NetworkingBasics
SECTION 7A
This lesson includes the following sections:
• The Uses of a Network
• How Networks are Structured
• Network Topologies for LANs
• Network Media and Hardware
• Network Software
大多數的辦公室幾乎在每個辦公桌上都有一部 PC。這些電腦彼此連線而構成一個網路。
• Simultaneous Access
• Shared Peripheral Devices
• Personal Communication
• Easier Backup
A network connects computers so they can communicate, exchange information, and share resources.
The main benefits of using a network are:
The Uses of a Network
• In organizations, many people may need to use the same data or programs. A network solves this problem.
• Shared data and programs can be stored on a central network server. A server that stores data files may be called a file server.
• Managers may assign access rights to users. Some users may only be able to read data, others may be able to make changes to existing files.
The Uses of a Network - Simultaneous Access
Read/writeRead/writeRead/writeRead/writeRead/writeRead only
使用者可共享儲存在中央檔案伺服器的資料。
• In an environment where PCs are not networked, a separate copy of each program must be installed on every computer. However, this would be costly.
•Software can be expensive, especially when you must buy many copies•Installing and configuring a program on many different computers can take a lot of time and labor, and maintaining many separate installations of a program is an ongoing expensive.
The Uses of a Network - Simultaneous Access
• Solution•Site Licenses: buy a single copy (or a few copies) of an application and pays the developer for a license to copy the application onto a specified number of computers•Network Versions: connect users’ computers to a central network server and enable users to share a network version of a program
•In network version, only one copy of the application is stored on the server, with a minimum number of supported files copies to each user’s PC
The Uses of a Network - Simultaneous Access
使用應用程式的網路版。
• Because peripheral (external) devices like printers can be expensive, it is cost-effective to connect a device to a network so users can share it.
• Through a process called spooling, users can send multiple documents (called print jobs) to a networked printer at the same time. The documents are temporarily stored on the server and printed in turn.
The Uses of a Network -Shared Peripheral Devices
• One of the most common uses of networks is for electronic mail (e-mail).
• An e-mail system enables users to exchange written messages (often with data files attached) across the local network or over the Internet.
• Two other popular network-based communications systems are teleconferencing and videoconferencing.
The Uses of a Network - Personal Communication
1 2 3 4
在一般的網路上傳送與接收電子郵件。
貼附一份文件到電子郵件信息上,是一種與其他人交換檔案的簡單方法。
參加線上視訊會議。
• Networks enable managers to easily back up (make backup copies of) important data.
• Administrators commonly back up shared data files stored on the server, but may also use the network to back up files on users' PCs.
The Uses of a Network - Easier Backup
備份系統可用來備份網路上的伺服器以及每部個人電腦。
• Local Area Networks (LANs)• Campus Area Networks (CANs)• Metropolitan Area Networks (MANs)• Wide Area Networks (WANs)• Server-Based Networks• Client/Server Networks• Peer-to-Peer Networks
How Networks are Structured
• A LAN is a network whose computers are located relatively near one another. The nodes may be connected by a cable, infrared link, or small transmitters.
• A network transmits data among computers by breaking it into small pieces, called packets.
• Every LAN uses a protocol – a set of rules that governs how packets are configured and transmitted.
How Networks are Structured – Local Area Networks (LANs)
電子郵件信息被分割到封包內。
• TCP/IP: the protocol of the internet and the default networking protocol of almost operating systems.
• IPX/SPX: A proprietary protocol of Novell for NetWare network operating system.
• NetBEUI: Excellent protocol for networking small offices but does not expand well into larger environment.
How Networks are Structured – Well-Known Protocols
• Hub: a hub is a simple connection point for different type of devices on a network
• Bridge: a bridge is a device that looks at the information in each packet header and forwards data that is traveling from one LAN to another
• Router: a router is a more complicated device that stores the routing information for packets. Like bridge, a router looks at each packet’s header to determine where the packet should go and then determines a route for the packet to reach its destination.
How Networks are Structured – Connecting Devices
• If two LAN are built around the same communication rules, then they can be connected by
•Bridge: forward data from one LAN to another•Router: A more complicated devices that store the routing information for networks. (Next page)
• If different networks are connected•Gateway: connects two network and translate information from one to the other.
How Networks are Structured – Network Connections
LAN 1
WAN
LAN 2
Type Aheader
Payload Type Aheader
Payload
Type Aheader
Payload
Significantgeographical
distance
ROUTER ROUTER
SERVER SERVER
A gateway performs the translationbetween two different types of networks.
1
2
3
• A CAN follows the same principles as a local area network, only on a larger and more diversified one.
How Networks are Structured – Campus Area Networks (CANs)
• A MAN is a large-scale network that connects multiple corporate LANs together.
How Networks are Structured – Metropolitan Area Networks (WANs)
• Multiple LANs can be connected together using devices such as bridges, routers, or gateways, which enable them to share data.
• A WAN is two or more LANs connected together. The LANs can be many miles apart.
• To cover great distances, WANs may transmit data over leased high-speed phone lines or wireless links such as satellites.
How Networks are Structured – Wide Area Networks (WANs)
都會網路和網域網路及區域網路間的使用
• In addition to the individual users' PCs (nodes), many networks use a central computer, called a server.
• A server has a large hard disk for shared storage. It may provide other services to the nodes, as well.
• In a file server network, nodes can access files on the server, but not necessarily on other nodes.
How Networks are Structured – Server-Based Networks
含有檔案伺服器的簡單型 LAN
• A popular type of server-based network
• In client/server computing, individual nodes share the processing and storage workload with the
server.
• Client/server networks require specialized software that enables nodes and the server to collaborate on processing and storage, but no special type of network hardware.
How Networks are Structured – Client/Server Networks
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2
3
在客戶 / 伺服器電腦環境模式下的分散處理。
• In a peer-to-peer network, all nodes have an equal relation to one another.
• Each node usually has access to some resources on other nodes, so users can share files, programs, or devices on other users' systems.
• Some peer-to-peer networks use a server, but some do not.
How Networks are Structured – Peer-to-Peer Networks
P2P (Peer-to-Peer)
• Bus. •Each node is connected in series along a single line. •At end node, a terminator is attached to prevent signal bounce back.
• Star. •The most common topology in use today.•All nodes are connected to a central hub.
A network's topology is the layout of the cables and devices that connect the nodes. The four most common network topologies are:
Network Topologies for LANs (Option)
• Ring. •Nodes are connected in a circular chain, with the conduit beginning and ending at the same computer.•No danger of collisions because only one packet of data may traverse the ring at a time
•By Token
• Mesh. •Each node has a separate connection to every other node. •The least used network topology.•The most expensive to implement.
Network Topologies for LANs (Cont.) (Option)
• In a network, the media are the wires, cables and other means by which data travels from its source to its destination.
• The most common network media are twisted-pair cable, coaxial cable, fiber-optic cable, and wireless links.
• Each node uses a special device, called a network interface card (NIC). The card connects to the network media and controls the flow of data.
• NICs must use a common network technology to communicate. The most popular network technologies for LANs are Ethernet, Fast Ethernet, and Token Ring.
Network Media and Hardware (Option)
• Ethernet: •10 Mbps•Original use coaxial cable (10Base-5 and 10Base-2)•Now use twisted-pair called 10Base-T by star technology
• Fast Ethernet (also called 100Base-T)•100 Mbps
• Gigabit Ethernet
• Token Ring•Proposed by IBM•Once hold token, a node can then transmit data
Network Technologies
• Novell NetWare
• Microsoft Windows NT Server
• Microsoft Windows 2000
• Microsoft XP
• Microsoft .NET Server
• Linux
A network operating system (NOS) is the group of programs that manages the resources on a network.
Common network operating systems for PC-based networks include:
Network Software
• List the four benefits of using a network.
• Differentiate between LANs and WANs.
• Identify three common network topologies.
• Name four common network media.
• List four examples of network operating systems.
Section 7a review
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