Matakuliah : H0524/Jaringan Komputer
Tahun : 2009
ARP,RARP, ICMP
Pertemuan 08
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menjelaskan protokol pada Network Layer
seperti ARP, RARP, ICMP
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Outline Materi
• Protokol ARP
• Protokol RARP
• Protokol ICMP
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Protocols at network layer
Role of ARP and RARP
• Internet is made of a combination of physical network
interconnected by network devices
• TCP/IP network uses logical address (IP address) at
network
• To pass through packets to its destination via the
physical network, physical address must be used
• A table at each device is created to map logical
address to physical address
• Static mapping must periodically update its table
• Dynamic mapping is using a protocol to create the
table
• The protocols are ARP (Address Resolution Protocol)
ad RARP (Reverse Address Resolution Protocol)
ARP and RARP
ARP : Get physical address of the known IP address
RARP : Get IP address from the known physical addres
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ARP Operation
ARP Packet
RARP Operation
The RARP request packets are broadcast; the RARP reply
packets are unicast
RARP Packet
Role of ICMP
• Internet Protocol has no error reporting and
error correcting mechanism
• Possible problems:
• Dicard packets due inability to find a
router to the final destination or TTL=0
• Discard all fragments due to time out of
receiving all fragments
• No mechanism for host and management
queries
• ICMP (Internet Control Message Protocol)
has been designed to compensate the above
deficiencies
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ICMP messages
Error-reporting messages
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Error-reporting messages
Important points about ICMP error messages
• No ICMP error message for a datagram carrying an
ICMP error message
• No ICMP error message for a fragmented datagram
that is not the first fragment
• No ICMP error message for a datagram having a
multicast address
• No ICMP error message for a datagram with a special
address such as 127.0.0.0 or 0.0.0.0.
Destination Unreachable
• Destination-unreachable messages with codes 2 or 3
can be created only by the destination host.
• Other destination-unreachable messages can be
created only by routers.
• A router cannot detect all problems that prevent the
delivery of a packet.
Query messages
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General Format
Echo Request and Reply
• Echo-request and echo-reply messages can be
used by network managers to check the operation
of the IP protocol.
• Echo-request and echo-reply messages can test
the reachability of a host.
• An echo-request message can be sent by a host
or router.
• An echo-reply message is sent by the host or
router which receives an echo-request message.
• Echo-request and echo-reply messages is invoked
by the ping command.
Error-reporting messages
Ping command can use these
messages.