Coverage of the computer
WAN (Wide Area Network Wide Area Network): a large coverage in several cities, a national, even global several countries are all areas of WAN, from tens of kilometers to thousands or tens of thousands of kilometers.
LAN (Local Area Network LAN): distributed between a room, between each floor, the whole building buildings and the like, generally within the range of 2km, the maximum distance of not more than 10km. Mainly used to build a unit of the internal network, such as an office network, a local school campus network in the office building, factory business networks, campus networks and large companies and other research institutions.
MAN (Metropolitan Area Network Metropolitan Area Network): an intermediate form between a wide range of WAN and LAN high-speed network, its coverage is usually a few kilometers to tens of kilometers. Computer networking to meet the needs of tens of kilometers within the city limits of a large number of enterprises, institutions, companies and social services, to achieve a large number of users, a variety of integrated information network information transmission.
PAN (Personal Area Network Personal Area Network): a network where individual work are regarded as personal use of electronic devices (such as portable computers, etc.) connected by wireless technology, often referred to as wireless personal area network WPAN (Wireless PAN).
Packet switching
VC Network
虚电路是分组交换的两种传输方式中的一种. And a communication network, the virtual circuit packet communication service is provided by connection-oriented communication exchange. After the application process between two nodes or a connection is established, or a logical virtual circuit, can be sequentially transmitted between two nodes each packet, the receiver receives a packet necessarily consistent with the order of the transmission order of the transmitting side, Therefore the receiving end need not be responsible for re-ordering after receiving a packet. VC protocol hiding the data into segments, packets or frames to the higher layer protocol process.
Common software port numbers
The FTP: 21
TELNET (Windows provide remote service the Telnet): 23
the SMTP: 25
the DNS: 53
the TFTP: 69
HTTP: 80
POP3: 110
UDP and TCp common
udp is applied to less need for reliable and fast communication
LAN awareness and build
Enail agreement
SMTPPOP3IMAP
iP Service
IP services for three characteristics
不可靠,面向无连接and尽最大努力投递.
IP is controlled by the IP transport protocol is referred to as an IP datagram protocol unit. Shielding the underlying IP protocol differences various physical networks, providing a unified IP datagram to an upper layer (mostly TCP layer or UDP layer). As an Internet protocol running on the network layer, and the shield details difference respective physical network, to provide services for the following three high-level user:
不可靠的数据投递服务. Datagram delivery without any quality assurance, data packets may be delivered correctly, it may be discarded;
面向无连接的传输服务. In this manner regardless of which transmit data packets through the node, even regardless of the data packets initiation and termination computer. May transmit data packets via different transmission paths, and these data packets may be lost during transmission, it is also possible to correct transmission destination node;
尽最大努力投递服务. IP packet loss will not go down unless the system resource depletion, reception error occurs, or network failure situation, was compelled to discard packets
HTTP protocol status code
1xx (Provisional response)
2xx (success)
3xx (Redirected)
301 permanent redirect
302 temporary redirect
4xx (Request error)
404 Page Not Found
403 Forbidden
401 Unauthorized
failed 400 requests; server does not understand the request syntax
Routing Protocol
RIP protocol
RIP (Routing Information Protocol)
RIP 是一种分布式的基于距离向量的路由选择协议.
从一路由器到直接连接的网络的距离定义为 1.
从一个路由器到非直接连接的网络的距离定义为所经过的路由器数加 1。 RIP 协议中的“距离”也称为“跳数”(hop count)，因为每经过一个路由器，跳数就加 1。
RIP allows a path can contain up to 15 routers.
Maximum "distance" is 16 which is equivalent unreachable. RIP visible only for small Internet.
IP addresses
127.0.0.0 ~ 127.255.255.255A loopback test, the native loopback address belongs.
240.0.0.0 ~ 255.255.255.255A class E addresses are reserved addresses unused.
192.240.150.255/24The mask is 24, the lower 8 bits of host address, but since all 1, indicates the broadcast address.
Subnet Mask
子网掩码是由连续的1加连续的0组成
Subnetting subnet mask
网络号
The result of the operation with the subnet mask for the IP address of the network number of the network
ip & Network Number Subnet Mask = = = certainly the same network segment under the same subnet. And the route is till not need forwarding.
The same network to see whether the same network number
Private address
device
网络层Used above is a gateway .
ARP and RARP protocol agreement
- · APR protocols: IP address mapping problem solving and hardware address of the host or router on the same LAN.
- RARP protocol: solve a mapping problem with the hardware address of the host or router on the LAN and IP addresses.
