamidAliKhan
The Network Layer is Layer 3 (of seven) in the OSI model of computer networking. The Network Layer is responsible for end-to-end (source to destination) delivery of packets.
Posted by sagitraz
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