How does communication work when devices are on the SAME network?

Their IP network portions match, so the source sends the frame directly to the destination — the frame's destination MAC is the destination device's actual MAC, and no router is involved.

* On the same network the frame's destination MAC is the actual destination device. *

When source and destination are on the same network:

1. The network portions of their IP addresses match (e.g., both are 192.168.1.x)
2. The source device sends the frame directly to the destination
3. The destination MAC address in the frame is the actual destination device's MAC

Example:

• PC1: 192.168.1.110 (MAC: AA-AA-AA-AA-AA-AA)
• FTP Server: 192.168.1.9 (MAC: CC-CC-CC-CC-CC-CC)
• Frame destination MAC = CC-CC-CC-CC-CC-CC (server's actual MAC)

No router is needed for same-network communication.

Go deeper:

• Host to Host Communication — Practical Networking — how a host detects "same network" and delivers directly via ARP/MAC.
• MAC address — the Layer-2 address used for direct local delivery.