It is possible to attach a modifier definition to one or more fields. A modifier will exercise the field with various values during the test and can be used to emulate a certain dynamic behavior. Modifiers are often used to exercise either the VLAN PCP or the IP DHCP fields. Alternatively one could apply modifiers to address fields like the DMAC field or the source or destination IP address fields.
A Value Range is intended to exercise one or more fields in a Valkyrie2544 protocol segment profiles with varying values. It is kind of similar to the hardware modifier explained above, with the following differences:
- A Modifier is handled by hardware and varies a field value between packets on the same stream.
- A Value Range is handled by software and varies a field value between different streams. All packets on the same stream have the same value.
- A Value Range is defined on a field in a protocol segment profile, just like a modifier. It will then be used for all streams created on a port which is assigned this profile.
- Value ranges can be used for both normal single-stream and advanced multi-stream scenarios. For normal scenarios it is most applicable for mesh configurations where multiple streams will be created on each port.
- There is no limit to the number of values ranges added to a configuration. It is also possible to add both a modifier and a value range to a field. Whether that would yield usable results is unclear but it might be useful for larger fields.
To configure streams as shown in the figure where each stream has:
- an UDP destination port differs from others (i.e. stream0/port 80, stream1/port 81, ...)
- 50 simulated clients
First, go to Protocol Segment Profiles -> Ethernet / IPv4 / UDP and add a VALUE RANGE to field Dest Port as shown below.
Second, add a HW Modifier to field Src IP Addr as shown below. You can change the Address Mask to 0.255 in order to only modify the last byte of the address. Modifier Count should be set to 50 since each stream should simulate 50 clients.
Then, go to Multi-Stream Configuration. Enable Multi-Stream option, set Stream Count Per Port-Pair to 3 (the port will create 3 physical streams). Set the Address Increment to 128 and Address Offset to 1 as shown below.
Last, remember to assign the Protocol Segment Profile of the ports accordingly as below: