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21-1 ADDRESS MAPPING
21-1 ADDRESS MAPPING
The delivery of a packet to a host or a router requires The delivery of a packet to a host or a router requires
two levels of addressing:
two levels of addressing: logical
logical and
and physical
physical
. We need . We need
to be able to map a logical address to its corresponding to be able to map a logical address to its corresponding
physical address and vice versa. This can be done by physical address and vice versa. This can be done by
using either static or dynamic mapping. using either static or dynamic mapping.
Figure 21.1 ARP operation
21-2 ICMP
21-2 ICMP
The IP protocol has no error-reporting or error- The IP protocol has no error-reporting or error-
correcting mechanism. The IP protocol also lacks a
correcting mechanism. The IP protocol also lacks a
mechanism for host and management queries. The mechanism for host and management queries. The
Internet Control Message Protocol (ICMP) Internet Control Message Protocol (ICMP) has been has been
designed to compensate for the above two deficiencies. designed to compensate for the above two deficiencies.
It is a companion to the IP protocol. It is a companion to the IP protocol.
Figure 21.8 General format of ICMP messages
21-3 IGMP
21-3 IGMP
The IP protocol can be involved in two types of The IP protocol can be involved in two types of
communication: unicasting and multicasting. The
communication: unicasting and multicasting. The
Internet Group Management Protocol (IGMP) is one Internet Group Management Protocol (IGMP) is one
of the necessary, but not sufficient, protocols that is of the necessary, but not sufficient, protocols that is
involved in multicasting. IGMP is a companion to the involved in multicasting. IGMP is a companion to the
IP protocol. IP protocol.
Figure 21.16 IGMP message types
