Network Layer Protocols

Network Layer Protocols

Let's see how many network layer protocols exist and which ones are usually implemented. Also the IPv4 and IPv6 packages.

NETWORK LAYER

The network layer or layer 3 of the OSI model provides services to allow the terminals to exchange data on the network. The Network layer uses 4 basic processes (End-to-end transport processes):

• Terminal Addressing : The terminals must be configured with a unique IP address to identify them in the network.
• Encapsulation : The network layer encapsulates the protocol data unit (PDU) of the transport layer to a packet (add IP header information)
• Routing or Routing : The network layer provides services to direct packets to a destination host on another network
• Decapsulation : Once the network layer uncapsulates the packet, the layer 4 PDU that is obtained is transferred to the appropriate service in the transport layer.

Each router that crosses a packet before reaching the destination host is called a "jump."

NETWORK LAYER PROTOCOLS

There are several network layer protocols. However, there are only two network layer protocols that are usually implemented:

• Internet Protocol version 4 (IPv4)
• Internet Protocol version 6 (IPv6)

Old Network Layer Protocols

• Novell internetwork packet exchange (IPX)
• AppleTalk
• Offline network service (CLNS / DECNet)

IP FEATURES

IP was designed as a protocol with low overhead.  This means that it only provides the necessary functions to send a packet from a source to a destination through an interconnected network system. The protocol was not designed to track or manage packet flow.

The following describes the basic characteristics of IP:

IP: NO CONNECTION

IP has no connection, which means that an exclusive full connection is not generated before sending the data and then the following happens:

• The sender does not know if the receiver is listening or if the message arrived on time.
• The receiver does not know that data is coming.

 IP: MINIMUM SERVICE DELIVERY

To be unreliable means that IP does not have the functionality to manage or recover packets not received or damaged . This is because, although IP packets are sent with information about the delivery location, they do not have information that can be processed to inform the sender if the delivery was successful.

IP: INDEPENDENT OF THE MEDIA

Regardless of the means it means that the transport of IP packets is not limited to a particular medium (it can be transmitted by copper cables, optical signals or wireless radio signals). However, the network layer takes into account one of the most important characteristics of the medium, the " maximum transmission unit " (MTU) which is the maximum size of PDUs that each medium can carry.

The data link layer passes the MTU value to the network layer. The network layer then determines what size the packets can be. A router must divide the packet when it is forwarded from one medium to another with a lower MTU. This process is called " packet fragmentation " or "fragmentation."