Terminal access types
The following types of terminal access are used in different applications:
True type terminal (TTY) access
Telnet terminal access
Enhanced Telnet (ETelnet) terminal access
Secure Shell (SSH) terminal access
Remote terminal connection (RTC) access
TTY terminal access, Telnet terminal access, ETelnet terminal access, and SSH terminal access are used to help implement services between a terminal and an FEP, with a router as the initiator and the FEP as the receiver. The difference between them is their method of data encryption and their way of establishing a connection between the initiator and the receiver. Each terminal supports up to eight virtual type terminals (VTYs) using these access types, and supports switchover between the VTYs.
RTC terminal access is used to monitor terminal data. It is initiated by a router and received by another router. Only RTC terminal access supports UDP connections with synchronous terminals.
Support for features depends on the terminal access type. For more information, see "Terminal access feature list" and "Terminal access features."
TTY terminal access
The initiator and receiver of TTY terminal access are a router and an FEP respectively. The service terminal is connected to the router through an asynchronous serial interface. The router is connected to the FEP through a network. Application services run on the FEP. The FEP interacts with the router through the ttyd program, and the router pushes the service display to the service terminal. The router transports data transparently between the connected service terminal and FEP to implement service interaction and processing.
The initiator and receiver programs of TTY terminal access are developed by Hewlett Packard Enterprise. TTY terminal access implements the fixed terminal number function and offers many enhanced functions such as dynamic multi-service switching, real-time screen saving, terminal reset, and data encryption. The FEP provides professional terminal management software. The combination of TTY terminal access and routers makes remote offices possible and implementation of IP telephony easier, offering a solution for establishing highly efficient networks with diverse functions.
Telnet terminal access
The initiator and receiver of Telnet terminal access are a router and an FEP respectively. A service terminal is connected to the router (Telnet client) through an asynchronous serial interface. The router is connected to the FEP (Telnet server) through a network. Application services run on the FEP. The FEP interacts with the router through standard Telnet, thereby implementing data exchange between the terminal and the FEP.
ETelnet terminal access
The initiator and receiver of ETelnet terminal access are a router and an FEP respectively. A service terminal is connected to the router (ETelnet client) through an asynchronous serial interface. The router is connected to the FEP (ETelnet server) through a network. Application services run on the FEP. The FEP interacts with the router through an encrypted Telnet connection to further exchange data with the terminal.
In addition to the functions supported by Telnet terminal access, ETelnet terminal access implements data encryption and terminal number binding to improve security.
SSH terminal access
The initiator and receiver of SSH terminal access are a router and an FEP respectively. A service terminal is connected to the router (secure shell) through an asynchronous serial interface. The router is connected to the FEP (SSH server) through a network. Application services run on the FEP. The FEP interacts with the router through standard SSH.
RTC terminal access
The initiator and receiver of RTC terminal access are both routers. RTC terminal access is another typical application of terminal access. It interconnects a local terminal and a remote terminal through routers for data exchange and data monitoring. RTC terminal access supports synchronous mode and asynchronous mode.
The monitoring terminal at the data center and the monitored terminal are each connected to a different router through a serial interface, and the routers exchange data with each other through an IP network. Normally, the router connected to the monitoring device acts as the terminal access initiator (the RTC client). The monitoring device is always ready to initiate a connection request at any time to access the data on the monitored device. The router connected to the monitored terminal acts as the terminal access receiver (the RTC server) and is always ready to receive the connection requests from the monitoring device and send monitored data in response. RTC terminal access also supports TCP-based many-to-one transparent data transmission and UDP-based one-to-many transparent data transmission.
RTC terminal access serves the following purposes:
Enabling the monitoring device to manage and monitor remote terminals.
Sharing data among multiple terminals such as radar devices.
Collecting data from remote terminals.
Fulfilling the functions of a multiplexing device and transmitting data over IP networks for easy network upgrade.