P-660H/HW-T Series User’ Guide
Introduction to DSL
40
Introduction to DSL
DSL (Digital Subscriber Line) technology enhances the data capacity of the existing twisted-
pair wire that runs between the local telephone company switching offices and most homes
and offices. While the wire itself can handle higher frequencies, the telephone switching
equipment is designed to cut off signals above 4,000 Hz to filter noise off the voice line, but
now everybody is searching for ways to get more bandwidth to improve access to the Web -
hence DSL technologies.
There are actually seven types of DSL service, ranging in speeds from 16 Kbits/sec to 52
Mbits/sec. The services are either symmetrical (traffic flows at the same speed in both
directions), or asymmetrical (the downstream capacity is higher than the upstream capacity).
Asymmetrical services (ADSL) are suitable for Internet users because more information is
usually downloaded than uploaded. For example, a simple button click in a web browser can
start an extended download that includes graphics and text.
As data rates increase, the carrying distance decreases. That means that users who are beyond
a certain distance from the telephone company’s central office may not be able to obtain the
higher speeds.
A DSL connection is a point-to-point dedicated circuit, meaning that the link is always up and
there is no dialing required.
Introduction to ADSL
It is an asymmetrical technology, meaning that the downstream data rate is much higher than
the upstream data rate. As mentioned, this works well for a typical Internet session in which
more information is downloaded, for example, from Web servers, than is uploaded. ADSL
operates in a frequency range that is above the frequency range of voice services, so the two
systems can operate over the same cable.
Summary of Contents for P-660H Series
Page 2: ......
Page 10: ...P 660H HW T Series User Guide 9 Customer Support ...
Page 32: ...P 660H HW T Series User Guide 31 List of Figures ...
Page 38: ...P 660H HW T Series User Guide 37 List of Tables ...
Page 42: ...P 660H HW T Series User Guide 41 Introduction to DSL ...
Page 62: ...P 660H HW T Series User Guide 61 Chapter 3 Wizard Setup for Internet Access ...
Page 90: ...P 660H HW T Series User Guide 89 Chapter 5 Wireless LAN ...
Page 132: ...P 660H HW T Series User Guide 131 Chapter 10 Firewalls ...
Page 162: ...P 660H HW T Series User Guide 161 Chapter 13 Remote Management Configuration ...
Page 176: ...P 660H HW T Series User Guide 175 Chapter 14 Universal Plug and Play UPnP ...
Page 182: ...P 660H HW T Series User Guide 181 Chapter 15 Logs Screens ...
Page 196: ...P 660H HW T Series User Guide 195 Chapter 16 Media Bandwidth Management Advanced Setup ...
Page 208: ...P 660H HW T Series User Guide 207 Chapter 17 Maintenance ...
Page 218: ...P 660H HW T Series User Guide 217 Chapter 19 Menu 1 General Setup ...
Page 222: ...P 660H HW T Series User Guide 221 Chapter 20 Menu 2 WAN Backup Setup ...
Page 226: ...P 660H HW T Series User Guide 225 Chapter 21 Menu 3 LAN Setup ...
Page 230: ...P 660H HW T Series User Guide 229 Chapter 22 Wireless LAN Setup ...
Page 236: ...P 660H HW T Series User Guide 235 Chapter 23 Internet Access ...
Page 250: ...P 660H HW T Series User Guide 249 Chapter 25 Static Route Setup ...
Page 254: ...P 660H HW T Series User Guide 253 Chapter 26 Bridging Setup ...
Page 270: ...P 660H HW T Series User Guide 269 Chapter 27 Network Address Translation NAT ...
Page 286: ...P 660H HW T Series User Guide 285 Chapter 29 Filter Configuration ...
Page 306: ...P 660H HW T Series User Guide 305 Chapter 32 System Information and Diagnosis ...
Page 318: ...P 660H HW T Series User Guide 317 Chapter 33 Firmware and Configuration File Maintenance ...
Page 324: ...P 660H HW T Series User Guide 323 Chapter 34 System Maintenance ...
Page 328: ...P 660H HW T Series User Guide 327 Chapter 35 Remote Management ...
Page 338: ...P 660H HW T Series User Guide 337 Chapter 36 IP Policy Routing ...
Page 342: ...P 660H HW T Series User Guide 341 Chapter 37 Call Scheduling ...
Page 358: ...P 660H HW T Series User Guide 357 Appendix A ...
Page 360: ...P 660H HW T Series User Guide 359 Appendix B ...
Page 384: ...P 660H HW T Series User Guide 383 Appendix D ...
Page 388: ...P 660H HW T Series User Guide 387 Appendix F ...
Page 394: ...P 660H HW T Series User Guide 393 Appendix G ...
Page 398: ...P 660H HW T Series User Guide 397 Appendix H ...
Page 401: ...P 660H HW T Series User Guide Appendix I 400 ...
Page 402: ...P 660H HW T Series User Guide 401 Appendix I ...
Page 456: ...P 660H HW T Series User Guide 455 Appendix M ...