Practical examples of IP impairment
Any IP network will benefit from testing, and using dedicated tools for the task will reduce the effort needed and add to the accuracy of the conclusions drawn from the tests.
Here we have collected a list of possible use cases with practical examples for the tests.
Examples of IP impairment include:
- 5G fronthaul testing
- Testing of streaming applications
- Creating challenging scenarios easily with modifying priority classes with Rude
- Creating accurately repeatable drop test scenarios with targeting the most significant packets
Example: Streaming video
In real life, IP traffic will not be a constant flow of flawless packets. Instead, the traffic may be delayed or bursty, the bandwidth may be limited or the line may be down entirely for periods of time. On the byte level, packets may be dropped or corrupted or fragmented into smaller packets, and data may be lost or changed on the way. In streaming protocols, the initial delay is not the main concern, but the focus is on systems robustness to errors to ensure a smooth experience for the end user.
The picture above outlines an example of a video streaming service that is followed by a multitude of users with various types of equipment. Using the Rude IP deviation emulator, the desired data streams can be targeted on the basis of the IP address, protocol etc. The targeted data streams can then be deviated to emulate realistic network conditions that vary over time. The effect of each deviation on the Quality of Experience can be tested empirically.
Example: 5G fronthaul
For 5G the basestation elements will be split into central unit and distributed units, introducing new fronthaul interfaces that require timing accuracy and low latency with attention to jitter.
As an example, testing the F1 interface between the Central unit and the distributed unit has certain specific challenges:
- The physical distance between the units may be as much as 40km. This will cause time delay, as a rule of thumb 5us/km.
- The interface needs to maintain an accurate time synchronization, and stressing that will reveal the system robustness.
- A low BER is expected, and increasing it will reveal the system limits.
- Finally, it is possible to emulate line breaks between the units to test recovery and replacement procedures in case a distributed unit goes dark.
Example: Rare priority classes: Easy setup for a complex scenario
How would a network handle several high priority class traffic streams at the same instance? This might be a rare occurrence, but one that must not affect the system robustness.
Creating this scenario manually would be a burdensome task, but IP impairment can reduce the work time significantly.
By using the data modification feature of Rude, it is possible to directly alter the traffic contents in real time. Using this feature it is possible to:
- Select the data streams to be modified
- Modify the priority header directly on the traffic
- Repeat with a a different set of modified streams and priority settings