This chapter describes how to configure lines, modems, and terminal settings to access the ATM switch for management purposes. The Cisco DSLAM has two types of terminal lines:

A console line
An auxiliary line

Most line setup is the same for all types of lines, but certain commands, such as those having to do with modem control, apply only to the auxiliary port.

This chapter includes these sections:

Configuring Terminal Lines

Configuring terminal lines is a two-step process:

Step 1 Set up the lines for the terminals or other asynchronous devices attached to them.

Step 2 Configure the parameters for each line.

The tasks involved in these steps are described in the following sections:

Preparing to Configure Lines

Use line configuration mode to enter line configuration commands that affect a specified console, auxiliary, or virtual terminal line. To enter line configuration mode, use this command in global configuration mode:

Command	Task
`DSLAM(config)# line [aux\|console\|vty] line-number [ending-line-number]`	Specify an auxiliary, console, or virtual terminal line to configure.

The terminal from which you locally configure the system is attached to the console port.

Example

This example specifies the console port and begins line configuration mode:

DSLAM(config)# line con 0

DSLAM(config-line)#

The auxiliary port supports modem connections. See the "Setting Up Modem Control on the Auxiliary Port" section, to set up modem support on the auxiliary port.

Configuring the console port or virtual terminal lines allows you to specify communication parameters and automatic baud connections, and configure terminal operating parameters for the terminal you are using. These tasks are described in the "Defining Terminal Operation Characteristics" section.

You can also use the line command to create virtual terminal lines. This example shows how to create and configure the maximum 4 virtual terminal lines with the no login command:

DSLAM(config)# line vty 0 4

DSLAM(config-line)# no login

Setting Communication Parameters

You can change the default parameters for terminal communications to meet the requirements of the terminal or host to which you are attached. To do so, use one or more of these commands in line configuration mode:

Command	Task
`speed bps txspeed bps rxspeed bps`	Set the line speed. Choose from line speed, transmit speed, or receive speed. Speed applies to the auxiliary port only.
`databits {5 \| 6 \| 7 \| 8}`	Set the data bits.
`stopbits {1 \| 1.5 \| 2}`	Set the stop bits.
`parity {none \| even \| odd \| space \| mark}`	Set the parity bit.

This example shows how to configure the auxiliary line with a speed of 19,200 bps:

DSLAM(config)# line aux 0

DSLAM(config-line)# speed 19200

Configuring Flow Control for Communication

On the auxiliary port, you can set both hardware and software flow control between the DSLAM and the devices attached to it.

To configure flow control between the DSLAM and attached device, use one or more of the commands in line configuration mode:

Command	Task
flowcontrol {none \| software [in \| out] \| hardware [in \| out]}	Set the terminal flow control.
start ascii-number	Set the flow control start character.
stop-character ascii-number	Set the flow control stop character.

Allowable values for the start and stop-character commands are CHAR or 0 through 255.

Both software and hardware flow control are bidirectional. If you do not specify a direction, the DSLAM enables software flow control in both directions. For information about setting up hardware flow control on the EIA/TIA-232 line, see the hardware installation and maintenance manual for your product.

Specifying the Transport Protocol for a Specific Line

You can specify the protocols for individual lines by setting the protocol for incoming and outgoing connections and changing the default (preferred) protocol for a line. The default transport protocol is Telnet.

To specify transport protocols, use one or more of these commands in line configuration mode:

Command	Task
transport input {all \| telnet \| none}	Define which protocols can connect to a specific line of the DSLAM.
transport output {all \| telnet \| none}	Determine the protocols for outgoing connections from a line.
transport preferred {all \| telnet \| none}	Specify the protocol to use if the user did not specify one.
transport preferred none	Prevent errant connection attempts.

The system accepts a host name entry at the EXEC system prompt as a Telnet command. If you incorrectly type the host name, the system interprets the entry as an incorrect Telnet command and displays an error message indicating that the host does not exist. The transport preferred none command disables this option if you incorrectly type a command at the EXEC prompt, and the system does not attempt to make a Telnet connection.

Establishing Terminal Session Limits

You can set a time limit on a terminal session. To limit terminal sessions, use the following command in line configuration mode:

Command	Task
`session-timeout minutes [output]`	Set the idle session timeout interval.

Setting Up Modem Control on the Auxiliary Port

This section describes modem control and how to configure it on the modem port:

Modem Control Process

Figure 2-1 illustrates how modem control works on the DSLAM auxiliary port.

Figure 2-1: EXEC and Daemon Creation on a Line with No Modem Control

The figure shows two processes:

The create daemon process, used to create a TTY daemon that handles the incoming network connection
The create EXEC process, used to create the process that interprets user commands

In the figure, the current signal state and the signal line are listed inside each box. The state of the line is listed next to the box. (You can display the current state of a line with the show line command.) Events that change that state appear in italics along the event path, with the software actions described within the ovals.

Figure 2-1 illustrates line behavior when no modem control is set. The data terminal ready (DTR) output is always high, and CTS and RING are ignored. The DSLAM creates an EXEC when the you type an activation character. Incoming TCP connections occur instantly if the line is not in use and can be closed only by the remote host.

Supporting Dial-In and Dial-Out Modems

To configure a line for both incoming and outgoing calls, use this command in line configuration mode:

Command	Task
`DSLAM (config-line)# modem inout`	Configure a line for both incoming and outgoing calls.

Figure 2-2 illustrates the modem in-out process.

Figure 2-2: EXEC and Daemon Creation on a Line Configured for Incoming and Outgoing Calls

If the line is activated by:

Raising RING, it behaves exactly as a line configured with the modem dialin subcommand.
An incoming TCP connection, the line behaves similarly to a nonmodem line.

Note If your system uses dial-out modems, consider using access lists to prevent unauthorized use.

Configuring a Line Timeout Interval

You can change the interval that the DSLAM waits for CTS after raising DTR in response to RING from the default of 15 seconds. To do so, use this command in line configuration mode:

Command	Task
`modem answer-timeout seconds`	Configure modem line timing.

Closing Modem Connections

You can configure a line to close all connections from a user terminal when the terminal is turned off, and prevent inbound connections to devices that are out of service. To do so, use this command in line configuration mode:

Command	Task
`modem printer`	Configure a line to close all connections.

Figure 2-3 illustrates the modem printer process requirement for a high CTS throughout the use of the line.

Figure 2-3: EXEC and Daemon Creation on a Line Configured for Continuous CTS

If CTS is not high, your typed input is ignored and incoming connections are refused (or stepped to the next line in a rotary group).

A DSLAM can reliably detect a CTS signal change if the signal remains in the new state for at least one full second.

Configuring Rotary Groups

You can make connections to the next free line in a group of lines, also called a rotary or hunt group. A line can be in only one rotary group. A rotary group can consist of a single line or several contiguous lines. The console line (line 0) cannot be in a rotary group.

If you want to assign the rotary as the single auxiliary port line you can do so because the auxiliary port is not necessarily the same line number on all hardware. When you assign the line to a rotary group, you do not have to track the actual line number. Another reason to use a rotary group is that if the device supports local area transport (LAT), an inbound service can only be bound to a rotary group. It cannot be bound to a port number.

To configure a rotary group, use this command in line configuration mode:

Command	Task
`rotary group`	Add a line to the specified rotary group.

Configuring High-Speed Modem Support

Modems that operate over normal dial-up telephone lines at speeds of 9600 bps and higher do not guarantee a specific throughput; instead, they operate at a speed that depends on the quality of the line, the effectiveness of data compression algorithms on the data being transmitted, and other variables. These modems use hardware flow control to stop the data from reaching the host by toggling an EIA/TIA-232 signal when they cannot accept any more data.

In addition to hardware flow control, dial-up modems require special software handling. You must configure the modems to:

Create an EXEC when you dial in.
Hang up when you exit the EXEC.
Close any existing network connections if the telephone line hangs up in the middle of a session.

The DSLAM supports hardware flow control on its CTS input, which is also used by the normal modem handshake. To configure and use a high-speed modem, perform these tasks, beginning in line configuration mode:

	Command	Task
Step 1	`DSLAM(config-line)# flowcontrol hardware`	In line configuration mode, enable outgoing hardware flow control based on the CTS input.
Step 2	`DSLAM(config-line)# end`	Enter privileged EXEC command mode.
Step 3	`DSLAM# debug modem`	Display informational messages on the console terminal about modem control events, such as signal transitions and automatic baud progress.
Step 4	`DSLAM# show line`	Display the status of a line. In the detailed command output, a Status line of Idle identifies inactive modem dial-in lines and all other modem lines; a Status line of Ready identifies lines in use.

Supporting Reverse TCP Connections

The DSLAM can receive incoming connections on the auxiliary port. This capability allows you to attach serial printers, modems, and other shared peripherals to the DSLAM and drive them remotely from other systems. The DSLAM supports reverse TCP connections.

Front-Ending

The specific TCP port or socket to which you attach the peripheral device determines the type of service the DSLAM provides on that line. When you attach the serial lines of a computer system or a data terminal switch to the auxiliary port of the DSLAM, the DSLAM acts as a network front end for a host that does not support the TCP/IP protocols. This arrangement is sometimes called front-ending or reverse connection mode.

To connect the auxiliary port, the remote host or terminal must specify a particular TCP port on the DSLAM. If Telnet protocols are required, that port is 2000 (decimal) plus the decimal value of the line number.

TCP Streams

If a raw TCP stream is required, the port is 4000 (decimal) plus the decimal line number. The raw TCP stream is usually the required mode for sending data to a printer.

The Telnet protocol requires that carriage return characters be translated into carriage return and line feed character pairs. You can turn this translation off by specifying the Telnet binary mode option. To specify this option, connect to port 6000 (decimal) plus the decimal line number.

Defining Terminal Operation Characteristics

In line configuration mode, you can set terminal operation characteristics for that line until you change the line parameters.

You can temporarily change the line settings using the terminal EXEC commands described in "Cisco DSLAM User Interface."

Define the terminal operation characteristics by performing the tasks in the following sections:

Specifying the Terminal Type

You can specify the type of terminal connected to a line. This feature has two benefits: it records the type of terminal attached to a line, and it can inform the remote host of the terminal type for display management. To specify the terminal type, use this command in line configuration mode:

Command	Task
terminal-type terminal-name	Specify the terminal type.

Setting the Terminal Screen Length and Width

By default, the DSLAM provides a screen display of 24 lines by 80 characters. You can reconfigure these values if they do not meet the needs of your terminal by performing the following tasks in line configuration mode:

	Command	Task
Step 1	`length screen-length`	Set the screen length.
Step 2	`width characters`	Set the screen width.

The values set can be learned by some host systems that use this type of information in terminal negotiation. Set a value of 0 for the screen length to disable pausing between windows of output.

Defining the Escape Character

You can define or modify the system escape function with the escape-character command in line configuration mode:

Command	Task
escape-character ascii-number	Change the system escape sequence. The escape sequence indicates that the codes that follow have special meaning. The default sequence is Ctrl-^.

Note If you are using the autoselect command, do not change the activation character from the default value of Return. If you change this default, autoselect may not function immediately.

Specifying the International Character Display

You can use a 7-bit character set (such as ASCII) or you can enable a full 8-bit international character set (such as ISO 8859) to allow special graphical and international characters for use in banners and prompts, and to add special characters such as software flow control. You can configure these settings globally by interface or locally at the user level. Use these criteria for determining the configuration mode to use when setting up this feature:

If a large number of connected terminals support nondefault ASCII bit settings, use the global configuration commands.
If only a few of the connected terminals support nondefault ASCII bit settings, use line configuration commands or the EXEC local terminal setting commands.

Note Setting the EXEC character width to 8 bits can cause failures. If you enter the help command on a terminal that is sending parity, an unrecognized command message appears because the system is reading all 8 bits, although the eighth bit is not needed for the help command.

To specify a character set on a global basis, use one or both of these commands in global configuration mode:

Command	Task
default-value exec-character-bits {7 \| 8}	Specify the character set used in EXEC and configuration command characters.
default-value special-character-bits {7 \| 8}	Specify the character set used in special characters such as software flow control, hold, escape, and disconnect characters.

To specify a character set based on hardware or software, or on a per-line basis, use the appropriate command in line configuration mode:

Command	Task
databits {5 \| 6 \| 7 \| 8}	Set the number of databits per character that are generated and interpreted by hardware.
data-character-bits {7 \| 8}	Set the number of databits per character that are generated and interpreted by software.
exec-character-bits {7 \| 8}	Specify the character set used in EXEC and configuration command characters on a per-line basis.
special-character-bits {7 \| 8}	Specify the character set used in special characters such as software flow control, hold, escape, and disconnect characters on a per-line basis.

Note If you are using the autoselect function, set the activation character default to Return, and exec-character-bits default to 7. If you change these defaults, the application does not recognize the activation request.

Setting Character Padding

You can change the character padding on a specific output character. Character padding adds a number of null bytes to the end of the string and can make a string conform to an expected length. To set character padding, use this command in line configuration mode:

Command	Task
padding ascii-number count	Set padding count, on a specific output character, ascii-number, for the specified line.

Disabling Enhanced Editing Mode

To disable enhanced editing mode and revert to the editing mode of earlier software releases, use this command in line configuration mode:

Command	Task
no editing	Disable the enhanced editing features for a particular line.

You can disable enhanced editing if you have prebuilt scripts that do not interact well when enhanced editing is enabled. You can re-enable enhanced editing mode using the editing command.

Providing Line Connection Information after the Login Prompt

You can provide the host name, line number, and location each time an EXEC is started or an incoming connection is made. The line number banner appears immediately after the EXEC banner or incoming banner. It is useful for tracking problems with modems because it lists the host and line for the modem connection. Modem information is also included if applicable.

To provide service line number information, use this command in global configuration mode:

Command	Task
service linenumber	Provide service line number information after the EXEC or incoming banner.

Enabling Password Checking at Login

You can enable password checking on a particular line so that the user is prompted to enter a password at the system login screen. You must then also specify a password. To do so, perform these tasks in line configuration mode:

	Command	Task
Step 1	`login`	Enable password checking on a per-line basis using the password specified with the password command.
Step 2	`password password`	Assign a password to a particular line.

You can enable password checking on a per-user basis so that authentication is based on the user name specified with the username global configuration command. To enable this type of password checking, use one of these commands in line configuration mode:

Command	Task
login local	Enable password checking on a per-user basis using the user name and password specified with the username global configuration command.
login tacacs	Select the TACACS-style user ID and password-checking mechanism.

Use the login tacacs command with Terminal Access Controller Access Control System (TACACS) and extended TACACS Plus.

By default, virtual terminals require passwords. If you do not set a password for a virtual terminal, it responds to attempted connections by displaying an error message and closing the connection. Use the no login command to disable this behavior and allow connections without a password.

Checking Password Examples

This example shows password checking enabled for a virtual terminal line 1:

DSLAM(config)# line vty 1

DSLAM(config-line)# login

DSLAM(config-line)# password letmein

This example shows password checking enabled on a per-user basis:

DSLAM(config)# username jksmith password 0 letmein

DSLAM(config)# username lmjones password 0 littlerock

DSLAM(config)# line vty 1

DSLAM(config-line)# login local

Configuring Terminal Banner Messages

The following sections explain how to configure terminal messages:

Configuring a Message-of-the-Day Banner

You can configure a message-of-the-day (MOTD) banner to display on all connected terminals. This message is displayed at login and is useful for sending messages that affect all network users, such as impending system shutdowns. To do so, use this command in global configuration mode:

Command	Task
banner motd c message c	Configure a message-of-the-day banner.

Configuring a Line Activation Message

You can configure a line activation message to display when an EXEC process such as line activation or an incoming connection to a virtual terminal is created. To do so, use this command in global configuration mode:

Command	Task
banner exec c message c	Configure a message to be displayed on terminals with an interactive EXEC.

Configuring an Incoming Message Banner

You can configure a message to display on terminals connected to reverse Telnet lines. This message is useful for providing instructions to users of these types of connections. Reverse Telnet connections are described in more detail in the "Supporting Reverse TCP Connections" section.

To configure the message that will be sent on incoming connections, use this command in global configuration mode:

Command	Task
banner incoming c message c	Configure messages to display on terminals connected to reverse Telnet lines.

Configuring an Idle Terminal Message

You can configure messages to display on a console or terminal that is not in use. Also called a vacant message, this message is different from the banner message displayed when an EXEC process is activated. To configure an idle terminal message, use this command in line configuration mode:

Command	Task
vacant-message c message c	Display an idle terminal message.

Enabling or Disabling the Display of Messages

You can control display of the MOTD and line activation banners. By default, these banners display on all lines. To suppress or resume these messages, use one of these commands in line configuration mode:

Command	Task
no exec-banner	Suppress banner display.
exec-banner	Resume the display of the EXEC or MOTD banners.

Banner Message Example

This example shows how to use the banner global configuration command and no exec-banner line configuration command to notify your users that the server will be reloaded with new software:

DSLAM(config)# banner exec /

Enter TEXT message.  End with the character '/'.
 
Unauthorized access prohibited./
DSLAM(config)# banner incoming /

You are connected to a Hayes-compatible modem.
 
Enter the appropriate AT commands.
Remember to reset anything to change before disconnecting.
/
DSLAM(config)# banner motd /

The switch will go down at 6pm for a software upgrade.
/
DSLAM(config)# line vty 0 4

DSLAM(config-line)# no exec-banner

DSLAM(config-line)#

Table of Contents

Configuring Terminal Lines and Modem Support