Configuring Two-way Frame Delay Measurement in VLL Networking

In VLL networking, the clock frequencies between the two ends are not synchronized and CFM is enabled to monitor link connectivity. If the bidirectional delay measurement needs to be performed for a link, two-way frame delay measurement can be configured to monitor the quality of the link.

Context

Two-way frame delay measurement in VLL networking can be either on-demand or proactive. On-demand two-way frame delay measurement is manually initiated for diagnosis of the frame transmission delay in a limited time. It can be singular or periodic measurement. Proactive two-way frame delay measurement is carried out continuously to permit proactive reporting of frame transmission delays or performance results.

To implement singular or periodic two-way frame delay measurement for a PW or an AC, configure on-demand two-way frame delay measurement in VLL networking.
To implement continual two-way frame delay measurement for a PW, configure proactive two-way frame delay measurement in VLL networking.

802.1p priorities carried by packets on a network are used to differentiate services, and therefore different policies can be deployed for services. As shown in Figure 1, the 802.1p priority values contained in traffic passing through the P are 1 and 2.

Two-way frame delay measurement is performed for the link between PE1 and PE2. Assume that traffic (with the priority value of 2) that is not involved in frame delay measurement is sent out after two-way frame delay measurement is enabled. The traffic is forwarded preferentially, because its priority is high. As a result, the traffic (with the priority value of 1) that is involved in frame delay measurement fails to reach PE2 in time, causing incorrect frame delay statistics.

802.1p-priority-based two-way frame delay measurement can be configured for the VLL for accurate proactive frame delay tests.

Figure 1 Networking diagram for Y.1731 priority-based frame loss measurement on a VLL

Procedure

Configure on-demand two-way frame delay measurement.
- Configure on-demand two-way frame delay measurement for a PW.
  1. Perform the following steps on the devices at both ends of a PW where two-way frame delay measurement will be implemented:
    1. Run system-view
      
      The system view is displayed.
    2. Run cfm md md-name
      
      The MD view is displayed.
    3. Run ma ma-name
      
      The MA view is displayed.
    4. Associate the MA with a service.
      LDP VLL scenarios
      
      Run map mpls l2vc[ peer-address ] l2vc-id { raw | tagged }
      
      The MA is bound to a specified L2VC.
      
      BGP VLL scenarios
      
      Run mapmpls l2vpnl2vpn-namecece-idce-offsetce-offset-id
      
      The MA is bound to a specified PW.
    5. Run mep mep-id
      
      The MEP is configured.
    6. Run remote-mep mep-id mep-id
      
      The remote MEP ID is configured.
    7. Run mep ccm-send enable
      
      The CCM transmission function is enabled.
    8. Run remote-mep ccm-receive [ mep-id mep-id ] enable
      
      The CCM reception function is enabled.
    9. Run measure-point mep mep-id pw
      
      A measurement point for collecting Y.1731 statistics is configured.
  2. Configure the test instance.
    1. To configure a test instance on the receiving device on a PW where two-way frame delay measurement will be implemented, run the test-idtest-id [ testid-file ]mep mep-id [ 8021p 8021p-value ] [ descriptiondescription ] command.
    2. To configure a test instance on the transmitting device on a PW where two-way frame delay measurement will be implemented, run the test-idtest-id [ testid-file ]mepmep-id [ macmac-address | remote-mepmep-id ] [ 8021p8021p-value ] [ descriptiondescription ] command.
  3. On the receiving device on a PW where two-way frame delay measurement will be implemented, run delay-measure two-way receive test-id test-id
    
    The DMM reception function is configured on the device.
  4. On the transmitting device on a PW where two-way frame delay measurement will be implemented, run delay-measure two-way send test-id test-id } interval { 1000 | 10000 } count count-value
    
    On-demand two-way frame delay measurement is configured for a PW.
  5. Run commit
    
    The configuration is committed.
- Configure on-demand two-way frame delay measurement for an AC.
  1. Perform the following steps on the devices at both ends of an AC where on-demand two-way frame delay measurement will be implemented:
    1. Run system-view
      
      The system view is displayed.
    2. Run cfm md md-name
      
      The MD view is displayed.
    3. Run ma ma-name
      
      The MA view is displayed.
    4. Perform the following steps on the devices where the MEPs reside:
      - On the CE, run:
        
        mapvlanvlan-id
        
        The MA is bound to a VLAN.
      - Associate the MA with a service.
        LDP VLL scenarios
        
        Run map mpls l2vc[ peer-address ] l2vc-id { raw | tagged }
        
        The MA is bound to a specified L2VC.
        
        BGP VLL scenarios
        
        Run mapmpls l2vpnl2vpn-namecece-idce-offsetce-offset-id
        
        The MA is bound to a specified PW.
    5. Run mep mep-id
      
      The MEP is configured.
    6. Run remote-mep mep-id mep-id
      
      The remote MEP ID is configured.
    7. Run mep ccm-send enable
      
      The CCM transmission function is enabled.
    8. Run remote-mep ccm-receive [ mep-id mep-id ] enable
      
      The CCM reception function is enabled.
    9. Run measure-point mep mep-id ac
      
      A measurement point for collecting Y.1731 statistics is configured for an AC.
  2. Configure a test instance.
    1. To configure a test instance on the receiving device on an AC where two-way frame delay measurement will be implemented, run the test-idtest-id [ testid-file ]mep mep-id [ 8021p 8021p-value ] [ descriptiondescription ] command.
    2. To configure a test instance on the transmitting device on an AC where two-way frame delay measurement will be implemented, run the test-id test-id [ testid-file ]mepmep-id [ macmac-address | remote-mepmep-id ] [ 8021p8021p-value ] [ descriptiondescription ] command.
  3. On the receiving device on an AC where on-demand two-way frame delay measurement will be implemented, run delay-measure two-way receive test-id test-id
    
    The DMM reception function is configured on the device.
  4. On the transmitting device on an AC where on-demand two-way frame delay measurement will be implemented, run delay-measure two-way send test-id test-id } interval { 1000 | 10000 } count count-value
    
    On-demand two-way frame delay measurement is configured for an AC.
  5. Run commit.
    
    The configuration is committed.
Configure proactive two-way frame delay measurement.
1. Perform the following steps on the devices at both ends of a PW where proactive two-way frame delay measurement will be implemented:
  1. Run system-view
    
    The system view is displayed.
  2. (Optional) Run y1731 pm-mode enable
    
    Performance management (PM) to manage Y.1731 proactive performance statistics is enabled. PM saves the statistics to generated statistics files and then sends the files to the NMS.
  3. Run cfm md md-name
    
    The MD view is displayed.
  4. Run ma ma-name
    
    The MA view is displayed.
  5. Associate the MA with a service.
    - LDP VLL scenarios
      
      Run map mpls l2vc[ peer-address ] l2vc-id { raw | tagged }
      
      The MA is bound to a specified L2VC.
    - BGP VLL scenarios
      
      Run mapmpls l2vpnl2vpn-namecece-idce-offsetce-offset-id
      
      The MA is bound to a specified PW.
  6. Run mep mep-id
    
    The MEP is configured.
  7. Run remote-mep mep-id mep-id
    
    The remote MEP ID is configured.
  8. Run mep ccm-send enable
    
    The CCM transmission function is enabled.
  9. Run remote-mep ccm-receive [ mep-id mep-id ] enable
    
    The CCM reception function is enabled.
  10. Run measure-point mep mep-id pw
    
    A measurement point for collecting Y.1731 statistics is configured.
  11. (Optional) Run delay-measure two-way delay-threshold mep mep-id upper-limit upper-limit lower-limit lower-limit [ 8021p 8021p-value ],
    
    Alarm thresholds are configured for two-way frame delay in proactive two-way frame delay measurement based on MEP.
  12. (Optional) Run delay-measure two-way variation-threshold mep mep-id upper-limit upper-limit lower-limit lower-limit [ 8021p 8021p-value ],
    
    Alarm thresholds are configured for two-way frame jitter in proactive two-way frame delay measurement based on MEP.
2. Configure a test instance.
  1. On the receiving device on a PW where two-way frame delay measurement will be implemented, run test-idtest-id [ testid-file ]mep mep-id [ 8021p 8021p-value ] [ descriptiondescription ]
    
    A test instance is configured on the device.
  2. On the transmitting device on a PW where two-way frame delay measurement will be implemented, run test-idtest-id [ testid-file ]mepmep-id [ macmac-address | remote-mepmep-id ] [ 8021p8021p-value ] [ descriptiondescription ]
    
    A test instance is configured on the device.
  3. (Optional) Run delay-measure two-way delay-threshold test-id test-id-value upper-limit upper-limit lower-limit lower-limit,
    
    Alarm thresholds are configured for two-way frame delay in proactive two-way frame delay measurement based on the test instance.
  4. (Optional) Run delay-measure two-way variation-threshold test-id test-id-value upper-limit upper-limit lower-limit lower-limit,
    
    Alarm thresholds are configured for two-way frame jitter in proactive two-way frame delay measurement based on the test instance.
3. On the receiving device on a PW where proactive two-way frame delay measurement will be implemented, run delay-measure two-way receivetest-idtest-id
  
  The DMM reception function is configured on the device.
4. On the transmitting device on a PW where proactive two-way frame delay measurement will be implemented, run delay-measure two-way continualtest-id test-id-value interval interval-value
  
  Proactive two-way frame delay measurement is configured for a PW.
5. Run commit.
  
  The configuration is committed.

Verifying the Configuration

Run the display y1731 statistic-type twoway-delay [ test-id test-id-value ] [ count count-value ] command on the device that initiates two-way frame delay measurement to check statistics about the delay in bidirectional frame transmission.