Internet Control Message Protocol (ICMP) is one of the protocols used at the Internet layer of the DoD model. ICMP is important to Cisco because it is used for many different things, mainly to send updates to routers about problems with network routes or packets that are undeliverable in the internetwork.
Note When studying for the CCNA exam, be sure to remember what ICMP does when IP is configured with Cisco routers.
Exam Essentials
Remember what ICMP can do.
ICMP sends ¡°destination unreachable and ¡°buffer full messages. It can find the number of hops to a destination host.
Remember which programs use ICMP.
Packet Internet Groper (ping) uses ICMP echo messages to check the physical connectivity of machines on an internetwork. Trace route (trace) uses ICMP and TTL (time to live) time-outs to find a packet’s destination through an internetwork.
Key Terms and Concepts
Hop A unit of measurement used to describe the next device in a data path that data travels to. Each device a datagram passes through is considered a hop.
Internet Control Message Protocol (ICMP) Described at the Internet layer of the DoD model, ICMP is used for testing, verification, and notification services.
ping (Packet Internet Groper) Used to test IP connectivity between two IP hosts on an internetwork.
Related posts:
- Five Conversion Steps of Data Encapsulation Points
- RIP Routing Protocol
- Function of the MAC Address
- TCP-IP Network-layer protocol Exam Points
- Layered Model Exam Points
- IGRP Routing Protocol
- Full and Half-Duplex Ethernet
- MAC Addresses Exams Point
- Benefits of Network Segmentation With Routers
- Flow Control in Networking
