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Figure 69
Example of a LAN
What is a WAN?
A WAN (Wide Area Network), often referred to as “the WAN,” is that portion of a
network which involves use of the pre-existing public telephone network and
network infrastructures, such as the public Internet, or long-distance carrier
services such as DSL or cable, for transporting data over long distances and a wide
geographical area. The WAN segment of a network is that segment for which
access is typically subscriber-based—meaning its use is essentially “borrowed,”
through, for instance, dial-up or leased-line accounts. It is the WAN, with its
unlimited reach in terms of distance, which enables two or more LANs located at
far geographical distances to be linked as part of a single network. Whereas a LAN
is limited by the physical limits of its direct cabling, the WAN faces no such limits.
Ultimately, it is this absence of any distance limit to the WAN which gives networks
the potential to have global reach and expanse.
Networks which extend into the WAN require the use of WAN devices, such as
routers, which can link the LAN with the WAN by providing a means of access to
these borrowed services of the WAN, typically, through the device’s ability to make
dial-up calls and connections.
How is a LAN connected
to the WAN?
You can connect a LAN to the WAN using a device such as a router, which has the
ability to establish a connection out to the WAN and, in some cases, receive
connections in the from the WAN.
Since different WAN services use different physical media and different
technologies for transporting data (for example, cable is different from analog,
which is different from ISDN), a WAN device has to have the proper “interface“
to match the particular type of WAN service that is being utilized. Since a WAN
device must also serve as a link to the LAN, it must have another interface to
match the media and technology used for data transport on the LAN (typically,
Ethernet). Thus, for example, the Dual 56K LAN Modem has Ethernet ports which
serves as its link to the LAN on one side, and analog modem ports which serve as
its link to the analog telephone network on the other.
What is a LAN Modem?
A LAN Modem is a hybrid device which combines the dial-up capabilities of a
standard modem with the LAN expansion and sharing capabilities of an Ethernet
hub. Because a computer’s access to the modems in the LAN Modem is achieved
through a 10 Mbps Ethernet connection rather than through a serial (COM) port,
the traditional COM port speed bottleneck associated with serial port-based
modems is eliminated. At the same time, the LAN Modem’s Ethernet hub provides
local networking capability among the attached computers.
10 Mbps Ethernet LAN
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Summary of Contents for 3C888 - OfficeConnect Dual 56K LAN Modem Router
Page 10: ...GLOSSARY 3COM CORPORATION LIMITED LIFETIME WARRANTY REGULATORY AND APROVAL INFORMATION ...
Page 30: ...30 CHAPTER 2 DUAL 56K LAN MODEM FUNCTIONALITY DESCRIPTION ...
Page 46: ...46 CHAPTER 4 INSTALLING THE DUAL 56K LAN MODEM ...
Page 58: ...58 CHAPTER 5 CONFIGURING THE DUAL 56K LAN MODEM FOR INTERNET ACCESS ...
Page 124: ...124 CHAPTER 9 PLACING RECEIVING AND DISCONNECTING CALLS ...
Page 136: ...136 CHAPTER 10 TROUBLESHOOTING AND MAINTENANCE ...
Page 146: ...146 APPENDIX A NETWORKING PRIMER ...
Page 154: ...154 APPENDIX D FACTORY DEFAULTS ...
Page 156: ...156 APPENDIX E SPECIFICATIONS ...
Page 166: ......
