Amazon's Latest Graviton 4 EC2 Instances Pack Dual 300Gbps NICs

Amazon Web Services has cooked up a new Graviton 4-powered instance tuned for network-intensive applications like cloud firewalls and load balancers.

The C8gn instances revealed this week offer up to 192 Arm-based vCPUs across a pair of Graviton 4 processors and 384GB of DDR5 memory, which Amazon Web Services (AWS) says gives the system a 30 percent performance advantage over its Graviton 3E-based C7gn instances.

However, the offering's headline feature isn't core count or memory capacity, but rather the 600Gbps of network and 60Gbps of Elastic Block Store (EBS) bandwidth delivered by its twin Nitro 6 data processing units (DPUs).

Here's a quick run down of all the different C8gn SKUs available starting this week - Click to enlarge

AWS has pitched these instances at workloads that push and process packets, such as mostly aimed these instances at workloads like virtualized firewalls, routers, load balancers, proxy servers, and distributed denial of service prevention tools.

In case you're wondering, AWS exposes that bandwidth to the instances as what looks like a pair of 300Gbps NICs, at least on the two top specced SKUs.

AWS VP and distinguished engineer Ali Saidi told The Register "The two NICs is the way we see a lot of these high networking workloads work with one device that ends up being exposed to the internet and another device that ends up being exposed to your private instances.”

If you feel 300Gbps is an unusual port speed for a NIC, you're not alone. Normally you might have 100Gbps, 200Gbps, or 400Gbps ports on a NIC, which themselves are actually aggregated from four 25, 50, or 100Gbps links. 300Gbps ports are not common- and if you look at the back of AWS 6th-gen Nitro DPUs you actually won't find one.

Announced in December 2024, the cards offer up to 400Gbps of network bandwidth apiece. Amazon has capped the network bandwidth in software so that it appears to the virtual machine as a 300Gbps NIC. Doing so leaves plenty of bandwidth left over to provide each instance with another 60Gbps (30Gbps per NIC) of bandwidth dedicated to EBS storage.

Customers still want block storage, Saidi explained, adding that by partitioning bandwidth this way AWS can continue to provide that service without adding another physical NIC, which would have increased the cost of leasing these instances.

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For what it's worth, Amazon could probably have given us more network bandwidth, but didn't to maintain the ratio of compute to bandwidth we saw on the cloud giant's older C7gn instances, which topped out at 64 cores and 200Gbps of aggregate bandwidth. In theory this should allow folks to consolidate three or more C7gn instances down into just one big C8gn VM.

Amazon's C8gn instances are currently available in its US East and West regions, though meta versions of its two largest instances are only available on the cloud giant’s Northern Virginia datacenters. ®