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Inline Transmission Mode

 

Use this topic to understand what inline transmission is and how to enable it for maximum scaling for CFM, LFM, and performance monitoring functions.

Enabling Inline Transmission of Continuity Check Messages for Maximum Scaling

Scaling is the ability of a system to handle increasing amounts of work and to continue to function well. Scaling can refer to increasing capacity and the ability to handle increasing workload, number of subscribers or sessions, hardware components, and so on. Continuity check protocol is used for fault detection within a maintenance association. The maintenance association end points (MEPs) send continuity check messages (CCMs) periodically. The time between the transmissions of CCMs is known as the interval. The receiving MEP maintains a database of all MEPs in the maintenance association.

By default, CCMs are transmitted by the CPU of a line card, such as a Modular Port Concentrator (MPC). If the duration between transmissions of CCMs is low or if the CCMs for a specific line card scale, then we recommend that you delegate transmission of CCMs to the forwarding ASIC (that is, to the hardware) by enabling inline transmission of CCMs. Inline transmission of CCMs is also known as inline keepalives or Inline-KA. Inline transmission enables the system to handle more connectivity fault management (CFM) sessions per line card. By enabling inline transmission of CCMs, you can achieve maximum scaling of CCMs.

To enable inline transmission of CCMs, perform the following steps:

  1. In configuration mode, go to the [edit protocols oam ethernet connectivity-fault-management performance-monitoring] hierarchy level.
  2. Delegate transmission of CCMs to hardware by enabling hardware-assisted keepalives.
    Note

    Inline transmission of CCMs is not enabled when there is a CFM session already established. To enable inline transmission, you must first deactivate the CFM session using the deactivate command and then reactivate the CFM session using the activate command.

To disable inline transmission, use the hardware-assisted-keepalives disable statement. After disabling inline transmission, you must reboot the router for the changes to take effect.

Scaling is the ability of a system to handle increasing amounts of work and to continue to function well. Scaling can refer to increasing capacity and the ability to handle increasing workload, number of subscribers or sessions, hardware components, and so on.

By default, LFM keepalive packets are transmitted by the periodic packet management ppm process on the line-card. You can delegate transmission of LFM keepalive packets to the forwarding ASIC (that is, to the hardware) by enabling inline transmission. Inline transmission of LFM keepalives is also known as inline keepalives or Inline-KA. By enabling inline transmission of LFM keepalive packets, you can achieve maximum scaling of keepalive packets, reduction of the load on the ppm process, and support LFM in-service software upgrade (ISSU) for non-juniper peers (for a keepalive interval of 1 second).

Note

Do not enable or disable inline transmission of LFM when an LFM session is already established. To enable or disable inline transmission, you must first deactivate the existing established LFM session using the deactivate command, and then reactivate the LFM session using the activate command after enabling or disabling inline LFM.

Before you enable inline transmission of LFM keepalive packets, complete the following tasks:

  • Verify if any LFM session is online and active. To verify if any existing or established LFM session is online and active, issue the following command:

    user@host> show oam ethernet link-fault-management detail

    The OAM transmit statistics reflect that the ppm process is handling the transmission of LFM keepalive packets.

  • Deactivate the LFM session so that you can enable inline LFM mode. To deactivate the LFM session, issue the following command:

  • Commit the configuration. To commit the configuration, issue the following command:

To enable inline transmission of LFM keepalive packets, perform the following steps:

  1. In configuration mode, go to the [edit protocols oam ethernet link-fault-management] hierarchy level.
  2. Delegate transmission of LFM keepalive packets to hardware by enabling hardware-assisted keepalives.
  3. Commit the configuration.
  4. Re-activate the LFM session as follows:
  5. Commit the configuration.
  6. Verify that the trasnmission of LFM keepalive packets is delegated from the ppm process to the hardware. To verify that you have enabled inline transmission, issue the following command:
    user@host> show oam ethernet link-fault-management detail

    The OAM transmit statistics are not updated. When you enable inline transmission of LFM keepalive packets, the OAM transmit statistics are not updated.

To disable inline LFM, verify if any existing established LFM session is online and active. Deactivate the LFM session and commit. Disable inline LFM by deleting the hardware-assisted-keepalives statement and commit. Then, reactivate LFM session and commit the configuration.

Enabling Inline Mode Of Performance Monitoring To Achieve Maximum Scaling

Performance monitoring is useful for studying the traffic pattern in a network over a period of time. It helps to identify network problems before you are impacted by network defects.

By default, performance monitoring packets are handled by the CPU of a line-card, such as Modular Port Concentrator (MPC). Enabling inline mode of performance monitoring delegates the processing of the protocol data units (PDUs) to the forwarding ASIC (that is, to the hardware). By enabling inline mode of performance monitoring, the load on the CPU of the line-card is reduced and you can configure an increased number of performance monitoring sessions and achieve maximum scaling for service OAM performance monitoring sessions. On MX Series routers, you can configure inline mode of performance monitoring only if the network services mode on the router is configured to enhanced-ip and enhanced connectivity fault management (enhanced-cfm-mode)) is configured.

By enabling inline mode of performance monitoring, you can achieve maximum scaling for performance monitoring sessions. To achieve maximum scaling for performance monitoring sessions, you must enable scaling of continuity check messages (CCMs) sessions. To enable scaling of CCM sessions, enable inline transmission of continuity check messages. For more information on inline transmission of continuity check messages, see Enabling Inline Transmission of Continuity Check Messages for Maximum Scaling. To view the supported scaling values for CCM and PM, see Supported Inline CCM and Inline PM Scaling Values.

Inline mode of performance monitoring is supported only for proactive mode of frame delay measurement (Two-way Delay Measurements) and synthetic loss measurements (SLM)sessions. Performance monitoring functions configured using the iterator profile (CFM)are referred to as proactive performance monitoring. Inline mode of performance monitoring for frame loss measurement using service frames (LM) is not supported.

Note

MPC3E (MX-MPC3E-3D) and MPC4E (MPC4E-3D-32XGE-SFPP and MPC4E-3D-2CGE-8XGE) do not support inline mode of performance monitoring. User-defined Data TLV is not supported if you have configured inline mode of performance monitoring. Also, only 12 history records per PM sessions are supported.

We recommend that you enable inline mode of performance monitoring before you configure the performance monitoring sessions as the change may interfere with the existing performance monitoring sessions.

To enable inline mode of performance monitoring, perform the following steps:

  1. In configuration mode, go to the [edit chassis] hierarchy level and configure the network services mode of the router. The network service mode of the router must be configured as enhanced ip to enable enhanced connectivity fault management (CFM) mode.Note

    If the network services mode is not enhanced-ip, and you have enabled enhanced CFM, the following warning message is displayed:

    [edit protocols oam ethernet]

    'connectivity-fault-management'

    enhanced ip is not effective please configure enhanced ip and give router reboot

  2. In configuration mode, go to the [edit protocols oam ethernet connectivity-fault-management] hierarchy level and enable enhanced connectivity fault management mode by using the enhanced-cfm-mode option.
  3. In configuration mode, go to the [edit protocols oam ethernet connectivity-fault-management performance-monitoring] hierarchy level. Configure the enhanced iterator profile by using the enhanced-sla-iterator option and specify the measurement interval by using the measurement-interval option.
  4. Enable inline performance monitoring.Note

    You can enable inline mode of performance monitoring for both the originator and the responder of the service OAM performance monitoring sessions by using the hardware-assisted-pm command.

  5. (Optional) Enable inline transmission of CCMs to enable better scaling if inline transmission of CCMs is not automatically enabled.Note

    You can achieve better scaling if both inline performance monitoring and inline transmission of CCMs is enabled.

  6. Commit the configuration.

Supported Inline CCM and Inline PM Scaling Values

This topic lists the scaling values for inline mode of performance monitoring and inline transmission of continuity check messages. The scaling values are based on the different cycle-time interval values. Each table lists the maximum number of connectivity fault management (CFM) sessions and performance monitoring (PM) sessions per line card and per chassis when you configure inline CCM, enhanced CFM, and enhanced PM by using the hardware-assisted-keepalives, enhanced-cfm-mode, and hardware-assisted-pm options.

Note

The scaling values do not consider the load from other protocols in the system and so the actual realized scaling values for line card and chassis vary depending on other protocol configurations and scaling in the system. We recommend that you configure DDoS for CFM. Limit the number of CFM packets, that are sent to the CPU of the line card, to 3000. Limiting the number of packets safeguards the CPU from scaled CFM configurations of various CFM protocol events.

Table 1 lists the maximum number of connectivity fault management (CFM) sessions and performance monitoring (PM) sessions per line card and per chassis when you configure both the CCM interval and the PM interval as 1 second.

Table 1: Scaling Values for CFM and PM (CCM Interval: 1 sec and PM Interval: 1 sec )

CFM Line Card Scale

PM Line Card Scale

CFM Chassis Scale

PM Chassis Scale

4000

4500

16000

16000

6000

3750

16000

16000

7000

3375

16000

16000

8000

3000

16000

16000

Table 2 lists the maximum number of connectivity fault management (CFM) sessions and performance monitoring (PM) sessions per line card and per chassis when you configure the CCM interval as 1 second and the PM interval as 100 milliseconds.

Table 2: Scaling Values for CFM and PM (CCM Interval: 1 sec and PM interval: 100 ms )

CFM Line Card Scale

PM Line Card Scale

CFM Chassis Scale

PM Chassis Scale

4000

450

12000

4000

6000

375

12000

4000

7000

337

12000

4000

8000

300

12000

4000

Table 3 lists the maximum number of connectivity fault management (CFM) sessions and performance monitoring (PM) sessions per line card and per chassis when you configure the CCM interval as 100 milliseconds and the PM interval as 1 second.

Table 3: Scaling Values for CFM and PM (CCM Interval: 100 ms and PM interval: 1 sec )

CFM Line Card Scale

PM Line Card Scale

CFM Chassis Scale

PM Chassis Scale

4000

3000

8000

6000

3000

3750

8000

6000

2000

4500

8000

6000

1000

4500

8000

6000

Table 4 lists the maximum number of connectivity fault management (CFM) sessions and performance monitoring (PM) sessions per line card and per chassis when you configure both the CCM interval and the PM interval as 100 milliseconds.

Table 4: Scaling Values for CFM and PM (CCM Interval: 100 ms and PM interval: 100 ms )

CFM Line Card Scale

PM Line Card Scale

CFM Chassis Scale

PM Chassis Scale

4000

300

8000

3000

3000

375

8000

3000

2000

450

8000

3000

1000

450

8000

3000

Enabling the Hardware-Assisted Timestamping Option

By default, Ethernet frame delay measurement uses software for timestamping transmitted and received ETH-DM frames. For Ethernet interfaces, you can optionally use hardware timing to assist in the timestamping of received ETH-DM frames to increase the accuracy of delay measurements.

Enabling hardware-assisted timestamping of received frames can increase the accuracy of ETH-DM calculations when the DPC is loaded with heavy traffic in the receive direction.

To enable Ethernet frame delay measurement hardware assistance on the reception path, include the hardware-assisted-timestamping statement at the [edit protocols oam ethernet connectivity-fault-management performance-monitoring] hierarchy level: