NVIDIA Switch Selection Worksheet: Logical Ports, Cages and Rack Requirements
Select a NVIDIA network switch by fabric role, logical-port budget, supported modes, installation constraints and operational baseline.
This worksheet turns a network role into a switch requirement. Use it before comparing prices or chassis photographs. The purpose is to identify usable logical interfaces, supported system behavior and installation requirements for the exact variant being considered.
1. State the network role
Identify compute, storage, service access or management traffic. Record protocol, endpoint count, intended topology and the failure condition the design must tolerate. Ethernet and InfiniBand systems require their own supported operating and management arrangements. R52
Do not select a switch only because its advertised aggregate capacity exceeds the sum of endpoint rates. Port distribution, fabric topology and operating mode still matter.
2. Build a logical-port budget
| Budget field | Meaning |
|---|---|
| Endpoint-facing ports | Active logical links to hosts or downstream devices |
| Inter-switch ports | Links consumed by the approved topology |
| Expansion reserve | Ports assigned to a named next-stage requirement |
| Unusable or restricted ports | Interfaces unavailable in the required mode |
| Management interfaces | Separate administrative connectivity, not fabric capacity |
Count cages afterward from the documented port map. NVIDIA’s XDR documentation distinguishes chassis arrangements, and the Q3200 design guidance describes two independent switch instances within one chassis. The entire front panel therefore must not be assumed to form one unrestricted logical switch. R43R48
3. Confirm every required mode
Check logical link rates, supported splitting or breakout, interconnect types and any port-specific restrictions. Record the source and release. A physical connector that accepts a module does not prove the required lane arrangement or protocol support.
Module aggregate capacity also needs separate treatment. Twin-port optical products can represent multiple links, so a single speed label should not drive topology or quantity calculations. R01
An illustrative budget with thirty-two endpoint links and thirty-two inter-switch links requires sixty-four usable logical ports in the intended arrangement. A chassis advertised with that many ports is not automatically suitable if its independent-switch boundaries or mode restrictions conflict with the topology.
4. Check the rack as an engineering constraint
Record height, depth, weight, airflow or cooling arrangement, supported rails, power input and connector type. Confirm installation and service clearance with the actual rack. Do not substitute one airflow or power suffix for another without documented support.
Include management access and qualified spares. A switch that fits the rack but cannot be maintained under the site’s operating process is not fully selected.
5. Define the software and management baseline
Identify the operating system, release, required functions and applicable entitlements. Record who configures and monitors the fabric and how access is restored after a failure. For InfiniBand, include the relevant fabric-management responsibilities; for Ethernet, include the required routing and congestion features.
6. Release a qualified candidate record
The final record should contain the exact ordering identifier, port budget, supported mode map, installation requirements and acceptance plan. Mark unresolved conditions explicitly.
Use the record to compare candidates on the same requirement. It prevents a lower-priced chassis with missing accessories, unsuitable power or a different logical architecture from being mistaken for an equivalent system.
Engineering illustrations
These figures illustrate the design concepts discussed here. They are not measured results, certified configurations or a supplied-equipment list.
Related reading
- NDR 400G InfiniBand Design: Endpoint Counts, Topology and Acceptance
- AI Ethernet Fabric Design: From GPU Traffic to a Qualified BOM