Chapter 18 Practical ADSL Techniques
18.1 Internet ADSL connection of A Computer
ADSL is short for Asymmetric Digital Subscriber Line. It accomplishes quickly bilaterally transmitting digital signals for voice and data on a pair of ordinary telephone line by nowaday advanced digital codings、the modulation and demodulation technologies such as FDM
(Frequency-Division Multiplexing) and DMT (Discrete Multiaudio Technology).Its effective transmitting range is 3~5 kilometers, with upper speed 640kbps, the top lower speed 6~8Mbps.
The device used in Internet ADSL connection is called ADSL modem. ADSL modems are now mainly divided into three kinds: the one with a PCI port, the next one with a USB port, another one with a RJ-45 port, of which the ADSL modem with a PCI port is cheap, but complex to install, therefore it is sparsely used; the ADSL modem with a USB port is popular without dismantling the computer for installing it; the ADSL modem with a RJ-45 port needs no installing the drives, but runs with a Ethernet Networking Interface Card(NIC).Next comes introducting how to accomplish Internet connection of a computer with ADSL modem.
18.1.1 Installing the ADSL modem with a RJ-45 port
(1) TO connect the RJ-45 port of a NIC and E port(Ethernet 10BaseT/MDI-X) of the modem with accessary straight-through linking line, PWR port and a transformer.
Fig. 18.1 A method to connect them Fig. 18.2 The other method to connect
(2) TO connect the modem and ADSL splitter. There are two connecting methods(according to Fig.18.1 and Fig.18.2), of which the first is held to by Chinese Telecommunication, while the other method is requested to held in the manual. As a result of the fact, they are both feasible.
(3) To turn on the power of the ADSL modem, which will come into working state half a minute later.Then the synchronal light begin to aglow.
18.1.2 Installing and configuring the software
The steps lie below: The first thing is to configure Microsoft Internet Explorer(IE).An user can click the item “Internet options” in the tool menu, and click the item “connecting”,and then
cross out the item "automatically to seek the proxy server. The other thing is to install the relative
protocols and dialing software. The familiar dialing softwares for ADSL include WinpoET、
EnterNet and RASpppoE. During their installings the relative protocols will be automatically added to the computer. Because installing EnterNet and WinpoET is quite easy, the user can accomplish it by clicking the button“Next”or “Finish”. After WinpoET has been installed, the
dial-up window will automatically pop up(according to Fig. 18.3), then what the user has to do is to fill the window with a correct account and the password, thus the computer can be connected to Internet.
Fig. 18.3 The dialing dialog box of WinpoET Fig. 18.4 The main window of EnterNet
While EnterNet requests that the user has to create the connection by himself. The user ought to open the window according to Fig.18.4 by doubly clicking the icon of EnterNet, in the window the user should click the item “Creat New Profile” and fill it with the connecting symbol by the
prompts, and then fill it with the account and password. Next pops up the dialog box demanding the user to select devices, the user can click the button “Next” after clicking the symbol of the
NIC connected to the ADSL modem in the popped menu. Then EnterNet demand the user to select a protocol, he should choose PPPoE(according to Fig. 18.5).Finally the user can make the computer to be connected to Internet by doubly clicking the created connection(according to Fig. 18.6).
Fig. 18.5 The interface of selecting a protocol Fig. 18.6 The interface of loginning
Installing RASpppoE is an intricate thing because it does not provide the installing interface, but it has been popular for consuming little resource and good being integrated with another dialing networks. The user must install the protocol PPP over Ethernet and reboot the computer and run the program raspppoe.exe. In the popped dialog box, the user ought to select the very NIC and click the button “Query Available Services”.The next thing he should do is to select a symbol
of Access Control and click the button “Create a Dial-up Connection for the selected
Service”.Thus the computer can be connected to Internet.
18.2 The Optimization of Internet ADSL connection
We can optimize many aspects of Internet ADSL connection such as selecting the dialing software, upgrading the Firmware, modifying the register, enhancing bandwidth, changing the hardware. With an example of the ADSL modem in type of ETED TD-2001 in this text, the topic
how to o-ptimize an ADSL modem is to be discussed aiming at bringing its performance into top play.
18.2.1. Selecting the dialing software
Here we discuss the characteristics of various dialing softwares.
EnterNet 300 is a dialing software which Chinese Telecommunication provide as an enclosure. It acts the part of real-time monitoring the speed but takes on some obvious shortcomings such as consuming much resource, dialing for a long time, intricately creating a connection. Because of actu-alizing Internet connection by virtualizing a NIC, so it can not automatically dial to Internet in the conditions of various proxy softwares and NAT softwares.
Since WinPoET is a quite good dialing software, many foreign telecommunication companies provide as an enclosure. It may be conveniently installed, and is a good choice for excellent compatibility with Internet connection sharewares such as SyGate. While it consumes more resource than RASpppoE.
Generally speaking, RASpppoE is the most excellent dialing software of the kind. 18.2.2.Upgrading the firmware
Firmware is actually the operating system of the ADSL modem, which possesses its own CPU and operating system just like a PC. The fact known to everyone is that the CPU and the operating system can both affect the performance of the system. We can not change the CPU with another one since it is solidified, but enhancing the performances is still possible by way of the operating syste-m. We should run a TFTP software (according to Fig. 18.7) and fill it with the password (the
Fig. 18.7 The loginning interface of TFTP Fig. 18.8 WinPoET属性
default is 12345)、IP address of the ADSL modem and choose the downloaded pack unpacked. We may click the button “FileInfo” to browse the files within the pack and click the button
“Download”to upgrade the TFTP software.
If upgrading the firmware failed, the help we should adopt is to join the RS-232 port of the modem to the PC with a serial line, and recover the flash by means of Windows Super Terminal.
18.2.3。Modifying the register
A few key values in the register must be modified because they affect the velocity of the
modem, while it is a troublesome thing to do it manually. So the best way to do so is to modify these values with a ptimizing software for the ADSL modem, while the performance-enhancing Soldier of ADSL is a familiar one.
18.2.4。Enhancing the bandwith
If ISP(Internet Service Provider) didn’t ban repetitive dialing-up, an user may enjoy the
services of ADSL with double bandwith. The user may install WinPoET and create a dialing Internet connection, in the attribute window of the connection(according to Fig. 18.8), the user should choose the items “iVasion PoET Adapter(SERIAL7-0)” and “iVasion PoET
Adapter(SERIAL7-1)” and “all devices dialing-up to the same telephone number”, then he must
click the button“ok”.
18.2.5。Changing the hardware
The power design of ETEK TD-2001 is not rational. For example, the input voltage three voltages higher than what is needed. Higher voltage would easily lead to producing higher heat in the inner stabilivolt tubes, which may make them burnt if being sufficiently high. A effective way to solve the problem is to replace the transformer of the modem with the one on the input voltage of twelve.
In a word, the optimization in the five aspects can enhance the performances of the ADSL modem.
18.3 The techniques of Internet ADSL Connection
There are three kinds of techniques of Internet ADSL connection sharing including the one without any server, the one with a server, another with more servers.
18.3.1. The technique of the connection sharing without any server
The connecting to Internet by a shared ADSL device is today one of the most popular techniques of Internet Connection Sharing. The device is a miniative router or server, which is integrated with some additional functions such as NAT、DHCP、Dial-on-Demand、Proxy、IP
Filter、Firewall、Static Routing Table. This makes it possible for the user to access Internet by sharing ADSL or ISDN connection. Some of the functions above have been integrated with the ADSL modem，while the producers have forcibly hogtied these functions to fixed IP address, that is to say, the user can not make use of the routing function of the ADSL modem until he has applied for and gained at least one fixed IP address.
The main advantage of the sharing technique is simple configuration. While the chief shortco-
ming is represented that the ADSL devices shared are pricey.
18.3.2 The technique of the connection sharing without a server
The fundamental to carry the technique into execution is that a PC acting as a server provide
others with the service of sharing Internet ADSL Connection. There are two feasible projects: proxy server project(Proxy), networking addresses transferring project(NAT).
The advantages of Proxy include rapid Internet access and easy management,etc. The obvious shortcoming is troublesome configuration. The familiar proxy softwares include WinGate and WinProxy, etc.
The NAT technique is an efficient and convenient method and help computers connect Internet with a public IP address. Each client firstly takes the IP address on the server as its own gateway and then access Internet. But it does not offer enough functions to be engaged in monitoring and administration. The familiar NAT software contains WinRoute, Sygate, Windows ICS, the routing and remote access in Windows2000, etc.
Proxy has been popular to companies with powerful functions. Few families use it for its complex configuration. In the text below, the usage of NAT softwares is to be mainly argued about.
1. Internet connection sharing in Windows
Firstly we should finish connecting the network according to the topology in Fig.18.9. Secondly we should add ICS to windows. Thirdly we are to choose an Internet connection to be shared.
Then we ought to make a client-configuring floppy. By now the configuration has been finished. The next thing for us to do is to reboot the server and let clients run the program Icsclset.exe on the floppy to be automatically configured.
It must be noticed that Internet connection sharing in Windows should not be applied for
Fig. 18.9 Connectiong sharing topology Fig. 18.10 The topology of one NIC project
large networks because it may influence the its communication for changing the configuration of the networks.
It is a famous NAT software for Internet connection sharing and supports all application protocols and all kinds of topologies.It gives full support to the ADSL technique.
There are two familiar projects to access Internet with SyGate such as the one with a NIC (according to Fig. 18.10) and the other with double NICs (according to Fig. 18.11). The fore is appropriate for the networks with a few users, while the rear for the one with many users. According to the fore, the NICs on the servers undertake much more burthen for having to process both the data of the ADSL modem and that on the Local Area Networks, and easily conflict with one another, that lowers the performances of the networks. On the other hand, the fore project stints a piece of NIC. Therefore it is the best choice for miniative networks.
Fig. 18.11 The topology of double NICs project Fig. 18.12 The topology of more servers project
3. The routing and remote access in Windows2000
It is also a good choice for providing excellent NAT service and easy installation and
18.3.3. The technique of the connection sharing without more
The technique succeeds in conquering the shortcomings above and comes to be an ideal way
for miniative networks to access Internet. The train of thought to carry the technique into
execution is that every computer is both the server and client.(according to Fig. 18.12)。
The three kinds of techniques above is now quite popular to the users not only for its easy
operatings but also for its saving the users much cost. New Words and Expressions
optimize [！)????，??] vt. 优化
aspect [！：?????] n. 方面
firmware [‘??，????；?？] n. 固件
register [！????????；?？] n. 注册表
bandwidth [！?：?????，] n. (网络)带宽
enclosure [??！??????；?？] n. 附件
compatibility [???！?：????????] n. 兼容性
conveniently [???！??，?????] adv. 便利地;合宜地
consume [???！???，?(;；；，？;???！??，?] vt. 消耗;消费
solidify [??！?????，?] vt. 固化
download [‘?，??????] vt. (从网上)下载(资料)
help [????] n. 补救办法
velocity [??！?)????] n. 速度;速率
manually [！?：??????] adv. 手工地
familiar [??！?????；?？] adj. 常见的；常用的
transformer [??：??！?~，??；?？？;??；，，] n. 变压器
rational [！?：???；?？?] adj. 合理的
technique [???！??，?] n. 技术
producer [???！???，??；?？(;；；，？;，！??，，] n. 生产商
advantage [??！?；，?????] n. 优点，优势
configuration [?????：???！????；?？?] n. 配置
pricey [！??，???] adj. 昂贵的
project [！??)?????] n. 项目;方案
public [！?(????] adj. 公用的
client [！??，????] n. 客户机
administration [??????！??????；?？?] n. 管理
miniative [！?????????] adj. 小型的
performance [??！?~，????] n. 性能
Phrases and Expressions
dialing software 拨号软件
aim at 旨在
bring sth into play 发挥;调动
such as 例如
generally speaking 一般地说
the best way to do something 做...的最好方法
make use of 利用
apply for 为了得到...而申请
carry ..into execution 实现;实施
act as 充当；作为
..做.. help sb. do sth. 帮助
be engaged in doing 从事...
argue about 探讨...
finish doing sth. 做完...事
give support to 支持
be appropriate for 适合
succeeds in doing 完成做...事
both ... and 兼具，既是...又是...
carry...into execution 实现
1.Fill in the blanks according to the text:
(1) We can optimize many aspects of Internet ADSL connection such as selecting
, , , changing the ardware.
(2) Here we discuss the of various dialing softwares.
(3) With an example of the ADSL modem in type of ETED TD-2001 in this text, the topic
how to an ADSL modem is to be discussed aiming at bringing its performance into top
(4) EnterNet 300 is a dialing software which Chinese Telecommunication provide as
(5) It acts the part of monitoring the speed but takes on some obvious shortcomings
such as consuming much resource, dialing for a long time, intricately creating a connection.
(6) Firmware is actually the of the ADSL modem, which possesses its own CPU and operating system just like a PC.
(7) We can not change the CPU with another one since it is , but enhancing the
performances is still possible by way of the operating system.
(8) If upgrading the firmware failed, the we should adopt is to join the RS-232 port of the modem to the PC with a , and recover the flash by means of Windows Super Terminal.
(9) A few key values in the register must be modified because they affect the of the
modem, while it is a troublesome thing to do it manually.
(10) The power design of ETEK TD-2001 is not .
(11) The connecting to Internet by a shared is today one of the most popular techniques of Internet Connection Shared. The device is a miniative or .
(12) The main advantage of the sharing technique is . While the chief
oming is represented that the ADSL devices shared are .
(13) The advantages of Proxy include and ,etc. The obvious
shortcoming is . The familiar proxy softwares include and , etc.
(14) The NAT technique is an efficient and convenient method and help computers connect
Internet with a IP address.
(15) The familiar NAT software contains , , , the of
(16) It must be noticed that Internet connection sharing in Windows should not be applied for
networks because it may influence the its communication for changing the configurati-
on of the networks.
(17) There are two familiar projects to access Internet with SyGate such as the one with
NIC and the other with NICs.
(18) The routing and remote access in Windows2000 is also a good choice for providing
excellent and easy and .
2.Translate the following terms or phrases from English into Chinese and vice versa:
(1) virtualize a NIC (11) 自动拨号到因特网
(2) serial line (12) 众所周知(的事实)
(3) key value (13) 网际协议地址
(4) stabilivolt tube (14) 超级终端
(5) input voltage (15) 中国电信
(6) Internet ADSL Connection Sharing (16) 因特网连接共享
(7) the connection sharing without any server (17) 路由与远程访问
(8) the connection shared without a server (18) 代理服务器
(9) the connection shared without more servers (19) 代理软件
(10) networking addresses transferring (20) 单网卡方案
参考译文： 第18章 ADSL实用技术
18.1 计算机的ADSL Internet接入
ADSL的全称是“非对称数字用户传输线(Asymmetric Digital Subscriber)”。它采用FDM(频
(1) 用附送的直通(Straight-through link；线把网卡的RJ-45口与Modem的E口(Ethernet 10BaseT/MDI-X；相连，PWR口连接变压器。
(3) 开启ADSL Modem电源，大约30秒以后ADSL Modem进入工作状态，同步灯发光。
EnterNet需要用户自己创建连接：点激EnterNet图标，打开如图18.4所示的窗口，,点击“Creat New Profile”，按提示填入连接名称。随便填入连接一个名称，然后按提示填入帐号名与密码。EnterNet弹出设备选择框，在下拉菜单中选择连接ADSL Modem的网卡名字，按下一步。此时EnterNet提示选择协议，选择PPPoE(如图18.5所示)。完成设置，双击刚才创建的的连接，选择connect就可以上网了，如图18.6所示。
RASpppoE没有安装界面，安装过程比较麻烦，但是由于它资源占用少，与系统的拨号网络集成，受到很多人们的青睐。安装PPP over Ethernet协议，重启后，运行raspppoe.exe。 在出现的对话框中选择网卡，然后按“Query Available Services”查询(如图18.7所示)后出现访问控制名称，选择一个，“Create a Dial-up Connection for the selected Service”。
Firmware其实就是ADSL MODEM的操作系统，ADSL MODEM与PC一样，拥有自己的CPU与操作系统。大家都知道，CPU与操作系统都会影响系统的性能。CPU是固化的，我们没有能力去更换，不过可以从操作系统入手，提高ADSL MODEM的性能。打开TFTP工具(如图18.7所示)，填入登录密码(默认是12345；、IP地址(ADSL MODEM的IP地址；并选择下载并解压了的压缩包文件。
如果ISP没有禁止重复拨号，可以以双倍的带宽享受ADSL服务。用户可以安装WinPoET并创建拨号连接，在此连接的“属性”窗口(如图18.8所示)中，选中iVasion PoET Adapter(SERIAL7-0)与iVasion PoET Adapter(SERIAL7-1),选中“所有设备呼叫同一个号码”，单击“确定”。
通过ADSL共享器是目前最流行的Internet共享接入方法。它是一台小型的路由器，也可以说是一台小型的服务器，其集成了NAT(网址转换；、DHCP(动态主机配置协议；、Dial-on-Demand(按需拨号；、Proxy(代理服务器；、IP Filter(IP过滤；、Firewall(防火墙；、Static Routing Table(静态路由表；等功能的其中几种，使用户能方便实现ADSL或ISDN的共享上网。这些功能在ADSL MODEM上也有部分集成，但可能是ADSL MODEM厂商的问题，把这些功能都定位在固定IP接入方式上，即只有申请了固定IP才可以使用MODEM的路由功能。
使用代理服务器的好处是访问速度快，管理方便等优点；但存在配置麻烦的缺点。常用的代理软件有WinGate , WinProxy等。
网址转换技术是一种高效率、方便的方法，实现使用一个公共IP多机共享上网。各客户机只须将网关指向服务器就能正常工作了。但也存在监控与管理能力比较弱的缺点。常用的NAT软件有WinRoute , Sygate , Windows的ICS ，Windows2000 Server的路由与远程访问等。