首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
How does E-mail travel on the Internet to reach someone far away? When Jennifer, Who lives in Pasadena, Calif. wants to send
How does E-mail travel on the Internet to reach someone far away? When Jennifer, Who lives in Pasadena, Calif. wants to send
admin
2010-06-18
69
问题
How does E-mail travel on the Internet to reach someone far away?
When Jennifer, Who lives in Pasadena, Calif. wants to send an E-mail message from her home computer to her mother in Washington, D. C., she uses a local Internet service provider (ISP) such as EarthLink Network Inc. (ELNK). EarthLink gives Jennifer access to the Internet, much in the way that a ramp puts a driver on the national highway system.
After Jennifer’s computer makes a local telephone call to EarthLink’s local bank of modems, Jennifer types in her E-mail message and hits "send." Based on Mom’s E-mail address, EarthLink will recognize that Mom is a customer of an ISP in Washington called Erols Internet Inc. (RCNC). EarthLink will then send the E-mail to an Internet backbone provider, such as GTE Corp. (GTE), to route it along its way
What is a backbone provider and why is it important on the Internet?
Backbone providers are the Internet players that typically own and lease long-haul fiber-optic cables spanning a large region. They also own the communications gear that directs traffic over the Internet. There are only a handful of major backbone providers, including MCI, WorldCom, Sprint Corp. , GTE, and PSINet Inc. (PSIX).
Backbone providers connect to each other to exchange data between their customers. They also pick up and deliver traffic for a fee from the 7,000 or so smaller ISPs, who give residential and small-business users access to the Internet. Backbone carriers are like the highway system over which most of the freight of the Internet travels to reach its destination. How did the current backbone providers come to be?
When the Internet was still a government-run system, there was only a single Internet backbone: the NSFNET, operated by the National Science Foundation, which connected the regional government-funded Internet networks that were run by various research universities. When the government privatized the NSFNET in 1995, companies such as MCI, UUNET Technologies (now owned by Worldcom), BBN (now owned by GTE), and PSINet stepped into the breach by setting up commercial Internet backbone services. Now, instead of one NSFNET backbone, there are many of them that link together to provide the global connectivity, that is the Internet.
How do Internet companies connect to each other?
When the NSFNET was privatized, the government set up three locations in the U. S. where various Internet backbone companies could place their communications gear side by side and connect to each other. These so-called "public peering points" are in Chicago, Palo Alto, Calif., and Pennsauken, N.J.. Later, the government sanctioned two industry-run public peering points called Metropolitan Access Exchange East and West — MAE-East, in Vienna, Va., and MAE- West in San Jose, Calif..
The problem was, as the Internet grew, the public points became overburdened and traffic slowed at these bottlenecks. So backbone providers started making arrangements with each other, called "private peering." These are direct, bilateral connections between two carriers in which no fees are charged.
Do the largest backbone providers charge each other?
Backbone providers aren’t charging peers now, but there is a lot of discussion about whether they should. Most industry experts say the Internet needs to develop some payment scheme. After all, it is now a commercial, profit-making business, not a government freebie.
But the industry has not figured out how to calculate who owes what to whom. Without an industry standard or government regulation, smaller companies fear that larger ones will set these charges in an arbitrary and discriminatory fashion.
America’s first backbone Internet Service provider was ______.
选项
A、EarthLink
B、MCI
C、GTE Corp
D、NSFNET
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/XmlO777K
0
专业英语八级
相关试题推荐
A、AprofessorofTrinityCollege.B、AlecturerofClareCollege.C、TheDirectoroftheBoard.D、Thetreasurerofacollege.D
ForquiteafewyearswehavebeentalkingaboutaddictiontotheInternet.Nowweareputtingtogether【C1】______thosestudents
ForquiteafewyearswehavebeentalkingaboutaddictiontotheInternet.Nowweareputtingtogether【C1】______thosestudents
ThewelfareofchildrenisapriorityfortheUN.In【B1】______Europeand【B2】______Asiatheresearchisfocussingonthosekept
SincetheendofWorldWarII,abroadconsensusinsupportofglobaleconomicintegrationasaforceforpeaceandprosperityh
A、Tocreateyourowndatabasesonthecomputer.B、Toenhanceyoursocialskillsbyholdingpartieswithyourfriends.C、Touset
Howisurbanizationnegativelyaffectingoursociety?Theanswertothisquestionisnotasimpleone.Urbanism【C1】______,polit
Oneofthemostunexpectedthingsabouthavingchildrenishowthequesttomoldperfectlittlehumansultimatelybecomesaproj
1 Aboutthetimethatschoolsandothersquitereasonablybecameinterestedinseeingtoitthatallchildren,whatevertheirb
随机试题
质检机构取得计量认证合格后,经()年要进行复查。
每个评价项目都有其自身的专业特点,因此,评价单位不可能事事依靠内部专家,还必须从社会上聘请一定数目的()来参加调查评价工作。
安全检查的内容不仅查管理、查隐患,还应查()。
发包人和承包人就有关工期、质量、造价等产生的建设工程合同争议,是建设工程领域最常见的()。
下列属于资产负债管理原则的有()。
流动性风险管理水平体现了商业银行的整体经营管理水平。()
旅游主管部门在作出行政处罚决定前,应当以()形式告知当事人作出行政处罚决定的事实、理由、依据和当事人依法享有的陈述、申辩权利。
不考虑价格因素,2011年与2003年相比,江苏金融业增加值增长的倍数是()。
《中华人民共和国物权法》第179条规定:“为担保债务的履行,债务人或者第三人不转移财产的占有,将该财产抵押给债权人的,债务人不履行到期债务或者发生当事人约定的实现抵押权的情形,债权人有权就该财产优先受偿。前款规定的债务人或者第三人为抵押人,债权人
TheplantspeciesthatDr.KinghorndiscoveredinPuertoRicoprovedtobe______tohismedicalresearch.
最新回复
(
0
)