Computer Level 3-Network Technology Summary

Chapter 3: Lan Basics

1. LAN topology: Bus, Star, and ring.

2. there are three types of shared media LAN defined in the IEEE 802.2 standard: Bus-type LAN Using the CSMA/CD media access control method (developed by 802.3) and Token Bus Media Access Control Method (developed by 802.4) and uses the Token Ring Media Access Control Method (developed by 802.5. The first type of shared media LAN is the most commonly used, also known as Ethernet. All nodes in the network can compete equally for the right to send data. In the future, we can think that 802.3 is equal to Ethernet.

3. In Ethernet, CSMA/CD is used for Media Access Control. In general, CSMA/CD is used to send the media after listening, and conflict is stopped. The media is resent after random delay.

4. The typical MAC address is 48 characters long. Stored in the ROM of the NIC.

The 5.802.2 Standard specifies the specification of the LLC layer. 802.3... 802.11 specification for MAC layer and physical layer. 802.11 the MAC layer is divided into two sub-layers: The Distributed Coordination function (DCF) Sub-layer and the point coordination function (PCF) Sub-layer.

6. The 802.x protocol only covers the physical layer and data link layer of the OSI reference model.

Chapter v ip protocol

1. A Router (also called a gateway in the internet) is responsible for the connection between the network and the network (different subnets). Data from the source host often needs to go through multiple routers to reach the target host, the router is responsible for transmitting data from one network to another. The router needs to select an optimal path based on the destination of the data, indicating the direction of data transmission.

2. IP Address: (P114)

An IP address consists of 32-bit binary numbers and is divided into five categories.

Class A: 7-bit indicates the network, and 24-bit indicates the host. Therefore, it can be used for large networks and 16777214 machines. The first byte range is 1 ~ 126.

Class B: 14-bit indicates the network, 16-bit indicates the host, medium-scale network, and 65534 machines. The first byte range is 128 ~ 191.

Class C: 21-bit indicates the network, and 8-bit indicates the host, removing all zero and all 1. A maximum of 254 machines can be accommodated. The first byte range is 192 ~ 223.

Class D: Send with a multi-destination address.

Class E: Reserved.

IP addresses are represented in dotted-decimal Notation: each byte is expressed in a decimal number. Therefore, a total of four decimal numbers are separated.

Several Special IP addresses:

Network Address: Valid network number and zero host number, used to represent a specific network.

Broadcast address: Valid network number and host number of "1". The host can use this IP address to broadcast information to machines in the subnet.

Delivery Address: 127.0.0.1, used for testing network software and communication between local machine processes.

Local Address: 192. x or 10. x is not assigned to Internet users. You can use these IP addresses in the internal LAN.