UDP/RTP Capacity Test

• Managing Work-From-Home networks: Quickly understanding, improving and resolving threats common to domestic ISP services.
• Ensuring ISP SLA delivery 24/7: Confirming that a connection can actually sustain the bandwidth quality you're paying for, not just burst to it momentarily.
• Identifying root cause and quality issues: Troubleshooting real-time media applications such as VoIP calls, video conferencing and other collaboration or streaming applications.
• Baseline and change monitoring: Establishing a known-good capacity measurement to expose degradation patterns over time, or to verify that network change investments deliver expected improvements.
• Pre and post deployment validation: Ensuring a network can support expected application demand (such as concurrency of VoIP calls or high video resolution) before rollout.
• Diagnosing buffering and congestion patterns: Identifying application sensitivity to packet loss thresholds, revealing congestion points or buffering limitations that simpler tests cannot detect.
• Assessing large-scale support services: Evaluating the effectiveness of distributed global call centre and customer support operations.

Why RTP instead of TCP?

The MCS UDP/RTP Capacity test measures the data throughput that a network connection can sustain using RTP, not TCP. Using RTP packets is a highly effective way to validate bandwidth demand versus quality delivered.

Unlike a traditional speed test where bandwidth demand is regulated by the TCP protocol (because data loss is not permitted), RTP bandwidth demand is dictated only by the test process itself (data loss is permitted). This difference is significant because it allows the test to precisely assess how well the network satisfies the scale factor of a connection relative to the application quality expected or required.

Consider the analogy of filling a bath with water. Using a tap, the flow rate varies based on how far the tap is opened — this is controlled directly by the test and mimics the RTP approach. Using a well and bucket, the flow rate varies dramatically based on the size of the bucket, the distance to the well, and spillage along the way (i.e. data loss) — this mimics the TCP speed test approach. The tap gives you precise, controllable demand; the well and bucket does not.

How the Test Works

The MCS Capacity test runs a series of short, repeating test cycles while increasing the payload demand logarithmically (not linearly). Three significant business-related thresholds govern the outcome of the test:

• Allowed Packet Loss % (threshold 1)
• Allowed Packet Loss % (threshold 2)
• Allowed Packet Delay Variance % — the official name for Jitter

Unlike TCP, when a connection degrades RTP will measure and report both Packet Loss and Packet Delay Variance. The test will stop when either metric breaches its configured threshold.

If the test encounters packet loss immediately on the first test cycle, it will automatically adjust by reducing the demand until the test passes the business zero-loss threshold setting. If the reduction process reaches zero packets, the test terminates.

Automatic Continuation and Confirmation

Once started, the test automatically continues until either the maximum bandwidth demand is reached or a business threshold is breached. Any failed test cycle will invoke one or more confirmation tests (if confirmations have been configured, a minimum of two is recommended). The purpose of a confirmation test is to ensure that transient network traffic does not trigger a false-positive threshold failure. If the confirmation test successfully passes the previously failed level, the test process is allowed to continue.

What the Test Delivers

The MCS Capacity test is specifically designed to deliver a measure of the true effective bandwidth that meets your business SLAs, independently for both downstream and upstream traffic. Because the RTP protocol is able to place a precise demand on a network, the test can quickly validate the usability and quality of specific business applications such as VoIP, video conferencing and other collaboration solutions.