The Octeon family has come a long way since the networking infrastructure chip was introduced by Cavium Networks in 2005.
Used for data centre switches and routers, the original chip family featured 1 to 16, 64-bit MIPS cores and hardware acceleration units for packet processing and encryption. The devices were implemented using foundry TSMC’s 130nm CMOS process.
Jeffrey Ho
Marvell, which acquired Cavium in 2018, has taped out the first two devices of its latest, seventh-generation Octeon 10 family.
The devices, coined data processing units (DPU), will feature up to 36 state-of-the-art ARM cores, support a 400-gigabit line rate, 1 terabit of switching capacity, and dedicated hardware for machine-learning and vector packet processing (VPP).
Marvell is using TSMC’s latest 5nm CMOS process to cram all these functions on the DPU system-on-chip.
The 5nm-implemented Octeon 10 coupled with the latest ARM cores and improved interconnect fabric will triple data processing performance while halving power consumption compared to the existing Octeon TX2 DPU.
DPUs join CPUs and GPUs
The DPU is not a new class of device but the term has become commonplace for a processor adept at computing and moving and processing packets.
Indeed, the DPU is being promoted as a core device in the data centre alongside central processing units (CPUs) and graphic processing units (GPUs).
As Marvell explains, a general-purpose CPU can perform any processing task but it doesn’t have the computational resources to meet all requirements. For certain computationally-intensive tasks like graphics and artificial intelligence, for example, the GPU is far more efficient.
The same applies to packet processing. The CPU can perform data-plane processing tasks but it is inefficient when it comes to intensive packet processing, giving rise to the DPU.
“The CPU is just not effective from a total cost of ownership, power and performance point of view,” says Nigel Alvares, vice president of solutions marketing at Marvell.
Data-centric tasks
The DPU is used for smart network interface controller (SmartNIC) cards found in computer servers. The DPU is also suited for standalone tasks at the network edge and for 5G.
Marvell says the Octeon DPU can be used for data centres, 5G wireless transport, SD-WAN, and fanless boxes for the network edge.
Data centre computation is moving from application-centric to more data-centric tasks, says Marvell. Server applications used to host all the data they needed when executing algorithms. Now applications gather data from various compute clusters and locations.
“The application doesn’t have all the data but there is a lot of data that needs to be pumped into the application from many points,” says Jeffrey Ho, senior product manager at Marvell. “So a lot of network overlay, a lot of East-West traffic.”
This explains the data-centric nature of tasks or, as Ho describes it, the data centre appearing as a mesh of networks: “It’s a core network, it is a router network, it is an enterprise network - all in one block.”
Octeon 10 archtecture
The Octeon 10 family uses ARM’s latest core architecture, the Neoverse N2 processor, Arm's first Armv9 Infrastructure CPU, for general-purpose computational tasks. Each ARM core has access to hierarchical cache memory and external DDR5 SDRAM memory.
The initial Octeon 10 family members range from the CN103XX which has up to eight ARM N2 cores, each with Level 1 and private Level 2 cache and shared level 2 and 3 caches (8MB and 16MB, respectively).
The most powerful DPU of the Octeon 10 family is the DPU400 which will have up to 36 ARM cores and 36MB level 2 and 72MB level 3 caches.
“Then you have the acceleration hardware that is very friendly to this generic compute,” says Ho.
Source: Marvell
One custom IP block is for vector packet processing (VPP). VPP has become popular since becoming available as open-source software that batch-processes packets with similar attributes. Marvell says that until now, the hardware processed the packets one at a time such that the potential of VPP has not been fully realised.
The Octean 10 is the first device family to feature hardware for VPP acceleration. Accordingly, only one look-up table operation and one logical decision may be required before header manipulation is performed for each of the grouped packets. The specialised hardware accelerates VPP by between 3-5x.
The DPU also integrates on-chip hardware for machine-learning inferencing tasks.
Machine learning can be applied to traffic patterns on a compute cluster such that every day or so, newly learned models can be downloaded onto the DPU for smart malware detection. This is learnt behaviour; no rules need be written in code, says Marvell. Machine learning can determine if a packet is malware to an accuracy of 80 per cent, says Ho.
The hardware can even identify suspect packets by learning application types even when the packets themselves are encrypted using the IPSec protocol.
The DPU’s machine learning inference hardware can also be used for other tasks such as beamforming optimisation in cellular networks.
Nigel Alvares
As for the 400-gigabit rating of the Octeon DPU, this is the maximum input and output that a CPU can cope with if every packet needs processing. And when each packet passes through the IPsec encyption engines, the maximum line rate is 400 gigabits.
In turn, if a packet need not pass through the CPU or no cryptography is required, one terabit of Layer 2/ Layer 3 switching can be done on-chip.
“All these are separate accelerator capability of the platform,” says Ho. The data path bandwidth of the DPU is 400Gbps+, IPSec throughput is 400Gbps+, and the switch capability is 1 terabit.”
Using software, the DPU accelerators are configured according to the data processing needs which may use all or some of the on-chip accelerators, he says.
4G and 5G cellular systems
For radio access networks, the radio head units talk to a distributed unit (DU) and a centralised unit (CU). (See diagram.)
Source: Marvell
The DU chassis houses six or eight line cards typically. The DU has a main controller that connects all the signals and backhauls them to the CU. This requires a two-chip solution with a switch chip next to each Octeon.
Using a 5nm process, the switch-integrated Octeon DPU reduces the DU’s overall power consumption and bill of materials. This Octeon DPU can be used for the DU, the fronthaul gateway and even the CU.
The DPU also exploits the 1-terabit switching capacity for the DU chassis example. Here, six Octeon Fusion-O chips, which perform Layer 1 processing, are connected to six radio units. Each of the six Fusion-O chips connects to the DPU via a 50-gigabit serialiser/ deserialiser (serdes).
Typical DU designs may use two Octeon DPUs, the second being a standby host DPU. This accounts for six line cards and two Octeon DPUs per DU chassis.
Source: Marvell
Market status
Marvell says that for 100-gigabit-throughput DPUs, up to 60 per cent of volumes shipped are used in the cloud and 40 per cent at the network edge.
Since throughput rates in the cloud are growing faster than the network edge, as reflected with the advent of 200- and 400-gigabit SmartNIC cards, the overall ratio of devices used for the cloud will rise.
The first two Octeon 10 devices taped out two months ago were the CN106XX and CN106XXS. These devices will sample in the second half of 2021.
The two will be followed by the CN103XX which is expected around spring 2022 and following that will be the DPU400.