Optical switching
AT&T sets 1.6 Tbps long distance speed record on its white box based fiber optic network
AT&T claims it achieved a long distance world record top speed of 1.6Tb/s over a single wavelength across 296 km of its long haul fiber optic network (spanning Newark, New Jersey to Philadelphia, Pennsylvania). That is four times faster than its current top speed of 400Gb/s per wavelength!
The 1.6Tb/s wavelength carried two IEEE 802.3df-2024 standard-based 800 Gigabit Ethernet end-to-end circuits, an industry first. It is a full, uninterrupted data path utilizing a single light frequency across the entire fiber length between two endpoints. The single-carrier 1.6 Tb/s wavelength was transported alongside existing live customer traffic on 100Gb/s and 400Gb/s wavelengths.
Open-sourced white box switches were the network equipment used during the trial. The white boxes are designed using the Broadcom Jericho3 packet processor chip and can provide up to 18 x 800G network interface ports all within a 2RU platform. The (Israel based) DriveNets Network Cloud software-based solution is hardware-agnostic and runs open APIs on the white boxes to perform data and control plane functions, including routing at 800G. The use of white boxes and the disaggregation of the hardware and software control costs and facilitate faster innovation.
The two 800GbE signals from the white box were multiplexed to 1.6 Tb/s in Ciena’s WaveLogic 6 Extreme coherent optical transponder, which is the first coherent optical solution to use a 200Gbaud design and 3nm coherent DSP ASIC and to reach speeds up to 1.6 Tb/s on a single carrier. The WL6e technology reduces the space and power per transmitted bit by 50% compared to current 800G transponders. This trial is the first to demonstrate WL6e at 1.6Tb/s with standards compliant 800GbE clients.
In the Newark and Philadelphia offices, 800G DR8 pluggable transceivers from Coherent were installed in the white box router and WL6e transponder to create the cross-office connectivity between the packet and optical technologies. And 800GbE client signals, provided by Keysight’s AresOne-M 800GE testset, fed the white box through additional pairs of 800G DR8 pluggable client optics, allowing verification of end-to-end performance of the two 800GbE services from Newark to Philadelphia.
Quotes:
“Traffic on AT&T’s network continues to increase as consumers are using more connected devices,” said Mike Satterlee, vice president, Network Infrastructure and Services, AT&T. “We anticipate network traffic growth to double by 2028 and the technologies demonstrated in this trial will play a key role in AT&T’s continued efforts to keep up with increasing customer demand to send data, watch videos, and use streaming services.”
“This groundbreaking achievement with AT&T adds to a growing list of Ciena industry-firsts that push the boundaries of optical network speed and capacity,” said Dino DiPerna, senior vice president, Global Research and Development, Ciena. “Ciena’s WaveLogic 6 coherent optics will support AT&T’s next gen converged optical network and efforts to build a cloud-based and AI-ready network with greater scale, flexibility and efficiency.”
Verizon’s 1.6Tb/s on Metro Fiber Network:
AT&T’s announcement comes just a few months after arch-rival Verizon announced a 1.6 Tb/s milestone of its own. Verizon also, working with Ciena, achieved that peak speed on a single wavelength, but on its metro fiber (not long distance) network. Verizon is mainly looking to advance through M&A. Its proposed acquisition of Frontier Communications is still pending, with some Frontier shareholders insisting that the US$20 billion price tag undervalues the operator.
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AT&T has spent the past six months demonstrating that it aims to build its way to fiber domination. It rolled out fiber to around 600,000 premises in the 4th quarter of last year, taking its total fiber footprint to 28.9 million locations; it is shooting for 50 million by the end of 2029.
References:
https://about.att.com/story/2025/data-transport.html
https://www.business.att.com/products/wavelength-services.html
https://www.telecoms.com/fibre/at-t-touts-1-6-tbps-fibre-speed-milestone-as-us-battle-continues
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Light Counting on Silicon Photonics and Optical Switching at SC22
Silicon photonics continues to progress but is yet to be adopted for high-performance computing and server architectures, according to market research firm Light Counting.
However, the Super Compute 2022 (SC22) conference hosted two silicon photonics firsts:
- Professor Keren Bergman of Columbia University reported a working 5Tbit/s transmitter optical chiplet implemented using 80 channels and 3D packaging. The accompanying receiver chip is working and is being lab-tested.
- Ayar Labs demonstrated its 2Tbit/s TeraPHY chiplet in an end-to-end link, sending and receiving data.
During the panel discussion on high-performance computing and silicon photonics, Intel’s Fabrizio Petrini addressed head-on why optics had such a low profile at the show. “The reality is there is a lot of skepticism about this technology. The adoption is not going to happen anytime soon,” he said.
Systems designers don’t see the implications until they embrace this technology. But factors are aligning for change, and a transition point is being approached in how systems are built, he says; the implications for systems and disaggregation are enormous.
Optical switching is another technology that has been on the fringes of the market for decades. It was all the rage from 1998-2001, but then fizzled out as there weren’t any large scale commercial deployments of photonic switches.
LightCounting reported in August that Google had been using photonic circuit switching in its cloud resident data centers for several years. The 136×136 port optical circuit switch is Google’s own design.
At SC22, a start-up, Drut Technologies, demonstrated its interface card working with a photonic switch at the top of a SuperMicro server rack. The system allows the server’s CPUs to dynamically configure the resources they need (memory, GPUs) tailored for workloads.
