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

Chapter II

Know the bag is called Understand network!!!!

The encapsulation and encapsulation process of a packet

1 , Encapsulation

process: From inside to outside ---- Example: Postal parcel

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2 , Solution encapsulation

process: From outside to inside ---- Example: receiving a parcel

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Here to emphasize one thing, on the internet every packet in the transmission process will have the Ethernet frame head, but will be stripped through the router, and then look at the source IP, the destination IP, and then at the exit on the Ethernet frame head, the following is the format of the Ether II-frame package:

dm6b| sm6b| type2b|46-1500b| fcs|

Here the DM (destination mac) and SM (source Mac) is the relative address, than the packet from the router to send out, to the interface of another router to receive, this time the DM is the interface to receive this packet physical address, while the source, Mac is the physical address of the interface to emit this packet! So the DM and SM are changing during the transmission of the packet. Unlike IP, the source address of the IP is fixed, which is the address of the sender and receiver.

2 , TCP/IP the content of the protocol stack passing by layer

Data Layer ---- Data Frame

Network Layer ---- Data Package

Transport Layer ---- Data Segment

Application Layer ---- Data

two, local area network ( LAN --local Area Network ) Introduction

1 , what is a local area network?

In a relatively limited range, many network devices (routers, switches, terminals, etc.) that are very close together are connected through some media and use various protocols to meet our business needs.

2 , the importance of the switch network device in the network

1 ) Conflict Domain

Each interface of the switch represents a conflict domain!

2) broadcast domain (broadcast address: 255.255.255.255 )

3 ) Basic functions of the switch

a , learn --mac Address (Dynamic -- default behavior, Manual, paste)

b , forwarding -- based on MAC Address Table Forwarding

C , filtering -- Data

4 ) features of the switch

a , mixed port rate ( 10m/100m/1g self-adapting)

b , high port density (many interfaces --24/48 , Stacking

C , based on low cost per port

D , fast switching speed

e , Cache

Each interface of a router cannot be configured with the same network segment because the router is an isolated broadcast domain.

each port of the switch is shared bandwidth, for example, the switch is 100M , each interface will have 100M bandwidth, if it is in full duplex mode, the throughput of this interface is 200M.

This article is from the "Boundless" blog, please make sure to keep this source http://shixungan.blog.51cto.com/8883838/1795589

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