Deutsche Telekom explains its IP-over-DWDM thinking

Telecom operators are always seeking better ways to run their networks. In particular, operators regularly scrutinise how best to couple the IP layer with their optical networking infrastructure.

The advent of 400-gigabit coherent modules that plug directly into an IP router is one development that has caught their eye.

Placing dense wavelength division multiplexing (DWDM) interfaces directly onto an IP router allows the removal of a separate transponder box and its interfacing.

IP-over-DWDM is not a new concept. However, until now, operators have had to add a coherent line card, taking up valuable router chassis space.

Werner Weiershausen

Now, with the advent of compact 400-gigabit coherent pluggables developed for the hyperscalers to link their data centres, telecom operators have realised that such pluggables also serve their needs.

BT will start rolling out IP-over-DWDM in its network this year, while Deutsche Telekom has analysed the merits of IP-over-DWDM.

"The adoption of IP-over-DWDM is the subject of our techno-economical studies," says Werner Weiershausen, senior architect for the transport network at Deutsche Telekom.

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Lumentum’s CTO discusses photonic trends

CTO interviews part 2: Brandon Collings

• The importance of moving to parallel channels will only increase given the continual growth in bandwidth.
• Lumentum's integration of NeoPhotonics’ engineers and products has been completed.
• The use of coherent techniques continues to grow, which is why Lumentum acquired the telecom transmission product lines and staff of IPG Photonics.

Brandon Collings has been a CTO for over 13 years; first as CTO of the commercial optical products (CCOP) business within JDSU and then CTO of Lumentum when it spun out in 2015. In that time, the scope of his work has continued to grow.

Brandon Collings

"It has changed quite significantly given what Lumentum is engaging in," he says. "My role spans the entire company; I'm engaged in a lot of areas well beyond communications."

A decade ago, the main focus was telecom and datacom. Now Lumentum also addresses commercial lasers, 3D sensing, and, increasingly, automotive lidar.

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BT's IP-over-DWDM move

• BT will roll out next year IP-over-DWDM using pluggable coherent optics in its network
• At ECOC 2022, BT detailed network trials that involved the use of ZR+ and XR optics coherent pluggable modules

Telecom operators have been reassessing IP-over-DWDM with the advent of 400-gigabit coherent optics that plug directly into IP routers.

According to BT, using pluggables for IP-over-DWDM means a separate transponder box and associated 'grey' (short-reach) optics are no longer needed.

Until now, the transponder has linked the IP router to the dense wavelength-division multiplexing (DWDM) optical line system.

"Here is an opportunity to eliminate unnecessary equipment by putting coloured optics straight onto the router," says Professor Andrew Lord, BT's head of optical networking.

Removing equipment saves power and floor space too.

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Telecoms embraces 400ZR optics for IP-over-DWDM

Verizon Media has trialled 400-gigabit coherent pluggable optics to improve the delivery of video content to subscribers.

Tomas Maj

Verizon Media added a 400ZR QSFP-DD module from Inphi to a switch already using 100-gigabit optics to upgrade its content delivery network.

Adding dense wavelength-division multiplexing (DWDM) optics to a switch enables it to send IP traffic (IP-over-DWDM) directly without needing a separate DWDM data centre interconnect box and additional client-side optics to link the two platforms (see diagram).

“Verizon Media, showing leadership outside the hyperscalers, is moving to IP-over-DWDM,” says Tomas Maj, senior director, marketing, optical interconnect at Inphi. “It shows the maturity of the ecosystem and the confidence of more and more operators in IP-over-DWDM and 400ZR.”

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P-OTS 2.0: 60s interview with Heavy Reading's Sterling Perrin

Heavy Reading has surveyed over 100 operators worldwide about their packet optical transport plans. Sterling Perrin, senior analyst at Heavy Reading, talks about the findings.

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OTN processors from the core to the network edge

The latest silicon design announcements from PMC and AppliedMicro reflect the ongoing network evolution of the Optical Transport Network (OTN) protocol.

"There is a clear march from carriers, led in particular by China, to adopt OTN in the metro"

Scott Wakelin, PMC

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