OSI with the structure and function of TCP / IP layers, what are the protocols? Protocol share port numbers?
1) physical layer ---- defined for the establishment, maintenance and removal of desired physical link mechanical, electrical, functional and procedural characteristics, its role is to make the original stream of data bits can be transmitted on the physical medium . In particular to a connector specification, "0", "1" level representation of the signal, send and receive content and coordination between the two sides.
2) data link layer ---- bitstream is organized into a data link protocol data units (commonly referred to as frames), and its transmission units of frames having address, control, information and check code data . Data link layer main role is to check, acknowledgment feedback and retransmission and other means unreliable physical link layer, the network for the transformation of the pair of error-free data link. The data link layer also coordinate both send and receive data transmission rate, i.e., flow control, in order to prevent the recipient by the sender processing time to be caused by high-speed data lines and the blocking buffer overflow.
3) Network Layer ---- data to the network protocol data unit (packet) transmission units. The network layer is concerned with running subnetworks control , mainly to solve how to make the data packets across subnetworks from a source to a destination of the problem, which requires routing the communication subnet. Moreover, to avoid excessive packet communication subnet occurs caused by network congestion, the need to control the number of incoming packets. When the packet is to communicate across multiple subnets to reach their destination, but also solve the problem of network interconnection.
4) Transport Layer ---- is a first end - the end, i.e. the host - the host level. To-end transparent data transport services provided by the transport layer , so that users do not have the presence of high-level communication subnet, thus with a unified transport primitives written in high-level communication software can run on any subnet. Transport layer have to deal with end to end error control and flow control problems.
5) session layer ---- is a process - a process level, and its main function is communication between various organizations and synchronize processes on different hosts (also known as a session). The session layer is responsible for setup and teardown session connection between two session layer entity. In the case of half-duplex session layer provides a data token to control when a party's right to transmit data. After the session layer also provides a synchronization point of the insertion in the data stream unit so that the data transmission interrupted due to network failure, you may not have to start only after the retransmission of the most recent data synchronization point.
6) Presentation Layer ---- provides common syntax for the data or information represented by the upper layer user transformation. In order to let the computer using different coding methods can understand each other in the communication of content data, a method may be employed to define the abstract data structure standard and encoded using standard representation. The presentation layer manages these abstract data structures, and the internal representation of the computer communications network into a standard representation employed. Data compression and encryption are represented represents the conversion of the functional layer may be provided.
7) application layer ---- is OSI environment of the highest level. Different application layer OSI environment as a means to provide access to specific types of network applications. Network Environment File Transfer Access and Management (FTAM) between different hosts, standard e-mail transmission of telegrams handling system (MHS), the different types of terminals and the host via virtual terminal access network interaction (VT) protocol belong Category application layer.
Protocol layers:
Physical layer: RJ45, CLOCK, IEEEE802.3
Data Link: PPP, FR, HDLC, VLAN, MAC
Network layer: IP, ICMP, ARP, RARP, OSPF, IPX, RIP, IGMP
Transport Layer: TCP, UDP, SPX
Session layer: RPC, SQL, NETBIOS, NFS
Presentation Layer: JPEG, MPEG, ASCII, MIDI
Application Layer: RIP, BGP, FTP, DNS, Telnet, SMTP, HTTP, WWW, NFS
Port number of commonly used protocols: the HTTP 80, 20, 21 are FTP, Telnet 23 is, the SMTP 25.
Classification of IP addresses
Class A: 10.0.0.0 to 10.255.255.255
Class B: 172.16.0.0 to 172.31.255.255
Class C: 192.168.0.0 to 192.168.255.255
