Summary

  • A September 8 operator report places 72% of one scoped Google delivery split on named local GGC assets, not 72% of the operator's entire traffic.
  • Cache filling and proxying mean local delivery is not identical to avoiding external traffic; neither measure alone establishes capacity or invoice savings.

The tempting calculation is also the wrong one: if most content is delivered locally, reduce upstream capacity by the same proportion. A new account from SkyTel in Georgia offers a useful reason to stop before that subtraction.

Writing on RIPE Labs on September 8, Arman Obosyan presents a Google portal split for August 5–September 4 in which named Google Global Cache assets account for 72% of the included delivery. He identifies himself as leading SkyTel. The figures are operator-supplied aggregates, published with the company's authorisation, not an independent audit of all its traffic. Operator report.

What that share cannot reveal is how much outside capacity must remain available. Google's documentation says a new GGC node initially needs cache-fill traffic matching user demand; popular content accumulates as requests arrive. Fill can come from another cache within the same network, a different network, or Google's core through peering or transit. This is documented behaviour, not a reported cold-start incident at SkyTel. Cache-fill documentation.

Three different boundaries matter. A delivery counter describes where content reaches users. A cache hit means content was already present, without retrieval elsewhere, as Google defines it. An external-link measurement records what actually crosses a particular connection at a particular time. None is a substitute for the other. Cache-hit definition.

There is a further complication: a local appliance can proxy content rather than serve a stored copy. Google retains discretion over serving location, taking factors including capacity and maintenance into account. A locally visible delivery path therefore does not guarantee that every byte originated in local storage—or will follow that path tomorrow. Content-serving rules.

That does not make embedded caching uneconomic. It makes the investment case more specific. Reduced external traffic may ease a busy link, improve service or postpone an upgrade. Whether it reduces an invoice depends on the actual path and purchasing terms. Some fill stays within the operator's network; treating all fill as paid transit would be another error.

No invoice evidence or controlled cache-loss test in the material reviewed supports a numerical saving for SkyTel. The report supplies a scoped delivery observation; the documentation supplies mechanisms to examine. Keeping those roles separate follows the operating-reality approach of Lu Heng's Note 36, without turning an operator case into a claim about the entire Internet.