Sharing the table I keep next to me during labs — each OSI layer mapped to protocols you actually touch and the PDU name: | Layer | Name | Examples | PDU | |------|------|----------|-----| | 7 | Application | HTTP, DNS, DHCP, SSH | Data | | 4 | Transport | TCP, UDP | Segment | | 3 | Network | IP, ICMP, OSPF | Packet | | 2 | Data Link | Ethernet, ARP, STP | Frame | | 1 | Physical | cables, RJ-45, signals | Bits | Mnemonic I use top-down: **"All People Seem To Need Data Processing"**. Hope it helps someone.

Cheat sheet: OSI layers mapped to real protocols & PDUs

ben31833 · posted Jun 6, 2026 · 58 views

Sharing the table I keep next to me during labs — each OSI layer mapped to protocols you actually touch and the PDU name:

Layer	Name	Examples	PDU
7	Application	HTTP, DNS, DHCP, SSH	Data
4	Transport	TCP, UDP	Segment
3	Network	IP, ICMP, OSPF	Packet
2	Data Link	Ethernet, ARP, STP	Frame
1	Physical	cables, RJ-45, signals	Bits

Mnemonic I use top-down: "All People Seem To Need Data Processing". Hope it helps someone.

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