Cisco ME-3600X-24CX Series Switch Chassis Configuration Guide, Release 15.2(4)S
Configuring Clocking and Timing
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Configuring Clocking and Timing

Table Of Contents

Configuring Clocking and Timing

Network Clocking Overview

Precision Timing Protocol (PTP)

Clock Synchronization

Synchronous Ethernet

Synchronous Ethernet ESMC and SSM

Configuring Clocking and Timing

Configuring PTP Clocking

Prerequisites for Configuring PTP Clocking

Configuring an Ordinary Clock

Configuring a Master Ordinary Clock

Configuring a Slave Ordinary Clock

Configuring a Boundary Clock

Configuring PTP Input and Output

Configuration Examples

Configuring Synchronous Ethernet

Configuring an External Clock Source

Configuring Synchronous Ethernet ESMC and SSM

Verifying Clock-Related Settings

Clocking Sample Configurations


Configuring Clocking and Timing


Clock synchronization is important for a variety of applications, including synchronization of radio cell towers. While legacy TDM protocols incorporate timing features, packet-switched networks such as Ethernet do not natively include these features. The Cisco ME 3600X 24CX Series Switch supports legacy TDM technologies while supporting a variety of technologies that distribute clocking information over packet-switched networks.

The following sections describe the clocking and timing features available on the Cisco ME 3600X 24CX Series Switch.

Network Clocking Overview

Configuring Clocking and Timing

Clocking Sample Configurations

Network Clocking Overview

Clocking is typically distributed from the core network outward to the BTS or Node B at the network edge. The Cisco ME 3600X 24CX Series Switch receives and transmits clocking information using any of the following ports:

T1/E1

GigabitEthernet

BITS/SYNC port

1PPS

10Mhz

ToD

The Cisco ME 3600X 24CX Series Switch supports the following clocking types:

Precision Timing Protocol (PTP)

Synchronous Ethernet

Precision Timing Protocol (PTP)

The Cisco ME 3600X 24CX Series Switch supports the Precision Time Protocol (PTP) as defined by the IEEE 1588-2008 standard. PTP provides for accurate time synchronization on over packet-switched networks. Nodes within a PTP network can act in one of the following roles:

Ordinary clock—An ordinary clock is a 1588 clock with a single PTP port that can serve in one of the following roles:

Master mode—Distributes timing information over the network to one or more slave clocks, thus allowing the slave to synchronize its clock to the master.

Slave mode—Synchronizes its clock to a master clock. You can enable slave clocking on up to two interfaces simultaneously in order to connect to two different master clocks.

Boundary clock—The device participates in selecting the best master clock and can act as the master clock if no better clocks are detected.


Note The Cisco ME 3600X 24CX Series Switch does not currently act as a transparent clock.

The 1588-2008 standard defines other clocking devices that are not described here.



Note When a shut/no shut is carried on the loopback interface, the PTP port is deleted and recreated. This causes the PTP counters to reset.


Clock Synchronization

PTP master devices periodically launch an exchange of messages with slave devices to help each slave clock recompute the offset between its clock and the master clock. Periodic clock synchronization mitigates any drift between the master and slave clocks.

Synchronous Ethernet

Synchronous Ethernet is a timing technology that allows the Cisco ME 3600X 24CX Series Switch switch to transport frequency information over Ethernet. Because frequency is embedded in Ethernet packets, synchronous Ethernet must be supported by each network element in the synchronization path. Synchronous Ethernet is defined in the ITU-T G.781, G.8261, G.8262, and G.8264, Telcordia GR-253-CORE, and Telcordia GR-1244-CORE standards.

Synchronous Ethernet ESMC and SSM

The Cisco ME 3600X 24CX Series Switch supports Ethernet Synchronization Message Channel (ESMC) and Synchronization Status Message (SSM) to provide clock synchronization on Synchronous Ethernet. For more information about Ethernet ESMC and SSM, see Chapter 5 "Configuring Clocking and Timing."


Note SSM is only supported on BITS interface.


Configuring Clocking and Timing

The Cisco ME 3600X 24CX Series Switch switch supports the following network clocking types:

Precision Time Protocol (PTP)—Clocking and clock recovery based on the IEEE 1588-2008 standard; allows the Cisco ME 3600X 24CX Series Switch switch to receive clocking from another PTP-enabled device or provide clocking to a PTP-enabled device. To configure PTP clocking, see Configuring PTP Clocking.

Synchronous Ethernet—Allows the network to transport frequency and time information over Ethernet. To configure synchronous Ethernet, see Configuring Synchronous Ethernet.

Verifying Clock Settings—To verify a clocking configuration, see Verifying Clock-Related Settings.

Configuring PTP Clocking

This section describes how to configure PTP-based clocking on the Cisco ME 3600X 24CX Series Switch.

Prerequisites for Configuring PTP Clocking

Configuring an Ordinary Clock

Configuring a Boundary Clock


Note The settings shown in this section are an example only; you must determine the appropriate PTP settings based upon your network clocking design.



Note The configuration sections describing the 1PPS and 10Mhz timing ports only apply to the Cisco ME 3600X-24CX switch.


Prerequisites for Configuring PTP Clocking

To enable PTP v2 Ordinary Slave Clock, one of the following base licenses must be installed on the switch:

Metro IP Access

Advanced Metro IP Access

An additional 1588 feature license is required to enable the Ordinary master clock and boundary clock functionality.

You must reload the switch to activate the license.

Configuring an Ordinary Clock

The followign sections describe how to cofigure the switch as an ordinary clock.

Configuring a Master Ordinary Clock

Configuring a Slave Ordinary Clock

Configuring a Master Ordinary Clock

Enter the following commands to configure the switch to act as a master ordinary clock:

 
Command
Purpose

Step 1 

enable

Example:

Switch> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Switch# configure terminal

Enters global configuration mode.

Step 3 

ptp clock {ordinary | boundary | e2e-transparent} domain domain-number [hybrid]

Example:

Switch(config)# ptp clock ordinary domain 0

Configures the PTP clock. You can create the following clock types:

·Ordinary—A 1588 clock with a single PTP port that can operate in Master or Slave mode.

·Boundary—Participates in selecting the best master clock and can act as the master clock if no better clocks are detected.

Note The transparent clock and hybrid mode are not supported on the Cisco ME 3600X 24CX switch.

Step 4 

priority1 priorityvalue

Example:

Switch(config-ptp-clk)# priority1 128

Sets the preference level for a clock. Slave devices use the priority1 value when selecting a master clock: a lower priority1 value indicates a preferred clock. The priority1 value is considered above all other clock attributes.

Valid values are from 0-255. The default value is 128.

Step 5 

priority2 priorityvalue

Example:

Switch(config-ptp-clk)# priority2 128

Sets a secondary preference level for a clock. Slave devices use the priority2 value when selecting a master clock: a lower priority2 value indicates a preferred clock. The priority2 value is considered only when the router is unable to use priority1 and other clock attributes to select a clock.

Valid values are from 0-255. The default value is 128.

Step 6 

clock-port port-name {master | slave}

Example:

Switch(config-ptp-clk)# clock-port Master master

Router(config-ptp-port)#

Sets the clock port to PTP master or slave mode; in master mode, the port exchanges timing packets with PTP slave devices.

Step 7 

transport ipv4 unicast interface interface-type interface-number [negotiation]

Example:

Switch(config-ptp-port)# transport ipv4 unicast interface loopback 0 negotiation

Sets port transport parameters.

The negotiation keyword configures the router to discover a PTP master clock from all available PTP clock sources.

Note PTP redundancy is supported only on unicast negotiation mode.

Step 8 

clock-destination destination-address

Example:

Switch(config-ptp-port)# clock-destination 8.8.8.1

Specifies the IP address of a clock destination when the router is in PTP master mode.

The destination-address parameter is required in master mode.

The destination-address parameter is the loopback address of the slave clock.

Note The clock-destination command is not applicable in unicast negotiation mode.

Step 9 

sync interval value

Example:

Switch(config-ptp-port)# sync interval 1

Specifies the sync interval.

Step 10 

announce timeout value

Example:

Switch(config-ptp-port)# announce timeout 8

Specifies the number of PTP announcement intervals before the session times out. Valid values are 1-10.

Step 11 

exit

Example:
Switch(config)# exit

Exits configuration mode.

Configuring a Slave Ordinary Clock

Follow these steps to configure the switch to act as a slave ordinary clock.

 
Command
Purpose

Step 1 

Switch# configure terminal

Enter configuration mode.

Step 2 

ptp clock {ordinary | boundary | e2e-transparent} domain domain-number [hybrid]

Example:
Switch(config)# ptp clock ordinary 
domain 0

Configures the PTP clock. You can create the following clock types:

Ordinary—A 1588 clock with a single PTP port that can operate in Master or Slave mode.

Boundary—Participates in selecting the best master clock and can act as the master clock if no better clocks are detected.

Note The transparent clock and hybrid mode are not supported on the Cisco ME 3600X 24CX switch.

Step 3 

priority1 priorityvalue

Example:

Switch(config-ptp-clk)# priority1 128

Sets the preference level for a clock. Slave devices use the priority1 value when selecting a master clock: a lower priority1 value indicates a preferred clock. The priority1 value is considered above all other clock attributes.

Valid values are from 0-255. The default value is 128.

Step 4 

priority2 priorityvalue

Example:

Switch(config-ptp-clk)# priority2 128

Sets a secondary preference level for a clock. Slave devices use the priority2 value when selecting a master clock: a lower priority2 value indicates a preferred clock. The priority2 value is considered only when the router is unable to use priority1 and other clock attributes to select a clock.

Valid values are from 0-255. The default value is 128.

Step 5 

clock-port port-name {master | slave}

Example:

Switch(config-ptp-clk)# clock-port Slave slave

Sets the clock port to PTP master or slave mode; in slave mode, the port exchanges timing packets with a PTP master clock.

Step 6 

transport ipv4 unicast interface interface-type interface-number [negotiation]

Example:

Switch(config-ptp-port)# transport ipv4 unicast interface loopback 0 negotiation

Sets port transport parameters.

The negotiation keyword configures the router to discover a PTP master clock from all available PTP clock sources.

Step 7 

clock-source source-address

Example:
Switch(config-ptp-port)# 
clock-source 8.8.8.1 

Specifies the address of a PTP master clock.

Step 8 

sync interval value

Example:

Switch(config-ptp-port)# sync interval 1

Specifies the sync interval.

Step 9 

announce timeout value

Example:
Switch(config-ptp-port)# announce 
timeout 8

Specifies the number of PTP announcement intervals before the session times out. Valid values are 1-10.

Step 10 

delay-req interval interval

Example:
Switch(config-ptp-port)# delay-req 
interval 1

Configures the minimum interval allowed between PTP delay-request messages when the port is in the master state.

The intervals are set using log base 2 values, as follows:

3—1 packet every 8 seconds

2—1 packet every 4 seconds

1—1 packet every 2 seconds

0—1 packet every second

-1—1 packet every 1/2 second, or 2 packets per second

-2—1 packet every 1/4 second, or 4 packets per second

-3—1 packet every 1/8 second, or 8 packets per second

-4—1 packet every 1/16 seconds, or 16 packets per second.

-5—1 packet every 1/32 seconds, or 32 packets per second.

-6—1 packet every 1/64 seconds, or 64 packets per second.

-7—1 packet every 1/128 seconds, or 128 packets per second.

Step 11 

Router(config-ptp-port)# end

Exit configuration mode.

Configuring a Boundary Clock

Follow these steps to configure the switch to act as a boundary clock.

 
Command
Purpose

Step 1 

Switch# configure terminal

Enter configuration mode.

Step 2 

Router(config)# ptp clock {ordinary | boundary | e2e-transparent} domain domain-number [hybrid]

Example:
Switch(config)# ptp clock boundary 
domain 0

Configures the PTP clock. You can create the following clock types:

Ordinary—A 1588 clock with a single PTP port that can operate in Master or Slave mode.

Boundary—Participates in selecting the best master clock and can act as the master clock if no better clocks are detected.

Note The transparent clock and hybrid mode are not supported on the Cisco ME 3600X 24CX switch.

Step 3 

clock-port port-name {master | slave}

Example:
Switch(config-ptp-clk)# clock-port 
SLAVE slave

Sets the clock port to PTP master or slave mode; in slave mode, the port exchanges timing packets with a PTP master clock.

Step 4 

transport ipv4 unicast interface interface-type interface-number [negotiation]

Example:
Switch(config-ptp-port)# transport 
ipv4 unicast interface Loopback 0 
negotiation

Sets port transport parameters.

The negotiation keyword configures the router to discover a PTP master clock from all available PTP clock sources.

Step 5 

clock-source source-address [priority]

Example:
Switch(config-ptp-port)# clock 
source 133.133.133.133

Specifies the address of a PTP master clock. You can specify a priority value as follows:

No priority value—Assigns a priority value of 0.

1—Assigns a priority value of 1.

2—Assigns a priority value of 2, the highest priority.

Note This command is optional if PTP is configured in unicast negotiation mode.

Step 6 

clock-port port-name {master | slave}

Example:
Switch(config-ptp-port)# clock-port 
Master master

Sets the clock port to PTP master or slave mode; in master mode, the port exchanges timing packets with PTP slave devices.

Note The master clock-port does not establish a clocking session until the slave clock-port is phase aligned.

Step 7 

transport ipv4 unicast interface interface-type interface-number [negotiation]

Example:
Switch(config-ptp-port)# transport 
ipv4 unicast interface Loopback 1 
negotiation

Sets port transport parameters.

The negotiation keyword configures the router to discover a PTP master clock from all available PTP clock sources.

Step 8 

Switch(config-ptp-port)# end

Exit configuration mode.

Configuring PTP Input and Output

You can use the 1pps, 10Mhz and BITS timing ports on the Cisco ME 3600X-24CX to do the following:

Provide or receive 1PPS time of day messages

Provide output clocking at 10Mhz, 2.048Mhz, and 1.544Mhz

Receive input clocking at 10Mhz, 2.048Mhz, and 1.544Mhz


Note This section applies only to the Cisco ME 3600X-24CX.


The following section describes how to configure time of day messages, output clocking, and input clocking in master clock mode.

If you want to configure input clocking using the 10Mhz or BITS timing port, use the following command:

Use the network-clock input-source command to enable input clocking at 10Mhz, 2.048Mhz, or 1.544Mhz.

Switch(config)# network-clock input-source 2 external 1/0/0 10m
 
   

Input clocking applies when the switch is in master mode.

To configure output clocking using the 10Mhz or BITS timing port, use the network-clock output-source command to specify 10Mhz, 2.048Mhz, or 1.544Mhz output. Use this command when the switch is in slave mode.

Switch(config)# network-clock output-source system 2 external 1/0/0 10m
 
   

To configure the switch to send time of day messages using the 1PPS port, use the output 1pps command. Use the input or output parameters to specify the direction.

Switch(config)# ptp clock ordinary domain 0
Switch(config-ptp-clk)# output 1pps 0/0 
 
   

Note Input 1pps is only supported in master mode. Output 1pps configuration is supported in slave or boundary clock mode.


To configure the time of day message format, use the tod command.

Switch(config)# ptp clock ordinary domain 0
Switch(config-ptp-clk)# tod 0/0 ubx 
 
   
 
   

Configuration Examples

Use commands below for input and output.

network-clock input-source 2 external 1/0/0 10m

Switch(config)#network-clock input-source 2 external 1/0/0 ?   
  10m    10 MHz signal mode
  2048k  Option 1 2048kHz on BITS/SSU port
  e1     E1 Signal Mode
 
   

Tod and 1pps configuration.

Master:

Switch(config)#ptp clock ordinary domain 0
Switch(config-ptp-clk)#input 1pps 0/0 
Switch(config-ptp-clk)#tod 0/0 ?
  cisco  Set TOD format to CISCO
  nmea   Set TOD format to NMEA ZDA
  ntp    Set TOD format to NTP
  ubx    Set TOD format to UBX
 
   

Slave:

Switch(config)#ptp clock ordinary domain 0
Switch(config-ptp-clk)#output 1pps 0/0 ?
  offset       1PPS output offset
  pulse-width  1PPS output pulse width
Switch(config-ptp-clk)#tod 0/0 ?
  cisco  Set TOD format to CISCO
  nmea   Set TOD format to NMEA ZDA
  ntp    Set TOD format to NTP
  ubx    Set TOD format to UBX

Note To see further configuration examples for input and output timing, see Clocking Sample Configurations.


Configuring Synchronous Ethernet

The following sections describe how to configure synchronous Ethernet timing on the Cisco ME 3600X 24CX Series Switch switch.


Note Hybrid mode is not supported therefore, network-clock input-source command cannot be configured with Ordinary Slave mode or Boundary Clock mode.


Configuring an External Clock Source

To configure an external clock source using Synchronous Ethernet, use the network-clock input-source priority external 1/0/0 {{E1 {crc4 | cas |fas}} {T1 {d4 | sf | esf}} } command.

Switch(config)# network-clock input-source 1 external 1/0/0 
 
   

Configuring Synchronous Ethernet ESMC and SSM

For instructions on how to configure synchronous Ethernet Synchronization Message Channel (ESMC)and Synchronization Status Message (SSM), see Configuring Synchronous Ethernet in Cisco ME 3800x and ME 3600x Switch Software Configuration Guide

Verifying Clock-Related Settings

Use the following commands to verify the clock settings:

show ptp clock dataset

show ptp port dataset

show ptp clock running

show platform ptp all

For more information about these commands, see the Cisco ME 3800X and ME 3600X Switch Command Reference, Release 15.2(4)S.

Clocking Sample Configurations

The following sections show a sample configurations for clocking features on the switch.

Ordinary Clock—Slave

ptp clock ordinary domain 0
clock-port Slave slave
transport ipv4 unicast interface loopback 0 negotiation
clock-source 8.8.8.1
sync interval 1
announce timeout 7 
delay-req interval 3
 
   

Ordinary Clock—Master

ptp clock ordinary domain 0
 clock-port Master master
  transport ipv4 unicast interface loopback 0 negotiation
 
   

Unicast Configuration—Slave Mode

ptp clock ordinary domain 0
clock-port Slave slave
transport ipv4 unicast interface loopback 0
clock-source 8.8.8.1 
 
   

Unicast Configuration—Master Mode

ptp clock ordinary domain 0
clock-port Master master
transport ipv4 unicast interface loopback 0
clock-destination 8.8.8.2
sync interval 1
announce interval 2 
 
   

Unicast Negotiation—Slave

ptp clock ordinary domain 0
   priority1 2
   priority2 4
   clock-port Slave slave
      transport ipv4 unicast interface Loopback0 negotiation
      clock-source 8.8.8.1
      sync interval 3
      announce timeout 7
      delay-req interval 3
 
   

Unicast Negotiation—Master

ptp clock ordinary domain 0
   priority1 4
   priority2 2
   clock-port Master master
      transport ipv4 unicast interface Loopback0 negotiation
      sync interval 3
      announce timeout 7
 
   

Boundary Clock

ptp clock boundary domain 0
   priority1 2
   priority2 4
   clock-port Slave slave
      transport ipv4 unicast interface Loopback0 negotiation
      clock-source 8.8.8.1
      sync limit 3
      announce timeout 7
      delay-req interval 3
   clock-port Master master
      transport ipv4 interface Loopback1 negotiation
      sync interval 3
      announce interval 7

Clock Selection Parameters

network-clock synchronization automatic
network-clock synchronization mode QL-enabled
network-clock input-source 1 external 1/0/0 10m
 
   

ToD/1PPS Configuration—Master

network-clock input-source 1 external 1/0/0 10m
ptp clock ordinary domain 0
tod 0/0 ntp
input 1pps 0/0
clock-port master master
transport ipv4 unicast interface loopback 0
 
   

ToD/1PPS Configuration—Slave

ptp clock ordinary domain 0
tod 0/0 ntp
output 1pps 0/0
clock-port SLA slave
transport ipv4 unicast interface loopback 0 negotiation
clock source 33.1.1.
 
   

Show Commands

Router# show ptp clock dataset ?
  current          currentDS dataset
  default          defaultDS dataset
  parent           parentDS dataset
  time-properties  timePropertiesDS dataset
 
   
 
   
Router#show ptp port dataset ?
 foreign-master  foreignMasterDS dataset
 port            portDS dataset
 
   
Router#show ptp clock running domain 0
                      PTP Ordinary Clock [Domain 0] 
         State          Ports          Pkts sent      Pkts rcvd      Redundancy Mode
         ACQUIRING      1              98405          296399         Track one
 
   
                               PORT SUMMARY
                                                                                   		 PTP 
Master
Name               Tx Mode      Role         Transport    State        Sessions     Port 
Addr
SLAVE              unicast      slave              Lo0          Slave              1           
8.8.8.8
 
   
                             SESSION INFORMATION
SLAVE [Lo0] [Sessions 1]         
 Peer addr          Pkts in    Pkts out   In Errs    Out Errs  
 8.8.8.8            296399     98405      0          0         
Router#
 
   
 
   
Router#show platform ptp all
Slave info  : [Loopback0][0x38A4766C]
--------------------------------
clock role          : SLAVE
Slave Port hdl      : 486539266
Tx Mode             : Unicast-Negotiation
Slave IP            : 4.4.4.4
Max Clk Srcs        : 1
Boundary Clock      : FALSE
Lock status         : HOLDOVER
Refcnt              : 1
Configured-Flags    : 0x7F - Clock Port Stream 
Config-Ready-Flags  : Port Stream 
-----------
PTP Engine Handle   : 0
Master IP           : 8.8.8.8
Local Priority      : 0
Set Master IP       : 8.8.8.8