Cisco ASR 9000 Series Aggregation Services Router System Management Configuration Guide, Release 4.2.x
Configuring PTP on the Cisco ASR 9000 Series Router
Downloads: This chapterpdf (PDF - 1.25MB) The complete bookPDF (PDF - 4.36MB) | Feedback

Configuring PTP on the Cisco ASR 9000 Series Router

Configuring PTP on the Cisco ASR 9000 Series Router

Precision Time Protocol (PTP) is a protocol that provides a method of distributing time around the network. PTP support is based on the IEEE 1588-2008 standard.

This module describes the tasks you need to configure PTP on the Cisco IOS XR software.

For more information about PTP on the Cisco IOS XR software and complete descriptions of the PTP commands listed in this module, see Additional References. To locate documentation for other commands that might appear in the course of running a configuration task, search online in Cisco ASR 9000 Series Aggregation Services Router Commands Master List.

Table 1 Feature History for Implementing PTP on Cisco IOS XR Software

Release

Modification

Release 4.2.0

This feature was introduced.

This module contains the following topics:

Prerequisites for Implementing PTP on Cisco IOS XR Software

You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Information About Configuring PTP

PTP Implementation

IEEE Standard 1588-2008 defines a method for distributing time around a network using the Precision Time Protocol (PTP) version 2. PTP ensures that the best available clock is selected as the source of time (the grandmaster clock) for the network and that other clocks in the network are synchronized to the grandmaster.

PTP consists of two parts:

  • The port state machine and best master clock algorithm, which provides a method to determine which ports in the network will run as master (providing time to other clocks to the network), which will run as slaves (receiving time from other clocks in the network), and which will be passive (neither master nor slave).
  • Mechanisms for slave ports to calculate the difference between the time of their own clocks and the time of their master clock. To calculate the differences, PTP uses a delay request/response mechanism and a peer delay mechanism.

The implementation of PTP on Cisco IOS XR software is designed to operate effectively in Telecommunication networks, which are different from the networks for which PTP was originally designed.

PTP is configurable on Gigabit Ethernet interfaces and link aggregation group (LAG) Ethernet bundle interfaces. PTP is not configurable on LAG Ethernet subinterfaces.

PTP Transport Media

PTP is supported over the following transport media:

  • UDP over IPv4

PTP Messages

PTP supports the following message types:

  • Sync
  • Delay-request
  • Follow-up
  • Delay-Response
  • Announce
  • Signaling
  • Management

Unicast and Multicast Messages

PTP supports the following options for unicast and multicast:

  • Unicast mode: In this mode, all PTP messages are sent as unicast messages. This is the default behavior.
  • Mixed or Multicast mode: In this mode, Announce and Sync messages are sent as multicast messages, while Signaling, Delay-Request and Delay-Response messages are only sent unicast.

Frequency and Time Selection

The selection of the source to use to synchronize the backplane clock frequency and time is made by frequency synchronization, and is outside of the scope of PTP. The Announce, Sync and Delay-Request frequencies must be the same on the master and slave.

Delay-Response Mechanism

The Delay Request-Response Mechanism, defined in section 11.3 of IEEE Std 1588-2008, is a mechanism which allows a slave ports to estimate to a good degree of accuracy the difference between its own clock-time, and the clock-time of its master. The following options are supported:

  • One-step mechanism - The timestamp for the Sync message is sent in the Sync message itself.
  • Two-step mechanism - The timestamp for the Sync message in a later Follow-Up message.

When running a port in Slave state, a router can send Delay-Request messages and handle incoming Sync, Follow-Up and Delay-Response messages. The timeout periods for both Sync and Delay-Response messages are individually configurable.

PTP Interface and Profile Configuration

If a global PTP profile is attached to an interface, its values are used as the default settings for that interface. If additional settings are configured under the interface itself, these override the defaults in the profile. If no profile is attached to an interface, the configuration on the interface is used to determine the PTP settings for the interface.

You can use either of the following approaches when configuring PTP:

  • Create a profile (or multiple profiles) containing all the default settings to use on all PTP interfaces. Override any settings that differ for particular interfaces by using the interface configuration under the interfaces themselves.
  • Configure all settings separately for each interface, without using any global profiles. Use this approach if the interfaces do not have consistent settings, or if you are configuring only a small number of PTP interfaces.

How to Configure PTP

Configuring Frequency and Quality Settings for PTP

These steps configure frequency and quality settings for PTP:

SUMMARY STEPS

    1.    configure

    2.    frequency synchronization

    3.    quality itu-t option option generation number

    4.    Use one of these commands:

    • end
    • commit


DETAILED STEPS
      Command or Action Purpose
    Step 1 configure


    Example:
    RP/0/RSP0/CPU0:router# configure
     

    Enters global configuration mode.

     
    Step 2 frequency synchronization


    Example:
    RP/0/RSP0/CPU0:router(config)# frequency synchronization
     

    Enters frequency synchronization mode.

     
    Step 3 quality itu-t option option generation number


    Example:
    RP/0/RSP0/CPU0:router(config-freqsync)# quality itu-t 
    option 2 generation 2 
    
     

    Sets ITU-T quality parameters.

     
    Step 4 Use one of these commands:
    • end
    • commit


    Example:
    RP/0/RSP0/CPU0:router(config-freqsync)# end

    or

    RP/0/RSP0/CPU0:router(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]:
      
      • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
      • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
      • Entering cancel 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.
     

    Configuring Global Profile Settings for PTP

    Use these steps to configure a global configuration profile for a PTP interface. This profile can then be assigned to any interface as required. You can override this configuration for any particular interface using configuration commands in interface PTP configuration mode. See Configuring a PTP Slave Interface or Configuring a PTP Master Interface for more information.

    SUMMARY STEPS

      1.    configure

      2.    ptp

      3.    profile name

      4.    sync frequency rate

      5.    delay-request frequency rate

      6.    Use one of these commands:

      • end
      • commit


    DETAILED STEPS
        Command or Action Purpose
      Step 1 configure


      Example:
      RP/0/RSP0/CPU0:router# configure
       

      Enters global configuration mode.

       
      Step 2 ptp


      Example:
      RP/0/RSP0/CPU0:router(config)# ptp
      
       

      Enters PTP configuration mode.

       
      Step 3 profile name


      Example:
      RP/0/RSP0/CPU0:router(config-ptp)# profile tp64
      
       

      Enters PTP profile configuration mode for the specified profile.

       
      Step 4 sync frequency rate


      Example:
      RP/0/RSP0/CPU0:router(config-ptp-profile)# sync frequency 64
       

      Configures the Sync message frequency for the profile.

       
      Step 5 delay-request frequency rate


      Example:
      RP/0/RSP0/CPU0:router(config-ptp-profile)# delay-request 
      frequency 64
       

      Sets the delay request frequency for the profile.

       
      Step 6 Use one of these commands:
      • end
      • commit


      Example:
      RP/0/RSP0/CPU0:router(config-ptp-profile)# end

      or

      RP/0/RSP0/CPU0:router(config-ptp-profile)# 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]:
        
        • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
        • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
        • Entering cancel 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.
       

      Configuring a PTP Slave Interface

      Use these steps to configure an interface to be a PTP slave:

      SUMMARY STEPS

        1.    configure

        2.    interface type interface-path-id

        3.    ptp

        4.    profile name

        5.    transport ipv4

        6.    announce timeout timeout

        7.    port state slave-only

        8.    master ipv4 address

        9.    exit

        10.    ipv4 address address mask

        11.    transceiver permit pid all

        12.    Use one of these commands:

        • end
        • commit

        13.    show run interface value


      DETAILED STEPS
          Command or Action Purpose
        Step 1 configure


        Example:
        RP/0/RSP0/CPU0:router# configure
         

        Enters global configuration mode.

         
        Step 2 interface type interface-path-id


        Example:
        RP/0/RSP0/CPU0:router(config)# interface TenGigE 0/1/0/5
         

        Enters configuration mode for a specified interface.

         
        Step 3 ptp


        Example:
        RP/0/RSP0/CPU0:router(config-if)# ptp
         

        Enters PTP configuration mode for the interface.

         
        Step 4 profile name


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# profile tp64
         

        Specifies a previously-defined configuration profile to use for this interface. See Configuring Global Profile Settings for PTP for more information. Any additional commands entered in PTP interface configuration mode override settings in this profile.

         
        Step 5 transport ipv4


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# transport ipv4
         

        Specifies that IPv4 is the transport mode for PTP messages.

         
        Step 6 announce timeout timeout


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# announce timeout 2
         

        Sets the timeout for PTP announce messages.

         
        Step 7 port state slave-only


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# port state slave-only
         

        Specifies that the port state is for a slave.

         
        Step 8 master ipv4 address


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# master ipv4 192.168.2.1
         

        Specifies the IPv4 address for the PTP master.

         
        Step 9 exit


        Example:
        RP/0/RSP0/CPU0:router(config-if-ptp)# exit
        RP/0/RSP0/CPU0:router(config-if)
         

        Exits PTP interface configuration mode.

         
        Step 10 ipv4 address address mask


        Example:
        RP/0/RSP0/CPU0:router(config-if)# ipv4 address 1.7.1.1 255.255.255.0
         

        Configures the gateway for the interface.

         
        Step 11 transceiver permit pid all


        Example:
        RP/0/RSP0/CPU0:router(config-if)# transceiver permit pid all
         

        Configures the transceiver for the interface.

         
        Step 12 Use one of these commands:
        • end
        • commit


        Example:
        RP/0/RSP0/CPU0:router(config-if)# end

        or

        RP/0/RSP0/CPU0:router(config-if)# 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]:
          
          • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
          • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
          • Entering cancel 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.
         
        Step 13 show run interface value


        Example:
        RP/0/RSP0/CPU0:router# show run interface tengige0/1/0/5
        
        Fri Aug  3 19:57:14.184 UTC
        interface TenGigE0/1/0/5
         ptp
          profile tp64
          transport ipv4
          port state slave-only
          master ipv4 1.7.1.2
          !
          announce timeout 2
         !
         ipv4 address 1.7.1.1 255.255.255.0
         transceiver permit pid all
        !
         
         

        Displays the running configuration.

         

        Configuring the Clock Interface for a PTP Master

        Use these steps to configure a clock interface for the PTP master:

        SUMMARY STEPS

          1.    configure

          2.    clock-interface sync value location node

          3.    port-parameters dti

          4.    frequency synchronization

          5.    selection input

          6.    priority number

          7.    wait-to-restore number

          8.    ssm disable

          9.    quality receive exact itu-t option number generation number PRS

          10.    Use one of these commands:

          • end
          • commit


        DETAILED STEPS
            Command or Action Purpose
          Step 1 configure


          Example:
          RP/0/RSP0/CPU0:router# configure
           

          Enters global configuration mode.

           
          Step 2 clock-interface sync value location node


          Example:
          RP/0/RSP0/CPU0:router(config)# clock-interface sync 1 
          location 0/RSP0/CPU0 
           

          Enters configuration mode for the specified clock interface.

           
          Step 3 port-parameters dti


          Example:
          RP/0/RSP0/CPU0:router(config-clock-if)# port-parameters dti
          
           

          Configures the port parameters for the clock interface.

           
          Step 4 frequency synchronization


          Example:
           
          RP/0/RSP0/CPU0:router(config-clock-if)# frequency synchronization
          
           

          Enters frequency synchronization mode for the clock interface.

           
          Step 5 selection input


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# selection input
          
           

          Configures selection input for the clock interface.

           
          Step 6 priority number


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# priority 10
          
           

          Configures priority for the clock interface.

           
          Step 7 wait-to-restore number


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# wait-to-restore 0
          
           

          Configures the wait-to-restore time for the clock interface.

           
          Step 8 ssm disable


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# ssm disable
          
           

          Disables SSM packets for the clock interface.

           
          Step 9 quality receive exact itu-t option number generation number PRS


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# quality receive 
          exact itu-t option 2 generation 2 PRS
          
           

          Configures quality settings for frequency synchronization for the clock interface.

           
          Step 10 Use one of these commands:
          • end
          • commit


          Example:
          RP/0/RSP0/CPU0:router(config-clk-freqsync)# end

          or

          RP/0/RSP0/CPU0:router(config-clk-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]:
            
            • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
            • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
            • Entering cancel 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.
           

          Configuring a PTP Master Interface

          Use these steps to configure an interface that acts as a PTP master.

          SUMMARY STEPS

            1.    configure

            2.    interface type interface-path-id

            3.    ptp

            4.    profile name

            5.    transport ipv4

            6.    announce timeout timeout

            7.    exit

            8.    ipv4 address address mask

            9.    transceiver permit pid all

            10.    Use one of these commands:

            • end
            • commit

            11.    show run interface value


          DETAILED STEPS
              Command or Action Purpose
            Step 1 configure


            Example:
            RP/0/RSP0/CPU0:router# configure
             

            Enters global configuration mode.

             
            Step 2 interface type interface-path-id


            Example:
            RP/0/RSP0/CPU0:router(config)# interface TenGigE 0/1/0/5
             

            Enters configuration mode for a specified interface.

             
            Step 3 ptp


            Example:
            RP/0/RSP0/CPU0:router(config-if)# ptp
             

            Enters PTP configuration mode for the interface.

             
            Step 4 profile name


            Example:
            RP/0/RSP0/CPU0:router(config-if-ptp)# profile tp64
             

            Specifies a previously-defined configuration profile to use for this interface. See Configuring Global Profile Settings for PTP for more information. Any additional commands entered in PTP interface configuration mode override settings in this profile.

             
            Step 5 transport ipv4


            Example:
            RP/0/RSP0/CPU0:router(config-if-ptp)# transport ipv4
             

            Specifies that IPv4 is the transport mode for PTP messages.

             
            Step 6 announce timeout timeout


            Example:
            RP/0/RSP0/CPU0:router(config-if-ptp)# announce timeout 2
             

            Sets the timeout for PTP announce messages.

             
            Step 7 exit


            Example:
            RP/0/RSP0/CPU0:router(config-if-ptp)# exit
             

            Returns to configuration mode for the interface.

             
            Step 8 ipv4 address address mask


            Example:
            RP/0/RSP0/CPU0:router(config-if)# ipv4 address 1.7.1.2 255.255.255.0
             

            Configures the gateway for the interface.

             
            Step 9 transceiver permit pid all


            Example:
            RP/0/RSP0/CPU0:router(config-if)# transceiver permit pid all
             

            Configures the transceiver for the interface.

             
            Step 10 Use one of these commands:
            • end
            • commit


            Example:
            RP/0/RSP0/CPU0:router(config-if)# end

            or

            RP/0/RSP0/CPU0:router(config-if)# 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]:
              
              • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
              • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
              • Entering cancel 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.
             
            Step 11 show run interface value


            Example:
            RP/0/RSP0/CPU0:router# show run interface Te0/1/0/5
            Fri Aug  3 13:57:44.366 PST
            interface TenGigE0/5/1/0
             ptp
              profile tp64
              transport ipv4
              announce timeout 2
             !
             ipv4 address 1.7.1.2 255.255.255.0
             transceiver permit pid all
            !
              
             

            Shows the running configuration.

             

            Configuring GPS Settings for the Grand Master Clock

            Use these steps to configure GPS settings for PTP.

            SUMMARY STEPS

              1.    configure

              2.    clock-interface sync port-number location interface-location

              3.    port-parameters

              4.    gps-input tod-format cisco pps-input rs422

              5.    exit

              6.    frequency synchronization

              7.    selection input

              8.    priority number

              9.    wait-to-restore number

              10.    ssm disable

              11.    quality receive exact itu-t option option generation number

              12.    Use one of these commands:

              • end
              • commit

              13.    show run interface value


            DETAILED STEPS
                Command or Action Purpose
              Step 1 configure


              Example:
              RP/0/RSP0/CPU0:router# configure
               

              Enters global configuration mode.

               
              Step 2 clock-interface sync port-number location interface-location


              Example:
               
              RP/0/RSP0/CPU0:router(config)# clock-interface 
              sync 2 location 0/RSP0/CPU0 
               

              Enters configuration mode for the clock interface.

               
              Step 3 port-parameters


              Example:
              RP/0/RSP0/CPU0:router(config-clock-if)# port-parameters
               

              Enters configuration mode for the port parameters.

               
              Step 4 gps-input tod-format cisco pps-input rs422


              Example:
              RP/0/RSP0/CPU0:router(config-clk-parms)# gps-input tod-format 
              cisco pps-input rs422 
               

              Configures GPS input parameters.

               
              Step 5 exit


              Example:
              RP/0/RSP0/CPU0:router(config-clk-parms)# exit
               

              Exits clock port parameter configuration mode.

               
              Step 6 frequency synchronization


              Example:
              RP/0/RSP0/CPU0:router(config-clock-if)# frequency synchronization
               

              Enters frequency synchronization mode for the clock interface.

               
              Step 7 selection input


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# selection input
               

              Configures selection input for the clock interface.

               
              Step 8 priority number


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# priority 10
              
               

              Configures priority for the clock interface.

               
              Step 9 wait-to-restore number


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# wait-to-restore 0
              
               

              Configures the wait-to-restore time for the clock interface.

               
              Step 10 ssm disable


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# ssm disable
              
               

              Disables SSM packets for the clock interface.

               
              Step 11 quality receive exact itu-t option option generation number


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# quality receive 
              exact itu-t option 2 generation 2 PRS  
               

              Configures ITU-T quality parameters.

               
              Step 12 Use one of these commands:
              • end
              • commit


              Example:
              RP/0/RSP0/CPU0:router(config-clk-freqsync)# end

              or

              RP/0/RSP0/CPU0:router(config-clk-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]:
                  
                • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.
                • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.
                • Entering cancel 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.
               
              Step 13 show run interface value


              Example:
              RP/0/RSP0/CPU0:router# show run interface Te0/1/0/5
              
              Fri Aug  3 13:57:44.366 PST
              interface TenGigE0/5/1/0
               ptp
                profile tp64
                transport ipv4
                announce timeout 2
               !
               ipv4 address 1.7.1.2 255.255.255.0
               transceiver permit pid all
              !
                
               

              Shows the running configuration.

               

              Configuration Examples for Implementing PTP

              Configuring Slave Settings: Example

              The following example shows a PTP slave configuration .

               ptp
                profile tp64
                transport ipv4
                port state slave-only
                master ipv4 1.7.1.2
                !
                announce timeout 2
               !
               ipv4 address 1.7.1.1 255.255.255.0
               transceiver permit pid all
              !
              
                

              Configuring Master Settings: Example

              This example shows a PTP master configuration .

               ptp
                profile tp64
                transport ipv4
                announce timeout 2
               !
               ipv4 address 1.7.1.2 255.255.255.0
               transceiver permit pid all
              !
                

              Configuring GPS Settings: Example

              This example shows the GPS configuration for PTP.

              clock-interface sync 2 location 0/RSP0/CPU0
               port-parameters
                gps-input tod-format cisco pps-input rs422
               !
               frequency synchronization
                selection input
                priority 2
                wait-to-restore 0
                ssm disable
                quality receive exact itu-t option 2 generation 2 PRS
               !
              !
                

              Additional References

              The following sections provide references related to implementing PTP on Cisco IOS XR software.

              Related Documents

              Related Topic

              Document Title

              Cisco IOS XR PTP commands

              PTP Commands module of Cisco ASR 9000 Series Aggregation Services Router System Management Command Reference

              Cisco IOS XR SyncE commands

              Frequency Synchronization Commands module of Cisco ASR 9000 Series Aggregation Services Router System Management Command Reference

              Cisco IOS XR SyncE configuration information

              Configuring Ethernet Interfaces module of Cisco ASR 9000 Series Aggregation Services Router Interface and Hardware Component Configuration Guide

              Information about getting started with Cisco IOS XR Software

              Cisco ASR 9000 Series Aggregation Services Router Getting Started Guide

              Cisco IOS XR master command index

              Cisco ASR 9000 Series Aggregation Services Router Commands Master List

              Information about user groups and task IDs

              Configuring AAA Services on the Cisco ASR 9000 Series Router module of Cisco ASR 9000 Series Aggregation Services Router System Security Configuration Guide

              Standards

              Standards

              Title

              No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

              MIBs

              MIBs

              MIBs Link

              To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http:/​/​cisco.com/​public/​sw-center/​netmgmt/​cmtk/​mibs.shtml

              RFCs

              RFCs

              Title

              RFC 1588

              Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, 2008

              Technical Assistance

              Description

              Link

              The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

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