There is little equipment and application difference between a home user and a home office. In fact, there is little difference between an individual user with more than one computer and a small office. The components are nearly the same in all cases. An individual with separate computers for the children and maybe one for his wife, in reality, has the basic components of a small office. There are advantages to networking these computers together. The next logical step is to consolidate the outside connection with devices which have bandwidth to service all of the home computer communication needs. Consolidation by installing a network to combine computer usage, coupled with a terminal adapter which meets more than one user needs may be the answer. 

 Individuals may find that they need higher bandwidth technologies in order to conduct genealogy searches, or other collaboration on home or hobby projects. Moving large files such as photos, graphics, or art from one place to another can become a pain if you have to wait for twenty or thirty minutes for one file to up or down load. Each POTS telephone line has a cost. If there is more than one computer in the house, then each requires a telephone line, or only one user at a time if everyone shares the data telephone line. 

The home office takes our reasoning one step further as the user may be handling very large data files as a graphics artist or a sales representative who works at home and must transmit large files to a remote office. In both cases, time is money and time spent sending large files over an analog connection may be time wasted. 

 The small office has the same requirements as individuals and home office users plus the added need to be able to share the data between more than one user. Networks are required in this setting. The need to contact other offices or clients by more than one office user at a time also demands a connection which has enough bandwidth to efficiently move the data. 

Connectivity

 The technology options are varied and are becoming very cost effective. As was seen in the two previous articles on bandwidth, most of the technologies are straight digital connections. The exception is the use of multiple 56 Kbps modems either in a router device or directly in the computer under Windows 98 or other advanced Operating systems such as Windows NT, Linux UNIX, or IBM OS2. 

 The technologies as noted in the previous articles are Integrated Services Digital Network (ISDN), multiple 56 Kbps or ganged analog modems, Asymmetric Digital Subscriber Line (ASDL), satellite, cable modems, Multichannel Multipoint Distribution Service (MMDS), ie., microwave signals. Each technology has service and financial costs to be considered. All provide bandwidth greater than a single analog modem. 

 As individual and SOHO connection needs, ie., bandwidth, increase, the advanced terminal adapter technology becomes reasonable to consider. 

 ISDN capability is available both as terminal adapter internal cards and external units and provide bandwidth of up to 128 Kbps. Additionally the external units are available as routers. Multiple 56 Kbps modems are available as individual internal or external units and as routers which provide multiple bandwidth of up to 52 Kbps. POTS lines are required for each modem or multiple unit in the router. The ISP may require multiple Internet accounts. ASDL terminal adapters provide up to 1.5 Mbps downloads and 640 Kbps uploads. Satellite terminal adapters provide 400 Kbps download and a separate analog modem for uploads. Cable modems are normally external devices and provide up fro 1.5 to 3 Mbps connections. 

 Hardware and software are required for the connection. An analog modem, digital terminal adapter, or other device is required to handle the communication special purpose connections. Communications software applications are required to handle the actual encoding and decoding of the communication transmissions. Analog connections are adequate for individual connections, but they are still individual computer devices, only one user can be on-line at a time. Routers on the other hand, allow more than one user to be on-line at one time. 

Routers

 The telco xDSL and cable company modem capabilities are further downstream. Both of these technologies require provider investments which have not been made to date to make them available for widespread use. When they do become available, then the bandwidth offered will make all of us happy. 

 Routers also contain the capability to handle the advanced bandwidth we are looking for in order to provide connections for more than one user at a time. Router technology has improved to a point that one does not have to be a rocket scientist to install and maintain them. This is especially true for the ISDN and multiple 56 Kbps routers. Each of these technologies have become cost effective enough for individual and SOHO users to purchase. 

 ISDN routers offer the best near term solution to broader bandwidth. Routers require each computer be connected to an Ethernet network via a simple network hub. The class of personal ISDN routers being offered in today's market nearly all have wizard-based installation software for those of us who have limited network experience. Most of them are being offered in price ranges which lend usage by individuals and SOHO applications with limited budgets. 

 One of the application technologies being used in the routers is the ability to move all network-to-Internet traffic through a single IP address. This technology is IP Network Address Translation (NAT). NAT allows sharing a single ISDN line. The ISDN router sends all the traffic generated on the local network through the one IP address. Cost savings are the major benefit, as only one ISP account is required. The second application technology configured in these ISDN routers is Dynamic Host Configuration Protocol (DHCP) services. Any ISDN router with these two protocols will allow multiple users from a home or small office. 

 The basic requirement needed to gain this benefit are that the computers must be connected via a local area network (LAN). The network must be an Ethernet topology through a hub. Some of the ISDN routers provide limited hub capability. All of the routers will connect to the LAN through either their hub or the LAN hub. 

Benefits of ISDN routers are many. Routers provide 64 Kbps per channel (B channels) and with the Basic Rate Interface (BRI) giving a user two B channels and one 16 kbps control channel. This is 128 Kbps by bonding the B channels plus the 16 Kbps control channel. The two B channels can be used separately providing data on one and voice or FAX at the same time on the other. Each B channel has its own telephone number. Most of the routers have POTS line connections for voice and FAX built in. ISDN latency time, the time a data packet to travel from a computer to a remote server and back, is much faster than analog latency time. ISDN connects almost instantly. ISDN routers usually dial and discount on an as-needed basis. This is a very important point. Bonding or aggregation of the B channels is accomplished by using Multilink PPP (MP) protocol. Additionally, the Bandwidth Allocation Control Protocol (BACP) lets ISDN routers add the second channel to a connection or drop it as voice or data traffic warrants. 

 ISDN service has become available from nearly all telephone companies. Installation, monthly, and usage charges vary greatly from region to region. ISP charges also vary greatly. 

How Does It Work?

 The exact bandwidth availability depends on the number of users sharing the ISDN router and type of application each is running. If three users are sharing the ISDN router and two are scrolling through an already downloaded Web page, then when the third user logs on and loads a browser to check something, at that instant, the third users receives all the bandwidth, because the others are at idle. Now if one user is downloading a large file and a second user logs on, then each user will share the available bandwidth, most likely about half of the available bandwidth. 

 ISDN routers dial up as the users on the network request service. This is very important as only one IP account is required from the ISP. Once dialed on, then the router shares the available bandwidth with every user who requests service. Each client on the network is assigned an unregistered IP address under the DHCP. The unregistered IP addresses are not visible on the Internet. The NAT protocol routes the data packets from the single registered IP address to all LAN clients. 

Available Hardware

Conclusion