HCIA review

Catalog

 OSI/RM

 IP Address

Static routing  

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 OSI/RM

application layer       >> Provide various application services , Convert abstract language to coding , Provide human-computer interaction interface

The presentation layer       >> Convert the encoding to binary     Unified format

The session layer         >>   Maintain the session between the network application and the network server

Transport layer      >> End to end communication （ Apply to application ）   sport  dport

The network layer        >>  Use IP Address realizes logical addressing between hosts   --- SIP DIP

Data link layer >> Control physical hardware   Convert binary into electrical signal   

The physical layer       >> Handle the transmission of electrical signals

The length of the port number is 16 Binary bits

0-65535

among 0 It is not used as a port of the transport layer

The port number range is 1-65535

1-1023 For well-known port number

•      DNS Domain name resolution service （53）
•     DHCP（UDP67,68）

obtain DIP Address method

 1. Know the server's IP Address

 2. Access the server through the domain name

 3. Access the server through the application

 4. radio broadcast

 

MAC Address by 48 Bit binary structure

Global uniqueness , use the same pattern    --SMAC DMAC

Data link layer   adopt MAC Address for physical addressing

obtain DMAC Methods - -ARP agreement -- - - Address resolution protocol

1. positive ARP- - - adopt IP The address for MAC Address

The host by Broadcast transmission ARP, Based on the known IP Address , request MAC Address . All devices in the broadcast domain can receive request packets , All devices that receive packets will record the source in the packet IP Address and source MAC The correspondence of the address is local ARP The cache table . after , Look at the request IP Address , If it's local IP Address , Will be performed ARP The reply , Local MAC Address inform . If it's not local IP Address , The packet will be discarded directly . after , When sending data again , Give priority to local ARP Cache table , If there are records in the table , Then the information will be sent directly according to the record . If there is no record , Then send ARP Request package acquisition MAC Address

2. reverse ARP- - - adopt MAC The address for IP Address

3. free ARP

 

 IP Address

Static routing