IP Protocol Explained Simply | Generated by AI
Question: What does it mean by “IP protocol”? Is it that “ip link show” is used to show the MAC address? Or ping, but ping is an ICMP protocol?
Answer:
IP protocol means the Internet Protocol — the core protocol that makes the Internet work (defined in RFC 791 for IPv4 and RFC 8200 for IPv6).
Key characteristics of the IP protocol (most important points for exams):
- It is a Layer 3 (Network layer) protocol
- It is connectionless → no connection is set up before sending data
- It is unreliable / best-effort delivery → no guarantee packets arrive, arrive in order, or arrive without corruption
- Main jobs of IP:
- Addressing (using IP addresses – source and destination)
- Packet routing (deciding the path through routers)
- Fragmentation and reassembly (if needed)
- IP does not do: retransmission, ordering, flow control, error recovery → those are done by TCP (or ignored by UDP)
Clarifying your examples:
| Command / Protocol | Layer | What it actually shows / does | Related to IP protocol? |
|---|---|---|---|
ip link show |
Layer 2 | Shows network interfaces and their MAC addresses (link-layer addresses) | No – this is about Ethernet / link layer, not IP |
ip addr show |
Layer 3 | Shows IP addresses (IPv4 and IPv6) assigned to interfaces | Yes – directly related to IP |
ping |
Layer 3 + ICMP | Sends ICMP Echo Request packets → tests IP reachability | Yes – ping uses IP to carry ICMP messages |
| ICMP (Internet Control Message Protocol) | Layer 3 | Error reporting, diagnostics (ping, traceroute, destination unreachable, etc.) | Runs on top of IP (IP protocol number 1) |
| IP itself | Layer 3 | The actual packet format that carries TCP, UDP, ICMP, etc. | This is the IP protocol |
Summary – very clear distinction:
- IP protocol = the protocol that puts IP addresses in packet headers and routes packets across networks
- Showing MAC addresses →
ip link show→ Layer 2 (Ethernet / Wi-Fi link layer), not IP - Ping → uses ICMP (which is carried inside IP packets) → so ping tests whether the IP protocol can deliver packets to the destination and back
- You cannot have ping without IP (because ICMP rides inside IP datagrams)
Quick memory aid for exams:
- IP = addresses + routing + best-effort (unreliable, connectionless)
- MAC = hardware address on the local link (shown by
ip link) - Ping = ICMP over IP → tests if IP can reach the destination
So when someone says “IP protocol”, they almost always mean Internet Protocol (the one responsible for IP addresses and routing) — not showing MAC addresses or ping itself.
References:
- None (core concepts from RFC 791, RFC 792 (ICMP), and standard Linux networking commands documentation)