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 6 (ICMPv6) Error Message Types and Formats

ICMPv6 Time Exceeded Messages 1 2 3 ICMP Version 6 (ICMPv6) Informational Message Types and Formats

Parameter Problem Message Interpretation Codes and The Pointer Field

The Pointer field, which was only 8 bits wide in ICMPv4, has been widened to 32 bits in ICMPv6, to provide more flexibility in isolating the error. The Code value is also used somewhat differently in ICMPv6 than it was in the ICMPv4 version of this message type. In ICMPv4, the Pointer was used only when the Code field was 0, and other code values indicated other problem categories for which the Pointer field did not make sense. In ICMPv6, the Pointer field is used with all Code types, to indicate the general nature of what the problem is. This means the Pointer field tells the recipient of the Parameter Problem where in the message the problem happened, and the Code field tells it what the nature of the problem is. The following table shows the three Code values and provides a brief explanation of each:

ICMPv6 Time Exceeded Messages 1 2 3 ICMP Version 6 (ICMPv6) Informational Message Types and Formats