Module 13: ICMP

Internet Control Message Protocol (ICMP)

provides feedback about issues related to the processing of IP packets under certain conditions.

ICMPv4

is the messaging protocol for IPv4

ICMPv6

is the messaging protocol for IPv6 and includes additional functionality.

• Host reachability

• Destination or Service Unreachable

• Time exceeded

The ICMP messages common to both ICMPv4 and ICMPv6 include:

Echo Message/Host Reachability

can be used to test the reachability of a host on an IP network.

Destination or Service Unreachable

can be used to notify the source that a destination or service is unreachable.

Time to Live (TTL)

field in a packet is decremented to 0, an ICMPv4 Time Exceeded message will be sent to the source host.

duplicate address detection (DAD)

A device assigned a global IPv6 unicast or link-local unicast address, may perform ________________ to ensure that the IPv6 address is unique.

ping command

is an IPv4 and IPv6 testing utility that uses ICMP echo request and echo reply messages to test connectivity between hosts and provides a summary that includes the success rate and average round-trip time to the destination

Ping

can also be used to test the ability of a local host to communicate across an internetwork.

Traceroute (tracert)

is a utility that is used to test the path between two hosts and provide a list of hops that were successfully reached along that path.

asterisk (*)

is used to indicate a lost or unreplied packet.