peer-to-peer architecture Last modified: Thursday, October 09, 2003


Often referred to simply as peer-to-peer, or abbreviated P2P, a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler, but they usually do not offer the same performance under heavy loads.

client/server architecture Last modified: Wednesday, May 26, 2004


A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.
Another type of network architecture is known as a peer-to-peer architecture because each node has equivalent responsibilities. Both client/server and peer-to-peer architectures are widely used, and each has unique advantages and disadvantages.

Client-server architectures are sometimes called two-tier architectures.

原文岀處P2P

client/server

GOOGLE 搜尋定義:"definition peer to peer computer science"所有網站

只查一個沒想到全都出來了,很前面,簡單扼要,我看裡面英文都蠻簡單的,應該不需要翻譯吧

兩者差異在哪寫的清清楚楚....沒啥好凹的啦

我這人很壞心的... 再轉移話題就是千拖囉.....

.....這樣也能凹 ,想也知道指的是同一樣東西....真是受不了

我想請某人先了解一下現在最常用的TCP/IP用的是什麼技術再來說好了= =

真的看到某人的回應佛也會發火

不懂還硬坳

他當然在凹，前面說P2P技術是專門用來盜版的，現在看苗頭不對

改成說是軟體了

呵呵∼
實在忍不住，又來發了一篇。

我認為你mind8643(kog781)發言沒必要，但我現在這麼說，也不是在反對你發言？？？

「不反對」如果也「不支持」，那就是「不表示意見」囉？既然「不表示意見」，那你怎麼又「表示」出大家提的建議「沒必要」？？？
我現在真的覺得把你的文章當搞笑文看，其實也蠻Happy的∼

怕有人又一知半解的不好,附上英文定義...

TCP/IP Last modified: Friday, July 30, 2004




(pronounced as separate letters) Short for Transmission Control Protocol/Internet Protocol, the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. Even network operating systems that have their own protocols, such as Netware, also support TCP/IP.

我覺得這篇解釋的又太精簡了些沒有把握TCP/IP的重點...講TCP/IP一定要附圖的

原文出處TCP/IP


下面這個就跟我的COMPUTER SCIENCE講的一樣

Understanding TCP/IP


Topics covered in this tutorial



What is TCP/IP?


TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.


TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol (TCP), manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol (IP), handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.



Development of TCP/IP


The original research was performed in the late 1960s and early 1970s by the Advanced Research Projects Agency (ARPA), which is the research arm of the US Department of Defense (DOD). The DOD wanted to build a network to connect a number of military sites. The key requirements for the network were as follows:

It must continue to function during nuclear war (development took place during the 'cold war'). The 7/8th rule required that the network should continue to function even when 7/8th of the network was not operational
It must be completely decentralized with no key central installation that could be destroyed and bring down the whole network
It must be fully redundant and able to continue communication between A and B even though intermediate sites and links might stop functioning during the conversation
The architecture must be flexible as the envisaged range of applications for the network was wide (anything from file transfer to time-sensitive data such as voice)
ARPA hired a firm called BBN to design the network. The prototype was a research network called ARPANET (first operational in 1972). This connected four university sites using a system described as a packet switching network.

Prior to this development, any two computers wanting to communicate had to open a direct channel (known as a circuit) and information was then sent. If this circuit were broken, the computers would stop communicating immediately, which the DOD specifically wanted to avoid.

One computer could forward information to another by using packet-switching, so it superseded circuit-switched networks. To ensure information reached the correct destination, each packet was addressed with a source and destination and the packet was then transferred using any available pathway to the destination computer.

It was divided into small chunks or packets (originally 1008 bits). Sending large chunks of information has always presented problems, often because the full message fails to reach its destination at the first attempt, and the whole message then has to be resent. The facilities within the new protocol to divide large messages into numerous small packets meant that a single packet could be resent if it was lost or damaged during transmission, rather than the whole message.

The new network was decentralized with no one computer controlling its operation where the packet switching protocol controlled most of the network operations.

TCP/IP is a very robust protocol and can automatically recover from any communication link failures. It re-routes data packets if transmission lines are damaged or if a computer fails to respond, utilizing any available network path. The figure below shows an example of an Internet system. A packet being sent from Network A to Network F may be sent via Network D (the quickest route). If this route becomes unavailable, the packet is routed using an alternate route (for example, A B C E F).



Once ARPANET was proven, the DOD built MILNET (Military Installation in US) and MINET (Military Installation in Europe). To encourage the wide adoption of TCP/IP, BBN and the University of California at Berkeley were funded by the US Government to implement the protocol in the Berkeley version of Unix. UNIX was given freely to US universities and colleges, allowing them to network their computers. Researchers at Berkeley developed a program interface to the network protocol called sockets and wrote many applications using this interface.

During the early 1980s, the National Science Foundation (NSF) used Berkeley TCP/IP to create the Computer Science Network (CSNET) to link US universities. They saw the benefit of sharing information between universities and ARPANET provided the infrastructure. Meanwhile, in 1974 a successor to ARPANET was developed named NSFNET. This was based on a backbone of six supercomputers into which many regional networks were allowed to connect.

The first stage in the commercial development of the Internet occurred in 1990 when a group of telecommunications and computer companies formed a non-profit making organization called Advanced Networks and Services (ANS). This organization took over NSFNET and allowed commercial organizations to connect to the system. The commercial Internet grew from these networks.

Why TCP/IP?

There are numerous reasons why TCP/IP was chosen to be the protocol that drives the Internet; some of these include:

TCP/IP was accepted as an industry standard protocol.
It is a routable protocol suite.
It is provided on almost all computer operating systems, and therefore allows connectivity between dissimilar systems (for instance, from a UNIX computer to a Windows XP computer).
The protocols are in the public domain and are freely available, which makes it a popular choice for software companies. There are no restrictions on its use and no royalties to pay.
It is a well-designed protocol.
It is an open standard where no single vendor has any control over the protocol and anyone is allowed to use it and develop applications based on it.
TCP/IP as an Open Standard

TCP/IP and the Internet are inextricably linked. Although no organization owns the Internet or its technologies, a number of organizations are responsible for the development of the Internet and, since the Internet relies upon TCP/IP, for those protocols as well.



Internet Society ( ISOC )
The purpose of the ISOC is to encourage the development and availability of the Internet.

Internet Architecture Board ( IAB )
The IAB is the technical committee of ISOC and is responsible for setting Internet standards
and publishing these standards as Request for Comments (RFCs).

The IAB governs three groups:

Internet Research Task Force ( IRTF ) - responsible for TCP/IP related research projects
Internet Engineering Task Force ( IETF ) - focuses on solutions to Internet problems and the adoption of new standards
Internet Assigned Numbers Authority ( IANA ) - oversees the process of providing a unique number or port for each protocol used on the Internet
Request for Comment (RFC)

TCP/IP standards are not developed by a committee but rather by consensus. The process for adopting Internet standards revolves around the production of documents called Request for Comments (RFCs). When an RFC is published, it is assigned the next available number. Anyone can submit a document for publication as an RFC. A technical expert or task force then reviews all documents.

A period of time for comments is followed by an updated draft that responds to these comments. After several drafts, the proposed standard is either accepted or rejected.

The standards for TCP/IP are published through these RFCs. Some RFCs describe network services or protocols and their implementation while others summarize policies.

An older RFC is never updated. If changes are required, a new RFC is published with a new number. It is always important to verify you have the most recent RFC on a particular topic.

Internet Network Information Center (InterNIC)

For the Internet to function successfully, a central organization must assume two major responsibilities:

Oversee the assignment of IP addresses
Oversee the assignment of domain names to organizations wanting to connect to the Internet
InterNIC is responsible for ensuring the same IP address or domain name is not allocated twice. They partially delegate this responsibility by giving the Internet Service Providers (ISPs) a block of IP addresses that they can assign to customers.

The TCP/IP Protocol Suite

The figure below shows a comparison of the Open Systems Interconnection (OSI) model and the TCP/IP protocol suite. The TCP/IP set of protocols maps to a four-layer conceptual model: application, transport, Internet and network interface. This model is referred to as the Internet Protocol Suite or the ARPA model. As shown below, each layer in the darker green Internet Protocol Suite corresponds to one or more layers of the white OSI model.



Network Interface
The network interface layer is the equivalent of the OSI physical and data link layers as it defines the host's connection to the network. This layer comprises the hardware and software involved in the interchange of frames between computers. The technologies used can be LAN-based (e.g. Ethernet) or WAN-based (e.g. ISDN)

Internet Layer
The network layer uses a number of protocols to ensure the delivery of packets. These are described below:


IP (Internet Protocol)
IP is the protocol responsible for addressing and routing packets (on the basis of routing algorithms) between networks. It ensures they reach the correct destination network.

ARP
The Address Resolution Protocol (ARP) is responsible for obtaining hardware addresses and matching them to their IP address when the destination computer is on the same network.

ICMP
The Internet Control Management Protocol (ICMP) is used to report errors and send messages about the delivery of a packet. It can also be used to test TCP/IP networks. Two examples of ICMP messages include:
Destination unreachable - used when a router cannot locate the destination
Time exceeded - used when the Time To Live (TTL) of a packet reaches zero
The TTL field in a packet has a maximum value of 255 and this value is reduced by one every time the packet crosses a router. The TTL is eventually reduced to zero if the packet is looping (because of a corrupted routing table) or when congestion causes considerable delays. The router then discards the packet and a warning packet is sent back to the source host.


Transport Layer
The Transport layer provides communication between the source and destination computers, and breaks application layer information into packets. TCP/IP provides two methods of data delivery:
Connection-oriented delivery using TCP
Connectionless delivery using UDP
Application Layer
The Application layer is the layer at which many TCP/IP services (high-level protocols) can be run (such as FTP, HTTP and SMTP). Two application programming interfaces (APIs) are commonly used within the TCP/IP environment: sockets and NetBIOS.

這一篇還講到LAYER(層)的觀念,教科書的解釋果然經典 而且還有圖呢


UNDERSTANDING TCP/IP

犯罪的是人不是工具，
有人拿刀殺人也有人拿刀救人，
對與錯的根源是人，
不要因為人的關係而怪罪於工具

ezpeer和kuro本來就應該被封殺