SD-WAN Virtual Path Services Test

Virtual path service configured on the Citrix SD-WAN appliance manages traffic across Virtual Paths. A Virtual Path is a logical link between two WAN links established from the target appliance. Each virtual path comprises a collection of WAN Paths combined to provide high service-level communication between two SD-WAN nodes. The virtual path can be static (always exists) or dynamic (exists only when traffic between two SD-WAN appliances reaches a configured threshold). Maintaining the virtual paths at good state and transmitting the packets over the virtual paths with low latency and good/no jitter are important for administrators to ensure reliable communication between the SD-WAN nodes. If, for any reason, any of the virtual paths changes to bad/dead state and/or transmits packets with high latency and bad jitter, the packets transmitted through that virtual path will not reach the destination on time and thus, the communication will become unreliable. In such cases, administrators will have to direct the traffic from the affected virtual path to the other virtual path before anything untoward happens. Using the SD-WAN Virtual Path Services test, administrators can track the current status of the virtual path and latency and jitter over the virtual path. Analyzing the metrics reported by the test, administrators can easily detect whether the packet transmission over each virtual path is reliable or not.

This test auto-discovers the virtual paths configured on the target SD-WAN appliance, and for each virtual reports the current status and latency and jitter recorded while transmitting the packets.

Target of the test : A Citrix SD-WAN

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each virtual path configured on the target Citrix SD-WAN appliance.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed. By default, this is set to 5 minutes.

Host

The IP address of the target SD-WAN appliance for which this test is to be configured.

Port

Refers to the port at which the target SD-WAN listens to. By default, this will be NULL.

Timeout

Specify the time duration (in seconds) beyond which this test should time out in the Timeout text box. The default is 10 seconds.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

State

Indicates the current status of this virtual path.

 

The numeric values that correspond to the measure values are as follows:

Measure Value Numeric Value

Description

Dead 0

Indicates that the path hasn't received any packets since 1.5 seconds.

Bad 1

This state is reported when 3 or 4 packets out of 10 are lost.

Good 2

Every 2-3 packets of incoming packets are processed as a sample size used to report conditions back to the local device.

Note:

By default, this measure reports one of the Measure Values listed in the table above to indicate the current status of each virtual path link. The graph of this measure however, represents the same using the numeric equivalents alone.

The detailed diagnosis of this measure displays the type of each virtual path i.e. whether the link is static or dynamic, and how long the virtual path is in a particular state since it is created. In addition to the above details, whether the virtual path is affected by traffic congestion or not.

Maximum transmission unit

Indicates the maximum size of the packets/frames that this virtual path can transmit.

Bytes

A very high value of this measure may indicate the need for retransmissions if the virtual path can't transfer large packets. A very low value of this measure may indicate relatively more header overhead and more acknowledgments that have to be sent and handled over the path. Therefore, it is highly recommended that the administrators should not change the default Maximum transmission unit (MTU) value set by the service providers.

Latency

Indicates the time delay recorded while transmitting/receiving the packets through this virtual path.

Seconds

 

Worst jitter

Indicates the worst time variation in the delay recorded over this virtual path.

Seconds

A value of this measure should be very low.

Best jitter

Indicates the acceptable time variation in the delay while transmitting/receiving the packets over this virtual path.

Seconds

A gradual/sudden increase in the value of this measure indicates that the jitter on the virtual path is increasing which may lead to poor user experience with the virtual path.

Data received

Indicates the rate at which the data was received over this virtual path.

Mbps