NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Google
Web TCP/IP Guide






Table Of Contents  The TCP/IP Guide
 9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)
      9  TCP/IP Internet Layer (OSI Network Layer) Protocols
           9  Internet Control Message Protocol (ICMP/ICMPv4 and ICMPv6)
                9  ICMP Message Types and Formats
                     9  ICMP Version 4 (ICMPv4) Error Message Types and Formats

Previous Topic/Section
ICMP Version 4 (ICMPv4) Error Message Types and Formats
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
 ICMPv4 Source Quench Messages
Next Topic/Section

ICMPv4 Destination Unreachable Messages
(Page 2 of 4)

ICMPv4 Destination Unreachable Message Format

Table 88 and Figure 139 show the specific format for ICMPv4 Destination Unreachable messages.


Table 88: ICMPv4 Destination Unreachable Message Format

Field Name

Size (bytes)

Description

Type

1

Type: Identifies the ICMP message type; for Destination Unreachable messages this is set to 3.

Code

1

Code: Identifies the “subtype” of unreachable error being communicated. See Table 89 for a full list of codes and what they mean.

Checksum

2

Checksum: 16-bit checksum field for the ICMP header, as described in the topic on the ICMP common message format.

Unused

4

Unused: 4 bytes that are left blank and not used.

Original Datagram Portion

Variable

Original Datagram Portion: The full IP header and the first 8 bytes of the payload of the datagram that prompted this error message to be sent.


Figure 139: ICMPv4 Destination Unreachable Message Format

 

Previous Topic/Section
ICMP Version 4 (ICMPv4) Error Message Types and Formats
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
 ICMPv4 Source Quench Messages
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $


Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.