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Appendix A - Changes since RFC 2463

The following changes were made from RFC 2463:

  • Edited the Abstract to make it a little more elaborate.

  • Corrected typos in Section 2.4, where references to sub-bullet e.2 were supposed to be references to e.3.

  • Removed the Timer-based and the Bandwidth-based methods from the example rate-limiting mechanism for ICMP error messages. Added Token-bucket based method.

  • Added specification that all ICMP error messages shall have exactly 32 bits of type-specific data, so that receivers can reliably find the embedded invoking packet even when they don't recognize the ICMP message Type.

  • In the description of Destination Unreachable messages, Code 3, added rule prohibiting forwarding of packets back onto point-to-point links from which they were received, if their destination addresses belong to the link itself ("anti-ping-ponging" rule).

  • Added description of Time Exceeded Code 1 (fragment reassembly timeout).

  • Added "beyond scope of source address", "source address failed ingress/egress policy", and "reject route to destination" messages to the family of "unreachable destination" type ICMP error messages (Section 3.1).

  • Reserved some ICMP type values for experimentation.

  • Added a NOTE in Section 2.4 that specifies ICMP message processing rules precedence.

  • Added ICMP REDIRECT to the list in Section 2.4, (e) of cases in which ICMP error messages are not to be generated.

  • Made minor editorial changes in Section 2.3 on checksum calculation, and in Section 5.2.

  • Clarified in Section 4.2, regarding the Echo Reply Message; the source address of an Echo Reply to an anycast Echo Request should be a unicast address, as in the case of multicast.

  • Revised the Security Considerations section. Added the use of the Encapsulating Security Payload Header for authentication. Changed the requirement of an option of "not allowing unauthenticated ICMP messages" to MAY from SHOULD.

  • Added a new attack in the list of possible ICMP attacks in Section 5.2.

  • Separated References into Normative and Informative.

  • Added reference to RFC 2780 "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers". Also added a note that this document updates RFC 2780.

  • Added a procedure for new ICMPv6 Type and Code value assignments in the IANA Considerations section.

  • Replaced word "send" with "originate" to make it clear that ICMP packets being forwarded are out of scope of this specification.

  • Changed the ESP and AH references to the updated ESP and AH documents.

  • Added reference to the updated IPsec Security Architecture document.

  • Added a SHOULD requirement for allowing the sending of ICMP destination unreachable messages to be disabled.

  • Simplified the source address selection of the ICMPv6 packet.

  • Reorganized the General Message Format (Section 2.1).

  • Removed the general packet format from Section 2.1. It refers to RFC 2460 for more details.

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