Using the Performance Assurance Agent
  • 23 Jan 2024
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Using the Performance Assurance Agent

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Article Summary

Overview

This article describes how to use the Performance Assurance Agent (PAA™) for monitoring network performance.

The Performance Assurance Agent (PAA) is a hardware-assisted active-measurement function that computes Layer-2 or Layer-3 (IPv4 UDP) network delay (latency), delay variation (jitter), frame/packet loss, and continuity checks.

Two units with matching settings communicate with each other using measurement samples to collect data and measure system performance. A measurement sample is a frame/packet containing timing and sequence information. When such a frame/packet arrives at its destination, measurements (delay, delay variation and frame/packet loss) can be taken. The PAA operates continuously.

The PAA is capable of concurrently testing and maintaining multiple flows of active probes. The characteristics of the test frames/packets for each flow are set to match the Layer-2 (PCP value of the VLAN tag) or Layer-3 (IP ToS/DSCP value) characteristics of the services being monitored. These frames/packets may be independently directed to different peers or to the same peer, using a different class of service (CoS) and/or VLAN ID as appropriate. Up to two VLAN tags can be specified (.1Q-in.1Q).

The PAA can be configured in a point-to-point or point-to-multi-point fashion. In other words, you can enable a single PAA instance to exchange data with another PAA instance, or enable it to communicate with several PAA instances simultaneously. Typically, the PAA instance would be configured between the network-side port of the first unit and the network-side port of the second unit (point-to-point) in order to get live latency, jitter and frame/packet loss measurements. It is also possible to select a client-side port on a given unit for PAA measurements when it is directly connected to another unit, or through a network device in the same point-to-point fashion.

Concepts and Definitions

The Performance Assurance Agent performs measurements on network delay, delay variation, frame loss, and continuity. Before configuring PAA, it is important to understand basic concepts and definitions.

The sampling interval determines how frequently PAA frames/packets are sent between end-points. In other words, the sampling interval determines the granularity of the measurements. Configuring PAA with a smaller interval may seem more advantageous at first glance, but it also requires more system resources, which ultimately limits the maximum number of PAA instances that can be configured in the unit. To ensure PAA operates within the system capacity, a built-in resource manager keeps track of the resources that are used as PAA instances are added, and informs the user if the maximum capacity is reached.

The reference period determines how frequently performance measurements are computed and reported. For example, in the case of delay measurements, the minimum and maximum values are reported and the average value is calculated based on all samples received during the reference period.

Thresholds can be configured to trigger alarms and inform the user or a network monitoring system should any key performance index level be crossed.

Clock synchronization (NTP, PTP, or GPS) is mandatory for PAA one-way delay measurements. All units must be synchronized to perform one-way delay measurements. If synchronization is not enabled, PAA will only display two-way delay measurements.

Setting Up a Probe

To configure a PAA probe

  1. Access the page SOAM ▶ PAA ▶ Configuration.
    A summary of all PAA probes is displayed.

  2. Click Add to create a new probe or click the probe name to edit an existing probe.

  3. Complete the required fields, then click Apply.

For more information on specific parameters, refer to the following tables.


Note: The fields available for configuration vary depending on the probe type and operation mode you select.

PAA Configuration (SOAM ▶PAA ▶Configuration)
General

ParameterDescription
IndexThe unique identifier assigned to the probe.
NameThe name assigned to the PAA probe.
TypeThe type of probe
Operation Mode

Mode

Specifies whether a probe generates (Source) PAA samples, collects PAA samples (Sink) or does both operations (Bi-Dir).

The operation mode is Bi-Dir. In this mode, the probe both generates and collects PAA samples.

Packet SizeThe size of PAA samples to take.

Note: The size value indicated here does not include protocol headers (VLAN tags, UDP, IP or Ethernet) or the four FCS bytes.

Minimum value: 66

Layer-2 maximum value: 1500

Maximum value for UDP over IPv4: 1472

Maximum value for UDP over IPv6: 1500

Maximum value for UDP over IPv6: 1452

Sampling Period (msec)

Sampling

The time period to elapse between each issuing of PAA samples.

Range: 50–600,000 (steps of one millisecond).

Enable PAA ProbePAA probe may be enabled or disabled.
StateThe probe's current state:
  • Enabled: Enabled by configuration
  • Disabled: Disabled by configuration
  • Associating: Enabled and looking for peer
  • Associated: Enabled peer index resolved

Local and Peer Indexes

ParameterDescription
Local IndexThe probe's local identifier.

Acceptable index values range between 1–1000.

Note: To automatically allocate the next sequentially-available local identifier to the PAA instance, enter "0" for the local identifier or simply leave the field blank.

Remote Index

Peer Index

The remote peer identifier.

When 0 is specified, the remote peer identifier is discovered dynamically based on the probe name in the association phase.

Layer-2 Parameters (Layer-2 Probes Only)

ParameterDescription
Destination MAC Address

Destination

The peer MAC address.

When set to FF:FF:FF:FF:FF:FF, the unit is in auto-discovery mode and will automatically determine the peer MAC address based on the PAA name (provided the PAA name is the same on both units).

Port nameThe outgoing port used by this probe.
VLAN 1 encapsulationCheck box to encapsulate Layer-2 PAA frames into a VLAN.
VLAN 2 encapsulationCheck box to encapsulate Layer-2 PAA frames into a VLAN-in-VLAN. VLAN2 represents the inner VLAN.

Note: Only applies when VLAN 1 encapsulation is enabled.

VLAN 1 IDThe first VLAN ID.

When enabled, Layer-2 PAA frames are encapsulated into the specified VLAN.

VLAN 2 IDThe second VLAN ID. When enabled, Layer-2 PAA frames are encapsulated into a second VLAN.

Note: Only applies when VLAN 1 encapsulation is enabled.

VLAN 1 typeThe Ethertype of the first VLAN: C-VLAN, T-VLAN or S-VLAN.
VLAN 2 typeThe second VLAN Ethertype: C-VLAN, T-VLAN or S-VLAN.

Note: Only applies when VLAN 2 encapsulation is enabled.

VLAN 1 priorityThe first VLAN's priority bits.

Note: Only applies when VLAN 1 encapsulation is enabled.

VLAN 2 priorityThe second VLAN's priority bits.

Note: Only applies when VLAN 2 encapsulation is enabled.

Layer-2 Parameter Validation (Layer-2 Probes Only)

ParameterDescription
Validate Tx/Rx VLAN 1 ID

Couple Tx/Rx VLAN 1 ID

Rx VLAN 1 ID

Validate Tx/Rx VLAN 1 ID enables validating the transmitted VLAN 1 ID with the ID value that was received.

If you expect the transmitted and received values to be equal, enable Couple Tx/Rx VLAN 1 ID.

If you expect a different received value, enter the value in the Rx VLAN 1 ID field.

Range: 0-4,095

Validate Tx/Rx VLAN 1 Priority

Couple Tx/Rx VLAN 1 Priority

Rx VLAN 1 Priority

Validate Tx/Rx VLAN 1 priority enables validating the transmitted VLAN 1 priority with the priority that was received.

If you expect the transmitted and received values to be equal, enable Couple Tx/Rx VLAN 1 priority.

If you expect a different received value, enter the value in the Rx VLAN 1 priority field.

Range: 0-7

Validate Tx/Rx VLAN 2 ID

Couple Tx/Rx VLAN 2 ID

Rx VLAN 2 ID

Validate Tx/Rx VLAN 2 ID enables validating the transmitted VLAN 2 ID with the ID that was received.

If you expect the transmitted and received values to be equal, enable Couple Tx/Rx VLAN 2 ID.

If you expect a different received value, enter the value in the Rx VLAN 2 ID field.

Range: 0-4,095

Validate Tx/Rx VLAN 2 Priority

Couple Tx/Rx VLAN 2 Priority

Rx VLAN 2 Priority

Validate Tx/Rx VLAN 2 priority enables validating the transmitted VLAN 2 priority with the priority that was received.

If you expect the transmitted and received values to be equal, enable Couple Tx/Rx VLAN 2 priority.

If you expect a different received value, enter the value in the Rx VLAN 2 priority field.

Range: 0–7

EVC Fault Propagation (Layer-2 Probes Only)

ParameterDescription
Enable Fault PropagationUse this PAA probe's status in fault propagation.

The port configuration's Fault Propagation value must be Enabled and set to One-Way EVC mode for the fault to be propagated to the opposite port.

Propagate on PortThe EVC client port to which the MEP status should be propagated.

Note: This parameter is ignored if the port you select has not been set up to perform EVC fault propagation.

UDP Parameters (Probes with UDP over IPv4 or IPv6 Only)

ParameterDescription
Destination IP Address

Destination

Peer IPv4 or IPv6 Destination address.
Source UDP PortThe source UDP port. The default value is 8793.
Destination UDP PortThe destination UDP port. The default value is 8793.

A port cannot be defined as the UDP port here if it is already in use for any of the following features:

  • A Layer-3 PAA instance
  • TWAMP
  • Layer-3 RFC-2544 Generator
  • Layer-3 RFC-2544 Test Suite
  • Layer-3 Y.1564
  • SAT Protocol
Diff-Serv CodePoint (DSCP)The DSCP class selector. The expected length is 6 bits.
Explicit Congestion Notification (ECN)The ECN value. You can associate an ECN value with the PAA packets, thereby simulating ECN in the customer network.

The ECN bits are the last two bits of the IP ToS field.

Range: 0-3

VLAN 1 PriorityFirst VLAN priority bits. This can be used to associate a priority value for the first VLAN.

Range: 0-7

UDP and UDP IPv6 Parameter Validation (Probes with UDP over IPv4 and over IPv6 Only)

ParameterDescription
Validate Tx/Rx DSCP

Couple Tx/Rx DSCP

Expected RX DSCP

Validate Tx/Rx DSCP enables validating the transmitted DSCP value with the value that was received.

If you expect the transmit and receives values to be equal, enable Couple Tx/Rx DSCP.

If you expect a different received value, enter this value in the Expected RX DSCP field.

Range: 0–63

Validate Tx/Rx Traffic Class

Couple Tx/Rx Traffic Class

Rx Traffic Class (DSCP)

Validate Tx/Rx Traffic Class enables the validation of transmitted traffic class value versus the received value.

If you expect the transmit and receives values to be equal, enable Couple Tx/Rx Traffic Class.

If you expect a different received value, enter the value in the RX Traffic Class DSCP field.

Range: 0–63

Validate Tx/Rx VLAN 1 Priority

Couple Tx/Rx VLAN 1 Priority

Rx VLAN 1 Priority

b Priority enables validating the transmitted VLAN 1 priority with the priority that was received.

If you expect the transmit and receives values to be equal, enable Couple Tx/Rx VLAN 1 Priority.

If you expect a different received value, enter the value in the Rx VLAN 1 Priority field.

Range: 0–7

Continuity

ParameterDescription
Packet Loss Reference Period (msec)The reference period, expressed in seconds, for the continuity measurements.

This value must be at least 10 times the value of the Sampling Period.

Packet Loss Threshold (percent)The threshold, expressed as a percentage, at which an Excessive Packet Loss (EPL) alarm is triggered.
Continuity Check ThresholdThe number of consecutive sampling periods without receiving any peer samples that must occur before declaring a Continuity Loss alarm.

Minimum value: 4

Maximum value: 50% of the total number of samples in the reference period.

Default value: 4

One-Way

ParameterDescription
Reference Period (msec)The reference period, expressed in milliseconds, for one-way measurements.

This value must be at least 10 times the value of the Sampling Period.

Maximum Delay (msec)The one-way delay allowed for each sample in the Reference Period.

This value is used in conjunction with the Delay Threshold (samples) value to trigger the alarm PAA_OW_DELAY_ALERT.

Delay Threshold (sample)The number of consecutive samples exceeding the Maximum Delay that are allowed before declaring the one-way delay alarm for this Reference Period.
Average Delay Threshold (msec)The average one-way delay is calculated for the samples during the reference period. For example, for a reference period of 10 seconds, the average is calculated from samples taken during the last 10 seconds.

Exceeding the threshold triggers the alarm PAA_OW_AVG_DELAY_ALERT.

Maximum Delay Variation (msec)The maximum one-way delay variation threshold to monitor during a test period. This value is used in conjunction with the Delay Variation Threshold (samples) value to trigger the alarm PAA_OW_DV_ ALERT.
Delay Variation Threshold (sample)The number of consecutive samples exceeding the Maximum Delay Variation that are allowed before triggering the one-way delay variation alarm for this Reference Period.
Average Delay Variation Threshold (msec)The average one-way delay variation is calculated for the samples during the reference period. Exceeding the threshold triggers the alarm PAA_OW_AVG_DV_ALERT.

Two-Way

ParameterDescription
Reference Period (msec)The reference period, expressed in milliseconds, for two-way measurements.

This value must be at least 10 times the value of the Sampling Period.

Maximum Delay (msec)The two-way delay allowed for each sample in the Reference Period.

This value is used in conjunction with the Delay Threshold to trigger the alarm PAA_TW_DELAY_ALERT.

Delay Threshold (sample)The number of consecutive samples exceeding the Maximum Delay that are allowed before triggering the two-way delay alarm for this Reference Period.
Average Delay Threshold (msec)The average two-way delay is calculated from samples during the reference period.

Exceeding the threshold triggers the alarm PAA_TW_AVG_DELAY_ALERT.

Maximum Delay Variation (msec)The maximum two-way delay variation threshold to monitor during a test period.

This value is used in conjunction with the Delay Variation Threshold to trigger the alarm PAA_TW_DV_ALERT.

Delay Variation Threshold (sample)The number of consecutive samples exceeding the Maximum Delay Variation that are allowed before triggering the two-way delay variation alarm for this Reference Period.
Average Delay Variation Threshold (msec)The average two-way delay variation is calculated from samples during the reference period.

Exceeding the threshold triggers the alarm PAA_TW_AVG_DV_ALERT.

Deleting a Probe


CAUTION: Deleting a PAA probe instance will also delete all SA metrics that use this PAA probe instance as the metric source.

To delete a PAA probe

  1. Access the page SOAM ▶ PAA ▶ Configuration.

  2. Click the name of the probe you want to delete.

  3. Click Delete.

Viewing Probe Status

To view the status of all PAA probes

  1. Access the page SOAM ▶ PAA ▶ Status.

  2. Click a probe name to view its detailed information.

For more information on specific parameters, refer to the following table.

PAA Status (SOAM ▶ PAA ▶ Status)

ParameterDescription
Name Probe

Name

The name of the probe.
IndexThe unique identifier assigned to the probe.
StateThe probe's current state. Possible values are:
  • Disabled: Disabled by configuration
  • Associating: Enabled and looking for peer
  • Associated: Enabled peer index resolved
It also gives detailed state information about local and remote clock synchronization status that is used for one-way measurements.
Peer AddressThe address of its peer PAA probe (L2 and L3).
Status CodesThe current state (active or inactive) for all PAA alarms for the following status codes:
  • CC: Continuity Check
  • EPL: Excessive Packet Loss
  • OD: One-Way Delay
  • OAD: One-Way Average Delay
  • ODV: One-Way Delay Variation
  • OAV: One-Way Average Delay Variation
  • TD: Two-Way Delay
  • TAD: Two-Way Average Delay
  • TDV: Two-Way Delay Variation
  • TAV: Two-Way Average Delay Variation

Viewing Probe Results

To view a summary of all PAA probe results

  1. Access the page SOAM ▶ PAA ▶ Results.

  2. Click a probe name to view detailed results of a probe.

For more information on specific parameters, refer to the following table.

PAA Results (SOAM ▶ PAA ▶ Results)

ParameterDescription
Current Results for Probe

Probe Name

The name of the probe.
IndexThe unique identifier assigned to the probe.
StateThe probe's current state. Possible values are:
  • Disabled: Disabled by configuration
  • Associating: Enabled and looking for peer
  • Associated: Enabled peer index resolved
It also gives detailed state information about local and remote clock synchronization status that is used for one-way measurements.
PeriodThe number of periods that have elapsed since the probe was enabled.
Results CodesA summary of the results for the following parameters:
  • PL: Packet Loss Ratio
  • OAD: One-Way Average Delay
  • OADV: One-Way Average Delay Variation
  • TAD: Two-Way Average Delay
  • TADV: Two-Way Average Delay Variation

Packet Loss

ParameterDescription
PeriodProvides the results for the previous and current periods.

The current period is indicated to the right of Packet Loss.

Number of SamplesThe total number of samples taken during the period.
Loss RatioThe percentage of samples that were lost during the period.
Number of GapsThe total number of gaps that have been detected from the sequence of packets (or frames) that were received during the period.
Largest Gap SizeThe total number of gaps that have been detected from the sequence of packets (or frames) that were received during the period.

One-Way Delay

ParameterDescription
Instantaneous DelayThe one-way instantaneous delay value, expressed in microseconds. This is the latest one-way delay value measured when the window was last refreshed.
PeriodProvides the results for the previous and current periods.

The current period is indicated to the right of the One-Way Delay.

Nbr SamplesThe total number of samples taken during the period.
Minimum Delay (msec)The one-way delay of the fastest sample over the period, expressed in microseconds.
Maximum Delay (msec)The one-way delay of the slowest sample taken over the period, expressed in microseconds.
Average Delay (msec)The average delay of the samples taken during the reference period, expressed in microseconds.
Nbr Threshold Exceeded (msec)The number of times the one-way delay has exceeded the value of the Maximum Delay parameter.

One-Way Delay Variation

ParameterDescription
Instantaneous DV (msec)The one-way instantaneous delay variation value, expressed in microseconds. This is the latest one-way delay variation measured when the window was last refreshed.
PeriodProvides the results for the previous and current periods.

The current period is indicated to the right of the One-Way Delay Variation.

Nbr SamplesThe total number of samples taken during the period.
Minimum DV (msec)The one-way delay variation of the samples with the smallest delay skew over the period, expressed in microseconds.
Maximum DV (msec)The one-way delay variation of the samples with the highest delay skew over the period, expressed in microseconds.
Average DV (msec)The average one-way delay variation of the samples during the reference period, expressed in microseconds.
Nbr Threshold ExceededThe number of times the one-way delay variation has exceeded the value of the Maximum DV parameter.

Two-Way Delay

ParameterDescription
Instantaneous Delay (msec)Two-way instantaneous delay, expressed in microseconds. This is the latest two-way delay measured when the window was last refreshed.
PeriodProvides the results for the previous and current periods.

The current period is indicated to the right of the Two-Way Delay.

Nbr SamplesThe total number of samples taken during the period.
Minimum Delay (msec)The two-way delay of the fastest samples over the period, expressed in microseconds.
Maximum Delay (msec)The two-way delay of the slowest samples over the period, expressed in microseconds.
Average Delay (msec)The average two-way delay of the samples during the reference period, expressed in microseconds.
Nbr Threshold ExceededThe number of times the two-way delay has exceeded the value of the Maximum Delay parameter.

Two-Way Delay Variation

ParameterDescription
Instantaneous DV (msec)The two-way instantaneous delay variation, expressed in microseconds.
PeriodProvides the results for the previous and current periods.

The current period is indicated to the right of the Two-Way Delay Variation.

Nbr SamplesThe total number of samples taken during the period.
Minimum DV (msec)The two-way delay variation of the samples with the smallest delay skew over the period, expressed in microseconds.
Maximum DV (msec)The two-way delay variation of the samples with the highest delay skew over the period, expressed in microseconds.
Average DV (msec)The average two-way delay variation of the samples during the reference period, expressed in microseconds.
Nbr Threshold ExceededThe number of times the two-way delay variation has exceeded the value of the Maximum DV parameter.

IGMP Join Delay

ParameterDescription
Instantaneous DelayThe latest IGMP join delay value, expressed in microseconds, that was measured when the window was last refreshed.
PeriodGives the results for the previous and current periods.

The current period is to the right of the IGMP Join Delay.

Nbr SamplesThe total number of samples contained in the period.
Minimum DelayThe IGMP join delay of the fastest sample over the period, expressed in microseconds.
Maximum DelayThe IGMP join delay of the slowest sample over the period, expressed in microseconds.
Average DelayThe average delay over the period, expressed in microseconds.
Nbr Threshold ExceededThe number of times the IGMP join delay has exceeded the value of the Maximum Join Delay.

IGMP Leave Delay

ParameterDescription
Instantaneous DelayThe latest IGMP leave delay value, expressed in microseconds, that was measured when the window was last refreshed.
PeriodProvides the results for the previous and current periods.

The current period is to the right of the IGMP Leave Delay.

Nbr SamplesThe total number of samples taken during the period.
Minimum DelayThe IGMP leave delay of the fastest sample over the period, expressed in microseconds.
Maximum DelayThe IGMP leave delay of the slowest sample over the period, expressed in microseconds.
Average DelayThe average delay over the period, expressed in microseconds.
Nbr Threshold ExceededThe number of times the IGMP leave delay has exceeded the value of the Maximum Leave Delay.

VLAN 1

ParameterDescription
ID Mismatch0: The VLAN 1 ID received is equal to the expected value.

1: The VLAN 1 ID received is different from the expected value.

ID ExpectedIn the event of an ID mismatch, the VLAN 1 ID that was expected.
ID ReceivedIn the event of an ID mismatch, the VLAN 1 ID that was expected.
Priority Mismatch0: The VLAN 1 ID priority received is equal to the expected value.

1: The VLAN 1 ID priority received is different from the expected value.

Priority Expected InIn the event of a priority mismatch, the VLAN 1 priority that was expected.
Priority ReceivedIn the event of a priority mismatch, the VLAN 1 priority that was received.

VLAN 2 (Layer-2 Probes Only)

ParameterDescription
ID Mismatch0: The VLAN 2 ID received is equal to the expected value.

1: The VLAN 2 ID received is different from the expected value.

ID ExpectedIn the event of an ID mismatch, the VLAN 2 ID that was expected.
ID ReceivedIn the event of an ID mismatch, the VLAN 2 ID that was received.
Priority Mismatch0: The VLAN 2 ID priority received is equal to the expected value.

1: The VLAN 2 ID priority received is different from the expected value.

Priority ExpectedIn the event of a priority mismatch, the VLAN 2 priority that was expected.
Priority ReceivedIn the event of a priority mismatch, the VLAN 2 priority that was received.

DSCP (Probes with UDP-over-IPv4 Only)

ParameterDescription
DSCP Mismatch0: The DSCP value received is equal to the expected value.

1: The DSCP value received is different from the expected value.

DSCP ExpectedIn the event of a DSCP mismatch, the DSCP value that was expected.
DSCP ReceivedIn the event of a DSCP mismatch, the DSCP value that was received.

Configuration Examples

  • Example 1: Configuring PAA as point-to-multipoint at layer 2
  • Example 2: Configuring PAA without auto-discovery mode
  • Example 3: Configuring layer-2 parameter validation
  • Example 4: Configuring PAA as point-to-point at layer 3
  • Example 5: Configuring multicast PAA at layer 2
  • Example 6: Configuring multicast PAA at layer 3
  • Example 7: Configuring PAA to measure IGMP Join/Leave delay

Example 1: Configuring PAA as point-to-multipoint at layer 2

This example shows how to configure PAA between a central unit (Skylight element 1) and two remote units (Skylight element 2 and Skylight element 3).

Physical Setup:
Example 1 Configuring PAA as point-to-multipoint at layer 2.png
Layer-2 PAA in point-to-multipoint topology

Configuration Procedure:

  1. Configure two PAA instances in Skylight element 1.

  2. Configure a PAA instance in Skylight element 2.

  3. Configure a PAA instance in Skylight element 3.

  4. Validate the PAA status.

  5. View the PAA results.

Configure two PAA instances in Skylight element 1

  1. Connect to the central unit (Skylight element 1).

  2. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  3. Create a PAA instance (e.g. PAA1): enter all parameters, as shown in the image below, and click Apply. This instance will be associated with Skylight element 2.

Note that Local index, Peer index and Destination MAC address are left at their default value. This puts the unit in auto-discovery mode, where it will automatically find the peer MAC address and associate with the far-end unit based on the PAA name (the PAA name must be the same in both units).
image.png

  1. Repeat the last two steps to create a second PAA instance (PAA2) on the same port for VLAN 102. This instance will be associated with Skylight element 3.
    image.png

Configure a PAA instance in Skylight element 2

  1. Connect to Skylight element 2.

  2. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  3. Create a PAA instance (PAA1): enter all parameters, as shown in the image below, and click Apply. This instance will be associated with the instance named PAA1 in Skylight element 1.
    image.png

Before going any further, it is important to further examine the PAA status.

  1. Access the page SOAM ▶ PAA ▶ Status
    The PAA instances you just created are in the Associating state. This is normal as the peer instances have not been created yet and PAA is trying to discover them. As soon as the peer instances are active, the state will change to "Associated."
    image.png

Configure a PAA instance in Skylight element 3

  1. Connect to Skylight element 3.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.

  3. Create a PAA instance (PAA2): enter all parameters, as shown in the image below, and click Apply. This instance will be associated with the instance named PAA2 in Skylight element 1.
    image.png

Validate the PAA status

  1. Connect to the central unit (Skylight element 1).

  2. Access the page SOAM ▶ PAA ▶ Status.
    If all has been configured correctly, the PAA instances should be associated and functioning as expected, as shown in the following figure:
    image.png

  3. Click index 1 to see more details on the PAA alarms and status:
    image.png

View the PAA results

  1. Connect to the central unit (Skylight element 1).

  2. Access the page SOAM ▶ PAA ▶ Results.
    This menu shows the main results in a table format for all PAA instances:
    image.png

  3. If needed, click a specific index number (e.g. “1”) to view detailed PAA results.

Example 2: Configuring PAA without auto-discovery mode

This is a variant of Example 1 where, instead of using the auto-discovery mode and letting the PAA instances associate by their name, you will specify the index and peer MAC address for each instance. In this mode, you can use different PAA names at each endpoint if desired.

Configuration Procedure:

  1. Gather the MAC address information from all units.

  2. Configure two PAA instances in Skylight element 1.

  3. Configure a PAA instance in Skylight element 2.

  4. Configure a PAA instance in Skylight element 3.

Gather the MAC address information from all units

  1. Connect to Skylight element 1 and access the page Port ▶ Configuration.
    image.png

  2. Write down the MAC address of the port that is associated with the PAA instance.

  3. Repeat these steps for Skylight element 2 and Skylight element 3.

Configure two PAA instances in Skylight element 1
Best Practice: before configuring the PAA instances, plan how the index numbers and other parameters will be assigned.

PAA Configuration Parameters Summary for Example 2

SitePAA NameVLANLocal IndexPeer IndexPeer MAC Address
1 (Skylight element 1)PAA_Site1to21011200:15:AD:14:DF:C9
1 (Skylight element 1)PAA_Site1to31022300:15:AD:14:DF:49
2 (Skylight element 2)PAA_Site2to11012100:15:AD:10:E7:19
3 (Skylight element 3)PAA_Site3to11023200:15:AD:10:E7:19
  1. Connect to Skylight element 1.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.

  3. Using the parameters from the table above, configure the first PAA instance as follows:
    image.png

  4. Then configure the second PAA instance as follows:
    image.png

  5. Access the page SOAM ▶ PAA ▶ Status.
    Unlike what you saw in the previous example, you will notice that the PAA instances are already in the "Associated" state although the peer end has not yet been configured. This is normal because the PAA instances are associated by their index and MAC address. In this mode, a PAA instance is always in the Associated state.
    image.png

Configure a PAA instance in Skylight element 2

  1. Connect to Skylight element 2.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.

  3. Using the parameters from the table above, configure the first PAA instance as follows:

Configure a PAA instance in Skylight element 3

  1. Connect to Skylight element 3.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.
    image.png

Configure a PAA instance in Skylight element 3

  1. Connect to Skylight element 3.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.

  3. Using the parameters from the table above, configure the first PAA instance as follows:
    image.png

Example 3: Configuring the validation of layer-2 parameters

This example describes how PAA can be configured to validate that the layer-2 parameters seen by the peer unit are as expected. For example, if you set up two units to exchange PAA frames on VLAN 101 with priority (PCP) 5, you can validate that the correct priority is received at the far end.

Physical Setup:
Example 3 Configuring the validation of layer-2 parameters.png
Layer-2 PAA with priority validation

Configuration Procedure:

  1. Configure a PAA instance in Skylight element 1 and Skylight element 2.

  2. Configure the PAA instance in Skylight element 1 to validate the far-end priority.

  3. Validate the operation.

  4. Force a priority change.

  5. View the results.

Configure a PAA instance in Skylight element 1 and Skylight element 2

  1. Connect to Skylight element 1.

  2. Refer to Example 1 and configure the PAA instance in Skylight element 1 as described in Step 1, but set the value of VLAN 1 priority to 5.

  3. Connect to Skylight element 2.

  4. Refer to Example 1 and configure the PAA instance in Skylight element 2 as described in Step 2, but set the value of VLAN 1 priority to 5.

Configure the PAA instance in Skylight element 1 to validate the far-end priority

  1. Connect to Skylight element 1.

  2. Access the page SOAM ▶ PAA ▶ Configuration and click the probe name PAA1.

  3. Scroll down to the Layer-2 Parameters Validation section and put a check mark in the following checkboxes:

  • Validate Tx/Rx VLAN 1 ID
  • Couple Tx/Rx VLAN 1 ID
  • Validate Tx/Rx VLAN 1 priority
  • Couple Tx/Rx VLAN 1 priority
  1. Click Apply to save the changes. The screen should be as follows:
    image.png

Validate the operation

  1. Access the page SOAM ▶ PAA ▶ Results in Skylight element 1 and click index 1.

  2. Scroll down to the VLAN 1 section. The screen should be as follows, which indicates everything is normal; the peer has not detected any mismatch:
    image.png

Force a priority change

  1. Insert a device between Skylight element 1 and Skylight element 2 to change the priority of the tagged frames sent to Skylight element 2. For example, change the PCP value from 5 to 3. This can be achieved using a Skylight element or any device that can remark the VLAN priority.

View the results

  1. Access the page SOAM ▶ PAA ▶ Results in Skylight element 1 and click index 1.

  2. Scroll down to the VLAN 1 section. The screen should show the following information, which now indicates a priority mismatch has been detected:
    image.png

The peer was expecting VLAN 101/PCP 5 frames but received VLAN 101/PCP 3 instead. A priority mismatch was detected on 17 PAA frames (so far).

  1. Access the page Show ▶ Alarm.

  2. Set the filter to Description, set the value to PAA, then click Search.
    The display is limited to PAA-related alarms only. As shown in the following screen, the PAA priority mismatch was also reported by an alarm:
    image.png

It is important to note that this change of priority did not affect the other performance measurements being performed by this PAA. Consequently, this change of priority in the network could have gone unnoticed if you had not used this option to detect it.

Example 4: Configuring PAA as point-to-point at layer 3

This example shows how to configure PAA between two units (Skylight element 1 and Skylight element 2) in a layer-3 network. Note that this configuration can also be used in a point-to-multipoint topology (as shown in Example 1).

Physical Setup:
Example 4 Configuring PAA as point-to-point at layer 3.png
Layer-3 PAA in point-to-point topology

Setting up PAA at layer 3 requires the following:

  • An IP address configured on the interfaces used by PAA.
  • A route to forward the PAA packets out through the proper interface. If the peer IP is in the same sub-network, this step is not required as the route is automatically added when the IP interface is created. If the peer IP is in a different sub-network, a specific route needs to be defined.

Configuration Procedure:

  1. Configure IP interfaces in both units.

  2. Configure a PAA instance in Skylight element 1.

  3. Configure a PAA instance in Skylight element 2.

Configure IP interfaces in both units

  1. Connect to Skylight element 1.

  2. Access the page System ▶ Configuration ▶ Interface and click Add.

  3. Create an interface on Port 1 with IP address 10.10.10.11/24, as shown in the following screen, and click Apply.
    image.png

  4. Do the same in Skylight element 2 and create an interface on Port 9 with IP 10.10.10.12.

Configure a PAA instance in Skylight element 1

  1. Connect to Skylight element 1.

  2. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  3. Create a PAA instance (e.g., PAA1): enter all parameters, as shown in the image below, and click Apply.
    image.png

Configure a PAA instance in Skylight element 2

  1. Connect to Skylight element 2.

  2. Access the page SOAM ▶ PAA ▶ Configuration and then click Add.

  3. Configure a PAA instance as shown in the previous steps, but with peer IP address 10.10.10.11, and click Apply.

Example 5: Configuring multicast PAA at layer 2

This example has one unit as the PAA source and all the other units as sinks. The source unit will generate PAA multicast frames; the sink units will receive these frames and calculate the results. All results will be displayed on the sink units. There will be no results on the source unit.


Note: All units must be synchronized to a valid timing source (NTP, PTP or GPS) to perform accurate one-way measurements.

Physical Setup:
Example 5 Configuring multicast PAA at layer 2.png
Layer-2 Multicast PAA

Configuration procedure:

  1. Configure PAA in the source unit.

  2. Configure a traffic policy for multicast PAA in the sink units.

  3. Configure PAA in the sink units.

  4. View the results.

Configure PAA in the source unit (Skylight element 1)

  1. Connect to Skylight element 1.

  2. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  3. Create a PAA instance (e.g. L2_Multicast_Source): enter all parameters as shown in the figure below, and click Apply. Take note of the Local and Peer Index numbers: you will use these values when configuring the sink units. The destination MAC address must be a multicast address, i.e. a MAC address that starts with "01".
    image.png

Configure a traffic policy for multicast PAA in the sink units

  1. Connect to a sink unit (e.g., Skylight element 2).

  2. Access the page Traffic ▶ Filters ▶ L2 filters and click Add to configure a layer-2 filter. Configure the fields as in the following screen and click Add:
    image.png


Note: This filter must be applied to a policy in order to send the multicast PAA frames to the CPU of the sink unit.

  1. Access the page Traffic ▶ Policies and open a policy on Port 9 (e.g., policy 9-1). Configure the fields as in the following screen and click Apply:
    image.png

Configure PAA in the sink units

  1. Connect to a sink unit (e.g., Skylight element 2), access the page SOAM ▶ PAA ▶ Configuration and click Add.

  2. Create a PAA instance (e.g., L2_Multicast_Sink): enter all parameters as shown in the figure below, and click Apply. Take note that the Local and Peer Index numbers are reversed to match the source unit configuration. The Destination MAC address must be the same multicast MAC address that was configured in the source unit.
    image.png

  3. Repeat these steps for any other sink unit.

View the results

  1. Connect to a sink unit (e.g., Skylight element 2).

  2. Access the page SOAM ▶ PAA ▶ Results and click the PAA instance index 2.
    image.png

Example 6: Configuring multicast PAA at layer 3

This example has one unit as the PAA source and all the other units as sinks. The source unit will generate PAA multicast packets; the sink units will receive these frames and calculate the results. All results will be displayed on the sink units. There will be no results on the source Skylight element.


Note: All units must be synchronized to a valid timing source (NTP, PTP or GPS) to perform accurate one-way measurements.

Setting up multicast PAA at layer 3 requires the following:

  • A multicast IP address (the valid IPv4 range is 224.0.0.0 to 239.255.255.255).
  • An IP address configured on the source unit interface used by PAA.
  • A route to forward the PAA packets out through the proper interface on the source unit.
  • A traffic policy in the sink units to send the PAA multicast packets to the CPU.

Physical Setup:
Example 6 Configuring multicast PAA at layer 3.png
Layer-3 Multicast PAA

Configuration Procedure:

  1. Configure an IP interface in the source unit.

  2. Configure a route in the source unit.

  3. Configure PAA in the source unit.

  4. Configure a traffic policy for multicast PAA in the sink units.

  5. Configure PAA in the sink units.

  6. View the results.

Configure an IP interface in the source unit (Skylight element 1)

  1. Connect to Skylight element 1.

  2. Access the page System ▶ Configuration ▶ Interface and click Add.

  3. Create an interface on Port 1 with IP address 10.10.10.11/24 as shown in the following screen and click Apply.
    image.png

Configure a route in the source unit (Skylight element 1)

  1. Access the page System ▶ Configuration ▶ Interface, scroll down to the IPv4 routes section and click Add. Configure the route as follows:

Configure PAA in the source unit (Skylight element 1)

  1. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  2. Create a PAA instance (e.g., L3_Multicast_Source): enter all parameters as shown in the figure below, and click Apply. Take note of the Local and Peer Index numbers: you will use these values when configuring the sink units. The destination IP address must be a multicast address.
    image.png

Configure a traffic policy for multicast PAA in the sink units

  1. Connect to a sink unit (e.g., Skylight element 2).
  2. Access the page Traffic ▶ Filters ▶ IPv4 filters and click Add to configure an IP filter. Configure the fields as in the following screen and click Add:
    image.png


Note: This filter is applied to a policy in order to send the multicast PAA packets to the CPU of the sink unit.

  1. Access the page Traffic ▶ Policies and open a policy on Port 9 (e.g., policy 9-1). Configure the fields as in the following screen and click Add:
    image.png

Configure PAA in the sink units

  1. Connect to a sink unit (e.g., Skylight element 2), access the page SOAM ▶ PAA ▶ Configuration and click Add.

  2. Create a PAA instance (e.g., L3_Multicast_Sink): enter all parameters as shown in the figure below, and click Apply. Take note that the Local and Peer Index numbers are reversed. The Destination IP address must be the same multicast IP address that was configured in the source unit.
    image.png

PAA should now be functional in this sink unit. Repeat the last two steps on any other sink units that need to be configured.

View the results

  1. Access the page SOAM ▶ PAA ▶ Results in Skylight element 2 and click the PAA index 2.
    image.png

Example 7: Configuring PAA to measure IGMP Join/Leave delay

This is a variant of the previous example; in this case you will make a few modifications to the configuration in order to perform IGMP Join/Leave delay measurements.

This type of measurement cannot be performed from Skylight element to Skylight element. Multicast devices supporting IGMP must be present in the network to process the IGMP messages (Join/Leave requests) sent by the sink unit.

In this example, a Skylight element GT is used as the source unit and a Skylight element TE as the sink unit. A layer-2 switch supporting IGMP snooping is present at the edge of the network to process the Join/Leave messages sent by the sink unit.

Physical Setup:
Example 7 Configuring PAA to measure IGMP Join_Leave delay.png
Layer-3 Multicast PAA with IGMP Join/Leave delay measurements

How it works:

  • In this scenario, the source unit sends a continuous flow of multicast packets.
  • Initially, if the network equipment is properly configured, the sink unit should not receive any multicast packets.
  • When PAA is enabled, the sink unit sends a Membership Report message (Join request), which instructs the network device receiving it to start transmitting multicast packets from the requested multicast group.
  • The sink unit then receives multicast packets for a duration defined by the configured IGMP Reference Period.
  • The sink unit sends a Leave Group message, which stops the multicast flow.
  • The sink unit computes packet loss and delay measurements on the packets received during that period. It also measures the IGMP Join and Leave delay.
  • This Join/Leave sequence is repeated periodically and will start again after an interval defined by the configured One-way reference period.
  • Over a longer period (the IGMP Reference Period), the overall IGMP delay measurements are reported (minimum, maximum and average values).

Configuration Procedure:

  1. Configure an IP interface and a route in the source unit.

  2. Configure PAA in the source unit.

  3. Configure an interface and a route in the sink units.

  4. Configure a traffic policy for multicast PAA in the sink units.

  5. Configure PAA in the sink unit.

  6. View the results.

Configure an IP interface and a route in the source unit

  1. Connect to the source unit.

  2. Access the page System ▶ Configuration ▶ Interface and click Add.

  3. Create an interface on Port 1 with IP address 10.10.10.11/24, as shown in the following screen, and click Apply.
    image.png

  4. Access the page System ▶ Configuration ▶ Interface, scroll down to the IPv4 routes section, and click Add. Configure the route as follows:
    image.png

Configure PAA in the source unit

  1. Access the page SOAM ▶ PAA ▶ Configuration and click Add.
  2. Create a PAA instance: enter all parameters as shown in the figure below, and click Apply. Note that the sampling period is set to 50 ms in order to get a better granularity for the IGMP Join/Leave measurements.
    image.png

Configure an interface and a route in the sink unit
An interface and a route must be configured in the sink unit to send out the Join/Leave messages through the proper interface.

  1. Connect to a sink unit, access the page System ▶ Configuration ▶ Interface, and click Add.
    image.png

  2. Access the page System ▶ Configuration ▶ Interface, scroll down to the IPv4 routes section, and click Add. Configure the route as follows:

image.png

Configure a traffic policy for multicast PAA in the sink unit

  1. Configure an IP filter: access the page Traffic ▶ Filters ▶ IPv4 filters and click Add. Configure the fields as in the following screen, and click Add:
    image.png

Access the page Traffic ▶ Policies and open a policy on the Network port (e.g., policy 1-1). Configure the fields as in the following screen, and click Apply:

image.png

Configure PAA in the sink unit

  1. Access the page SOAM ▶ PAA ▶ Configuration and click Add.

  2. Create a PAA instance (e.g., L3_Multicast_Sink): enter all parameters as shown in the figure below, and click Apply. Take note that the Local and Peer Index numbers are reversed. The Destination IP address must be the same multicast IP address that was configured in the source unit.
    image.png

image.png

image.png

About the parameter settings used in this example:

  • One-way join period (msec) = 5000 (5 seconds)
    This is the interval between an IGMP Join and an IGMP Leave message. During this interval, the sink unit receives multicast packets and computes packet loss and one-way delay. The unit also measures the Join delay and the Leave delay (1 sample).

  • One-way: Reference period (msec) = 10000 (10 seconds)
    This period determines when the next IGMP Join/Leave sequence will start. In this example, the Join/Leave sequence lasts 5 seconds and is repeated every 10 seconds.

  • IGMP: Reference period (msec) = 120000 (120 seconds)
    This interval closes the overall IGMP Join/Leave measurements period. All Join/Leave delay measurements made in the 5-second tests are computed and a minimum, maximum and average value is reported. In this example, 12 IGMP Join/Leave measurements are made over a period of 120 seconds.

View the results

  1. Access the page SOAM ▶ PAA ▶ Results in the sink unit and click the PAA index 2.

image.png

image.png

image.png

Frequently Asked Questions

One-way delay value is larger than two-way delay

Question: PAA results report one-way delay values that are larger than the two-way delay. Furthermore, the peer unit reports negative one-way delay values. How is this possible?

Explanation: This is usually caused by a clock synchronization issue. When NTP or PTP synchronization is enabled in the unit, it usually takes some time for the local clock to converge and align on the reference clock. PAA displays one-way delay results when synchronization is enabled, but this does not mean that the clock has converged yet. The same process takes place in the peer unit. To achieve accurate one-way delay measurements, both units must be synchronized. If there is an offset between the clocks, it will be reflected in the time stamps that are used to measure the delay.

The following illustrates the effect of a clock offset on one-way delay measurements:

If Clock 2 is 10 ms ahead of Clock 1, unit 2 will timestamp with an offset of +10 ms, and vice versa in unit 1. If the actual one-way delay is 1 ms, unit 2 will measure a delay of 11 ms while unit 1 will measure a delay of -9 ms.

Figure 7 Effect of clock offset on one-way delay measurements.jpg

Solution: Units equipped with the GPS option offer the best possible synchronization method and perform well with one-way delay measurements. Otherwise, when synchronizing via NTP or PTP, allow enough time for the clocks to converge. The quality of the synchronization path also plays an important role in the synchronization process. Generally speaking, when the network delay is much larger than the clock offset between units, the impact on the one-way delay measurements will not be significant.

PAA period sometimes reports a few more, or fewer, samples than expected

Question: I sometimes have PAA periods that report a few more, or fewer, samples than expected. For example, I configured PAA with a reference period of 1 minute and a sampling rate of 100 ms. I expect all periods to register 600 samples, but I sometimes see 599 or 601 samples.

Explanation: This can be caused by delay variation in the network. For example, a sudden increase in the delay can cause a PAA frame to reach destination just after a period was closed. The "late" frame is still valid, but it will be registered in the next period. This is a common phenomenon and it does not affect the validity of the performance measurements.

The first PAA period is longer or shorter than configured

Question: I configure all my PAA instances with a reference period of 1 minute and a sampling rate of 1 second. All periods show 60 samples, as I expected. However, I noticed that just after I enabled a PAA instance, the first period is different: it can be either shorter (e.g., 43 samples) or longer (e.g., 64 samples). How can this variation be explained?

Explanation: When a new PAA instance is created, the system ensures that its period is synchronized so that all PAA instances configured with the same period duration will start their measurements at the same time and report consistent measurements.

For example, all 1-minute periods are synchronized to start at xxh:00m:00s, xxh:01m:00s, xxh:02m:00s, etc. All 5-minute periods are synchronized to start at xxh:00m:00s, xxh:05m:00s, xxh:10m:00s, etc.

Note that enabling time synchronization (NTP, PTP or GPS) on a unit while PAA instances are active may trigger resynchronization of the periods.

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