Broadcom has developed the new high-radix Tomahawk 5 chip with six ARM CPUs for L2 and L3 switches with 64 × 800GE or 256 × 200GE ports.
Broadcom has completed its new StrataXGS Tomahawk 5 family of chips for 51.2 Tbps Ethernet switches and is beginning shipments to switch manufacturers. The officially named BCM78900 family can control up to 64×800GE, 128×400GE or 256×200GE ports, as well as 256×100GE or 256×50GE ports. As a result, scalable leaf, spine, blade or aggregation switches can be built with one chip. The BCM78900 family offers full L2 and L3 switching, routing and tunneling functions. It is software compatible with all StrataXGS products.
The Tomahawk 5 chips belong to the class of high-radix network switches, i.e. on-chip crossbar switches with high port density, and have up to 64 integrated Peregrine SerDes (Serializer-Deserialize) cores with each eight 106 Gbit/s PAM4 SerDes (Pulse Amplitude Modulation) transceivers and associated PCS (Physical Coding Sublayer) for which a variety of port types, media and ranges can be implemented. They are implemented as six on-chip ARM processors on a monolithic 5 nm chip, which should also increase energy efficiency.
Also suitable for AI and ML clusters thanks to low latency
According to Broadcom, this is the first chip to feature 256 × 200GE ports. This also makes it suitable for flat AI/ML clusters with low latency. Due to the low latencies and its shared buffer architecture, it should also be suitable for RoCEv2 (RDMA over Converged Ethernet) and other RDMA protocols (Remote Direct Memory Access).
It also offers advanced adaptive routing, hardware-based link failover, dynamic load balancing, and high-precision PTP (Precision Time Protocol) and SyncE (Synchronous Ethernet) time synchronization. It also supports end-to-end congestion control features specifically designed to handle the large, low-entropy flows typical of AI/ML workloads. Broadcom has not yet announced which manufacturers will use the Tomahawk 5 chips for their switches. The last update of the Tomahawk series was released in 2019.
