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This chapter describes how to use the Cisco terminal server. You will find information about these tasks in this chapter:
Refer to the chapter "Startup and Basic Configuration" for configuration procedures to use the setup command facility. Refer to the chapter "System Configuration," for details about system-wide configuration features. The chapter "System Management" addresses facilities for monitoring and managing Cisco terminal servers. Configuration utilities associated with specific transmission protocols (TCP/IP, DEC LAT, SLIP, IBM TN3270, and XRemote) are addressed in Part Five of this publication, "Transmission Protocols." If you have special applications, or wish to customize your connections, refer to these other chapters for details.
See the end of the chapter for a command summary.
The Cisco terminal server provides a broad range of connection service capabilities. Users can make simple automated terminal-to-host connections, or can establish custom terminal sessions tailored to specific terminal or application requirements. The connection descriptions in this section define the connection capabilities available to users and the syntax associated with each user-level EXEC connection command.
DEC's Local Area Transport (LAT) protocol is the protocol used most often to connect terminal servers to DEC hosts. LAT is a DEC-proprietary protocol. Cisco uses LAT technology licensed from DEC.
The LAT protocol allows a user at one site to establish a connection to a host at another site, then passes the keystrokes from one system to the other. A user can establish a LAT connection through the terminal server to a DEC host, simply by entering the host name.
Use the EXEC command lat to establish a connection to a LAT learned service. Enter this command at the EXEC prompt:
lat name [node nodename|port portname|/debug]You can type the name of the service to which you want to attach, or include the optional keywords listed in the above syntax description. You can also just type the service name without the lat command to make the connection.
The optional keyword node specifies connection to a specific LAT node which offers a service. Enter the name of the node in place of the nodename argument. If you do not include the node option, the node with the highest rating offering the service is used. Use the EXEC command show lat nodes to display information about all known LAT nodes (see the section "Monitoring LAT" in the chapter "LAT Configuration and Management" for more information about this command).
The optional keyword port specifies a destination LAT port name. This keyword is ignored in most timesharing systems, but is used by terminal servers offering reverse LAT services. Reverse LAT services are discussed in the section "Configuring a Rotary Group," in the chapter "LAT Configuration and Management." Generally, reverse LAT involves connecting to one terminal server from another. In this case, the target terminal server runs the host portion of the protocol. Enter the port name in the format of the remote system in place of the portname argument.
The optional keyword /debug is a switch that, when enabled, prints parameter changes and other special messages on the terminal.
The following sample session establishes a LAT connection from the terminal server named ts to the host Eng2.
ts>lat eng2
Trying ENG2...Open
ENG2 - VAX/VMS V5.2
Username:JSmith
Password:
Welcome to VAX/VMS version V5.2 on node ENG2
Last interactive login on Friday, 6-APR-1990 19:46
The LAT protocol is explicitly specified. You specify the protocol when your preferred transport is set to "none" or to another protocol. The system informs you of its progress by displaying the messages "Trying <system>..." and then "Open." If the connection were not successful, you receive a failure message.
The following sample session establishes a LAT connection from the terminal server named ts to the cisco-modems service and specifies port 24, which is a special modem:
ts>lat cisco-modems port 24
The following sample session establishes a LAT connection from the terminal server named ts to the cisco-modems service and specifies a node named Eng:
ts>lat cisco-modems node eng
The following sample session uses the LAT session debugging capability.
ts>lat Eng2 /debug
Trying ENG2...Open
ENG2 - VAX/VMS V5.2
Username:JSmith
Password:
Welcome to VAX/VMS version V5.2 on node ENG2
Last interactive login on Tuesday, 10-APR-1990 19:02
[Set Flow out off, Flow in on, Format 8:none, Speed 9600/9600]
[Set Flow out off, Flow in on, Format 8:none, Speed 9600/9600]
$ set ter/speed=2400
[Set Flow out off, Flow in on, Format 8:none, Speed 2400/2400]
A variety of LAT events are reported, including all requests by the remote system to set local line parameters. The messages within brackets ([ ]) above are the messages produced by the remote system setting line characteristics to operating system defaults.
You may open more than one connection by typing the escape sequence Ctrl ^ X (done by typing and holding the Ctrl and SHIFT and ^ keys, then releasing those keys and typing the X key) to return to the EXEC prompt. Enter the show session EXEC command to display open sessions. Enter the resume command with the connection number desired to return to a connection. (See the section "Connection Management Commands" later in this chapter for further information about these command.)
When you attempt to connect to a password-protected service, the terminal server prompts for a password. You can abort the connection by typing Ctrl-C, or enter the password for a given service to complete the connection.
The Serial Line Internet Protocol, or SLIP, defines a method of sending IP packets over standard RS-232 asynchronous serial lines.
SLIP is an inexpensive way of connecting PCs to a network. SLIP can be used over asynchronous dial-up modems, allowing personal computers to be connected to a network without the cost of a leased line. Dial-up SLIP links can also be used for remote sites that need only occasional or backup connectivity.
The terminal server can support any combination of SLIP lines and lines dedicated to normal asynchronous devices, such as terminals and modems.
You use one of two EXEC commands to make a SLIP connection, depending on how the line is set up:
slipIt is also possible to configure a dedicated SLIP line, in which case no EXEC command is required to make the connection.
The following paragraphs describe the ways in which the SLIP lines can be configured and which command to use to make the connection.
A line can be permanently configured for SLIP by the system administrator. In this case, an EXEC is not started on the line, so you need not enter a command to initiate SLIP. You need only to make the physical connection to the line and then are immediately placed in SLIP mode. No prompt or status message is issued.
A line can be assigned a permanent SLIP address by the system administrator. In this case, you issue the slip EXEC command to put the line into SLIP mode. An address is assigned to the line, so there is no prompt for an address. If the server has been configured to authenticate SLIP connections, you are prompted for a password before the line is placed in SLIP mode.
This sample illustrates how to enter the slip EXEC command to make a connection when a permanent SLIP address has been assigned. Once a correct password is entered, you are placed in SLIP mode, and the IP address is displayed.
TS>slip
Password:
Entering SLIP mode.
Your IP address is 192.31.7.28, MTU is 1524 bytes
A line can be configured for dynamic assignment of SLIP addresses by the system administrator, in which case, you are prompted for the IP address to use when you enter the slip EXEC command. This address is validated via TACACS and, if validated, the line is put into SLIP mode using the address requested.
This sample illustrates the "IP address or hostname?" prompt displayed and the response required when dynamic addressing is used to assign the SLIP address.
TS>slip
IP address or hostname? 192.31.6.15
Password:
Entering SLIP mode
Your IP address is 192.31.6.15, MTU is 1524 bytes
A line that is configured for dynamic address assignment can also be given a default address to use if it has not been assigned a dynamic address. In this case, you issue the slip default EXEC command, the transaction is validated by the TACACS server, and the line is put into SLIP mode.
In this sample session, the address 192.31.6.15 has been assigned as the default. Password verification is still required before SLIP mode can be enabled.
TS>slip default
Password:
Entering SLIP mode
Your IP address is 192.31.6.15, MTU is 1524 bytes
The chapter "SLIP Configuration and Management" describes how to configure a line for SLIP mode, and how to maintain the SLIP line.
Two TCP/IP protocols, Telnet and rlogin, are available for making connections to a host. Telnet, a virtual terminal protocol that is part of the TCP/IP protocol suite, allows for connections to hosts. Telnet is the more widely used protocol. The rlogin protocol is a remote login service developed for the BSD UNIX system. It provides better control and output suppression than Telnet, but may only be used when the host (typically, a UNIX system) also supports rlogin.
To make a Telnet connection, type the name or address of the host to which you want to connect at the EXEC prompt and press Return. Type the connect command before the host name, if the name of the host is the same as a command word. To make an rlogin connection, type the rlogin command before the host name or address. In either case, the terminal server either connects you to the host or prints a message stating that the connection failed.
When you are done, log off the host. The EXEC terminates any connection after ten minutes (default) of inactivity, or when you enter the exit command at the EXEC prompt.
However, the Cisco software also provides additional connection options. The following sections explain these options, and commands to display and monitor the connections.
Use either the EXEC command connect or telnet to start a Telnet connection; the commands are synonymous. Enter this command at the EXEC prompt.
{connect|telnet} host [port] [/keyword]The argument host is a host name or an Internet address. The optional argument port is a decimal TCP port number; the default is the Telnet server port (decimal 23) on the host. The optional argument keyword is one of the following:
You may omit the command word connect or telnet, if the host name you want to use is not the same as a terminal server command word.
The terminal server assigns a logical name to each connection; several commands use these names to identify connections. The logical name is the same as the host name, unless that name is already in use or you change the connection name with the EXEC command name-connection. If the name is already in use, the terminal server assigns a null name to the connection.
The following command routes packets from the source system to kl.sri.com, then to 10.1.0.11, and finally to mathom.
TS>connect mathom /route:kl.sri.com 10.1.0.11 mathom
The following command connects to a host with logical name mathom.
TS>mathom
The Cisco Telnet software supports special Telnet commands in the form of Telnet sequences that map generic terminal control functions to operating system-specific functions.
To issue a special Telnet command, type the escape sequence (usually Ctrl ^) and then a command character. You can type the command character as you hold down Ctrl or with Ctrl released; you can type either uppercase or lowercase letters.
Table 1-1 lists the special Telnet commands.
| Command Name | Command Character |
|---|---|
| Break | Ctrl-^, B |
| Interrupt Process (IP) | Ctrl-^, C |
| Erase Character (EC) | Ctrl-^, H |
| Abort Output (AO) | Ctrl-^, O |
| Are You There? (AYT) | Ctrl-^, T |
| Erase Line (EL) | Ctrl-^, U |
At any time during an active Telnet session, you can list the Telnet commands by typing this command at the system prompt:
Ctrl ^ ?This is done by typing the escape sequence followed by a question mark. This command displays an online table of the special Telnet commands, for quick reference.
A sample of this list follows (the Ctrl key is represented by the first ^ character).
[Special telnet escape help]
^^B sends telnet BREAK
^^C sends telnet IP
^^H sends telnet EC
^^O sends telnet AO
^^T sends telnet AYT
^^U sends telnet EL
The rlogin command starts a connection using the UNIX rlogin protocol. Enter this command at the EXEC prompt.
rlogin host [debug]The argument host is a host name or an Internet address. The optional keyword debug enables debugging output from the rlogin protocol.
The rlogin protocol provides better flow control and output suppression than Telnet. The Cisco implementation of rlogin does not subscribe to the trusted host model. That is, a user cannot automatically log onto a UNIX system from the terminal server, but must provide a user ID and a password for each connection.
This example makes an rlogin connection to a host at address 108.33.21.2 and enables the message mode for debugging.
TS>rlogin 108.33.21.2 debug
You can have several concurrent Telnet or rlogin connections open and switch back and forth between them. The number of connections that may be opened is defined by the session-limit command; see the chapter "System Configuration" for more information about this command. To switch between connections, first type the escape sequence, which by default is Ctrl ^ X (press the Ctrl and Shift and ^ keys simultaneously, let go, then press the X key), to return to the system command prompt.
To make a new connection, use the procedure described in the sections "Making Telnet Connections," or "Making Rlogin Connections," above. To get back to an existing connection, use the resume command, described next. Use the where command to list your open connections.
The EXEC command resume returns to a previous connection. Enter this command at the EXEC prompt:
resume [connection] [/keyword]The optional argument connection is the connection name or number; the default is the most recent connection. The optional argument /keyword is one of the following keywords:
You can omit the command word resume and simply type the connection number to resume a connection. You can also return to the most recent session by just pressing the Return key.
This command resumes connection 2 in Telnet line mode.
TS>resume 2 /line
This command resumes Telnet connection 3.
TS>3
The EXEC command where displays information about all open Telnet or rlogin connections associated with the current terminal line. Enter this command at the EXEC prompt:
whereThis session shows the display seen by entering the where EXEC command.
TS>where
Conn Host Address Byte Idle Conn Name
1 DREGGS 131.108.19.50 0 0 DREGGS
* 2 CLASH 192.31.7.24 0 0 CLASH
The information includes the host name, address, number of characters waiting to be sent to the terminal, idle time, and connection name. An asterisk (*) indicates the current connection.
If your network administrator has configured an appropriate default terminal type, then you can use the EXEC command tn3270 to start a TN3270 session via a Cisco terminal server. Enter this command at the EXEC prompt:
tn3270 hostnameThe argument hostname is the name of a specific host on a network that is reachable by the terminal server. The default terminal emulation mode allows access using a VT100 emulation. If your terminal requires a different emulation, you must configure your terminal server to support different terminal types.
The process for configuring the Cisco terminal server to include alternative (and custom) terminal emulations is described in the chapter "TN3270 Configuration and Management."
The following example allows the Cisco terminal server to establish a terminal session with an IBM host named finance.
ts>tn3270 finance
XRemote can be invoked in these ways:
The following brief procedures outline steps required for starting up XRemote in several typical environments. When possible, use the automated processes. See the chapter "XRemote Configuration and Management" for information about configuring XRemote and fonts for screen display.
If your host computer supports a server for XDMCP, such as the xdm program included in X11R4 or later, you can use automatic session startup to make an XRemote session connection. Use the EXEC command xremote xdm to initiate XRemote using XDMCP.
xremote xdm hostnameThis command causes an XDMCP session start up request to be made to the computer specified (hostname). If a host name is not specified, a broadcast message is sent to all hosts. The first host to respond by starting up a session is used.
The terminal server and X terminal stay in XRemote mode until either the display manager terminates the session, or a reset request is received from the X terminal.
This command starts a session with a remote host named VMS-1.
TS>xremote xdm VMS-1
If your host computer supports DECwindows login sessions, you can use automatic session startup to make an XRemote session connection. Once the system administrator at the remote host has configured support for DECwindows over LAT, you can use the EXEC command xremote lat to initiate the connection. Enter this command at the EXEC prompt:
xremote lat serviceThe argument service is the name of the desired LAT service.
Once you issue this command, perform the following action:
If you are not using a host computer that supports XDMCP or LAT, you must use manual session startup. Manual session startup involves several steps:
Step 1: Enabling XRemote manually on the terminal server port.
Step 2: Connecting to the host computer.
Step 3: Setting the location of the X display.
Step 4: Starting up client applications.
Step 5: Returning to the EXEC prompt.
Step 6: Enabling XRemote manually again on the terminal server port.
The EXEC command xremote prepares the terminal server for your use of XRemote. The system replies with a message informing you of your X display location:
Xremote enabled; your display is darkstar:2018
Start your clients and type Xremote again
In the above message, the terminal server informs you that your display is darkstar:2018. This information will be used in a following step.
Connect to the host computer using the telnet, lat, or rlogin commands, and log in normally.
Inform the host computer of the location of your X display, which was provided to you by the terminal server when you entered the xremote command above.
For most versions of the UNIX operating system, the X display location is set by using the setenv command to set the environment variable DISPLAY. Refer to your UNIX systems' online, X(1) manual page for more information.
host_prompt% setenv DISPLAY darkstar:2018
On VAX/VMS, use the SET DISPLAY command. Refer to the VMS DCL Dictionary for more information.
$ SET DISPLAY/CREATE/NODE=DARKSTAR/SERVER=2018/TRANSPORT=[transport]
At this point, you must start your client applications for your host operating system.
The terminal server accepts the X connection attempt from the client application, and places the client into a dormant state.
If it is possible to log off the host computer and keep your X clients running in the background, you can do so now. This conserves resources on the host and terminal server that would otherwise be inaccessible until you exited from XRemote state.
If not, you may simply escape back to the terminal server prompt using the escape character (Ctrl ^ X by default).
Enter the command xremote to access XRemote mode. If the X clients connected successfully, the session will be put into XRemote mode, and the clients will be allowed to complete their startup.
If no clients were found, you will see the following message:
No X clients waiting - check that your display is darkstar:2018
Check your hosts to determine if an error was made when starting the session. The most likely cause is an improperly specified display location. Another possible cause is the host computer does not recognize the name of the terminal server through which you are attempting to make a connection.
In manual operation, the terminal server and X terminal remains in XRemote mode until either all clients disconnect or a reset request is received from the X terminal.
If a session terminates during startup, it may be because you invoked transient X clients which set some parameters and disconnected (such as xset or xmodmap). There must always be one session connected or the connection will be reset.
In addition to support of PAD-based X.25 connection service for terminal servers with protocol capability, the server also supports use of X.25 as a transport mechanism for IP-based traffic. This capability covers the Telnet connect and rlogin connection commands, but also extends to XRemote and TN3270. In addition, a serial terminal server can provide SLIP on an asynchronous line, and route IP over X.25. LAT is not supported over X.25. Refer to the chapter "X.25 Configuration and Management" for complete details concerning configuration requirements for setting up X.25 encapsulation on terminal servers.
This capability is most useful on terminal servers with a serial network interface. From a user's point of view, connections are relatively transparent when making a remote connection over a PDN. In general, users simply make a connection request.
This example illustrates a connection attempt to an X.25 host named far_host using Telnet.
ts>telnet far_host
If properly configured, the terminal server takes this connection request, encapsulates the IP-based frame in an X.25 packet and sends it over the X.25 PDN to a specified location (based on the X.121 address).
At the remote location, a Cisco router takes the request, strips encapsulation from the X.25 packet, and puts the IP-based frame on the appropriate network. A virtual terminal connection is then made between the originating node and the target host.
The following user-level commands and facilities apply to all transmission protocols supported by Cisco terminal servers and protocol translators:
You can have several concurrent connections open and switch back and forth between them. The number of connections that can be opened is defined by the session-limit command, described in the chapter "System Configuration."
To switch between connections, first type the escape sequence, which by default is Ctrl ^ X (press the Ctrl and SHIFT and ^ keys simultaneously, let go, then press the X key), to return to the system command prompt.
To make a new connection, use the procedures described in the preceding sections. To get back to an existing connection, use the resume command. Use the where command to list your open connections.
The EXEC resume command returns to a previous connection. The general form is available with all connection protocols supported by the terminal server. The general command syntax is as follows:
resume [connection]The optional argument connection is the connection name or number; the default is the most recent connection.
You can omit the command word resume and simply type the connection number to resume a connection. You can also return to the most recent session by just pressing the Return key.
This command resumes connection 2.
TS>resume 2
You can omit the command name and simply type the connection number to resume that connection. This example resumes connection 3.
TS>3
To resume the most recent connection, simply press the Return key.
Use the EXEC command login to log into a system with a specific user name. This command can be used to change your login name. You may choose to change your login name because an outgoing access list may expect a particular user name. (Refer to the sections about Cisco's TACACS and other user authentication facilities in the chapter "System Configuration." IP access lists are described in the chapter "TCP/IP Configuration and Management.")
loginThe system returns prompts for user name and password. If both are entered correctly, your session becomes associated with the specified user name. If there is no match, your connection reverts to the user name with which the login command attempt was made, if applicable. If no login name and password were originally required, the connection reverts to a session that is not associated with any name.
In this sample session, a user named foouser wants to change the login name being used to sloan. After entering the login command, the new name is entered along with an incorrect password. The system rejects the attempt to change the user name. Next, foouser attempts to change the login name to klaus. This time the correct password is entered and the user is now allowed access to the EXEC at the user-level under the user name of klaus.
TS>login
Username:sloan
Password:
% Access denied
Still logged in as "foouser"
TS>login
Username:klaus
Password:
TS>
You can prevent access to your session while keeping your connection open by using the lock EXEC command. Enter this command at the EXEC prompt:
lockThis command locks your keyboard. You need to include the global configuration command lockable in your system configuration. This configuration command is described in the chapter "System Configuration." The lock EXEC command remains in effect until the clear line privileged EXEC command, described in the chapter "System Management" is executed.
When you lock a session, you are prompted for a password, which can be any arbitrary string. Enter the password you want to assign. The screen clears and displays the message "Locked." To regain access to your sessions, re-enter the password. The terminal server honors session timeouts on a locked line.
The EXEC command where displays information about all open LAT, Telnet, or rlogin connections associated with the current terminal line. Enter this command at the EXEC prompt:
whereFollowing is a sample output from this command:
ts>where
Conn Host Address Byte Idle Conn Name
1 MIS1 131.108.19.50 0 0 MIS1
* 2 OTTER 192.31.7.24 0 0 OTTER
The information displayed includes the host name, address, number of characters waiting to be sent to the terminal, idle time, and connection name. An asterisk (*) indicates the current connection.
The name-connection command assigns a logical name to a connection. The EXEC prompts for the connection number and name to assign when you enter this command. The where command displays a list of the assigned logical connection names.
The following checks the connection number for the host Eng1, assigns the logical name my host to it, and then confirms the assignment.
ts>where
Conn Host Address Byte Idle Conn Name
* 1 Eng1 192.31.6.22 0 0 Eng1
2 Term2 192.33.6.21 0 0 Term2
ts>name-connection
Connection number:1
Enter logical name: my host
Connection 1 to Eng1 will be named "my host" [confirm]
ts>where
Conn Host Address Byte Idle Conn Name
* 1 Eng1 192.31.6.22 0 0 my host
2 Term2 192.33.6.21 0 0 Term2
To send messages to one or all terminal lines, use the privileged send EXEC command. Enter this command at the EXEC prompt:
send {line-number|*}A common way of using this command is to inform users of an impending shutdown.To send a message to a particular line, use the argument line-number to specify the line. To send a message to all lines, use an asterisk (*). The system prompts for the message, which may be several text lines long. End the message by typing the Ctrl-Z key sequence. Type Ctrl-C to abort the command.
This sample session illustrates how to send a message to all terminal users.
TS> send all
Enter message, end with CTRL/Z; abort with CTRL/C:
System shutdown in 10 minutes.
<Ctrl-Z>
Send message? [confirm] yes
***
***
*** Message from tty56, cube CE10, to all terminals:
***
System shutdown in 10 minutes.
To display information about your active terminal sessions, enter the show sessions EXEC command at the system prompt:
show sessionsThe following illustrates how to obtain information about active sessions.
ts>show sessions
Conn Host Address Byte Idle Conn Name
* 1 GUN 131.222.3.11 0 0 GUN
2 BIG 131.222.3.14 0 5 BIG
The information displayed includes the host name, address, number of characters waiting to be sent to the terminal, idle time, and connection name. An asterisk (*) indicates your current terminal session.
The EXEC command show terminal displays the configuration parameter settings for the current terminal line. Enter this command at the EXEC prompt:
show terminalFollowing is a sample display of the command's output:
ts>show terminal
Line 3, Location: "Library x1234", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
The escape character is "^^", followed by "x"
The local hold character is disabled
No flowcontrol in effect.
Status: Ready, Active
Capabilities: none
Idle EXEC timeout is 10 minutes.
Idle session timeout is not set.
Modem answer timeout is 15 seconds
Dispatch timeout is not set.
Allowed transports are telnet rlogin. Preferred is telnet
Disconnect character is not set
Activation character is ^M (13)
No output characters are padded
Characters causing immediate data dispatching:
Char ASCII
The display includes a comprehensive report on the terminal settings in effect, including the preferred transport protocol.
The EXEC commands show users and systat display information about the active ports of the terminal server. The commands are synonymous and have this syntax:
show users [all]The information displayed includes the line number, connection name, idle time, and terminal location. The optional keyword all requests information for both active and inactive ports.
Following is a sample display of the command's output:
ts>systat all
Line User Host(s) Idle Location
0 con 0 otter console
1 tty 1 Bill x1234
2 tty 2 DAVE-SS2 1:32 Dave x1235
* 3 tty 3 STUFT 0 Denise x1236
4 tty 4 incoming 11:17 remote.host.com
5 tty 5 Sam- ROM emulator
6 tty 6 CD4 ???
7 tty 7 Teresa x1236
10 tty 10 STUFT 3 Mark x1237
11 tty 11 HEAT 1 Eng32-1
12 tty 12 STFUT 17:32 CD8 ???
13 tty 13 1525: Sandy x1238
14 tty 14 MEDDLE 23 Marsha x1239
15 tty 15 Randy x1240
16 tty 16 Kevin x2120
17 tty 17 Robert x2141
20 tty 20 Bill x2142
21 tty 21 Laser printer
22 tty 22 ""
The information displayed includes the line number, connection name, idle time, and terminal location. The optional keyword all requests information about both active and inactive ports.
The exit or quit commands terminate the EXEC and close any active terminal sessions. The commands are synonymous; enter either command when you are finished with your session.
The EXEC command disconnect closes a connection, and has this syntax:
disconnect [connection]The optional argument connection is a connection name or number; the default is the current connection. To list your open connection, use the where command.
This sample illustrates how to disconnect a specific session.
ts>where
Conn Host Address Byte Idle Conn Name
* 1 Eng1 192.31.6.22 0 0 my host
2 Term2 192.33.6.21 0 0 Term2
ts>disconnect my host
Closing connection to Eng1 [confirm]
This section describes how to locally change the terminal parameters using the EXEC terminal commands. The new settings temporarily override those made with the line subcommands, remaining in effect only until the user exits the system.
Most terminal commands can be executed at the user-level prompt (>). To obtain information about the current terminal configuration parameter settings, enter the show terminal EXEC command. Settings can be changed or removed by using the keyword no; the command descriptions indicate the command syntax.
To display a list of supported terminal commands, enter the terminal ? EXEC command.
Some terminal commands use the decimal representation of an ASCII character as an argument. Refer to the appendix "ASCII Character Set" for an ASCII chart.
To record or remove the current terminal type, enter the terminal terminal-type EXEC command.
terminal terminal-type terminal-nameThe argument terminal-name records the type of current terminal. The information can be passed as information to a remote host. For example, the terminal-name is used by TN3270 for display management, and by Telnet and rlogin to inform the remote host of the terminal type.
Use the terminal no terminal-type command to remove the terminal type.
This example sets the terminal type to VT-220.
TS>terminal terminal-type vt-220
To set the number of lines on the current terminal screen, enter the terminal length EXEC command.
terminal length screen-lengthThe argument screen-length is the desired number of lines. The terminal server uses this value to determine when to pause during multiple-screen output. The default length is 24 lines. A value of zero disables pausing between screens of output.
The screen length specified can be learned by remote hosts. For example, the rlogin protocol uses the argument columns to set up terminal parameters on a remote UNIX host.
This example disables pausing between screen output.
TS>terminal length 0
To set the number of columns on the terminal screen, enter the terminal width EXEC command.
terminal width columnsThe argument columns is the desired number of columns. The default is 80 columns.
The column width specified can be learned by remote hosts. For example, the rlogin protocol uses the argument columns to set up terminal parameters on a remote UNIX host.
This example sets the terminal character columns to 132.
TS>terminal width 132
To set the escape character for the current terminal line, enter the terminal escape-character EXEC command.
terminal escape-character decimal-numberThe argument decimal-number is the ASCII decimal representation of the desired escape character or a control sequence (Ctrl-P, for example). Typing the escape character followed by the X key returns you to the EXEC when you are connected to another computer. The default escape characters are Ctrl ^.
The terminal no escape-character command makes the Break key function as the escape sequence; Break need not be followed by typing the X key. However, you cannot set the console escape character to Break, because the operating system software interprets Break as an instruction to halt the system.
Refer to Table 1-1 for a complete list of escape character sequences supported by the terminal server.
This example sets the escape character to Ctrl-P (ASCII decimal 17).
TS>terminal escape-character 17
To set, change, or remove the hold character, enter the terminal hold-character EXEC command.
terminal hold-character decimal-numberThe argument decimal-number is either the ASCII decimal representation of the desired hold character or else a control sequence (for example, Ctrl-C).
Typing the hold character temporarily halts the output at the terminal. To continue the output, type any other character. To send the hold character to the host, precede it with the escape character. By default, no local hold character is set.
The terminal no hold-character command clears the hold character.
This example removes the previously set hold character.
TS>terminal no hold-character
To change the terminal parity, enter the terminal parity EXEC command.
terminal parity {none|even|odd|space|mark}The terminal parity command defines the generation of the parity bit for the current terminal line. The default setting is none.
To set the transmit and receive speeds of the current terminal line, enter the terminal speed EXEC command.
terminal speed baudThe argument baud can be: 300, 1200, 2400, 4800, 9600, 19200, or 38400. It can also be set to any user-defined speed in a range from 75 to 57600. The default speed is 9600 baud.
This example sets the baud rate to 19,200.
TS>terminal speed 19200
To set the number of data bits per character for the current terminal line, enter the terminal databits EXEC command.
terminal databits {5|6|7|8}If parity is being specified, specify 7 data bits per character. If no parity generation is in effect, specify 8 data bits per character. The default is 8 data bits per character.
To set the number of stop bits transmitted per byte by the current terminal line, enter the terminal stopbits EXEC command.
terminal stopbits {1|1.5|2}The default is 2 stop bits.
To set up the method of data flow control for the current terminal line, enter the terminal flowcontrol EXEC command.
terminal flowcontrol {none|software [in|out]|hardware}The keyword software sets software flow control. An additional keyword specifies the direction: in causes the terminal server to listen to flow control from the attached device, and out causes the terminal server to send flow control information to the attached device. If you do not specify a direction, both directions are assumed.
The keyword hardware sets hardware flow control. For information about setting up the RS-232 line, see the hardware manual for your Cisco product.
By default, no flow control method is set for a line. This default is returned with the none keyword.
This example sets incoming software flow control.
TS>terminal flowcontrol software in
To change the character that signals the start of data transmission when software flow control is in effect, enter the terminal start-character EXEC command.
terminal start-character decimal-numberThe argument decimal-number is the ASCII decimal representation of the desired start character. The default start character is Ctrl-Q (ASCII character 17).
Use the terminal no start-character command to remove the start character.
This example removes the start character.
TS>terminal no start-character
To change the character that signals the end of data transmission when software flow control is in effect, enter the terminal stop-character EXEC command.
terminal stop-character decimal-numberThe argument decimal-number is the ASCII decimal representation of the desired stop character. The default stop character is Ctrl-S (ASCII character 19).
Use the terminal no stop-character command to remove the stop character.
This example changes the stop character to Ctrl-O (ASCII decimal character 15).
TS>terminal stop-character 15
To set padding on characters, enter the terminal padding EXEC command.
terminal padding decimal-number countThe command sets padding for a specified output character. The argument decimal-number is the ASCII decimal representation of the character, and can be any of the 127 ASCII characters. The argument count is the number of NULL bytes sent after that character, up to 255 padding characters in length.
The terminal no padding command ends this padding after the character represented by decimal-number.
This example pads Ctrl-D (ASCII 4) with 164 NULL bytes.
TS>terminal padding 4 164
The terminal telnet-transparent command causes the current terminal line to send a Return (CR) as a CR followed by a NULL instead of a CR followed by a Line Feed (LF). This scheme permits interoperability with different interpretations of end-of-line handling in the Telnet protocol specification. To set or remove this scheme, enter one of these commands at the EXEC prompt:
terminal telnet-transparentTo define or remove a character or string that causes a packet to be sent, enter the terminal dispatch-character EXEC command.
terminal dispatch-character decimal-number1 [decimal-number2... decimal-numberx]This command causes the terminal server to attempt to buffer characters into larger-sized packets for transmission to the remote host. The terminal server normally dispatches each character as it is typed.
The argument decimal-number is the ASCII decimal representation of the character or string; any number of characters can be entered.
This examples defines the string "Escape C I" as the dispatch character.
TS>terminal dispatch-character 27 67 73
To establish or remove input notification, enter the terminal notify EXEC command.
terminal notifyWhen you have multiple concurrent connections, you may want to know when output is pending on a connection other than the current connection. For example, you may want to know when another connection receives mail or a message. The terminal notify command causes the terminal server to notify you of pending output. The terminal no notify command ends such notifications.
To temporarily set or remove the ability of a line to act as a transparent pipe for file transfers, enter the terminal download EXEC command.
terminal downloadUse the terminal download command when running a program such as KERMIT, XMODEM, or CrossTalk that downloads a file across a terminal server line.
This command sets up the terminal line to transmit data, and is equivalent to entering all the following commands:
terminal telnet-transparent
terminal no escape-character
terminal no hold-character
terminal no pad 0
.
.
.
terminal no pad 128
terminal parity none
terminal databits 8
The terminal no download command restores the line's original parameter settings.
To select a preferred remote terminal protocol, enter the terminal transport EXEC command.
terminal transport preferred {telnet|pad|lat|rlogin|none}This EXEC command sets the preferred protocol for the duration of the current session. For details on the parameters of this command, refer to "Defining the Transport Protocol for a Specific Line" in the chapter "System Configuration."
The following session makes a connection using Telnet, after rlogin is refused as a preferred protocol by the remote host Eng2:
ts>terminal transport preferred rlogin
ts>Eng2
Trying Eng2.Cisco.com (121.108.145.12)...
ts>Eng2
Trying Eng2.Cisco.com (121.108.145.12)...Open
login:
The following session sets the preferred transport to none and then attempts to make a connection without specifying a protocol. A Telnet connection is made successfully once telnet is specified.
ts>terminal transport preferred none
ts>Eng2
% unknown command "Eng2"
ts>telnet Eng2
Trying Eng2.Cisco.com (121.108.145.12)...Open
login:
To set or remove the ability to copy debug command output and system error messages to the current terminal, enter the terminal monitor EXEC command.
terminal monitorTo use this command, you must first issue the enable command and enter the password to access the privileged command mode.
All Cisco internetworking products include a server that implements a subset of DEC's Maintenance Operation Protocol (MOP) for Ethernet interfaces. The MOP server supports the request ID message, periodic system ID messages, and the remote console carrier functions.
Once enabled, the MOP server periodically multicasts a system ID message, which is used by DEC's Ethernet configurator to determine what stations are present in an Ethernet network. The configurator is controlled by the Network Control Program (NCP) command define module configurator. For more information on this command, consult DECnet or VAX documentation.
The Cisco internetworking products use a MOP communication device code of 121. This code has been assigned to Cisco by DEC, although some versions of DECnet-VAX software may report the code numerically, rather than with a device name. The DEC Ethernet product also makes use of system ID messages received when building network maps.
The MOP server supports the DEC remote console function. Using this capacity, a system manager on a DECnet system can create a virtual terminal connection to a Cisco terminal server. Only a single inbound connection per Ethernet interface is supported. The MOP protocol does not contain the necessary mechanisms for supporting more than one connection at a time.
MOP is not a routable protocol. To bridge the MOP console carrier and system ID functions, you must enable bridging for protocol type 6002. The periodic system ID messages are sent to the multicast address AB00.0002.0000.
The EXEC command debug mop reports events occurring within the MOP server, including reception of request ID messages, transmission of system ID messages, and reservation and release of the remote console. The next sections describe how to enable the DEC MOP server, and how to enable or disable MOP system identification messages.
To control whether MOP is enabled for an interface, use the mop enabled interface subcommand. The command syntax is:
mop enabledThe default is enabled. Use the no mop enabled command to disable the MOP if you do not want to run it.
To control whether MOP periodic system ID messages are sent out to an interface, use the mop sysid interface subcommand. The command syntax is:
mop sysidYou can still run MOP without having the background system identification (ID) messages sent out. This lets you use the MOP remote console, but does not generate messages used by the configurator.
Use the no mop sysid command to disable MOP from sending the system ID messages.
A PAD is a packet assembler/disassembler, which is a device that collects data from a group of terminals and periodically outputs the data in packets (data organized in a special format). A PAD also does the reverse. It can take data packets from a host and return them into a character stream that can be transmitted to the terminals. A PAD is defined by CCITT Recommendations X.3, X.28, and X.29.
For a discussion and sample scenarios of one-step and two-step connections using PAD and Telnet, refer to the section "Protocol Translation Methods" in this chapter.
CCITT Recommendation X.3 specifies the parameters for terminal-handling functions such as baud rate, flow control, character echoing, and so on, for a connection to an X.25 host. The X.3 parameters are similar in function to the Telnet options.
CCITT Recommendation X.29 specifies a protocol for setting the X.3 parameters via a network connection. When a connection is established, the destination host can request that the PAD or terminal change its parameters using the X.29 protocol. A PAD can refuse to do this, in which case a terminal user can change the parameter later. A PAD cannot tell the destination host to change its X.3 parameters, but it can communicate that its own parameters were changed.
Along with Recommendations X.3 and X.29, the CCITT also provides Recommendation X.28 to specify the user interface for locally controlling a PAD; however, the terminal server is not a PAD and this recommendation is not supported.
You use the pad EXEC command to initiate outgoing connections to a PAD host. Enter this command at the EXEC prompt:
pad x121-address [/cud text] [/debug] [/reverse]The argument X121-address is the X.121 address of the X.25 host. If the host-to-address mapping has been set with the x25 host command, you can use the host name instead of the address. (The pad command supports one-word connections; in other words, you are not required to enter the pad command, just the address is enough to start connection.)
The optional keyword and argument /cud text is a switch that includes text in the Call User Data field of the outgoing Call Request Packet.
The optional keyword /debug is a switch that causes the informational level of logging messages to be printed whenever the remote host changes an X.3 parameter setting or sends any other X.29 control packet.
The optional keyword /reverse is a switch that causes Reverse Charge calls to be accepted on a per-call, rather than a per-interface, basis.
To connect to PAD host address 77630, enter this command:
TS#pad 77630
The X.3 parameters are normally set by the host system; however, there are occasions when the PAD is connected as a front end for some other computer or device that is not configured to set these parameters. To accommodate such systems, an X.29 READ PARAMETER message is sent immediately after opening the connection.
If the connection is made to a PAD, a PARAMETER INDICATION message is returned, and the X.3 parameters are set to match those required by the PAD. If the connection is made to a host, the READ request is ignored and an X.29 SET PARAMETER message is sent. If a host sends both a PARAMETER INDICATION and X.29 SET PARAMETER message, the X.29 SET PARAMETER message takes precedence.
You use the standard escape sequence to return to the EXEC. Multiple outgoing PAD connections are supported.
You use the resume command to resume a connection. The resume command also has a feature for setting X.3 PAD parameters, as explained in the subsection "Setting X.3 PAD Parameters" in this chapter.
You can have any number of PAD connections at a time and you can switch back and forth among them. To switch from one connection to another, first type the escape sequence (Ctrl ^ X by default) to return to the EXEC. Then use the pad command to make the new connection.
Use the EXEC where command to check the logical name or number of a connection. Use the EXEC resume command to return to a previous connection.
Once you have the connection number from the where command, use the resume command and the connection number to resume the connection. The command syntax is:
resume [connection] [/keyword] [/set parameter:value]This command also has a feature for setting X.3 PAD parameters, as explained in "Setting X.3 PAD Parameters." Local X.3 parameters can be changed during a connection by escaping back to the EXEC and issuing the resume command with the appropriate parameter set.
The optional argument connection is a connection name or number; the default is the most recently used connection.
The optional /keyword specifies line options for the connection, and can be one of the following:
The /set switch is described in the next section.
You can change local X.3 parameters during a connection by using either the /set switch of the resume command or the x3 EXEC command.
To reset the outgoing connection default for local echo mode, enter this command:
TS#resume 3 /set 2:1
The /set switch sets the X.3 parameters defined by parameter number and value, separated by a colon. These parameters and their values are described in the "The X.3 PAD Parameters" section. For outgoing connections, the X.3 parameters default to the following:
2:1, 3:2, 4:1, 7:4, 16:127, 17:21, 18:19
All other parameters default to zero, but can be changed using the /set switch.
For incoming PAD connections, software sends an X.29 SET PARAMETER packet to set only the following parameters:
2:0, 4:1, 7:21, 15:0
If you remain at the EXEC prompt, use the x3 command to set local PAD parameters.
Parameters are set directly, without using a command switch.
This example resets the outgoing connection default for local echo mode.
TS#x3 2:1
Following are descriptions of the X.3 parameters. Default values are noted in the descriptions. The default value for any parameter not so noted is zero for outgoing connections or not set for incoming PAD connections. For incoming PAD connections, the terminal server sends an X.29 SET PARAMETER packet to set the noted defaults.
Since the X.3 parameters describe the user's terminal, which exists on only one side of the connection, the PAD protocols are not always symmetric.
Some of these commands require ASCII decimal values which are listed in the appendix "ASCII Character Set."
Parameter 1 determines whether or not the terminal server will be allowed to escape from data transfer mode in order to send PAD command signals. Since the Cisco EXEC uses a two-character escape sequence, and there is no way to set the escape character on a Telnet connection, this parameter is refused on translation sessions as well.
Parameter 2 determines whether or not PAD is required to perform local echo of characters. This parameter can be negotiated end-to-end on translation sessions. On incoming PAD connections, software turns local echo off on the remote PAD to support the Cisco user interface.
| Value | Description |
|---|---|
| 0 | No local echo (incoming PAD connection default). |
| 1 | Local echo on (outgoing connection default). |
Parameter 3 sets up a packet forwarding mask, that is, it selects which character causes PAD to forward a packet either before expiration of the Idle Timer (see Parameter 4) or when in local editing mode.
| Value | Description |
|---|---|
| 0 | None - full packet. |
| 1 | Forward packet upon receipt of an alphanumeric character. |
| 2 | Forward packet upon receipt of a RETURN (outgoing connection default). |
| 4 | Forward packet upon receipt of ESCAPE, BEL, ENQ, or ACK. |
| 8 | Forward packet upon receipt of DEL, CAN, OR DC2. |
| 16 | Forward packet upon receipt of ETX or EOT. |
| 32 | Forward packet upon receipt of HT, LT, VT, or FF. |
| 64 | All other characters in the ASCII chart. |
As X.3 supports a wider variety of dispatch characters than Telnet does, parameter changes to or from the default causes a translation session to negotiate in or out of line mode on the Telnet connection.
A forwarding mask can be statically set using the Cisco terminal dispatch-character terminal parameter-setting EXEC command. This command can set any character or characters as the forwarding mask, and overrides (when logical) any values set by parameter 3.
Parameter 4 controls the amount of time the software waits for new data before sending a packet in the absence of a data forwarding character.
| Value | Description |
|---|---|
| 0 | No timer. |
| 1-255 | Delay value in twentieths of a second (default for both connection types is 1). |
Parameter 5 selects whether PAD can transmit flow control (ASCII XON/XOFF) characters during data transfer to the terminal to control the terminal and data flow. Flow control is not directly supported on terminal servers because data must make network hops to travel to its final destination. However, depending on the type of incoming connection, setting this parameter can cause similar negotiations to be sent over the connection, thereby attempting to change the state of the flow control option at the device closest to the user.
Parameter 6 selects whether or not PAD is required to transmit service signals. As the terminal server does not use Recommendation X.28 for its user interface, this parameter is ignored.
Parameter 7 defines the action of the PAD after receiving a BREAK signal from the terminal.
| Value | Description |
|---|---|
| 0 | Ignore the BREAK signal. |
| 1 | Transmit an interrupt packet to notify the remote host or another PAD that the BREAK signal has been generated. |
| 2 | Transmit a Reset packet to reset the virtual circuit. |
| 4 | Transmit an X.29 Break indication to the remote host, or to a PAD (out-going connection default). |
| 8 | Escape from data transfer mode. |
| 16 | Discard output to the terminal by setting parameter 8 to a value of 1. |
| 21 | Combination of values 1, 4 and 16 (incoming connection default). |
The PAD protocols allow you to send a special Indication of Break X.29 packet, send an Interrupt packet, perform a Reset operation, act as if the Recall character had been typed, or begin discarding output to the user. Combinations of these options are also allowed, as long as they make sense. Common options are to begin discarding output and send both an X.25 Interrupt packet and an X.29 Indication of Break packet, and these options are supported. All other options are not supported and are silently ignored.
Parameter 8 indicates to the PAD whether to discard received packets rather than disassemble and transmit them. This parameter works in conjunction with parameter 7. If value 16 is chosen for parameter 7, all output is discarded after reception of the BREAK signal. Setting parameter 8 to zero restores normal data delivery to the terminal.
| Value | Description |
|---|---|
| 0 | Normal data delivery to the terminal (outgoing connection default). |
| 1 | Discard all output to the terminal. Set by parameter 7; see previous description. |
This parameter can also be set and unset manually using the PAD resume EXEC command.
Parameter 9 determines whether or not PAD should provide padding (insert filler characters) upon receipt of a Return character from the terminal.
Line folding means inserting a LINE FEED at a certain point which places subsequent characters on the next line. Parameter 10 determines selection of this function and specification of the line length.
Parameter 11 is a read-only value that determines the baud rate transmitted across the interface between PAD and the terminal.
| Value | Description (in bits per second) |
|---|---|
| 10 | 50 |
| 5 | 75 |
| 9 | 100 |
| 0 | 110 |
| 1 | 134.5 |
| 6 | 150 |
| 8 | 200 |
| 2 | 300 |
| 4 | 600 |
| 3 | 1200 |
| 7 | 1800 |
| 11 | 75/1200 |
| 12 | 2400 |
| 13 | 4800 |
| 14 | 9600 |
| 15 | 19200 |
| 16 | 48000 |
| 17 | 56000 |
| 18 | 64000 |
Parameter 12 determines whether or not the terminal can transmit ASCII XON/XOFF (transmission on and off) characters to PAD during the data transfer mode. Flow control is not directly supported on terminal servers because data must make network hops to travel to its final destination. However, depending on the type of incoming connection, setting this parameter can cause similar negotiations to be sent over the connection, thereby attempting to change the state of the flow control option at the device closest to the user.
Parameter 13 determines the procedure for inserting the LINE FEED character upon receipt of a RETURN character. The PAD also responds to a value that results from the addition of any of the values in Table 1-8.
| Value | Description |
|---|---|
| 0 | Do not insert the LINE FEED character (outgoing connection default). |
| 1 | Insert a LINE FEED after transmitting RETURN to the terminal. |
| 2 | Insert a LINE FEED after echoing RETURN to the terminal. |
| 4 | Insert a LINE FEED after echoing RETURN to the remote host. |
Parameter 14 determines whether or not PAD should provide padding (insert filler characters) upon receipt of a LINE FEED character from the terminal. This function is generally provided by the end user's operating system.
Parameter 15 enables or disables a PAD editing function for the terminal in data transfer mode. Enabling the editing function disables the Idle Timer (see parameter 4). The user at the terminal can make corrections and display the line buffer containing the characters to be transmitted when the forwarding character (see parameter 3) is received.
| Value | Description |
|---|---|
| 0 | Disables editing capabilities in data transfer mode. Any characters entered become part of the data stream and are transmitted (default for both connection types). |
| 1 | Enables editing capabilities in the data transfer mode which suspends the following PAD operations:
1) Full packet data forwarding until the edit buffer is full, and 2) Forwarding of DATA packets upon expiration of the Idle Timer. |
Parameters 16, 17, and 18 provide the editing functions.
Parameter 16 allows you to select a character that will delete characters while in PAD editing mode. This character is valid only if parameter 15 is set to one.
| Value | Description |
|---|---|
| 0-127 | Select one character from the ASCII character set to represent the delete character. Default is character 18 (CTRL-R). |
Parameter 17 allows you to select a character that will delete a line while in PAD editing mode. This character is valid only if Parameter 15 is set to one.
| Value | Description |
|---|---|
| 0-127 | Select one character from the ASCII character set to represent the delete character. Default is character 21 (CTRL-U). |
Parameter 18 allows you to select a character that will display a line while in PAD editing mode. This character is valid only if Parameter 15 is set to one.
| Value | Description |
|---|---|
| 0-127 | Select one character from the ASCII character set to represent the delete character. Default is character 18 (CTRL-R). |
Protocol translation allows two systems running different networking protocols to communicate as if the protocols were the same. This can be a difficult task, as networking protocols may require different numbers of network connections to run an application, or may have different formats for their data and commands.
For this reason, there may never be a protocol translator that handles electronic mail or file transfer in a completely transparent manner. Fortunately, there are fewer differences among protocols that connect remote terminals to a computer (called virtual terminal protocols).
The terminal server attempts to provide transparent protocol translation between systems running disparate protocols. Cisco protocol translation fully supports two-way virtual terminal protocol translation between nodes running X.25, DEC LAT, and TCP/Telnet. Limited translation (two-step only) is supported for XRemote (to X.25 PAD environments) and TN3270 (to LAT, X.25, and TCP/Telnet). This allows terminal users on one network to access hosts (or host-like devices) on another network, despite differences in the native protocol stacks associated with the originating device and the target host. You can use either of two methods to accomplish this, as discussed in the following sections.
The one-step method invokes a translation session process to provide fully transparent protocol conversion. In this method, the terminal server masquerades as two or more hosts on the same network. When a connection is made to the terminal server, it determines which host the connection is for, and what protocol that host is using. It then establishes a new network connection, using the networking protocol required by that host.
This connection is more efficient, and allows the terminal server to act upon greater knowledge of the protocols in use, as the terminal server acts as a network connection rather than a terminal. One disadvantage, however, is that the initiating computer or user does not know that two networking protocols are being used. This creates the limitation that parameters of the foreign network protocols cannot be changed, once the connections are established. The exception to this limitation is the set of parameters common to both networking protocols. Any parameter in this set can be changed from the first host to the final destination.
To support connections in each direction, you must specifically include translate command statements in the configuration file to handle bidirectional connections.
A typical one-step translation application might feature a UNIX workstation user attempting a connection to a remote X.25 host, named host1, over an X.25 PDN. In this case, the terminal server automatically converts the Telnet connection request to an X.25 connection request and transmits the request as specified in the system configuration.
A connection is established by first entering the telnet command at the UNIX workstation system prompt, as follows:
unix%telnet host1
The terminal server accepts the Telnet connection, and immediately forms an outgoing connection with the remotely located host1 as defined in a translate command in your terminal server's active configuration file. Next, host1 sets several X.3 parameters, including local echo. Since the Telnet connection is already set to local echo (at the UNIX host), no changes are made on the TCP connection.
The host1 connection prompts for a user name, which is provided (and echoed locally), as follows:
login name:
Then host1 sets the X.3 parameter to cause remote echo (the same process as setting X.3 PAD parameter 2:0), and prompts for a password. The terminal server converts this to a Telnet option request on the UNIX host, which then stops the local echo mode.
At this point the user is connected to the PAD application and the application will set the X.3 PAD parameters (although they can always be overridden by the user). When the user is finished with the connection, he enters the escape character to exit back to the host connection, then enters the appropriate command to close the connection.
The host1 host immediately closes the X.25 connection. The terminal server then drops the TCP connection, leaving the user back at the UNIX system prompt.
In the two-step method, you explicitly establish a network connection to a protocol translator, and from there establish an outgoing network connection on a different type of network. The two steps are:
Step 1: Establish the incoming connection directly to the protocol translator.
Step 2: Establish the outgoing connection from the protocol translator to another network host.
This process is similar to connecting a group of terminal lines from a PAD, to a group of terminal lines from a TCP terminal server. The difference is that you do not encounter the wiring complexity, unreliability, management problems, and performance bottlenecks that occur when two separate devices are connected via asynchronous serial lines. With the two-step connection process, you can individually modify the parameters of either network connection, even while a session is in process.
The terminal server supports the two-step model in both directions (for example, from Telnet to PAD, and the reverse).
If you use the two-step method to connect, you can change PAD and local terminal parameters dynamically during a session.
The following sample session shows how to make a dynamic change during a session. In this example, you want to type in some information at a remote host called the Information Place. Suppose that you need to change the X.3 PAD parameters that define the editing characters from the default Delete key setting to the Ctrl-D sequence.
To do this, first enter the escape sequence to return to the system EXEC:
Ctrl ^ x
Then at the EXEC prompt, type in the resume command with the /set keyword and the desired X.3 parameters.
ts>resume /set 16:4
You also want to set the /debug switch to check that your parameter setting has not been changed by the host PAD. The /debug switch provides helpful information about the connection.
At the EXEC, you can also set a packet dispatch character or sequence using the terminal dispatch-character command. The dispatch-character line subcommand is discussed in the chapter "System Configuration." This example shows how to set ESC (ASCII character 27) as a dispatch character using the EXEC command version of dispatch-character:
ts>terminal dispatch-character 27
To return to the PAD connection, simply enter:
ts>resume
Now you can use your new settings for your session.
The first step in any two-step translation is to connect directly from a terminal or workstation to a protocol translator. For example, you might make the following connection request:
unix_host%telnet pt
If a protocol translator named ts can be reached, it returns a login message and you enter your login name and password.
The next step then is to connect from the protocol translator to the target system. For example, you connect to an X.25 host using the pad command by entering the following:
ts>pad 71330
Once the connection is established, the protocol translator immediately sets the PAD to single character mode with local echoing, since this is the behavior the protocol translator expects. The PAD responds with its login messages and a prompt for a password:
Trying 71330...Open
Welcome to the Information Place
Password:
As the password should not echo on your terminal, the PAD requests remote echoing so that characters will be exchanged between the PAD and the protocol translator, but not echoed locally or displayed. After the password is verified, the PAD again requests local echoing from the protocol translator, which it does from then on.
To complete this sample session, you log off, which returns you to the terminal server system EXEC prompt. From there, you execute the quit command and the protocol translator drops the network connection to the PAD.
This section provides a list of the interface subcommands described in this chapter, in alphabetic order.
Controls whether MOP is enabled for an interface or disabled.
The default is enabled.
Use the no mop enabled to disable the MOP if you do not want to run it at all.
Controls whether MOP periodic system ID messages are sent out to an interface.
Use the no mop sysid to disable the MOP from sending the sysid messages.
Following is an alphabetically arranged summary of the terminal server user EXEC commands.
[connect|telnet] host [port] [/keyword]
Enter either connect or telnet with a host name to make a TCP Telnet connection, or just enter a host name or Internet address. The argument host is a host name or Internet address. The argument port is an optional TCP port number; default is Telnet server port 23. The optional /keyword is one of following:
Use only when the exit or quit commands do not terminate a connection.
Terminates the EXEC and closes any active terminal session.
lat name [node nodename|port portname|/debug]
Connects to a learned service on a host running DEC LAT. Argument name specifies a LAT learned service. The keyword and argument node nodename specifies a connection to a LAT node. The keyword and argument port portname specifies a destination LAT port name. The keyword /debug enables LAT message mode.
Locks access to the terminal by requesting a temporary password that must be re-entered to access the terminal.
Allows you to change your login name by prompting for a new user name and password.
Displays prompts to rename a connection number. The name is displayed by the where command.
pad {X.121-address|hostname} [/cud text] [/debug] [/reverse]
Begins connection to an X.3 PAD host. The argument X.121-address is the X.121 address; use hostname to specify a defined X.25 host name. argument /cud text is a switch that includes text in the Call User Data field of the outgoing Call Request Packet. Keyword /debug is a switch that causes the informational level of logging messages to be printed whenever the remote host changes an X.3 parameter setting or sends any other X.29 control packet. Keyword /reverse is a switch that causes Reverse Charge calls to be accepted on a per-call, rather than a per-interface, basis.
Resumes the previous connection unless the optional connection argument is entered to resume a specific connection number or name. Pressing the Return key also resumes the previous connection. Use the where command to display open connections.
resume [connection] [/keyword]
Resumes previous Telnet connections.The argument connection is the connection name or number; the default is the most recent connection.
The argument /keyword is one of the following:
resume [connection] [/keyword] [/set parameter:value]
Resumes PAD connections and allows changing local X.3 parameters during a connection.The argument connection is the connection number. The argument /keyword is one of:
The X.3 parameters default to the following for outgoing connections: 2:1, 3:2, 4:1, 7:4, 16:127, 17:21, 18:19.
For incoming PAD connections, software sends an X.29 SET PARAMETER packet to set only the following parameters: 2:0, 4:1, 7:21, 15:0.
Connects to a UNIX host using the rlogin protocol.The argument host is a host name or Internet address. The keyword debug enables rlogin message mode.
Sends message to other terminals. The optional argument line-number specifies a particular line. To send a message to all lines, use an asterisk (*). The system prompts for the message, which may be several text lines long. End the message by typing the Ctrl-Z key sequence. Type Ctrl-C to abort the command.
Lists all open connections, including connection number, host address, and name. Same as entering the where command.
Displays local terminal parameter settings.
Either command displays list of users currently logged in, along with host name, line number, and location.
slip default
Begins a SLIP connection when a default SLIP address has been configured.
slip
Begins a SLIP connection.
Begins a terminal emulation session with a remote IBM host using the TN3270 application. The argument hostname is the name of the IBM host.
Lists all open connections. The list includes connection number, host address, and name.
Startup command for host supporting DECwindows login session. The argument service is the DEC LAT service name.
Startup command for host supporting XDMCP. The argument hostname is the name of host computer.
Following is a summary, arranged alphabetically, of the terminal parameter setting commands that locally effect the terminal settings.
Specifies data bits per character. Default is 8 bits per character.
terminal [no] dispatch-character decimal-number1 [decimal-number2... decimal-numberx]
Defines or removes a character or string that causes a packet to be sent. The argument decimal-number is the ASCII decimal representation of the character or string of characters.
Sets or removes the ability of a line to act as a transparent pipe that can transmit data when running a program such as KERMIT, XMODEM, or CrossTalk that downloads a file across a terminal server line.
terminal [no] escape-character decimal-number
Sets the escape character for the current terminal line. The argument decimal-number is the ASCII decimal representation of the desired escape character or an escape sequence (Ctrl-P, for example). Default is Ctrl-X
terminal flowcontrol {none|software [in|out]|hardware}
Sets the method of data flow control for the current terminal line. The keyword software sets software flow control; keyword in causes the terminal server to listen to flow control from the attached device, and keyword out causes the terminal server to send flow control information to the attached device. If not set, both directions are assumed. The keyword hardware sets hardware flow control. The keyword none sets no flow control (default).
terminal [no] hold-character decimal-number
Sets, changes, or removes the hold character for the current terminal line. The argument decimal-number is either the ASCII decimal representation of the desired hold character or a control sequence (for example, Ctrl-C). By default, no local hold character is set.
Sets the number of lines on the screen of the current terminal. The argument screen-length is the desired number of lines. The default length is 24 lines. A value of zero disables pausing between screens of output. The screen length specified can be learned by hosts.
Enables/disables logging of system debugging and event messages on the current terminal.
Establishes/removes incoming message notification.
terminal [no] padding decimal-number count
Sets or removes the character padding on the current terminal line. The argument decimal-number is the ASCII decimal representation of the character. It can be any of the 127 ASCII characters, up to 255 padding characters in length. The argument count is the number of NULL bytes sent after that character.
terminal parity {none|even|odd|space|mark}
Defines the generation of the parity bit for the current terminal line. The default setting is none.
Changes the transmit and receive speeds of the current terminal line. When used, argument baud is typically specified as 300, 1200, 2400, 4800, 9600, 19200, or 38400, but can be set to any user-defined speed in a range from 75 to 57600. The default speed is 9600 baud.
terminal [no] start-character decimal-number
Sets or removes the character that signals the start of data transmission when software flow control is in effect. The argument decimal-number is the ASCII decimal representation of the desired start character. The default start character is Ctrl-Q (ASCII character 17).
Sets the number of stop bits transmitted per byte by the current terminal line. The default is 2 stop bits.
terminal [no] stop-character decimal-number
Sets or removes the character that signals the end of data transmission when software flow control is in effect. The argument decimal-number is the ASCII decimal representation of the desired stop character. The default stop character is Ctrl-S (ASCII character 19).
terminal [no] telnet-transparent
Sets or removes ability of the terminal line to send a Return (CR) as a CR followed by a NULL instead of a CR followed by a Line Feed (LF). This scheme permits interoperability with different interpretations of end-of-line handling in the Telnet protocol specification.
terminal [no] terminal-type terminal-name
Records, removes, or changes the current terminal type. The type in the argument terminal-name is passed to applications that set terminal types.
terminal transport [telnet|lat|pad|rlogin|none]
Sets the preferred protocol for the duration of the current session. Default is LAT.
Sets or changes the number of columns on the current terminal screen. The default is 80 columns.
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