ICMP

ICMP

1. Messages are carried as IP datagrams

2. Messaging service provider for IP

3. Can provide hosts with information about network problems

4. Common events and messages that ICMP relate to

   • Destination Unreachable
     • If a router can't send an IP datagram any further, it alerts the sender with ICMP.
   • Buffer full/source quench
     • If a routers buffer is full, it will use ICMP to send out this message until the congestion stops.
   • Hops/time exceeded
     • Uses ICMP to alert the sending computer if the number of hops are exceeded for a datagram.
       • Last router that deletes an IP datagram sends the message.
   • Ping
     • Uses the alphabet in the data portion of the packet as the payload.
     • Around 100 bytes
   • Traceroute
     • Used to discover the path a packet takes as it travels the internetwork.

5. Does not rely on any application