Chapter III: LAN Basics
1. Topological structure of the LAN: Bus type, star, annular.
2. IEE802.2 Standard defined shared media LAN has three categories: using the bus type LAN for the CSMA / CD Media Access Control (802.3), using the bus type LAN for TOKEN BUS Media Access Control (manufactured by 802.4), using TOKEN RING Media Access Control Method (Developed by 802.5). The first type of shared media LAN is most common, also known as Ethernet (Ethernet), all of the nets all the nodes are equal to the right to send data. You can think that 802.3 is equal to Ethernet.
In the 3.Thernet, the media access control method adopts CSMA / CD, summarized: first listening, while listening, the conflict is stopped, and the random delay is retransmitted.
4. Typical MAC address is 48. Store in the ROM of the NIC.
5.802.2 The standard specified the LLC layer specification. 802.3. . . 802.11 specifies the specification of the MAC layer and the physical layer. 802.11 divide the MAC layers into two sub-layers: distributed coordination function (DCF) sub-layer and point coordination function (PCF) sub-layers.
6.ieeE802.x protocol covers the physical layer and data link layer of the OSI reference model.
Chapter 5 IP Agreement
1. Router (also known in the Internet) Responsible for connection between networks and networks (different subnets), and data from the source host often needs to pass multiple routers to reach the host, the router passed by the router is responsible for the data from one The network is sent to another network, and the router needs to select an optimal path according to the destination arriving according to the data, that is, indicating the direction of the data transmission.
2.ip Address: (p114)
The IP address consists of 32-bit binary numbers and is divided into 5 categories.
Class a Class: 7 represents the network, 24 bits represents the host, so it can be used in large networks, 16777214 setsters. The first byte range: 1 to 126.
Class B: 14 represents the network, 16 represents the host, medium-size network, 65534 machines. The first byte range: 128 ~ 191.
Class C: 21 represents the network, 8 represents the host, remove all zero and all 1, up to 254 machines. The first byte range: 192 ~ 223.
Class D: Multi-destination address is sent.
C Class: Reserved.
IP address uses a dicot decimal representation: each byte is represented by 1 10-based number, so a total of 4 10 encenrations are separated by ".".
Several special IP addresses:
Network address: a valid network number and a total host number, used to represent a specific network.
Broadcast address: a host number of a valid network number and full "1", the host can use the IP address to broadcast information to the machine.
Retall Address: 127.0.0.1, communication between network software and local machine processes.
Local address: 192.x.x.x or 10.x.x.x is not assigned to the Internet user, you can use these IP addresses in the internal local area network.
