ICMPv6 Errors for Discarding Packets Due to Processing Limits
RFC 8883
Internet Engineering Task Force (IETF) T. Herbert
Request for Comments: 8883 Intel
Category: Standards Track September 2020
ISSN: 2070-1721
ICMPv6 Errors for Discarding Packets Due to Processing Limits
Abstract
Network nodes may discard packets if they are unable to process
protocol headers of packets due to processing constraints or limits.
When such packets are dropped, the sender receives no indication, so
it cannot take action to address the cause of discarded packets.
This specification defines several new ICMPv6 errors that can be sent
by a node that discards packets because it is unable to process the
protocol headers. A node that receives such an ICMPv6 error may use
the information to diagnose packet loss and may modify what it sends
in future packets to avoid subsequent packet discards.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8883.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction
1.1. Extension Header Limits
1.2. Aggregate Header Limits
1.3. Nonconformant Packet Discard
1.4. Terminology
2. ICMPv6 Errors for Extension Header Limits
2.1. Format
2.2. Unrecognized Next Header Type Encountered by Intermediate
Node (Code 5)
2.3. Extension Header Too Big (Code 6)
2.4. Extension Header Chain Too Long (Code 7)
2.5. Too Many Extension Headers (Code 8)
2.6. Too Many Options in Extension Header (Code 9)
2.7. Option Too Big (Code 10)
3. ICMPv6 Error for Aggregate Header Limits
3.1. Format
3.2. Usage
4. Operation
4.1. Priority of Reporting
4.2. Host Response
5. Applicability and Use Cases
5.1. Reliability of ICMP
5.2. Processing Limits
5.2.1. Long Headers and Header Chains
5.2.2. At End Hosts
5.2.3. At Intermediate Nodes
6. Security Considerations
7. IANA Considerations
7.1. Parameter Problem Codes
7.2. Destination Unreachable Codes
7.3. ICMP Extension Object Classes and Class Sub-types
8. References
8.1. Normative References
8.2. Informative References
Acknowledgments
Author's Address
1. Introduction
This document specifies several new ICMPv6 errors that can be sent
when a node discards a packet due to it being unable to process the
necessary protocol headers because of processing constraints or
limits. New ICMPv6 code points are defined to supplement those
defined in [RFC4443]. Six of the errors are specific to the
processing of extension headers; another error is used when the
aggregate protocol headers in a packet exceed the processing limits
of a node.
1.1. Extension Header Limits
In IPv6, optional internet-layer information is carried in one or
more IPv6 extension headers [RFC8200]. Extension headers are placed
between the IPv6 header and the upper-layer header in a packet. The
term "header chain" refers collectively to the IPv6 header, extension
headers, and upper-layer headers occurring in a packet. Individual
extension headers may have a maximum length of 2048 octets and must
fit into a single packet. Destination Options and Hop-by-Hop Options
contain a list of options in type-length-value (TLV) format. Each
option includes a length of the data field in octets: the minimum
size of an option (non-pad type) is two octets, and the maximum size
is 257 octets. The number of options in an extension header is only
limited by the length of the extension header and the Path MTU from
the source to the destination. Options may be skipped over by a
receiver if they are unknown and the Option Type indicates to skip
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