From a topological level, a remote access network consists of three network segments:

•  The user’s network is the point of origin of access requests. It can be a branch office network, a home office consisting of a personal computer (PC) equipped with a modem, or a mobile office with a PC and a mobile transceiver.

•  The corporate network is the destination of the user’s traffic. Generally, a remote access device receives remote access calls and transforms the calls into a format that can be transmitted on the corporate LAN.

•  The wide area network (WAN) enables the user to access the corporate network. The WAN spans a large geographical area and can be a public switched telephone network (PSTN), the Internet, or a private data network. It provides the switching and/or routing function required to get a remote call from the user’s network to the corporate network.

Both the user’s network and the corporate network are linked to the WAN via an access network. An access network is the portion of the WAN that connects individual subscribers to the access devices located in the WAN. The access devices are responsible for concentrating the individual access lines from subscribers into a smaller number of feeder lines used in the WAN. Currently, the predominant access network for a residential user is the twisted-pair copper wire. However, both coaxial cable (from cable TV operators) and optical fiber are becoming increasingly common. For corporate users, the predominant access network is the T1, with optical fiber becoming increasingly available.

It illustrates the three network segments. It shows a user who can dial into the corporate network via the PSTN, the Internet, or through a private data network. Sometimes user traffic may traverse more than one WAN to get to the corporate network. For example, a user may not have direct access to the Internet, and thus must first go through the PSTN to reach the ISP’s point-of-presence (POP). From there the traffic is forwarded to the Internet.

From a logical level, the remote access network consists of access protocols that allow the devices in the user’s network and corporate network to communicate with the WAN devices. It may also consist of protocols that ensure secure communication through a non-secure transmission environment.