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Using a 3640 as a Terminal Server

What does the following command do and how does it work?

"telnet break-on-ip"

We have several of these Cisco 3640 chassis that we are deploying as terminal servers. We are having some difficulty figuring out the configurations used to support the various kinds of servers that will be connected to the Cisco box. Thanks for your help!


Re: Using a 3640 as a Terminal Server



Generating a Hardware Break Signal

The telnet break-on-ip line configuration subcommand causes the system to generate a hardware Break signal on the RS-232 line that is associated with a Telnet connection, when a Telnet Interrupt-Process (IP) command is received on that connection. The syntax for this command is:

telnet break-on-ip

Use this command to work around the following situations:

Several user Telnet programs send an IP command, but cannot send a Telnet break command.

Some Telnet programs implement a Break command that sends an IP command.

Some RS-232 hardware devices use a hardware Break command for various purposes.

A hardware Break command is generated when a Telnet break command is received.

In the following example, line 5 is configured with the telnet break-on-ip command. The location text notes that this refers to the high-speed modem. The telnet transparent command sets end-of-line handling.


line 5

location high-speed modem

telnet transparent

telnet break-on-ip

Besides that, the minimal config needed is:

line # #

no exec

transport input all

As for having difficulty with some devices attached, you need to check the cabling required by the device. The octal cable used for this application is rolled. So , if you attach a coupler to RJ45 and then a cisco blue cable and the RJ45/DB9 adapter in the cisco kit that straightens the cable out to a standard RS-232.

HTH, Erick