Shulou(Shulou.com)06/03 Report--

The OSI model is divided into physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer.

II. Functions of physical layer and data link layer

III. Functions of the network layer and the transport layer

IV. Functions of session layer, presentation layer and application layer

V. composition of TCP/IP protocol suite

ICMP- Datagram Control Protocol

IGMP- user data message Management Protocol

ARP- address Resolution Protocol; (IP-- > MAC)

RARP- inverse address Resolution Protocol; (MAC-- > IP)

TCP- security protocol

UDP- efficient protocol

TFTP- simple File transfer Protocol

SMTP- Mail transfer Protocol

SNMP- simple Network Management Protocol

VI. The encapsulation process of data in the interlayer

1. Application layer: data is "translated" into binary encoded data, which is the language used in the network world.

2. Transport layer: the upper data is divided into effective data segments, and the TCP header is encapsulated for each segmented data.

3. Network layer: the upper layer data is encapsulated with a new message header-IP header based on the TCP header. The IP header contains the target IP address and the source IP address.

4. Data link layer: the upper data is encapsulated with MAC header on the basis of IP header and TCP header. There is a key field information-MAC address in MAC header, which is composed of a set of 48-bit binary numbers.

5. Physical layer: both the previous encapsulated message header and market data information are composed of binary numbers, where the bit stream composed of these binary numbers is converted into electrical signals to be transmitted in the network.

VII. Data unencapsulation process

1. Physical layer: convert the electrical signal into binary data and send the data to the data link layer.

2. Data link layer: the destination MAC address will be checked to determine whether it matches your own MAC address, and subsequent processing will be completed accordingly. If the destination MAC address of the Datagram is its own MAC address, the MAC header of the data will be "removed" and the data will be sent to the upper layer; if the destination MAC address does not match its own MAC address, it will discard the data.

3. Network layer: the network layer is similar to the data link layer, and the destination IP address will be verified to be the same as its own IP address, so as to determine that the identity is sent to the upper layer.

4. Transport layer: determine which application layer protocol or application the data is sent to according to the TCP header, and then reassemble the data segments of the packet to the application layer.

Application layer: decode these binary data and restore them to the original information transmitted by the sender.

7. PDU protocol data unit

1. After the upper data is encapsulated in the TCP header, this unit is called the data segment.

2. The data segment is transferred down to the network layer, and after the IP header is encapsulated, this unit is called a packet.

3. After the packet is sent to the data link layer and encapsulated with the MAC header, this unit is called the data frame.

4. After the data frame is transmitted to the physical layer, it becomes a bit stream, and then is transmitted through the physical medium.

8. Typical hardware devices in each layer of the network

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