Rack Unit
UBack to Glossary
Networking
Top of Rack Switch
ToR
Network switch at the top of a server rack that aggregates all server connections within that rack.
Full Definition
A Top of Rack (ToR) switch aggregates network connections from all servers in a rack via short copper or DAC cables, then uplinks to aggregation or spine switches via higher-speed fibre optic connections. ToR architecture reduces cable lengths, simplifies management, and enables per-rack network isolation. In high-density GPU clusters, ToR switches must support 400G or 800G Ethernet or InfiniBand to sustain collective communication bandwidth for distributed AI training workloads.
Also Known As
top of rack switchtor
Source Reference
IEEE 802.3 — Ethernet Standards