Local Area Transport
Encyclopedia
Local Area Transport is a non-routable (Data Link Layer
) networking technology developed by Digital Equipment Corporation
to provide connection between the DECserver
90, 100, 200, 300, 500, 700 and DECserver 900 terminal server
s and Digital's VAX
and Alpha
and MIPS architecture
host computers via Ethernet
, giving communication between those hosts and serial devices such as video terminals and printers. The protocol itself was designed in such a manner as to maximize packet efficiency over Ethernet by bundling multiple characters from multiple ports into a single packet for Ethernet transport (Mann). Over time, other host implementations of the LAT protocol appeared allowing communications to a wide range of Unix
and other non-Digital operating systems using the LAT protocol.
VAX-Cluster
in Spit Brook Road, Nashua, NH. By "virtualizing" the terminal port at the host end, a very large number of plug-and-play VT100-class terminals could connect to each host computer system. Additionally, a single physical terminal could connect via multiple sessions to multiple hosts simultaneously. Future generations of terminal servers included both LAT and TELNET
protocols, one of the earliest protocols created to run on a burgeoning TCP/IP based Internet. Additionally, the ability to create reverse direction pathways from users to non-traditional RS232 devices (i.e. UNIX Host TTYS1 operator ports) created an entirely new market for Terminal Servers, now known as console server
s in the mid to late 1990s, year 2000 and beyond through today.
LAT and VMS drove the initial surge of adoption of "thick-wire"
Ethernet
by the computer industry. By 1986, terminal server networks accounted for 10% of Digital's $10 billion revenue. These early Ethernet LANs scaled using Ethernet bridges (another DEC invention) as well as DECnet routers. Subsequently, Cisco routers, which implemented TCP-IP and DECnet, emerged as a global connection between these packet-based Ethernet LANs.
Data link layer
The data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....
) networking technology developed by Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
to provide connection between the DECserver
DECserver
In computer networking, DECserver initially referred to a highly successful family of asynchronous console server / terminal server / print server products introduced by Digital Equipment Corporation and later referred to a class of UNIX-variant application and file server products based upon the...
90, 100, 200, 300, 500, 700 and DECserver 900 terminal server
Terminal server
A terminal server enables organizations to connect devices with an RS-232, RS-422 or RS-485 serial interface to a local area network . Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such as data encryption and user authentication...
s and Digital's VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
and Alpha
DEC Alpha
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
and MIPS architecture
MIPS
MIPS may refer to:* Maharana Institute of Professional Studies, an institution in Kanpur, Uttar Pradesh, India* Mansehra International Public School and College, in Mansehra, Pakistan* Material input per unit of service, an economic efficiency indicator...
host computers via Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
, giving communication between those hosts and serial devices such as video terminals and printers. The protocol itself was designed in such a manner as to maximize packet efficiency over Ethernet by bundling multiple characters from multiple ports into a single packet for Ethernet transport (Mann). Over time, other host implementations of the LAT protocol appeared allowing communications to a wide range of Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
and other non-Digital operating systems using the LAT protocol.
History
In 1984, the first implementation of the LAT protocol connected a terminal server to a VMSOpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
VAX-Cluster
VMScluster
A VMScluster is a computer cluster involving a group of computers running the OpenVMS operating system. Whereas tightly coupled multiprocessor systems run a single copy of the operating system, a VMScluster is loosely coupled: each machine runs its own copy of OpenVMS, but the disk storage, lock...
in Spit Brook Road, Nashua, NH. By "virtualizing" the terminal port at the host end, a very large number of plug-and-play VT100-class terminals could connect to each host computer system. Additionally, a single physical terminal could connect via multiple sessions to multiple hosts simultaneously. Future generations of terminal servers included both LAT and TELNET
TELNET
Telnet is a network protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communications facility using a virtual terminal connection...
protocols, one of the earliest protocols created to run on a burgeoning TCP/IP based Internet. Additionally, the ability to create reverse direction pathways from users to non-traditional RS232 devices (i.e. UNIX Host TTYS1 operator ports) created an entirely new market for Terminal Servers, now known as console server
Console server
A console server is a device or service that provides access to the system console of a computing device via networking technologies....
s in the mid to late 1990s, year 2000 and beyond through today.
LAT and VMS drove the initial surge of adoption of "thick-wire"
10BASE5
10BASE5 was the original commercially available variant of Ethernet.For its physical layer it used cable similar to RG-8/U coaxial cable but with extra braided shielding. This is a stiff, diameter cable with an impedance of 50 ohms , a solid center conductor, a foam insulating filler, a shielding...
Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
by the computer industry. By 1986, terminal server networks accounted for 10% of Digital's $10 billion revenue. These early Ethernet LANs scaled using Ethernet bridges (another DEC invention) as well as DECnet routers. Subsequently, Cisco routers, which implemented TCP-IP and DECnet, emerged as a global connection between these packet-based Ethernet LANs.
Early Terminal Server Vendors
- Digital Equipment CorporationDigital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
- An early provider of Terminal Server products. - Xyplex Corporation - An early provider of Terminal Server products based in Massachusetts.
- Hughes LAN Systems - Provided LAT capability in 1989.
- Cisco SystemsCisco SystemsCisco Systems, Inc. is an American multinational corporation headquartered in San Jose, California, United States, that designs and sells consumer electronics, networking, voice, and communications technology and services. Cisco has more than 70,000 employees and annual revenue of US$...
- Provided LAT on Terminal Servers as early as 1990. - Able Computer - An early provider of Terminal Server products.
- Emulex Corporation - An early provider of Terminal Server products based in California.
- Chase Research - An early provider of Terminal Server products based in Europe.
See also
- Terminal serverTerminal serverA terminal server enables organizations to connect devices with an RS-232, RS-422 or RS-485 serial interface to a local area network . Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such as data encryption and user authentication...
- An active device to connect serial devices to Local Area Networks - Console serverConsole serverA console server is a device or service that provides access to the system console of a computing device via networking technologies....
- An active device to connect LAN attached users to Linux/Unix server operator ports - http://sourceforge.net/apps/mediawiki/linux-decnet/index.php?title=LAT - Open sourceOpen sourceThe term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
LAT project for LinuxLinuxLinux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...