Logical (horizontal) vs real (vertical) communication
Network Architecture I · S1.2 · Every entity believes it exchanges its PDU directly with its peer. None of them does.
Point of view of layer:
What the layer perceives
What is happening right now
Example:
Highlight:
The three words
This is the frame leaving A. Click a piece: who wrote it, and who is going to read it?
Who writes it and who reads it
Everyone else
Keyboard: 1 2 3 switch view · ← → step · space play/pause · ↑ ↓ change layer (view 1) · R open/close the black box