What a network switch is

A network switch forwards frames between devices on a network. Most switching happens at Layer 2 by MAC address; many switches also route at Layer 3. For fibre links, a switch's ports are populated with optical transceivers — which is where CodingBox comes in.

Where switches sit

• Access — connects end devices and servers.
• Distribution / aggregation — gathers access switches together.
• Core — the high-speed backbone between aggregation blocks.

Higher up the hierarchy usually means higher port speeds and denser optics — SFP at the edge, QSFP and QSFP-DD in the core.

Switches and transceivers

• Fibre ports take pluggable modules whose form factor sets the port speed (see

Form factors).

• The switch reads each module's memory to identify it and, on many platforms, to

decide whether to accept it — the subject of Transceiver compatibility.

CodingBox reads and codes the very memory a switch inspects, so a module presents the identity the switch expects.