Access Methods and Standards
Manufacturers and ISVs continue to develop innovative RASs that incorporate additional functionality and features to improve security, management, and performance over slow links. Standard bodies, supported by leading manufacturers and telecommunication vendors have adopted several technologies for remote access, including faster analog dial-up access speeds (28.8–56 Kbps) using V.90 modems over the PSTN network. In addition, basic rate ISDN is a fast data service offered by Telcos—faster than typical analog modems, with top speeds of 128 Kbps—but deployment in the US is slow and expensive and throughput is typically not fast enough for today's multimedia Internet.
Recently, standard bodies, such as ITUT, have adopted an informal name for a technology called asymmetric digital subscriber line (ADSL) slow as , known as G.Lite or Universal DSL. The G.Lite standard (officially, G.992.2), or ADSL, is becoming a popular method for providing high-speed connectivity to residential communities or small office/home office (SOHO) over traditional "copper" networks.
ADSL is capable of speeds as 64 Kbps and as fast as 8 Mbps. ADSL is becoming a viable transmission mechanism for businesses and enterprise customers requiring high-speed remote access to connect remote users, SOHOs, and branch offices. ADSL is a necessary technology for the increasing demands of fast, reliable remote access. With bandwidth capabilities at speeds greater than T1 (1.54 Mbps), ADSL can be deployed inexpensively compared to traditional technologies, such as frame relay, Point-to-Point T1, and Fractional T1.
Competing with ADSL are broadband and wireless technologies. Broadband technologies from cable TV providers use cable modems over the cable television network to provide Internet access through a "supported" ISP. Cable modems provide excellent transmission speeds to residential communities and the SOHO; they are widely deployed for remote access to home users.
Alternatively, wireless solutions that use digital cellular, 900 MHz, or radio wave technologies offer excellent solutions for mobile users who are constantly on the move. Unfortunately, many of the wireless technologies deployed today do not offer the performance and reliability of traditional or broadband carrier technologies. As these technologies improve, you are able to choose from a variety of viable transmission mediums, including wireless, broadband, and satellite.
Bringing this all together, Windows 2000 is an operating system built on standards. Windows 2000 supports routing and remote access services (RRAS) that leverage all the remote access components previously listed. Furthermore, Windows 2000 Active Directory provides centralized administration of your remote access environment through MMC , and Active Directory delivers strong security authentication and encryption protocols to protect your corporate information assets while remote users access the network over the Internet. If coupled with the variety of transmission alternatives available to the market, businesses can now deploy a RAS that delivers users the flexibility to work securely from anywhere, at anytime.