How to Choose the Right Mellanox Switch for Your Datacenter
In high-performance computing (HPC) and AI training environments, networking throughput and latency are the primary bottlenecks. NVIDIA Mellanox Spectrum switches are the industry standard for Ethernet-based clusters.
Spectrum-1 vs. Spectrum-2 ASIC
The NVIDIA Mellanox SN2700 is powered by the Spectrum-1 ASIC. It delivers 6.4 Tbps throughput with 32 ports of 100GbE. It is known for its ultra-low cut-through latency of less than 300 ns, making it ideal for financial trading and general cloud infrastructure.
The NVIDIA Mellanox SN3700 steps up to the Spectrum-2 ASIC, offering improved efficiency and enhanced features for AI workloads. While both support 100GbE, the SN3700 is built for modern AI/ML clusters that require deep packet buffers and advanced RoCE v2 capabilities.
Key Comparison Table
| Feature | SN2700 (Spectrum-1) | SN3700 (Spectrum-2) |
|---|---|---|
| Max Throughput | 6.4 Tbps | 6.4 Tbps / 12.8 Tbps (Variant dependent) |
| Latency | < 300 ns | < 425 ns |
| Packet Rate | 4.76 Bpps | 8.33 Bpps |
| Best For | HPC, Finance, Cloud | AI/ML Training, Modern Datacenters |
Visit our product pages to view detailed specifications for the Mellanox SN2700 and Mellanox SN3700.
Mapping Spectrum models to fabric roles
- Edge and aggregation tier: SN2100-class platforms for 100GbE where the fabric ends
- Leaf tier: SN3700 and SN4600-class platforms sized by server port count
- Spine and AI core: SN3800 and SN5600-class platforms for 400G and 800G uplinks
The specs that actually decide the model
- Port count and breakout support set how many servers a leaf can serve
- Buffer depth decides whether a switch absorbs a burst instead of passing congestion upstream
- Forwarding performance and latency separate the mid-range from the flagship platforms
Software and lifecycle considerations
- ONIE versus a pre-installed network OS — decide before ordering, because it shapes the operations runbook
- Firmware support horizon matters on a used purchase: ask what level the unit ships with and whether updates still apply
- Airflow direction is a chassis property, so match it to your aisle layout at purchase time
Related reading
- 100GbE Spectrum guide — the model-by-model guide this complements
- Switch evolution — where the generations are heading
- 800G to 1.6T migration — the next step beyond Spectrum-4
- Network switches — category hub
Frequently Asked Questions
Which Mellanox Spectrum switch should I choose?
Start from the fabric role. SN2100 for edge and aggregation, SN3700 or SN4600 for the leaf tier sized by your server ports, and SN3800 or SN5600 where the core needs 400G or 800G. Then check buffer depth and breakout support, because those two decide whether the switch suits your traffic pattern. Tell us the server count, the port rate and the topology and we will size it with you.
What is the difference between the SN4600 and the SN5600?
The SN5600 is the Spectrum-4 flagship, a 2U 64-port platform built for 800GbE and the spine of AI fabrics. The SN4600 is a Spectrum-3 64-port 200GbE platform, which is the right fit for a 200G leaf tier and is considerably less expensive. The choice is about whether your core needs 800G links today.
Is buffer depth worth paying for?
It depends on your traffic pattern. Deep buffer absorbs burst congestion at the switch instead of passing it upstream, which matters in a fabric where many nodes synchronise and burst together. For general-purpose east-west traffic, front-to-back designs absorb bursts with less concern. It is a real differentiator in AI fabrics and less so elsewhere.
Should I buy an ONIE switch or one with a network OS?
An ONIE unit lets you install the network OS you standardise on, which is the right choice when you run a mixed fleet or want a single configuration standard across vendors. A unit with an OS installed is ready to configure and is easier if the platform is familiar. On a used switch we always state which one you are getting.
How do you verify a used Spectrum switch?
We clean, re-flash and bench-test on our own test line, then confirm port count, port speed, airflow direction, fan configuration and firmware level against the part number. We will also tell you whether the unit is an ONIE build or carries a network OS. Ask for photos of the actual unit before you commit.
Do Spectrum switches support 25GbE on 100GbE ports?
Where the port supports breakout, yes. A 100GbE QSFP28 port can present 25GbE, and a 25GbE adapter will negotiate down. This is the standard way to stage a migration to 100GbE uplinks without buying 25GbE access switches, and we will confirm the breakout support for the exact model.