<aside>
đź“– Making the Network Layer Work
- The Internet Protocol (IP)
- The creation of IP datagrams.
- Hop-by-hop delivery from end to end.
- Routing Tables
- Algorithms to populate router forwarding tables
- Internet Control Message Protocol (ICMP)
- Communicates network layer information between end hosts and routers
- Reports error conditions
- Helps us diagnose problems
</aside>
Internet Control Message Protocol, ICMP
- ICMP provides information about the network layer to end hosts and routers.
- It sits above IP and is therefore strictly a transport layer mechanism.
- The commonly used tools “ping” and “traceroute” both rely on ICMP.
| Property |
Behavior |
| Reporting Message |
Self-contained message reporting error |
| Unreliable |
Simple datagram service - no retries |
ICMP runs above the Network Layer, and hence it’s a Transport protocol.
ICMP Message Structure
Message Type
