A network switch connects devices on the same local network and forwards frames to the port where the destination sits. Cameras and recorders plug into it, and a PoE switch also powers the cameras. Managed switches add VLANs, link monitoring and per-port control.
The switch is the hub of any IP camera system. Its port count, power budget and uplink capacity decide what the network can carry.
Managed or unmanaged
An unmanaged switch works until something misbehaves. A managed switch reports errors, isolates the camera network with a VLAN and lets you restart a single port, which matters when a camera hangs.
Sizing the uplink
Cameras stream continuously, so the link from a switch to the recorder must carry every stream at once. That uplink, not the port count, is usually the first limit a growing system reaches.