|
|
This chapter provides an overview of the Cisco Systems terminal server product line. You will find the following information in this chapter:
The Cisco Systems terminal servers connect terminals, modems, and microcomputers over serial lines to local area networks (LANs) or wide area networks (WANs). They provide network access to terminals, printers, and computers that have no built-in network support.
As part of their software capability, Cisco terminal servers provide distributed network management facilities to assist in performance monitoring, runtime error logging, and the Simple Network Management Protocol (SNMP). These features allow the network manager to examine and adjust the terminal servers for optimum performance.
Full network access control helps the network manager ensure effective system use. Remote configuration is also available through Telnet and MOP connections to virtual ports on the terminal servers.
Security features allow restrictions to resources on the network. The network manager can specify access lists to establish which users have access to which computers. A user-name-and-password-pair authentication scheme is also supported.
The terminal servers are network-compatible with the Cisco Systems routers, which you can use to extend your network to any size you need. Additionally, protocol translation capability can be added as an option to the terminal server software, thereby providing connection service between different hosts and resources running different protocols
Cisco Systems designs the terminal servers to be an integral part of any distributed systems application. Although communications servers may be used as a distributed data switch or PBX, the Cisco Systems terminal servers can provide direct communication to hosts that support LAT, SLIP, TCP/IP, and TN3270 protocols in their system operating software.
Cisco Systems terminal servers provide a flexible set of capabilities providing connection service using different media and (with the protocol translation option) between different hosts and resources running different protocols. The following descriptions summarize the protocols and connection services supported by the Cisco Systems terminal servers.
The Cisco Systems terminal servers handle multiple device interfaces. They multiplex
asynchronous RS-232 serial lines onto a high-speed network interface. ASCII terminals, modems, printers, and host serial ports are among the devices you can connect to the terminal servers. You can use a number of methods to connect serial devices, including RJ-11, and 50-pin Telco connectors.
The Cisco Systems network interfaces for the terminal servers provide easy connectivity. The network interface is typically to Ethernet, but can also be synchronous serial lines and Token Rings.
Using terminal servers, any RS-232-compatible device--serial laser printer, film recorder, plotter, and the like--can become a shared resource to your organization over a local network. For customer convenience, Cisco Systems markets a broad line of media adapters, including RS-232, V.35, X.21, and RS-449.
Part of the power and flexibility of Cisco Systems' product components is derived from their physical configuration options. Customers can choose from single-board systems, or card-based chassis configurations that offer processor, back panel connector mountings, and communications interfaces best suited to their network.
The following terminal server models are available from Cisco Systems:
The protocol translation option for the terminal server allows users of X.25, DEC Local Area Transport (LAT), and TCP/IP networks to make virtual terminal connections between each of these environments. Access to IBM hosts via TN3270 terminal emulation is also available through the protocol translator. XRemote connections are also supported.
Example uses of protocol translation: A TCP user can make a connection to the protocol translator using TCP/Telnet; the protocol translator then makes an outgoing connection using the X.25 PAD protocols (X.3 and X.29). Similarly, an X.25 PAD user can establish a connection to the protocol translator, which then uses TCP/Telnet to make a connection to a TCP host.
The protocol translator automatically establishes the appropriate connections and converts between X.3 option negotiations and Telnet option negotiations. If you prefer, you can use the protocol translator commands to customize connection parameters that will supersede the X.3 parameters. The protocol translator can conduct up to 100 concurrent translation sessions.
Cisco Systems uses the MC68010, MC68020, or MC68030 microprocessors for high-speed operation in their terminal server products. All Cisco System microprocessors contain onboard RAM, system ROM holding all operating system, bootstrap, and diagnostic software, and hardware and software support for a control console.
Cisco Systems also offers optional nonvolatile memory that retains configuration information despite power losses or system reboots. With the nonvolatile memory option, the terminal and network servers need not rely on other network servers for configuration and boot service information.
The Cisco Systems TRouter, a combination terminal server and router, is ideal for providing a small number of asynchronous serial lines to remote "leaf" networks that have low traffic.
The TRouter includes IP terminal server capabilities. Its routing support includes TCP/IP, DECnet, XNS, AppleTalk, Novell, ISO CLNS, Banyan Vines, and Apollo Domain. You can add X.25, which permits attachment to commercial public data networks and the Defense Data Network (DDN). However, bridging support is not available.
The TRouter hardware system includes a processor, the nonvolatile configuration memory, a 16-line asynchronous serial card, and two network interfaces (Ethernet and/or high-speed serial) on a single MCI controller card. This configuration is available only in the M chassis and cannot be expanded or modified. No other interfaces or peripherals can be added.
The complete TRouter software documentation consists of the Cisco Router Products
Configuration and Reference publication as well as this publication.
|
|