What is Y.1564 and why your business fibre should have it

If you have ever switched operator only to discover that "up to 1 Gbps" was very different from what you actually got, you already know the problem. Residential operators sell a promise, not a guarantee. ITU-T Y.1564 is the international standard that turns that promise into a reproducible technical test.

It is the protocol for validating an Ethernet service: it simultaneously measures 5 key parameters under real load, with multiple flows at once, and compares them against contractual values. If the service passes, you get a signed report. If not, it is tuned before being delivered.

Why Y.1564 exists (RFC 2544 fell short)

For years the industry used RFC 2544 to test links — a method from the 1990s that runs a single flow at a time, covering latency, throughput, frame loss and back-to-back. It was fine for testing the device, but it did not replicate the real behaviour of a modern service network, where thousands of flows compete simultaneously with different priorities and QoS policies.

Y.1564 arrived in 2011 (revision 2016) to fill that gap: it tests multiple services at once, with QoS profiles and in two distinct phases. It is the standard tier-1 carriers use to validate a circuit before it can be billed.

The 5 KPIs it measures

A Y.1564 report is exactly that: 5 numbers validated against the contract. Each has a threshold; if one fails, the link fails.

• CIR (Committed Information Rate) — guaranteed bandwidth in bits per second. The minimum the operator must always deliver. For a 1 Gbps business fibre, the CIR must be exactly 1 Gbps.
• EIR (Excess Information Rate) — additional bandwidth usable on best-effort basis if there is free capacity on the backbone.
• FTD (Frame Transfer Delay) — end-to-end latency in milliseconds. For a regional business connection the typical threshold is < 10 ms; international, < 50 ms.
• FDV (Frame Delay Variation) — jitter: how much transit time varies between consecutive packets. For quality VoIP, < 2 ms.
• FLR (Frame Loss Ratio) — percentage of lost frames. Carrier-grade service expects < 0.001% (fewer than one in 100,000).

If any of these values falls outside its threshold, the test FAILS. The operator must tune the network before delivering service.

The two test phases

Y.1564 splits validation into two complementary phases:

• Phase 1 — Service Configuration Test. Verifies that configuration is correct: progressive ramps at different percentages of the CIR (25%, 50%, 75%, 100%), validation of CIR + EIR and verification of QoS policies. Takes a few minutes. Catches provisioning errors.
• Phase 2 — Service Performance Test. Runs all flows simultaneously at CIR for a long period (typically 15 minutes, can extend to 24 h). This is where FTD, FDV and FLR are measured under sustained load. Catches congestion, microbursts and broken QoS.

A full test with multiple services (voice, data, video) can take 30-60 minutes but is documented in a signed PDF that becomes part of the contract.

What Olivet Telecom does differently

Most operators do not run Y.1564 on a business fibre. They run a simple throughput test (often Iperf3 or equivalent) and send a screenshot. No auditable report, no contractual thresholds, no accountability.

Olivet Telecom delivers Y.1564 with every installation. The engineer runs a multi-stream test at the customer edge with an EXFO (or carrier-grade equivalent) and generates a signed report with the 5 KPIs. The report is part of the service contract. If the values later drift, the SLA includes financial compensation.

Conclusion

Y.1564 is not a marketing fad: it is the standard that separates a "commercial" link from a genuinely business-grade one. If your fibre doesn't ship with a signed Y.1564 report, you have no objective evidence of what you are getting — only the salesperson's word.

At Olivet Telecom, the Y.1564 report is the first document you receive, before we send the first invoice. So you know exactly what you are buying, and we commit to what we claim.

Frequently asked questions

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