CCNA notes--802 rules, Network layer, transport layer, Session layer, presentation layer, Application layer, encapsulation

802 provisions

802.1 bridging

802.2 Logical Link Control

802.3 Ethernet

802.4 Token delivery Bus

802.5 Token Ring

802.6 Distributed queue Dual-entry bus access Service

802.9 Integrated Services

802.11 Wireless LAN

802.14 Cable TV

802.15 Person Wireless LAN

Network layer

Transmission Unit: Packet

Devices: Routers, layer three switches

ARP: Address Resolution Protocol

Function: Logical Addressing

Transfer data by IP

Transport Layer

Transmission Unit: Data segment

Function: Flow transmission and control

TCP: Reliable Transmission Control Protocol, does not allow the phenomenon of dropped frames, http,ftp,smtp,ip,icmp

Apply File Transfer

UDP: Unreliable Transmission Control Protocol,

Apply Video Call

Three-time handshake: Host A sends data to Host B

1. I'm a, are you B?

I'm B, what are you doing?

2. I am a, I want to send you the data

Ok

3. Establish a connection

Fourth time handshake? Interrupt Connection

Session Layer

Function: Flow control check

Presentation Layer

Features: compression, decompression, decryption, encryption

Application Layer

Features: Applications and connections

Service: Port number

FTP: File transfer on: 20 under: 21

POP3: Mail Receive 110

SMTP: Mail Send 25

Http:web Service 80

Telnet: Telnet 23

DHCP: Dynamically distributed IP

DNS: Domain Name resolution

Icmp:ping Network Layer Service

Encapsulation and unpacking

Data Application Layer Data

Encryption + Compression +data presentation layer decryption + decompression +data

Verifying +data session-level validation

Tcp+data Transport Layer to TCP

SOURCE ip+ Purpose Ip+tcp+data Network layer de-source ip+ destination IP

SOURCE mac+ Purpose mac+ Source ip+ purpose Ip+tcp+data+fcs Data link layer first go FCS, go to source mac+ destination Mac

Bit stream: 010000.. Physical Layer

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CCNA notes--802 rules, Network layer, transport layer, Session layer, presentation layer, Application layer, encapsulation