Cisco Routing and Switching series--------NA series

Seniors, the great God, the younger brother is now want to record their own learning, hope in a few years after the turn will have feelings, write what shortcomings also hope that the predecessors more advice!!

The first chapter:

One, the network provides the application:

1, batch processing of applications

2, interactive application

3, the application of instant traffic

Second, the topology type of the network

1, star type

2, Ring type

3, Total line style

Most of them are star type and total Linetype.

Third, understand the host-to-host communication model

1 , Boss model

a , Private

b , Limitations ( Bug , Update )

C , the popularity of the degree is not high

D , the standard is not uniform

Because there are so many reasons for the boss model of the various restrictions.

2 , the new standard

custom industry Unified standards ---- ( level 5 must be mastered)

a , OSI (Open System Interconnection: Interconnect) --7 Layer Model -- More Perfect

Physical layer--------provides physical connection to the data link layer using the transmission media, and realizes the transparent transmission of the bit stream.

Data link------through a variety of control protocols, the error of the physical channel into error-free, reliable transmission of data frame data-linked sniper

The network layer--------Select the most appropriate path for the message or packet through the communication subnet through the routing algorithm.

The transport layer--------provide users with reliable end-to-end error and flow control to ensure the correct transmission of the message

Session Layer--------provides a way for the presentation layer of two entities to establish and use connections to the session

Presentation layer--------Handle the presentation of user information, such as encoding, data format conversion

The application layer --------provide services directly to the user, accomplishing all the work that the user wants on the network

It is important to note that starting from the physical layer to the application layer is 1-7 layers (be careful)

b , TCP/IP protocol Stack --4 Layer Model------science and engineering to be rigorous, must not be said to be TCP/IP 4 layer model!

Link Layer ---- ( OSI next two floors)

internet/network ( OSI -- Network layer)

Transport Layer --- ( osi-- Transport Layer)

Application Layer --- ( osi- Upper three floor)

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Cisco Routing and Switching series--------NA series