Test Execution Control

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Fig. 20 Test execution control panel

Flow Creation

These properties determine how the test flows between ports are created.

Stream-Based Flows

The default Stream-based setting will use one Xena stream for each flow from one port to another. This enables fine-grained per-port statistics and also allow you to specify field modifiers for various protocol fields. But as the number of streams that can be created on each test port is limited, this will limit the total number of test ports in your configuration.

The TID Alloc.Scope property determines how Xena2544 allocates test payload identifier (TID) values.

  • Configuration Scope: Allocates a unique TID value for each stream created. This option ensures that only packets intended for a given port is taken into account. The downside is that for large configurations you may quickly run out of TID values due to hardware constraints.

  • Rx Port Scope: Allocate TIDs so that all streams received on any given port have a unique TID. TID values are reused between ports. This allow for larger configurations but the test is no longer able to detect if packets are mis-delivered by the DUT.

  • Source Port ID: Allocate TIDs so that all streams from a given port is set equal to the port index in the configuration. This is a slight variation of the previous method.

Modifier-Based Flows

If you encounter the above mentioned limitations in a layer-2 test you can select the Modifier-based option instead. In this mode the Xena2544 will use a single stream for all flows from one port instead of one stream for every flow between two ports.

This will cause the Xena2544 to create the traffic flows using so-called modifiers instead of using streams (refer to the XenaManaeger documentation for details about this). This option will however force the Xena2544 to override the native port MAC addresses. The user can specify the 3 upper bytes of the MAC address using the MAC Base Address option but the lower part of the address will be assigned sequentially.

The modifier-based option is not available for layer-3 tests as we cannot emulate multiple MAC addresses the Xena2544 needs to.

Port Scheduling

If enabled the Speed Reduction Sweep property will assign a small speed reduction value to each port on a test module, so that each port on the module will get a different value. This property is available for Blocks and Mesh topologies.

If the Use Port Sync. Start option is checked the Start button will activate a synchronized port start mechanism for the ports - if the chassis firmware version supports this feature.

The Port Stagger Steps property delays start of traffic generation on one port relative to pressing Start button. The delay is programmed in steps of 64 microseconds. The Port Stagger function works between ports on test modules installed in the same chassis.

  • The 1st port will not be delayed.

  • The 2nd port will be delayed with the Port Stagger Steps.

  • The 3rd port will be delayed with the Port Stagger Steps * 2.

  • The 4th port will be delayed with the Port Stagger Steps * 3 etc.

The maximum value of Port Stagger Steps for a port is 31250. Therefore the programmed Port Stagger Steps must not exceed 31250/(number of ports).

Note

This requires that Use Port Sync. Start has been checked.

The Resulting Delta is Port Stagger Steps * 64 microseconds

Important

Please observe that on Z800 module (Freya), you will need to uncheck the Use Port Sync. Start box to get Xena2544 to complete.

MAC Learning Options

The MAC Learning Mode property can be used to instruct the testers to emit initial MAC learning packets in order for any network switches to learn the MAC addresses of the ports and avoid excessive flooding of packets. You can specify if you want MAC learning to be performed either at the start of every trial (the default), once when the test starts or not at all. You can also specify how many time each learning packet will be repeated every time with the Learning Frame Count option.

If the Toggle Sync State property is checked the sync state for all selected ports will be toggled off and on at the start of each test trial. This may ensure that the DUTs MAC-tables are cleared at the start of each test.

The Sync State Off Period is the number of seconds to keep the port sync state off.

ARP/NDP Learning

This set of options control how the Xena tester advertises the IP addresses configured for its ports. The tester will use ARP for IPv4 and NDP for IPv6. If the Enable Refresh checkbox is checked the tester will periodically emit ARP requests (for IPv4) or Neighbor Advertisement requests (for IPv6). The period can be set using the Refresh Period field. This will prevent the ARP/NDP caches in the attached router from timing out during long test period thus causing a packet loss.

If the test uses multiple ports and/or you have used modifiers to emulate multiple IP address on one port the number of periodic refresh requests may be large. The tester will retransmit all refresh requests within the specified period, but it will not send them all in one batch. The tester will distribute the necessary requests evenly over the specified period.

When the GW MAC as DMAC checkbox is checked Xena2544 will use the ARP-resolved gateway MAC address as DMAC address for test packets. This is only relevant for IP traffic where the test ports belong to different IP subnets and the traffic needs to go through an IP router.

Flow-Based Learning

This section contains a few properties that are mainly useful when working with flow-based switches.

The Use Flow-Based Learning Preamble property will make the Xena2544 emit a brief traffic preamble before starting the actual test. This can be used to ensure that the flow-based switch has learned all necessary addresses.

The Learning Frame Count controls how many frames are sent in the preamble.

The Delay After Preamble determines the size of the period between the preamble and the start of the actual test traffic.

Reset and Error Handling

If Stop on LOS is enabled, Xena2544 will abort the test if a port loses the sync state during test.

When a Xena2544 test is started, the selected ports will be reset to ensure a known starting point for the test. The Delay After Reset parameter defines how long time Xena2544 will wait after the reset before it continues with the test.

If Port Reset is enabled, Xena2544 will reset the test ports when starting the test.