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Table Of Contents
Asynchronous Call Queueing by Role
Prerequisites for Asynchronous Call Queueing by Role
Restrictions for Asynchronous Call Queueing by Role
Information About Asynchronous Call Queueing by Role
Benefits of Asynchronous Call Queueing by Role
How to Configure Asynchronous Call Queueing by Role
Configuring Asynchronous Call Queueing by Role
Monitoring and Maintaining Asynchronous Rotary Line Queues
Configuration Examples for Asynchronous Call Queueing by Role
Configuring Asynchronous Call Queueing by Role Example
Verifying Asynchronous Call Queueing by Role Example
Asynchronous Call Queueing by Role
The Asynchronous Call Queueing by Role feature allows priority users making Telnet connection requests to busy asynchronous rotary groups to be placed at the head of the queue when asynchronous rotary line queueing is enabled. If a second priority user makes a Telnet connection request, they will be placed behind the first priority user at the head of the queue. This feature allows a priority user to access the first available line.
Feature Specifications for Asynchronous Rotary Line Queueing
12.2(15)T
This feature was introduced.
The Asynchronous Call Queueing by Role feature is supported on any Cisco router that has an asynchronous port, but has been tested on the following platforms:
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Cisco 2500 series routers
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The Asynchronous Call Queueing by Role feature was designed to operate on routers with software that contains the communications server subsystem and that have multiple asynchronous interfaces. See the section "Prerequisites for Asynchronous Call Queueing by Role" for more information about system prerequisites.
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Contents
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Prerequisites for Asynchronous Call Queueing by Role
The router must have operational and successfully configured asynchronous interfaces, and asynchronous rotary groups must be enabled.
Restrictions for Asynchronous Call Queueing by Role
To configure the Asynchronous Call Queueing by Role feature, you must also configure asynchronous rotary line queueing. Make sure you comply with the following requirements when configuring asynchronous rotary line queueing:
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Additional information about configuring asynchronous lines and rotary groups can be found in the Cisco IOS Dial Technologies Configuration Guide, Release 12.2; refer to the part "Preparing for Dial Access."
Information About Asynchronous Call Queueing by Role
To configure asynchronous rotary line queueing and the Asynchronous Call Queueing by Role feature, you must understand the following concepts:
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Authentication of Connections
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.
Benefits of Asynchronous Call Queueing by Role
Cisco IOS Release 12.2(15)T introduces the ability to queue calls by role. This functionality allows priority users to bypass the queue and access the first available line, enabling the priority user to complete necessary administrative tasks more quickly.
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How to Configure Asynchronous Call Queueing by Role
This section contains the following procedures:
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Configuring Asynchronous Call Queueing by Role
This task configures asynchronous rotary line queueing and the Asynchronous Call Queueing by Role feature.
SUMMARY STEPS
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DETAILED STEPS
Troubleshooting Tips
In the event that asynchronous rotary line queueing is not operating correctly, use the following debug commands in privileged EXEC mode to determine the source of the problem:
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Refer to the Cisco IOS Debug Command Reference publication for information about the debug modem, debug ip tcp transactions, and the debug async async-queue commands.
Monitoring and Maintaining Asynchronous Rotary Line Queues
This task displays queued lines and removes lines from the queue:
SUMMARY STEPS
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DETAILED STEPS
Configuration Examples for Asynchronous Call Queueing by Role
This section provides the following configuration examples:
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Configuring Asynchronous Call Queueing by Role Example
The following example enables asynchronous rotary line queueing and by-role queueing on lines 1 and 2 on rotary group 1:
line 1 2rotary 1 queued by-roleVerifying Asynchronous Call Queueing by Role Example
The following example shows the output of the show line async-queue command when by-role queueing is enabled on lines tty35 and tty38:
Router# show line async-queueShowing async-queue for ALL rotary groupsQueue for Rotary Group 1:Pos Waiting TTY Dest Port Source Host Waiting Time1 tty66 3001 10.2.72.13 00:01:322 tty67 3001 10.2.72.13 00:01:23Lines which have queuing enabled [tty (group)]:tty33 (2) tty34 (2)Lines which have queuing by role enabled [tty (group)]:tty35 (1) tty38 (1)Additional References
The following sections provide additional references related to the Asynchronous Call Queueing by Role feature:
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Related Documents
Additional information about the Asynchronous Rotary Line Queuing feature
Asynchronous Rotary Line Queueing, Release 12.1(1)T
Additional information about configuring asynchronous lines and rotary groups
Cisco IOS Dial Technologies Configuration Guide, Release 12.2
Additional information about debug commands
Cisco IOS Debug Command Reference, Release 12.2
Standards
MIBs
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
RFCs
Technical Assistance
Command Reference
This section documents the modified rotary command. All other commands used with this feature are documented in the Cisco IOS Release 12.2 T command reference publications.
rotary
To define a group of lines consisting of one or more virtual terminal lines or one auxiliary port line, use the rotary command in line configuration mode. To remove a group of lines from a rotary group, use the no form of this command.
rotary group [queued [by-role]] [round-robin]
no rotary group [queued [by-role]] [round-robin]
Syntax Description
Defaults
No group of lines is defined.
Command Modes
Line configuration
Command History
10.0
This command was introduced.
12.1(1)T
The queued keyword was added.
12.1(2)T
The round-robin keyword was added.
12.2(15)T
The by-role keyword was added.
Usage Guidelines
Connections to a rotary group can take advantage of the following features:
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Typically, rotary groups are used on devices with multiple modem connections to allow connection to the next free line in a hunt group. In the event that there are no free asynchronous ports, the queued keyword enables outgoing connection requests to be queued until a free port becomes available. Periodic messages are sent to users to update them on the status of their connection request.
For a nonqueued connection request, the remote host must specify a particular TCP port on the router to connect to a rotary group with connections to an individual line. The available services are the same, but the TCP port numbers are different. Table 1 lists the services and port numbers for both rotary groups and individual lines.
For example, if Telnet protocols are required, the remote host connects to the TCP port numbered 3000 (decimal) plus the rotary group number. If the rotary group identifier is 13, the corresponding TCP port is 3013.
If a raw TCP stream is required, the port is 5000 (decimal) plus the rotary group number. If rotary group 5 includes a raw TCP (printer) line, the user connects to port 5005 and is connected to one of the raw printers in the group.
If Telnet binary mode is required, the port is 7000 (decimal) plus the rotary group number.
The by-role keyword enables priority users to bypass the queue and access the first available line.
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The round-robin selection algorithm enabled by the round-robin keyword improves the utilization of tty ports. When looking for the next available port, the default linear hunting algorithm will not roll over to the next port if the first port it finds is bad. This failure to roll over to the next port results in an unequitable utilization of the tty ports on a router. The round-robin hunting algorithm will roll over bad ports instead of retrying them.
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Examples
The following example establishes a rotary group consisting of virtual terminal lines 2 through 4 and defines a password on those lines. By using Telnet to connect to TCP port 3001, the user gets the next free line in the rotary group. The user need not remember the range of line numbers associated with the password.
line vty 2 4rotary 1password letmeinloginThe following example enables asynchronous rotary line queueing:
line 1 2rotary 1 queuedThe following example enables asynchronous rotary line queueing using the round-robin algorithm:
line 1 2rotary 1 queued round-robinRelated Commands
Glossary
asynchronous transmission—Term describing digital signals that are sent without precise clocking. Such signals generally have different frequencies and phase relationships. Asynchronous transmissions usually encapsulate individual characters in control bits (called start and stop bits) that designate the beginning and end of each character.
EIA/TIA-232—Common physical layer interface standard, developed by the Electronic Industries Association and Telecommunications Industry Association, that supports unbalanced circuits at signal speeds of up to 64 kbps. Closely resembles the V.24 specification. Formerly called RS-232.
rotary groups—Several contiguous lines that allow a connection to be made to the next free line in the group. Also called a hunt group.
TCP—Transmission Control Protocol. Connection-oriented transport layer protocol that provides reliable full-duplex data transmission. TCP is part of the TCP/IP protocol stack.
Telnet—Standard terminal emulation protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854.
Transmission Connection Protocol—See TCP.
TTY—terminal line.
VTY—virtual terminal line.
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