The document discusses the ICMP protocol and some of its applications. It provides the following key details: - ICMP is a supporting protocol used by network devices to send error messages and operational information. Unlike TCP and UDP, it is not used to exchange data between systems. - Common applications of ICMP include Ping, which is used to verify connectivity to an IP address, and Traceroute, which identifies each device on the network path and the response time between hops. - Traceroute works by sending ICMP Echo Requests and measuring the response time at each network hop to map the full route between two points. This can help troubleshoot connectivity issues.

1. Icmp protocol
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2. What icmp protocol
• Internet Control Message Protocol (ICMP) is a supporting protocol in
the Internet protocol suite
• It is used by network devices
• including routers
• the send error messages and operational information indicating
• ICMP differs from transport protocolssuch as TCP and UDP in that it is not
typically used to exchange data between systems

3. Technical details
• ICMP is part of the Internet protocol suite as defined in RFC 792
• ICMP messages are typically used for diagnostic or control purposes or generated
in response to errors in IP

4. Datagram structure
• Type :ICMP type, see Control messages.
• Code : ICMP subtype, see Control messages
• Checksum :Error checking data, calculated from
the ICMP header and data, with value 0
substituted for this field. The Internet Checksum
is used, specified in RFC 1071
• Variable

5. Application icmp

6. Ping
• Ping is a basic Internet program that allows a user to verify that a particular IP
address exists and can accept requests.
• Ping is used diagnostically to ensure that a host computer the user is trying to reach
is actually operating. Ping works by sending an Internet Control Message Protocol
(ICMP) Echo Request to a specified interface on the network and waiting for a
reply. Ping can be used for troubleshooting to test connectivity and determine
response time.
• Check ip or domain
• Ping 192.168.1.1
• Ping www.google.com

7. traceroute
• For most of us, phone calls and Internet
connections seem to happen
instantaneously. It feels as if our computer
has a direct line to our favorite websites.
Web pages load so fast that it seems that
we must have a direct connection to any
computer, even one across the country.But
we don't.

8. traceroute
• The traceroute identifies each computer/server on that list and the amount of
time it took the data to get from one computer to the next. If there was a hiccup
or interruption in the transfer of data, the traceroute will show where along the
chain the problem occurred.

9. Traceroute How data travels.
• Each computer on the traceroute is identified by its IP address, which is the nine-
digit number separated by periods that identifies that computer's unique
network connection.
•
n the past, computer hackers would routinely use traceroutes to map how
information moved within a company's computer network and then focus their
attacks on certain computers. To combat that security threat, some networks will
not allow you to perform a traceroute.

10. Traceroute How to run a traceroute
• Windows command line tracert tracert www.google.com
• Unix Traceroute Traceroute www.google.com