Three models of computer networks

OSI reference model, TCP / IP model production, five-layer structure Learning Network.

The actual production and not using standard OSI model, TCP / IP model is the actual production network architecture uses a five-layer network model is created to facilitate learning.

OSI (Open System Interconnection), International Organization for Standardization (ISO) standards developed a system for communication between computer systems or interconnected, typically referred to as the OSI reference model or seven layer model.

From top to bottom are:

Application layer:

   A computer with other application communication, data transmission communication parties to resolve the final issues, namely communication between different nodes on the two corresponding application process.

   There are protocols: HTTP FTP TFTP SMTP SNMP DNS TELNET HTTPS POP3 DHCP and so on.

Presentation Layer:

   And encrypted data format is defined. (Five in the model which has been incorporated into the application layer)

   Format, JPEG, ASCll, DECOIC, encrypted format.

Session Layer

   It defines how to start, control, and terminate a session. (Five in the model which has been incorporated into the application layer)

   Corresponding to the host process, it means the local host and the remote host ongoing conversation.

Transport Layer

   Definition of transmission of data protocol port, and flow control and error checking.

   There protocols: TCP UDP and the like, i.e. packets entering the network card upon leaving the transport layer.

Network layer

   Address logical address, to achieve routing between different networks. (Routing)

   There protocol: ICMP IGMP IP (IPV4 IPV6) ARP RARP

data link layer

   Establishing a logical connection, hardware address addressing, error checking and other functions. (Defined by the underlying network protocol, ATM, FDDI, etc.)

   Further the bits into bytes grouped into frames, using the MAC address access media, but can not correct the errors found.

Physical Layer

   The establishment, maintenance, disconnect the physical connection. (Defined by the underlying network protocol, RJ45,802.3 etc.)