Specifications

Configuring Asynchronous Lines and Interfaces
How to Configure Asynchronous Interfaces and Lines
DC-25
Cisco IOS Dial Technologies Configuration Guide
Connections are authenticated using the method specified for the line configurations for the
asynchronous rotary group. If a connection is queued, authentication is done prior to queueing and no
authentication is done when the connection is later established.
Make sure you comply with the following requirements when configuring asynchronous rotary line
queueing:
• Configure more virtual terminal lines than will ever be used by waiting asynchronous rotary
connection attempts. Even when the queue is at its maximum, there must be at least one virtual
terminal line available so that system operators or network administrators can use Telnet to access
the router to show, debug, or configure system performance.
• When adding lines to a rotary group, all lines must be either queued or not queued. A mixture of
queued and unenqueued lines in the same rotary group is not supported and can result in unexpected
behavior.
• All lines within a queued rotary group need to use the same authentication method. Using different
authentication methods within the same rotary group can result in unexpected behavior.
To configure asynchronous rotary line queueing, use the following commands beginning in global
configuration mode:
See the “Rotary Group Examples” section for configuration examples.
Verifying Asynchronous Rotary Line Queueing
To verify operation of asynchronous rotary line queueing, perform the following tasks:
• Use the show line command in EXEC mode to check the status of the vty lines.
• Use the show line async-queue command in EXEC mode to check the status of queued connection
requests.
Troubleshooting Asynchronous Rotary Lines
If asynchronous rotary line queueing is not operating correctly, use the following debug commands in
privileged EXEC mode to determine where the problem may lie:
• debug async async-queue
• debug ip tcp transactions
• debug modem
Refer to the Cisco IOS Debug Command Reference for information about these commands.
Command Purpose
Step 1
Router (config)# line [aux | console | tty | vty]
line-number [ ending-line-number ]
Starts line configuration mode on the line type and
numbers specified.
Step 2
Router(config-line)# rotary group [queued |
round-robin]
Enables asynchronous rotary line queueing on the
designated line or group of lines. The optional
round-robin keyword selects a round-robin port
selection algorithm instead of the default (queued)
linear port selection algorithm.