Configure Frequency Synchronization

This chapter describes the Cisco IOS XR commands to configure Frequency Synchronization.

Frequency Synchronization

Frequency synchronization is the ability to distribute precision frequency around the network. Precision frequency is required in the next generation networks for applications such as circuit emulation. To achieve compliance to ITU specifications for TDM, differential method circuit emulation must be used, which requires a known, common precision frequency reference at each end of the emulated circuit.

To maintain frequency synchronization links, a set of operations messages are required. These messages ensure a node is always deriving timing from the most reliable source, and transfers information about the quality of the timing source being used to clock the frequency synchronization link.

Configuring Frequency Synchronization

Enabling Frequency Synchronization on the Router

This task describes the router-level configurations required to enable frequency synchronization.

Procedure

Step 1

configure

Step 2

frequency synchronization

Example:

RP/0/(config)# frequency synchronization

Enables frequency synchronization on the router.

Step 3

clock-interface timing-mode system

Example:

RP/0/(config-freqsync)# clock-interface timing-mode system

Sets the timing source for clock-interface output.

Step 4

quality itu-t option {1 | 2 generation {1 | 2}}

Example:

RP/0/(config-freqsync)# quality itu-t 
option 2 generation 1

(Optional) Specifies the quality level for the router. The default is option 1 .

  • option 1 —Includes PRC, SSU-A, SSU-B, SEC and DNU.

  • option 2 generation 1 —Includes PRS, STU, ST2, ST3, SMC, ST4, RES and DUS.

  • option 2 generation 2 —Includes PRS, STU, ST2, ST3, TNC, ST3E, SMC, ST4, PROV and DUS.

Note

 

The quality option configured here must match the quality option specified in the quality receive and quality transmit commands in interface frequency synchronization configuration mode.

Step 5

log selection {changes | errors}

Example:

RP/0/(config-freqsync)# log selection changes

Enables logging to frequency synchronization.

  • changes —Logs every time when there is a change to the selected source, in addition to errors.

  • errors —Logs only when there are no available frequency sources, or when the only available frequency source is the internal oscillator.

Step 6

Use one of these commands:

  • end
  • commit

Example:


RP/0/(config-freqsync)# end

or 


RP/0/(config-freqsync)# commit

Saves configuration changes.

  • When you issue the end command, the system prompts you to commit changes: 

    
Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • When you enter yes, it saves the configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • When you enter no, it exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • When you enter cancel, it leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file, and remain within the configuration session.

What to do next

Configure frequency synchronization on any interface that should participate in Frequency Synchronization.

Configuring Frequency Synchronization on an Interface

By default, there is no frequency synchronization on line interfaces. Use this task to configure an interface to participate in Frequency Synchronization.

Limitations:

  • Maximum two interfaces are monitored for frequency synchronization selection.

  • Frequency Synchronization is supported only with the following:

    Interface Type

    Controller

    Mapping Type

    Ethernet packet (LAN PHY).

    TenGigE, FortyGigE, and HundredGigE

    N/A

    Ethernet terminated non-channelized OTN.

    OTU2e and OTU3

    bmp

    Ethernet terminated non-channelized OTN.

    OTU4

    gmp

Before you begin

You must enable frequency synchronization globally on the router.

Procedure

Step 1

config

Example:

RP/0/# config

Enters configuration mode.

Step 2

interface type interface-path-id

Example:

RP/0/(config)# interface tenGigE0/1/0/1

Enters interface configuration mode.

Step 3

frequency synchronization

Example:

RP/0/(config-if)# frequency synchronization

Enters interface configuration mode.

Step 4

selection input

Example:

RP/0/(config-if-freqsync)# selection input

(Optional) Specifies the interface as a timing source to be passed to the selection algorithm.

Step 5

priority priority-value

Example:

RP/0/(config-if-freqsync)# priority 100

(Optional) Configures the priority of the frequency source on a controller or an interface. Values can range from 1 (highest priority) to 254 (lowest priority). The default value is 100.

This command is used to set the priority for an interface . The priority is used in the clock-selection algorithm to choose between two sources that have the same quality level (QL). Lower priority values are preferred.

Step 6

wait-to-restore minutes

Example:

RP/0/(config-if-freqsync)# wait-to-restore 3

(Optional) Configures the wait-to-restore time, in minutes, for frequency synchronization on an interface. This is the amount of time after the interface comes up before it is used for synchronization. Values can range from 0 to 12. The default value is 5.

Step 7

ssm disable

Example:

RP/0/(config-if-freqsync)# ssm disable
(Optional) Disables Synchronization Status Messages (SSMs) on the interface.
  • For frequency synchronization interfaces, this disables sending ESMC packets, and ignores any received ESMC packets.

Step 8

quality transmit {exact | highest | lowest} itu-t option ql-option

Example:

RP/0/(config-clk-freqsync)# quality transmit 
highest itu-t option 1 prc

(Optional) Adjusts the QL that is transmitted in SSMs.

  • exact ql —Specifies the exact QL to send, otherwise DNU will be send.

  • highest ql —Specifies an upper limit on the received QL. The received QL will be used if the received value is higher than this specified QL.

  • lowest ql —Specifies a lower limit on the received QL. DNU will be used if the received value is lower than this specified QL.

The quality option specified in this command must match the globally-configured quality option in the quality itu-t option command.

Step 9

quality receive {exact | highest | lowest} itu-t option ql-option

Example:

RP/0/(config-clk-freqsync)# quality receive 
highest itu-t option 1 prc

(Optional) Adjusts the QL value that is received in SSMs, before it is used in the selection algorithm.

  • exact ql —Specifies the exact QL to send, otherwise DNU will be send.

  • highest ql —Specifies an upper limit on the received QL. The received QL will be used if the received value is higher than this specified QL.

  • lowest ql —Specifies a lower limit on the received QL. DNU will be used if the received value is lower than this specified QL.

The quality option specified in this command must match the globally-configured quality option in the quality itu-t option command.

Step 10

Use one of these commands:

  • end
  • commit

Example:


RP/0/(config-if-freqsync)# end

or 


RP/0/(config-if-freqsync)# commit

Saves configuration changes.

Configuring Frequency Synchronization on a Clock Interface

To enable a clock interface to be used as frequency input or output, you must configure the port parameters and frequency synchronization, as described in this task.

Note

The configuration on clock interfaces must be the same for corresponding clock interfaces across all RP's to avoid changes in frequency synchronization behavior in the event of an RP switchover.

Procedure

Step 1

configure

Step 2

Perform to configure a clock interface.

Step 3

ics

Example:

RP/0/(config)# ics

Enables chassis synchronization.

Step 4

frequency synchronization

Example:


RP/0/(config-clock-if)# frequency synchronization
RP/0/(config-clk-freqsync)#

Enters clock interface frequency synchronization mode to configure frequency synchronization parameters.

Note

 

The remaining steps in this task are the same as those used to configure the interface frequency synchronization.

Step 5

selection input

Example:

RP/0/(config-if-freqsync)# selection input

(Optional) Specifies the interface as a timing source to be passed to the selection algorithm.

Step 6

priority priority-value

Example:

RP/0/(config-if-freqsync)# priority 100

(Optional) Configures the priority of the frequency source on a controller or an interface. Values can range from 1 (highest priority) to 254 (lowest priority). The default value is 100.

This command is used to set the priority for an interface . The priority is used in the clock-selection algorithm to choose between two sources that have the same quality level (QL). Lower priority values are preferred.

Step 7

wait-to-restore minutes

Example:

RP/0/(config-if-freqsync)# wait-to-restore 3

(Optional) Configures the wait-to-restore time, in minutes, for frequency synchronization on an interface. This is the amount of time after the interface comes up before it is used for synchronization. Values can range from 0 to 12. The default value is 5.

Step 8

ssm disable

Example:

RP/0/(config-if-freqsync)# ssm disable
(Optional) Disables Synchronization Status Messages (SSMs) on the interface.
  • For frequency synchronization interfaces, this disables sending ESMC packets, and ignores any received ESMC packets.

Step 9

quality transmit {exact | highest | lowest} itu-t option ql-option

Example:

RP/0/(config-clk-freqsync)# quality transmit 
highest itu-t option 1 prc

(Optional) Adjusts the QL that is transmitted in SSMs.

  • exact ql —Specifies the exact QL to send, otherwise DNU will be send.

  • highest ql —Specifies an upper limit on the received QL. The received QL will be used if the received value is higher than this specified QL.

  • lowest ql —Specifies a lower limit on the received QL. DNU will be used if the received value is lower than this specified QL.

The quality option specified in this command must match the globally-configured quality option in the quality itu-t option command.

Step 10

quality receive {exact | highest | lowest} itu-t option ql-option

Example:

RP/0/(config-clk-freqsync)# quality receive 
highest itu-t option 1 prc

(Optional) Adjusts the QL value that is received in SSMs, before it is used in the selection algorithm.

  • exact ql —Specifies the exact QL to send, otherwise DNU will be send.

  • highest ql —Specifies an upper limit on the received QL. The received QL will be used if the received value is higher than this specified QL.

  • lowest ql —Specifies a lower limit on the received QL. DNU will be used if the received value is lower than this specified QL.

The quality option specified in this command must match the globally-configured quality option in the quality itu-t option command.

Step 11

Use one of these commands:

  • end
  • commit

Example:


RP/0/(config-if-freqsync)# end

or 


RP/0/(config-if-freqsync)# commit

Saves configuration changes.

  • When you issue the end command, the system prompts you to commit changes: 

    
Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • When you enter yes, it saves the changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • When you enter no, it exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • When you enter cancel, it leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file, and remain within the configuration session.

Verifying the Frequency Synchronization Configuration

After performing the frequency synchronization configuration tasks, use this task to check for configuration errors and verify the configuration.

Procedure

Step 1

show frequency synchronization configuration-errors

Example:


RP/0/# show frequency synchronization configuration-errors

  RP/0/RP0:ios#sh frequency synchronization configuration-errors 
  Tue Aug  2 05:59:14.516 UTC 
  Node 0/RP0:

==============
    interface TenGigE0/1/0/2 frequency synchronization
* Frequency synchronization is enabled on this interface, but isn't enabled globally.
RP/0/RP0:ios#

Displays any errors that are caused by inconsistencies between shared-plane (global) and local-plane (interface) configurations. There are two possible errors that can be displayed:

  • The QL option configured on some interface does not match the global QL option. Under an interface (line interface), the QL option is specified using the quality transmit and quality receive commands. The value specified must match the value configured in the global quality itu-t option command, or match the default (option 1) if the global quality itu-t option command is not configured.

Once all the errors have been resolved, meaning there is no output from the command, continue to the next step.

Step 2

show frequency synchronization interfaces brief

Example:

RP/0/# show frequency synchronization interfaces brief

Flags:  > - Up                D - Down              S - Assigned for selection
        d - SSM Disabled      x - Peer timed out    i - Init state
        s - Output squelched
Fl   Interface                QLrcv QLuse Pri QLsnd Output driven by
==== ======================== ===== ===== === ===== ========================
>S   TenGigE0/2/0/7           ST3   ST3   100 PRS   TenGigE0/13/0/7
>S   TenGigE0/2/0/8           ST3   ST3   100 PRS   TenGigE0/13/0/7
>    TenGigE0/13/0/5          PRS   Fail  100 PRS   TenGigE0/13/0/7
>    TenGigE0/13/0/6          PRS   Fail  100 PRS   TenGigE0/13/0/7
>S   TenGigE0/13/0/7          PRS   PRS   100 DUS   TenGigE0/13/0/7
>S   TenGigE0/13/0/8          ST3   ST3   100 PRS   TenGigE0/13/0/7
D    HundredGigE0/13/0/0      Fail  Fail  100 PRS   TenGigE0/13/0/7

Verifies the configuration. Note the following points:

  • All line interface that have frequency synchronization configured are displayed.

  • Sources that have been nominated as inputs (in other words, have selection input configured) have ‘S’ in the Flags column; sources that have not been nominated as inputs do not have ‘S’ displayed.

    Note

     

    Internal oscillators are always eligible as inputs.

  • ‘>’ or ‘D’ is displayed in the flags field as appropriate.

If any of these items are not true, continue to the next step.

Step 3

show frequency synchronization interfaces node-id

Example:


RP/0/# show frequency synchronization interfaces

Interface FortyGigE0/7/0/2 (unknown)
  Wait-to-restore time 0 minutes
  SSM Enabled
  Input:
    Down - not assigned for selection
    Supports frequency
  Output:
    Selected source: None
    Effective QL: DNU
  Next selection points: LC7_ING_SEL

Investigates issues within individual interfaces.

Step 4

show processes fsyncmgr location node-id

Example:


RP/0/# show processes fsyncmgr location 0/0/CPU0

                  Job Id: 134
                     PID: 30202
         Executable path: /pkg/bin/fsyncmgr
              Instance #: 1
              Version ID: 00.00.0000
                 Respawn: ON
           Respawn count: 1
  Max. spawns per minute: 12
            Last started: Mon Mar  9 16:30:43 2009
           Process state: Run
           Package state: Normal
       Started on config: cfg/gl/freqsync/g/a/enable
                    core: MAINMEM 
               Max. core: 0
               Placement: None
            startup_path: /pkg/startup/fsyncmgr.startup
                   Ready: 0.133s
        Process cpu time: 1730768.741 user, -133848.-361 kernel, 1596920.380 total
  --------------------------------------------------------------------------------

Verifies that the fsyncmgr process is running on the appropriate nodes.

Step 5

show frequency synchronization clock-interfaces

Example:


RP/0/#show frequency synchronization clock-interfaces

Node 0/RP0:
==============
Clock interface Sync0 (Down: NONE)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input:
      Down - not assigned for selection
      Last received QL: None
      Supports frequency
    Output is disabled
  Next selection points: T0_SEL

  Clock interface Sync1 (Down: NONE)
    Wait-to-restore time 0 minutes
    SSM supported and enabled
    Input is disabled
    Output:
      Selected source: None
      Effective QL: DNU
  Next selection points: None

  Clock interface Sync2 (Down: NONE)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input:
      Down - not assigned for selection
      Last received QL: None
      Supports frequency
    Output is disabled
  Next selection points: T0_SEL

  Clock interface Sync3 (Down: NONE)
    Wait-to-restore time 0 minutes
    SSM supported and enabled
    Input is disabled
    Output:
      Selected source: None
      Effective QL: DNU
  Next selection points: None

  Clock interface Internal0 (Up)
    Assigned as input for selection
    Input:
      Default QL: None
      Effective QL: Failed, Priority: 255, Time-of-day Priority 255
      Supports frequency
  Next selection points: T0_SEL T4_SEL

Step 6

show frequency synchronization clock-interfaces brief

Example:


RP/0/#show frequency synchronization clock-interfaces brief

Flags:  > - Up                D - Down              S - Assigned for selection
        d - SSM Disabled      s - Output squelched  L - Looped back
Node 0/RP0:
==============
  Fl    Clock Interface     QLrcv  QLuse  Pri QLsnd  Output driven by
  ===== =================== ====== ====== === ====== ========================
  D     Sync0               None   Fail   100 n/a    n/a                     
  D     Sync1               n/a    n/a    n/a DNU    None                    
  D     Sync2               None   Fail   100 n/a    n/a                     
  D     Sync3               n/a    n/a    n/a DNU    None                    
  DS    Internal0           n/a    Fail   255 n/a    n/a

Step 7

show frequency synchronization clock-interfaces

Example:


RP/0/#show frequency synchronization clock-interfaces

Node 0/RP0:
==============
  Clock interface Sync0 (Unknown state)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input:
      Down - not assigned for selection
      Last received QL: None
      Supports frequency
    Output is disabled
  Next selection points: T0_SEL

  Clock interface Sync1 (Unknown state)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input is disabled
    Output:
      Selected source: None
      Effective QL: DNU
  Next selection points: None

  Clock interface Sync2 (Unknown state)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input:
      Down - not assigned for selection
      Last received QL: None
      Supports frequency
    Output is disabled
  Next selection points: T0_SEL

  Clock interface Sync3 (Unknown state)
    Wait-to-restore time 5 minutes
    SSM supported and enabled
    Input is disabled
    Output:
      Selected source: None
      Effective QL: DNU
  Next selection points: None

  Clock interface Internal0 (Unknown state)
    Assigned as input for selection
    Input:
      Default QL: None
      Effective QL: Failed, Priority: 255, Time-of-day Priority 255
      Supports frequency
  Next selection points: T0_SEL T4_SEL

Step 8

show controllers timing controller clock

Example:


RP/0/#show controllers timing controller clock

SYNCEC Clock-Setting: 

          Port 0          Port 1          Port 2          Port 3
Config     : No             Yes            No             Yes            
BITS Mode  : -              E1             -              E1             
Framing    : -              CRC4           -              CRC4           
Linecoding : -              AMI            -              AMI            
Submode    : -              Sa4            -              Sa4            
Shutdown   : No             No             No             No             
Direction  : RX             TX             RX             TX             
QL Option  : O1             O1             O1             O1             
RX_ssm     : -              -              -              -              
TX_ssm     : -              SEC            -              SEC            
If_state   : ADMIN_DOWN     DOWN           ADMIN_DOWN     DOWN