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Cisco 4000 Series Integrated Services Routers

Network Synchronization for the Cisco ISR 4400 Series

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Table of Contents

Network Synchronization for the Cisco ISR 4400 Series

Contents

Information About Network Synchronization

Prerequisites for Network Synchronization

Restrictions for Network Synchronization

Configuring Network Synchronization

Configuring Clock Recovery with a Primary Clock Source

Example 1: Clock Recovery with a Primary Clock Source

Example 2: Clock Recovery with a Primary Clock Source

Example 3: Switching of Input Source Clock

Configuring the De-selection of a Primary Clock Source

Example: De-selection of a Clock Source

Configuring Participation of a Module in the Backplane Clock

Example 1: Verifying that a Module Participates in the Backplane Clock

Example 2: Verifying that a Module Participates in the Backplane Clock

Example 3: Disabling and Enabling a Module from Participating in the Backplane Clock

Configuring Network Clocking with Revertive Mode

Example: Configuring Network Clocking with Revertive Mode

Configuring the Wait-to-restore Timer

Example: Configuring the Wait-to-restore Timer

Configuring the Hold-off Timer

Example: Configuring the Hold-off Timer

Configuring Lockout of a Clock Source

Example: Configuring Lockout of a Clock Source

Configuring Network Clocking with Force Switching

Example: Configuring Network Clocking with Force Switching

Additional References

Finding Feature Information

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Network Synchronization

Network Synchronization for the Cisco ISR 4400 Series

Revised: April 7, 2014, OL-31796-01

To maintain the quality of the services offered by the network and to operate efficiently, devices must operate at the same clock rates. This document explains how to configure network synchronization between two devices—the router and a network information module (NIM), such as the
Cisco Fourth-Generation T1/E1 Voice and WAN Network Interface Module.

Information About Network Synchronization

Most of the services that are provided over networks must be fully synchronized with one another in order to operate efficiently. If the network devices that constitute a network do not operate at the same clock rates, there is an overall decrease in the performance of the network and a consequent degradation in the quality of the services offered by the network. This document explains how to configure network synchronization between modules and a router platform in the Cisco ISR 4400 Series.

Network synchronization is supported for Cisco Fourth-generation T1/E1 Voice and WAN Network Interface Modules (NIMs) on the Cisco ISR 4400 Series, by using the network-clock synchronization automatic command, which is issued in global configuration mode. This command is made ineffective for a particular NIM if you use the no network-clock participation slot / subslot command. See
Example 3: Disabling and Enabling a Module from Participating in the Backplane Clock. This causes the NIM to have its own separate clock domain.

Prerequisites for Network Synchronization

The following goals must be taken into account while designing the synchronization plan for a network:

  • Synchronize the greatest number of network elements to the smallest number of independent clock sources. Ideally, all network elements should be synchronized to a single clock source.
  • Use high quality clock sources for stability and long-term accuracy.
  • To ensure the resiliency of synchronization, plan for possible failure of clock sources, network elements and network trunks.

Restrictions for Network Synchronization

This section lists the restrictions for configuring network synchronization on a router. Network synchronization can only be configured for a Cisco Fourth-generation T1/E1 Voice and WAN Network Interface Module.

  • You can configure two ports per NIM as clock sources on a router.
  • We recommend that you do not configure multiple input sources with the same priority because this impacts the TSM (switching message delay).
  • Synchronization Status Messages (SSMs), which inform neighboring network elements about the quality level of the clock, are not supported on the router. All clock sources for the router operate in QL-disabled mode.

Configuring Network Synchronization

You can configure network synchronization by using the following procedures:

Configuring Clock Recovery with a Primary Clock Source

This section describes how to configure clock recovery with a primary or secondary clock source.

SUMMARY STEPS

1. configure terminal

2. network-clock synchronization automatic

3. controller [t1|e1] slot/bay/port

4. clock source line primary

5. network-clock input-source priority controller [t1|e1] slot/bay/port

6. exit

DETAILED STEPS

Command
Purpose

Step 1

configure terminal

 

Router# configure terminal

Enters the global configuration mode.

Step 2

network-clock synchronization automatic

 

Router(config)# network-clock synchronization automatic

Enables the network clock selection algorithm. (Note that network clock synchronization is disabled by default.) Disables the Cisco-specific network clock process, and turns on the G.781-based automatic clock selection process.

Step 3

controller [t1|e1] slot/bay/port

 

Router(config)# controller t1 0/2/0

 

Selects the controller.

Step 4

clock source line [ primary|secondary]

 

Router(config)# clock source line primary

Sets the controller to be a primary or secondary clock source. It is recommended to at least set a controller to be the primary clock source, then optionally set another controller as a secondary clock source, to act as a back-up, going to the same network.

Step 5

network-clock input-source priority controller [t1|e1] slot/bay/port

 

 

Router(config)# network-clock input-source 1 controller t1 0/2/0

Assigns a controller to be the primary or secondary clock source. To set the controller to be a primary clock source, set the value of priority for the input source to be low value, such as 2, (a low value indicates a high priority).

Note The network-clock input-source priority command, which selects the configured controller clock as the backplane clock source, is only available if the module is participated to the backplane.

Step 6

exit

 

Router(config)# exit

Exits the global configuration mode.

Examples

The following example shows how to configure clock recovery for controller t1 on the slot/bay/port of 0/2/0 as the primary clock source.

Router# configure terminal
Router(config)# network-clock synchronization automatic
Router(config)# controller t1 0/2/0
Router(config)# clock source line primary
Router(config)# network-clock input-source 1 controller t1 0/2/0
Router(config)# exit
 

Example 1: Clock Recovery with a Primary Clock Source

In this example the controller T1 0/2/0 has a higher priority (value = 1) than the Internal clock. T1 0/2/0 is the primary clock source indicated the asterisk “*” in the interfaces listed below (“*T1 0/2/0 “).

Router# show network clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T1 : 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 1 QL-SEC NA NA
 

Example 2: Clock Recovery with a Primary Clock Source

In this example the controller T1 0/2/0 is shown to have a high priority (value = 1) which is higher than the priority of controller T1 0/3/0 (value = 2), therefore controller T1 0/2/0 is the primary clock source.

Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 1 QL-SEC NA NA
T1 0/3/0 NA NA/Dis 2 QL-SEC NA NA
Router#
 

Example 3: Switching of Input Source Clock

The following example shows how a primary clock source is affected by a signal failure which causes the primary clock source to change or switch to a different source.

Router# config terminal
Router(config)# network-clock input-source 1 controller t1 0/2/0

 

Perform a signal failure of the primary clock source, by doing a “shut” on the remote end or cause an “Out of Resource” condition of the primary clock source, by disconnecting a cable.

After the above signal failure or “Out of Resource”, verify the feature using the following
show network-clocks synchronization command. Note that the output shows the primary clock source T1 0/2/0 as having a QL_IN value of QL-FAILED and therefore the primary clock source has switched to the “Internal” clock (shown by an asterisk “*”).

Router# show network-clocks synchronization

Symbols: En - Enable, Dis - Disable, Adis - Admin Disable

NA - Not Applicable

* - Synchronization source selected

# - Synchronization source force selected

& - Synchronization source manually switched

Automatic selection process : Enable

Equipment Clock : 2048 (EEC-Option1)

Clock Mode : QL-Disable

ESMC : Disabled

SSM Option : 1

T0 : Internal

Hold-off (global) : 300 ms

Wait-to-restore (global) : 300 sec

Tsm Delay : 180 ms

Revertive : No

 

Nominated Interfaces

Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx

*Internal NA NA/Dis 251 QL-SEC NA NA

T1 0/2/0 NA NA/Dis 2 QL-FAILED NA NA

The next example shows a primary clock source being affected by a signal failure which then causes the primary clock source to change or switch to a different source.

Router# configure terminal
Router(config)# network-clock input-source 1 controller t1 0/2/0

 

Perform a signal failure of the primary clock source, by doing a “shut” on the remote end or cause an “Out of Resource” condition of the primary clock source, by disconnecting a cable.

After the above signal failure or “Out of Resource”, verify the feature using the following show network-clocks synchronization command. Note that the output shows the primary clock source T1 0/3/0/. The controller T1 0/2/0 has having a QL_IN value of QL-FAILED and therefore the primary clock source has switched to the controller T1 0/2/0 clock (shown by an asterisk “*”).

Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/3/0
 
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/2/0 NA NA/Dis 2 QL-FAILED NA NA
*T1 0/3/0 NA NA/Dis 2 QL-SEC NA NA
 

Configuring the De-selection of a Primary Clock Source

This section describes how to deselect a clock source. This ensures that the clock source does not reappear after the router is rebooted.

SUMMARY STEPS

1. configure terminal

2. no network-clock input-source priority controller [t1|e1] slot/bay/port

DETAILED STEPS

 

Command
Purpose

Step 1

configure terminal

 

Router# configure terminal

Enters the global configuration mode.

Step 2

no network-clock input-source priority controller [t1|e1] slot/bay/port

 

 

Router(config)# no network-clock input-source 1 controller t1 0/2/0

Deselects the clock source.

Example: De-selection of a Clock Source

In this example the controller T1 0/2/0, which has been deselected, does not appear in the list of clock sources shown by the show network-clocks synchronization command.

Router# show network-clocks synchronization

Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : Internal
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
* Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 2 QL-SEC NA NA
 
Router#

Configuring Participation of a Module in the Backplane Clock

By default, a NIM (module) participates in the backplane clock. In the first two examples below, the
show platform hardware subslot slot / subslot module device networkclock command verifies that a module participates in the backplane clock.

If you do not want clock synchronization with the backplane clock for a NIM, you can use the no network-clock synchronization participate slot / subslot command shown in Example 3: Disabling and Enabling a Module from Participating in the Backplane Clock.

Example 1: Verifying that a Module Participates in the Backplane Clock

In this example, the show platform hardware subslot slot / subslot module device networkclock command shows:

“ntwk_clk_selected No”—none of the ports of the NIM 0/2 are configured as an input-source. To assign a controller to be an input clock source, see the command network-clock input-source priority controller [t1|e1] slot/bay/port in the “Configuring Clock Recovery with a Primary Clock Source” section.

“ntwk_clk_participate Yes”—the NIM 0/2 participates in the router’s backplane clock. This is the default for a NIM attached to the router.

Router# show platform hardware subslot 0/2 module device networkclock
primary clock 255, secondary clock 0, ntwk_clk_selected No, ntwk_clk_participate Yes, current clock = 0
PLL status= 1, and cntl = 7
 

Example 2: Verifying that a Module Participates in the Backplane Clock

In this example, the command network-clock input-source priority controller [t1|e1] slot/bay/port configures NIM 0/2/0 as an input clock source.

The show platform hardware subslot slot / subslot module device networkclock command shows:

“ntwk_clk_selected Yes”—the NIM 0/2/0 participates in the router’s backplane clock.

“ntwk_clk_participate Yes”—the NIM 0/2 participates in the router’s backplane clock.

Router# configure terminal

Router(config)# network-clock input-source 150 controller T1 0/2/0

Router(config)# end

 

 

Router# show platform hardware subslot 0/2 module device networkclock

primary clock 255, secondary clock 0, ntwk_clk_selected Yes, ntwk_clk_participate Yes, current clock = 0

PLL status= 1, and cntl = 17

 

Example 3: Disabling and Enabling a Module from Participating in the Backplane Clock

In the following example, NIM 0/2 is disabled from participating in the backplane clock, using the
no network-clock synchronization participate 0/2 command. This is verified by the show platform hardware subslot slot / subslot module device networkclock command. ntwk_clk_participate = “No” indicates that the module participation is disabled.

Router# configure terminal

Router(config)# no network-clock synchronization participate 0 / 2

Router(config)# end

Router# show platform hardware subslot 0 / 2 module device networkclock

primary clock 255, secondary clock 0, ntwk_clk_selected No, ntwk_clk_participate No, current clock = 0

PLL status= 2, and cntl = 6

Then NIM 0/2 is made to participate in the backplane clock, by using the
network-clock synchronization participate 0/2 command. This is verified by the show platform hardware subslot slot / subslot module device networkclock command. ntwk_clk_participate = “Yes” indicates that the module participation is enabled.

 

Router# configure terminal

Router(config)# network-clock synchronization participate 0/2

Router(config)# end

Router# show platform hardware subslot 0/2 module device networkclock

primary clock 255, secondary clock 0, ntwk_clk_selected No, ntwk_clk_participate Yes, current clock = 0

PLL status= 2, and cntl = 6

Configuring Network Clocking with Revertive Mode

Revertive mode can be set for a clock source or reference. For example, if an original source is set to be in revertive mode and there is a failure in the original source, then the clock switches to using an alternate source. After the original clock source recovers from a failure, the clock source reverts back to this original source, independent of the condition of the alternate source.

The default value for network clock synchronization is non-revertive mode. In non-revertive mode, if a failure occurs for the original clock source, a switch to an alternate clock source occurs. This alternate clock source continues to be used, even after the original source recovers from the failure that caused the switch.

SUMMARY STEPS

1. network clock revertive

2. show network-clocks synchronization

DETAILED STEPS

 

Command
Purpose

Step 1

network clock revertive

 

Router(config)# network clock revertive

Configures revertive mode for the network clock.

Step 2

show network-clocks synchronization

 

Router# show network-clocks synchronization

Verifies that the network clock is now in revertive mode.

Example: Configuring Network Clocking with Revertive Mode

The following example starts by setting two clock sources:

  • T1 0/3/0—secondary clock source (lower priority than T1 0/2/0)
  • T1 0/2/0—primary clock source (higher priority than T1 0/3/0)

Revertive mode is set for network clocking using the network-clock revertive command for the primary clock source.

Because T1 0/2/0 has a higher priority than T1 0/3/0, T1 0/2/0 is selected as the clock source. The first
show network-clocks synchronization command in the example shows the T1 0/2/0 clock source selected and in revertive mode.

This example supposes that the primary clock source goes down after the first show network-clocks synchronization command. In this situation, T1 0/3/0 is selected as the clock source. The state of QL-IN is shown as “ QL-FAILED ” in the second show network-clocks synchronization command below.

Later, as a result of setting revertive mode, when clock source T1 0/2/0 comes back up again, the selected clock reverts to T1 0/2/0. This is shown by the third show-network-clocks synchronization command in the example. (If revertive mode had not been set, when T1 0/2/0 came back up, the clock source would stay as T1 0/3/0 and not revert to T1 0/2/0.)

 
Router# configure terminal
Router(config)# network-clock synchronization automatic
Router(config)# network-clock revertive
 
Router(config)# controller t1 0/2/0
Router(config-controller)# clock source line primary
Router(config)# network-clock input-source 1 controller t1 0/2/0
 
Router(config)# controller t1 0/3/0
Router(config-controller)# clock source line secondary
Router(config)# network-clock input-source 50 controller t1 0/3/0
 
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : Yes
 
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 1 QL-SEC NA NA
T1 0/3/0 NA NA/Dis 50 QL-SEC NA NA
 
 

(At this point, the primary clock source T1 0/2/0 becomes unavailable, e.g due to a signal failure.)

 
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : Yes
 
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/2/0 NA NA/Dis 1 QL-FAILED NA NA
*T1 0/3/0 NA NA/Dis 50 QL-SEC NA NA
 

 

(At this point, the primary clock source T1 0/2/0 becomes available again.)

Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : Yes
 
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 1 QL-SEC NA NA
T1 0/3/0 NA NA/Dis 50 QL-SEC NA NA
 
 

Configuring the Wait-to-restore Timer

Use the network-clock wait-to-restore timer command to specify how long the router waits before including a primary clock source in the clock selection process; for example, after a signal failure has affected the primary clock source.

SUMMARY STEPS

1. network clock wait-to-restore timer global

2. show network-clocks synchronization

DETAILED STEPS

 

Command
Purpose

Step 1

network clock wait-to-restore timer global

 

Router# network clock wait-to-restore 500 global

Changes the wait-to-restore timeout period. The default timer value is 300 ms.

Step 2

show network-clocks synchronization

 

 

Router# show network-clocks synchronization

Verifies the wait-to-restore timeout period has been set to the correct value.

Example: Configuring the Wait-to-restore Timer

The first part of this example is the same as shown in the “Configuring Network Clocking with Revertive Mode” section. The example starts after two clock sources have been set: T1 0/2/0 and
T1 0/3/0. T1 0/2/0 is the primary clock source—it has a higher priority than the T1 0/3/0 clock source.

Revertive mode is set for network clocking using the network-clock revertive command.

If a signal failure occurs, the system goes to hold-over (selects the “Internal” clock source) and waits for a period determined by the ‘wait-to-restore’ timer value, before switching back to the first clock source.

The show network-clocks synchronization command shows the time to be 300 seconds. Next, the wait-to-restore timeout is changed using the command network-clock wait-to-restore timer command. In this example, the wait-to-restore time is set to 500 seconds. You can configure the wait-to-restore time to any value between 0 to 86400 seconds. The default value is 300 seconds.

Entering the show network-clocks synchronization command now shows the wait-to-restore value of 500 seconds.

Router(config)# network-clock revertive
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 300 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 2 QL-SEC NA NA
T1 0/3/0 NA NA/Dis 2 QL-SEC NA NA
 
Router(config)# network-clock wait-to-restore 500 global
 
Router(config)# end
 
Router# show network-clocks synchronization
Feb 5 11:11:42.273 IST: %SYS-5-CONFIG_I: Configured from console by console
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 500 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/1/1 NA NA/Dis 50 QL-SEC NA NA
*T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
 

Configuring the Hold-off Timer

Use the network-clock hold-off timer command to specify the length of time that the router waits when a primary clock source fails before removing the primary clock source from the clock selection process.

SUMMARY STEPS

1. network clock hold-off timer global

2. show network-clocks synchronization

DETAILED STEPS

 

Command
Purpose

Step 1

network clock hold-off timer global

 

Router# network clock wait-to-restore 500 global

Changes the hold-off timeout period. The timer default value is 300 ms.

Step 2

show network-clocks synchronization

 

 

Router# show network-clocks synchronization

Verifies the hold-off timeout period has been set to the correct value.

Example: Configuring the Hold-off Timer

The show network-clocks synchronization command shows the hold-off time to be 300 seconds (the default value). The hold-off timeout is changed using the command network-clock hold-off 500 global command. Entering the show network-clocks synchronization command shows that the hold-off value is now 500 seconds.

Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 500 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/1/1 NA NA/Dis 50 QL-FAILED NA NA
*T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
Router(config)# network-clock hold-off 500 global
Router(config)# end
 
Router# show network-clocks synchronization
Feb 18 15:03:30.597 IST: %SYS-5-CONFIG_I: Configured from console by console
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 500 ms
Wait-to-restore (global) : 500 sec

 

Configuring Lockout of a Clock Source

The network clock set lockout controller command may be useful during testing and debugging.


Note To clear the lock-out on a source, use the network-clock clear lockout command.


SUMMARY STEPS

1. network clock set lockout controller [ t1|e1 ] slot / bay / port

2. show network-clocks synchronization

DETAILED STEPS

 

Command
Purpose

Step 1

network clock set lockout controller [t1|e1] slot/bay/port

 

Router# network clock set lockout controller t1 0/2/0

Sets a lockout on a controller clock source.

Step 2

show network-clocks synchronization

 

 

Router# show network-clocks synchronization

Verifies the clock has been set to revertive mode.

Example: Configuring Lockout of a Clock Source

The following example starts with a configuration in which several clock sources have different priority levels.

To start with, T1 0/1/1 is the primary clock source as shown by the first show network-clocks synchronization command. T1 0/2/0 is then locked out using the network-clock clear lockout controller command. A show network-clocks synchronization command shows the primary clock source is now T1 0/1/1. In the example, T1 0/1/1 goes down at this point. T1 0/2/0 is not selected as the primary clock source—Internal is selected instead, as shown by another show network-clocks synchronization command. The initial primary clock source is then cleared using the network-clock clear lockout controller command. Another show network-clocks synchronization command shows that the primary clock source is now T1 0/2/0 (T1 0/1/1 is still down).

 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/1/1
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/1/1 NA NA/Dis 50 QL-SEC NA NA
T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
 
Router# network-clock set lockout controller T1 0/2/0
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/1/1
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/1/1 NA NA/Dis 50 QL-SEC NA NA
T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
Router#
Feb 4 11:34:36.288 IST: %NETCLK-6-SRC_UPD: Synchronization source T1 0/2/0 status (set lockout) is posted to all selection process.
 
(T1 0/1/1 goes down.)
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : Internal
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
*Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/1/1 NA NA/Dis 50 QL-FAILED NA NA
T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
 
Router# network-clock clear lockout controller t1 0/2/0
 
 
Router#show netw sync
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/1/1 NA NA/Dis 50 QL-FAILED NA NA
*T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
Router#
 
 

Configuring Network Clocking with Force Switching

Instead of configuring using the set lockout controller command, you can force the network clock source to change to another clock source using the network-clock switch force controller command, irrespective of whether the source is available, and within range.

For example, this command is useful when you want to remove the module of the first controller for maintenance purposes. Use the network-clock switch force command to forcefully select another clock source.

Another command that performs the same function as network-clock switch force controller is the network-clock switch manual controller command. This command manually selects a synchronization source. The following example shows how to configure force switching:

Router# network-clock switch force controller t1 0/3/0 t0

Use the network-clock clear switch controller-id command to clear the effect of either a previous network-clock switch force controller command or a network-clock switch manual controller command.

SUMMARY STEPS

1. network clock force controller [t1|e1] slot / bay / port

2. show network-clocks synchronization

DETAILED STEPS

 

Command
Purpose

Step 1

network clock force controller [t1|e1] slot/bay/port

 

Router# network clock force controller t1 0/3/0 t0

Forces the specified controller clock source to be the primary clock source.

Step 2

show network-clocks synchronization

 

 

Router# show network-clocks synchronization

Verifies the primary clock source has been set to the required controller.

Example: Configuring Network Clocking with Force Switching

The following example starts with a configuration in which several clock sources have different priority levels.

The command network-clock switch force controller [ t1/e1 ] slot / bay / port
switches the network clock source to a second priority clock source. You can verify that the primary clock source is now controller T1 0/3/0 using the show network-clocks synchronization command. The switch is then cleared using the network-clock clear switch t0 command.

Router# network-clock switch force controller t1 0/2/0
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/1/1
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
 
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
*T1 0/1/1 NA NA/Dis 50 QL-SEC NA NA
T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
 
 
Router# network-clock switch force controller T1 0/2/0 t0
 
 
Router# show network-clocks synchronization
Symbols: En - Enable, Dis - Disable, Adis - Admin Disable
NA - Not Applicable
* - Synchronization source selected
# - Synchronization source force selected
& - Synchronization source manually switched
 
Automatic selection process : Enable
Equipment Clock : 2048 (EEC-Option1)
Clock Mode : QL-Disable
ESMC : Disabled
SSM Option : 1
T0 : T1 0/2/0
Hold-off (global) : 300 ms
Wait-to-restore (global) : 0 sec
Tsm Delay : 180 ms
Revertive : No
 
Nominated Interfaces
 
Interface SigType Mode/QL Prio QL_IN ESMC Tx ESMC Rx
Internal NA NA/Dis 251 QL-SEC NA NA
T1 0/1/1 NA NA/Dis 50 QL-SEC NA NA
#T1 0/2/0 NA NA/Dis 150 QL-SEC NA NA
 
Router# network-clock clear switch t0
 
 

Additional References

Finding Feature Information

Your software release might not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn . An account on Cisco.com is not required.

Related Documents

 

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Standards

 

Standard
Title

None

MIBs

 

MIB
MIBs Link

None

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at this URL:

http://www.cisco.com/go/mibs

RFCs

 

RFC
Title

None

Technical Assistance

 

Description
Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for Network Synchronization

Table 1 lists the features in this module and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn . An account on Cisco.com is not required.

Another similar feature (Network Synchronization Support) is used by the Cisco ASR 1000 Series. See “Synchronous Ethernet Support” in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide .


Note Table 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.


 

Table 1 Feature Information for Network Synchronization Support

Feature Name
Releases
Feature Information

Network Synchronization

Cisco IOS XE 3.12S

This feature was introduced into Cisco IOS Release 3.12 for the Cisco ISR 4451-X and ISR 4431.