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Aterminal server connects devices with aserial port to alocal area network (LAN). Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such asdata encryption and user authentication. The primary application scenario is to enable serial devices to access network server applications, or vice versa, where security of the data on the LAN is not generally an issue. There are also many terminal servers on the market that have highly advanced security functionality to ensure that only qualified personnel can access various servers and that any data that is transmitted across the LAN, or over the Internet, is encrypted. Usually, companies that need a terminal server with these advanced functions want to remotely control, monitor, diagnose and troubleshoot equipment over a telecommunications network.
Aconsole server (also referred to as console access server, console management server, serial concentrator, or serial console server) is a device or service that provides access to thesystem console of a computing device via networking technologies.
Although primarily used as anInterface Message Processor starting in 1971, theHoneywell 316 could also be configured as aTerminal Interface Processor (TIP) and provide terminal server support for up to 63ASCII serial terminals through a multi-line controller in place of one of the hosts.[1]
Historically, a terminal server was a device that attached to serialRS-232 devices, such as "green screen"text terminals or serial printers, and transported traffic viaTCP/IP,Telnet,SSH or other vendor-specific network protocols (e.g.,LAT) via anEthernet connection.
Digital Equipment Corporation'sDECserver 100 (1985), 200 (1986) and 300 (1991) are early examples of this technology. (An earlier version of this product, known as theDECSA Terminal Server was actually a test-bed or proof-of-concept for using the proprietary LAT protocol in commercial production networks.) With the introduction of inexpensiveflash memory components, Digital's later DECserver 700 (1991) and 900 (1995) no longer shared with their earlier units the need to download their software from a "load host" (usually a DigitalVAX or Alpha) using Digital's proprietaryMaintenance Operations Protocol (MOP). In fact, these later terminal server products also included much larger flash memory and full support for the Telnet part of the TCP/IP protocol suite. Many other companies entered the terminal-server market with devices pre-loaded with software fully compatible with LAT and Telnet.
A "terminal server" is used many ways but from a basic sense if a user has a serial device and they need to move data over the LAN, this is the product they need.
Aconsole server (console access server,console management server,serial concentrator, orserial console server) is a device or service that provides access to thesystem console of a computing device via networking technologies.
Most commonly, a console server provides a number ofserial ports, which are then connected to the serial ports of other equipment, such as servers, routers or switches. The consoles of the connected devices can then be accessed by connecting to the console server over a serial link such as amodem, or over a network withterminal emulator software such astelnet orssh, maintaining survivable connectivity that allows remote users to log in the various consoles without being physically nearby.
Dedicated console server appliances are available from a number of manufacturers in many configurations, with the number of serial ports ranging from one to 96. These Console Servers are primarily used for secure remote access to Unix Servers, Linux Servers, switches, routers, firewalls, and any other device on the network with a console port. The purpose is to allow network operations center (NOC) personnel to perform secure remote data center management andout-of-band management of IT assets from anywhere in the world. Products marketed as Console Servers usually have highly advanced security functionality to ensure that only qualified personnel can access various servers and that any data that is transmitted across the LAN, or over the Internet, is encrypted. Marketing a product as a console server is very application specific because it really refers to what the user wants to do—remotely control, monitor, diagnose and troubleshoot equipment over a network or the Internet.
Some users have created their own console servers using off-the-shelfcommodity computer hardware, usually with multiport serial cards typically running a slimmed-downUnix-like operating system such asLinux. Such "home-grown" console servers can be less expensive, especially if built from components that have been retired in upgrades and allow greater flexibility by putting full control of the software driving the device in the hands of the administrator. This includes full access to and configurability of a wide array of security protocols and encryption standards, making it possible to create a console server that is more secure. However, this solution may have a higherTCO, less reliability and higher rack-space requirements, since most industrial console servers have the physical dimension of onerack unit (1U), whereas a desktop computer with full-sizePCI cards requires at least 3U, making the home-grown solution more costly in the case of aco-located infrastructure.
An alternative approach to a console server used in somecluster setups is tonull-modem wire anddaisy-chain consoles to otherwise unused serial ports on nodes with some other primary function.
