• Telstra and Ciena transmitted 1.6Tbps over a 1,100km live-network route, carrying four 400GbE services on one optical wavelength without intermediate regeneration
  • The trial establishes a tested combination of capacity and reach between Melbourne and Sydney, rather than the same performance across Telstra's wider network

The fact

Telstra and Ciena said they transmitted 1.6 terabits per second over 1,100 kilometres between Melbourne and Sydney without regenerating the optical signal at an intermediate site. The live-network trial carried four 400-gigabit Ethernet services on a single wavelength using Ciena's WaveLogic 6 Extreme technology, a C- and L-band optical line system and Telstra's low-loss fibre infrastructure.

The companies said the test extended the reach of an earlier 1.6-terabit demonstration by about half. The 1.6Tbps figure refers to the transmission rate of the tested wavelength, not the aggregate capacity of Telstra's network or a guaranteed service rate for individual customers. Telstra and Ciena reported the result as a trial rather than a commercial launch of 1.6Tbps services across Telstra's long-distance network.

A December 2025 Ciena announcement provides a comparison from another network. Indian operator Constl transmitted 1Tbps over 1,450 kilometres between Mumbai and Chennai using WaveLogic 6 Extreme and without intermediate regeneration. The two trials used different routes, distances and transmission rates.

The assessment

The Melbourne–Sydney result extends the demonstrated operating range for a 1.6Tbps wavelength, but it does not turn that rate into a standard specification for every long-distance route. Optical performance depends on the characteristics of the fibre path, so planners still need to establish what rate a particular route can support and whether intermediate regeneration is required.

The Constl result helps show why that distinction matters. Both trials used WaveLogic 6 Extreme, but Telstra carried 1.6Tbps over 1,100 kilometres while Constl carried 1Tbps over 1,450 kilometres. The useful planning question is therefore not which trial produced the larger headline number, but which combination of rate, distance and regeneration works on the route being designed.

For BTW readers, the practical value is in route planning before capacity is ordered or deployed. If a path can support 1.6Tbps, four 400GbE services can be carried on one wavelength without an intermediate regeneration site on that route. Whether Telstra can offer the same configuration elsewhere still depends on the fibre path and the commercial service it makes available.

What to watch

Watch whether Telstra moves the 1.6Tbps configuration from trial to commercial deployment and identifies the routes, service rates and regeneration requirements it can support. Further tests on different fibre paths would show how widely the Melbourne–Sydney result can be reproduced and where distance or route conditions require a different transmission rate or network design.