At OCP Summit 2024, we saw a neat demo. Delta had a Broadcom Tomahawk 5 Bailly switch with 128x 400GbE ports on the front. Delta had a lot of really cool stuff that was hard to photograph in their OCP booth, but this is one we have been following for some time. Perhaps the coolest part is that this is one of the production-looking switches with external pluggable light sources.
Delta Shows Broadcom 128-port 400GbE Co-Packaged Optics Switch with Pluggable Light Sources
The switch was the Delta DD-S64C80. One of the really cool features of the switch is that it has a massive number of single-mode LC fiber connections on the front. Physically to fit this many FR4 ports into the front of the chassis it is massive.
It was challenging to get a photo based on where this was in the rack but here is what we got. We have seen Broadcom’s co-packaged optics Tomahawk 5 before.
The newer part was the light source. Here, each side has eight pluggable light sources for 16 across the chassis or one for every eight ports.
These pluggable modules take the highest failure rate part of optics and move them to the switch’s front panel. If one fails, a blast radius is larger than a single port. One of the challenges with co-packaging the light source inside the switch is that it is a maintenance nightmare if the light source fails. This pluggable version makes it about as easy as changing a current pluggable optic.
Final Words
While to many, these may look like standard pluggable optics with big heatsinks. Realistically, they are one of the key advancements required to turn co-packaged optics from an idea to something deployable with huge power savings along the way. Broadcom has some cool technology we have been watching for some time. Delta appears to have taken this beyond just being an early science experiment and toward broader adoption.
So a single laser is split eight ways and each one modulated separately?
The light source should be in a 1+1 backup configuration, meaning the 16 light sources are divided into two parts: 8 for working mode, and the other 8 as backup.
Yes, I suppose they could add some sort of redundancy, but that would double the cost and the added couplers between the two light sources would only add another point of failure, which won’t be as easily reachable as the light source itself.
It honestly seems like some decent training around maintenance for this switch will be required.
Looking at the pictures, my first impression is that there are 8 pluggable light sources, 4 on each side.
The back-to-back pull loops on each module makes it look more like it’s a pinch-then-pull release system for a single unit, rather than 2 distinct units next to each other. It is easy to imagine data center support staff pulling both on accident thinking they were a single unit without some kind of walk through for every new person who might be servicing them.
How much is this toy?