Shulou(Shulou.com)06/01 Report--

OSI (Open Systerm Interconnection) Open system Interconnection basic reference system

Number of layers

Name

Responsible for content

one

Physical layer

Responsible for defining the physical and electrical characteristics of the equipment

two

Data link layer

Because the lower layer of the second layer is the definition of the entity and the upper layer is the definition of software encapsulation, the second layer is divided into two sub-layers for data conversion.

1. In the part of partial hardware media, it is mainly responsible for MAC (Madia Access Control). The data unit of this sublayer is MAC data frame. MAC is the main data packet that can be processed by network interface equipment. It is also the data that is eventually encoded into a bit stream by the physical layer. Ethernet protocol is most commonly used.

two。 The software-oriented part is controlled by the logical connection layer (Logical Link Control LLC), which is mainly responsible for multitasking data packets and data from the upper layer and converting them into MAC format, including information exchange, flow control, error handling and so on.

three

Network layer

Define the connection establishment, termination and maintenance between computers, the choice of transmission path of data packets, etc.

four

Transport layer

Define the connection technology between the sender and the receiver (such as TCP, UDP technology), including the packet format, packet transmission, flow control, detection and retransmission of the transmission process, etc.

five

Session layer

Define the connection and interruption of the connection channel between two addresses, establish, manage and abort the session between programs

six

Presentation layer

Defining the conversion of data formats between network services (or programs), including data encryption, is also done at this level.

seven

Application layer

Define how the application enters the communication interface of this layer, receives or sends data to the application, and finally presents it to the user

TCP/IP

OSI

Correspondence

TCP/IP

Agreement

Application layer

Presentation layer

Session layer

Application layer

HTTP 、 FTP 、 SMTP 、 POP3 、 NFS 、 SSH

Transport layer

Transport layer

TCP 、 UDP

Network layer

Network layer

IP 、 ICMP

Data link layer

Physical layer

Network interface layer

LAN:Ethernet,Token Rain

WAN:Modem,ISDN,Serial

TCP/IP does not necessarily refer to two specific protocols, TCP and IP. It often refers to the entire family of TCP/IP protocols used by the Internet.

IP

Function: used to identify the network address of a node (to a certain extent, uniquely identify a network device)

Address composition: dotted decimal

-- A total of 32 binary digits

-- expressed as 4 decimal trees to. Separate

IP address classification

Types

The previous bit in the first byte of IP

Interval

Default subnet mask

Private address

A

0

0-127

255.0.0.0

10.0.0.0-10.255.255.255

B

01

128-191

255.255.0.0

172.16.0.0-172.31.255.255

C

one hundred and ten

192-223

255.255.255.0

192.168.0.0-192.168.255.255

D

1110

224-239

None

239.0.0.0-239.255.255.255

E

1111

240-255

Reserved use in the laboratory

127.0.0.0-127.255.255.255 local test address

Addresses starting with 0 and 127 cannot be directly configured on the device.

Subnet mask: used to divide IP addresses into network addresses and host addresses, which must be paired with IP addresses

Special IP address

1. Network address (network ID)

-function: represents a range / area, does not represent any equipment

-definition: host bits in the IP address, all 0. The IP is called the network address.

two。 Broadcast address

-function: represents all devices in a range / area

-definition: host bit in IP address, all 1. This IP is called broadcast address.

3. Private address: free, reusable, but can not surf the Internet, suitable for local area network, Internet can only be connected through the gateway

Public address: also known as public network address, belongs to the wide area network, suitable for Internet

IP address waste

Solution: 1. Private address

two。 Subnetting

3.IPv6

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