Redundant Dial Shelf Controller

Feature Overview

DSC Redundancy

Benefits

Restrictions

Redundant Dial Shelf Controller

This document describes Redundant Dial Shelf Controller (DSC) support for the Cisco AS5800 universal access server and contains the following sections:

Feature Overview

The Redundant Dial Shelf Controller feature consists of two DSC cards on the Cisco AS5800 dial shelf. The DSC cards provide clock and power control to the dial shelf cards. Each DSC card provides the following:

Master clock for the dial shelf
Fast Ethernet link to the router shelf
Environmental monitoring of the feature boards
Bootstrap images on start-up for the feature boards

The Redundant Dial Shelf Controller feature is automatically enabled when two DSC cards are installed. DSC redundancy is supported with Cisco AS5800 software at the Dial Shelf Interconnect Protocol (DSIP) level.

DSC Redundancy

This feature enables a Cisco AS5800 dial shelf to use dual DSCs for full redundancy. A redundant configuration allows for one DSC to act as backup to the active card, should the active card fail. This increases system availability by preventing loss of service.

The redundant DSC functionality is robust under high loads and through DSC or software crashes and reloads.

The redundant DSC functionality is driven by the following events:

User actions
Control messages
Timeouts
Detection of component failures
Error and warning messages

The following command enhancement is associated with this feature:

Router shelf console start and stop DSC privileged EXEC commands via the hw-module command

Benefits

DSC redundancy provides maximum system availability by preventing loss of service in the event of the failure of one of the DSCs.

Restrictions

There is no load-sharing between the Broadband Inter-Carrier Interfaces (BICs). One BIC is used as a backup, carrying only control traffic, such as keepalives, until there is a switchover.

Supported Platforms

Cisco AS5800 universal access servers

Supported Standards, MIBs, and RFCs

Standards

No new or modified standards are supported by this feature.

MIBs

No new or modified MIBs are supported by this feature.

For descriptions of MIBs and instructions on how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

No new or modified RFCs are supported by this feature.

Prerequisites

Your Cisco AS5800 router shelf and dial shelf must be fully installed, with two DSC cards installed on the dial shelf.
Your Cisco AS5800 must be running Cisco IOS Release Cisco IOS Release 12.1(2)T.
The external DSC clocking port must be configured identically on both router shelves and must be physically connected to both DSCs. This assures that if a DSC card needs replacing or if the backup DSC card becomes primary, clocking remains stable.

Configuration Tasks

See the following sections for configuration tasks for the DSC feature. Each task in the list indicates if it is optional or required:

Configuring the External Clocks (Required)

Configure the external clocks using the following commands from the router shelf login. One external clock is configured as the primary clock source, the other is configured as the backup clock source.

Command Purpose

Step 1

Router> enable
Enters the enable command mode (also called privileged EXEC).

Step 2

Router# configure terminal
Enters global configuration mode. The example shows the terminal configuration option.

Enter configuration commands, one per line.

Step 3

Router(config)# dial-tdm-
clock priority value
Configures the trunk card clock priority. Priority range is a value between 1 and 50.

Step 4

Router(config)# [no]
dial-tdm-clock priority X
{trunk-slot Y port Z}
external {t1 | e1} [120-ohm]
Selects the T1/E1 trunk slot and port that is providing the clocking source. T1/E1 selection is based on the signal coming in. Select the impedance. The default impedance is 75-ohm.

Step 5

Router(config)# dial-tdm-
clock priority value
external t1 [or] Router(config)# dial-tdm-clo
k priority value external e1
Configures the T1/E1 external clock on the dial shelf controller front panel. T1/E1 selection is based on the signal coming in. Priority range is a value between 1 and 50.

Step 6

Router(config)# Ctrl-Z Router#
Verifies your command registers when you press the return key. Enter Ctrl-Z to return to privileged EXEC mode.

Step 7

Router# copy running-config
startup-config
Saves your changes.

	Command	Purpose
Step 1	`Router>` enable	Enters the enable command mode (also called privileged EXEC).
Step 2	`Router#` configure terminal	Enters global configuration mode. The example shows the terminal configuration option. `Enter configuration commands, one per line.`
Step 3	`Router(config`)# dial-tdm- clock priority value	Configures the trunk card clock priority. Priority range is a value between 1 and 50.
Step 4	`Router(config`)# [no] dial-tdm-clock priority X `{`trunk-slot Y port Z} external {t1 \| e1} [120-ohm]	Selects the T1/E1 trunk slot and port that is providing the clocking source. T1/E1 selection is based on the signal coming in. Select the impedance. The default impedance is 75-ohm.
Step 5	`Router(config`)# dial-tdm- clock priority value external t1 [or] `Router(config`)# dial-tdm-clo k priority value external e1	Configures the T1/E1 external clock on the dial shelf controller front panel. T1/E1 selection is based on the signal coming in. Priority range is a value between 1 and 50.
Step 6	`Router(config)#` Ctrl-Z `Router#`	Verifies your command registers when you press the return key. Enter Ctrl-Z to return to privileged EXEC mode.
Step 7	Router# copy running-config startup-config	Saves your changes.

Verifying External Clock Configuration

To verify that the primary clock is running, enter the show dial-shelf clocks privileged EXEC command:

5800# show dial-shelf <slot number> clocks
 
Slot 12:
System primary is 1/2/0 of priority 202 
TDM Bus Master Clock Generator State = NORMAL
Backup clocks:
Source  Slot    Port    Priority      Status      State
-------------------------------------------------------
Trunk   2       1       208            Good        Default       
Slot    Type    11 10  9  8  7  6  5  4  3  2  1  0
2       T1       G  G  G  G  G  G  G  G  G  G  G  G

For more information on configuring external clocks, refer to the Cisco document, Managing Dial Shelves.

Configuring the DSC (Required)

To configure the redundant DSC feature, use the following commands from the router shelf login.

Command Purpose

Step 1

Router> enable Password: <password> Router#
Enters enable command mode (also called privileged EXEC).

Step 2

Router# hw-module shelf/slot {start|stop}
5800#
Stops the target DSC remotely from the router console. Restarts the DSC if it has been stopped.

Step 3

Router# show redundancy
[history]
Displays the current or history status for redundant DSC.

Step 4

Router# debug redundancy
{all|ui|clk|hub} Router#
Collects events for troubleshooting.

Step 5

Router# show debugging
Lists the debug commands that are turned on, including the debug command for the redundant DSC.

	Command	Purpose
Step 1	Router> enable Password: <password> Router#	Enters enable command mode (also called privileged EXEC).
Step 2	Router# hw-module shelf/slot {start\|stop} 5800#	Stops the target DSC remotely from the router console. Restarts the DSC if it has been stopped.
Step 3	Router# show redundancy [history]	Displays the current or history status for redundant DSC.
Step 4	Router# debug redundancy {all\|ui\|clk\|hub} Router#	Collects events for troubleshooting.
Step 5	Router# show debugging	Lists the debug commands that are turned on, including the debug command for the redundant DSC.

Verifying DSC Configuration

To verify that you have started the redundant DSC feature, enter the show redundancy privileged EXEC command:

Router# show redundancy
 
DSC in slot 12:
 
Hub is in 'active' state.
Clock is in 'active' state.
 
DSC in slot 13:
 
Hub is in 'backup' state.
Clock is in 'backup' state.
 
Router#

Troubleshooting Tips

If you are having trouble, check the following:

Verify that the redundant DSCs are properly installed.
Use the show redundancy command to display the current and past status of the feature.

Configuration Examples

None

Command Reference

This section documents the modified command related to the Redundant Dial Shelf Controller feature. All other commands used in this feature are documented in the Cisco IOS Release 12.1 command reference publications.

hw-module

hw-module

To enable the router shelf to stop a DSC or to restart a stopped DSC, use the hw-module privileged EXEC console command. The no form of this command does not exist.

hw-module slot shelf/slot {start | stop}

Syntax Description

shelf/slot

The shelf number is the number of the dial shelf. The slot number is number of the slot in the shelf where the target DSC is installed. The slot number must be either 12 or 13, where the DSCs are installed. You must enter the forward slash (/) as part of the command.

start

You must start the specified DSC using the corresponding keyword.

stop

You must stop the specified DSC using the corresponding keyword.

shelf/slot	The shelf number is the number of the dial shelf. The slot number is number of the slot in the shelf where the target DSC is installed. The slot number must be either 12 or 13, where the DSCs are installed. You must enter the forward slash (/) as part of the command.
start	You must start the specified DSC using the corresponding keyword.
stop	You must stop the specified DSC using the corresponding keyword.

Defaults

The DSC is started by default.

Command Modes

Privileged EXEC

Command History

Release Modification

11.3(6)AA

This command was introduced.

Release	Modification
11.3(6)AA	This command was introduced.

Usage Guidelines

The stop and start forms of this command apply to DSCs only, not to feature boards.

The stop form of this command is issued from the router shelf console. It is the equivalent of pressing the DISP (Display) button on the target DSC. A DSC should be stopped prior to testing or removing it from the chassis.

Note Confirmation to stop a DSC is displayed only when a command is being issued and not when the DISP button is pressed.

When a DSC is stopped, removed, then reinstalled, there is no need to restart it (whether it is the original or a replacement) since a freshly installed DSC reboots as the backup DSC automatically. However, if a DSC is stopped, either by using the DISP button or by issuing the hw-module stop command, but not removed, it can be restarted by using the start version of this command, whereupon it will become the backup DSC.

The reload form of the command applies only to feature boards not to DSCs. Enter the hw-module slot shelf/slot reload command to initiate the feature board reload process. You will be asked to confirm the reload request before it is carried out.

Examples

The following example starts one DSC and stops the other:

The following example stops (after confirmation) the DSC in slot 13 of the dial-shelf (with a shelf ID of one):

Router# hw-module slot 1/13 stop

The following example re-starts the DSC that was stopped in the previous example:

Router# hw-module slot 1/13 start

The following example reloads (after confirmation) the feature board in slot seven:

Router# hw-module slot 1/7 reload

Related Commands

Command Description

show redundancy [history]

Displays current or historical status and related information on dual (redundant) DSC cards.

The show redundancy history command displays a table of the last five redundancy events for each redundant component on the DSCs.

debug redundancy

Displays information used for troubleshooting dual (redundant) DSC cards.

Command	Description
show redundancy [history]	Displays current or historical status and related information on dual (redundant) DSC cards. The show redundancy history command displays a table of the last five redundancy events for each redundant component on the DSCs.
debug redundancy	Displays information used for troubleshooting dual (redundant) DSC cards.

Glossary

The terms in this section are used in context with the redundant DSC feature. For additional terminology definitions, see the Cisco Systems publication Internetworking Terms and Acronyms.

BIC—(or BICI) Broadband Inter-Carrier Interface. ITU-T standard that defines the protocols and procedures needed for establishing, maintaining, and terminating broadband switched virtual connections between public networks.

DSC—The dial shelf controller card for the dial shelf provides a master clock for the dial shelf, and links the dial shelf to the router shelf via a cable running Fast Ethernet. Each dial shelf can have one or two DSCs.

DSIP—Dial Shelf Interconnect Protocol is a protocol/encapsulation providing communication between the dial shelf and router shelf.

Feature boards—Modular system cards that perform specific functionality, for example DSC cards or modem cards.

IPC—Inter-process control.

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