rfc9740v1.txt		rfc9740.txt
	Internet Engineering Task Force (IETF) M. Boucadair		Internet Engineering Task Force (IETF) M. Boucadair
	Request for Comments: 9740 Orange		Request for Comments: 9740 Orange
	Category: Standards Track B. Claise		Category: Standards Track B. Claise
	ISSN: 2070-1721 Huawei		ISSN: 2070-1721 Huawei
	February 2025		February 2025
	Extended TCP Options and IPv6 Extension Headers IPFIX Information		New IPFIX Information Elements for TCP Options and IPv6 Extensions
	Elements		Headers
	Abstract		Abstract
	This document specifies new IP Flow Information Export (IPFIX)		This document specifies new IP Flow Information Export (IPFIX)
	Information Elements (IEs) to solve issues with existing		Information Elements (IEs) to solve issues with existing
	ipv6ExtensionHeaders and tcpOptions IPFIX IEs, especially the ability		ipv6ExtensionHeaders and tcpOptions IPFIX IEs, especially the ability
	to export any observed IPv6 extension headers or TCP options.		to export any observed IPv6 extension headers or TCP options.
	Status of This Memo		Status of This Memo
	skipping to change at line 129 ¶		skipping to change at line 129 ¶
	headers can be exported using the ipv6ExtensionHeaders IE. For		headers can be exported using the ipv6ExtensionHeaders IE. For
	example, the ipv6ExtensionHeaders IE can't report some IPv6 EHs,		example, the ipv6ExtensionHeaders IE can't report some IPv6 EHs,
	specifically EHs for the Host Identity Protocol (139), Shim6		specifically EHs for the Host Identity Protocol (139), Shim6
	Protocol (140), or extension headers for experimentation and		Protocol (140), or extension headers for experimentation and
	testing.		testing.
	* Specify whether the exported values match the full enclosed values		* Specify whether the exported values match the full enclosed values
	or only up to a limit imposed by hardware or software (e.g.,		or only up to a limit imposed by hardware or software (e.g.,
	Section 1.1 of [RFC8883]). Note that some implementations may not		Section 1.1 of [RFC8883]). Note that some implementations may not
	be able to export all observed extension headers in a Flow because		be able to export all observed extension headers in a Flow because
	of a hardware or software limit (see, e.g., [EH-LIMITS]). The		of a hardware or software limit (see, e.g., [EH-LIMITS]).
	specification of the ipv6ExtensionHeaders IE does not discuss
	whether it covers all enclosed extension headers or only up to a		* Discuss whether it covers all enclosed extension headers or only
	limit.		up to a limit.
	* Specify how to report the length of IPv6 extension headers.		* Specify how to report the length of IPv6 extension headers.
	* Optimize the encoding.		* Optimize the encoding.
	* Explain the reasoning for reporting values that do not correspond		* Explain the reasoning for reporting values that do not correspond
	to extension headers (e.g., "Unknown Layer 4 header" or "Payload		to extension headers (e.g., "Unknown Layer 4 header" or "Payload
	compression header").		compression header").
	* Specify how to report extension header chains or aggregate		* Specify how to report extension header chains or aggregate lengths
	extension headers length.		of extension headers.
	Section 3 addresses these issues.		Section 3 addresses these issues.
	This specification deprecates the ipv6ExtensionHeaders IPFIX IE in		This specification deprecates the ipv6ExtensionHeaders IPFIX IE in
	favor of the new IEs defined in this document.		favor of the new IEs defined in this document.
	1.2. Issues with tcpOptions Information Element		1.2. Issues with tcpOptions Information Element
	The specification of the tcpOptions IPFIX IE (209) does not:		The specification of the tcpOptions IPFIX IE (209) does not:
	skipping to change at line 194 ¶		skipping to change at line 194 ¶
	In addition, the document makes use of the following terms:		In addition, the document makes use of the following terms:
	Extension header chain: Refers to the chain of extension headers		Extension header chain: Refers to the chain of extension headers
	that are present in an IPv6 packet.		that are present in an IPv6 packet.
	This term should not be confused with the IPv6 header chain, which		This term should not be confused with the IPv6 header chain, which
	includes the IPv6 header, zero or more IPv6 extension headers, and		includes the IPv6 header, zero or more IPv6 extension headers, and
	zero or a single Upper-Layer Header.		zero or a single Upper-Layer Header.
	Flow with varying extension header chain: Refers to a Flow where		Flow with varying extension header chains: Refers to a Flow where
	distinct extension header chains are observed. Concretely,		distinct extension header chains are observed. Concretely,
	different packets in such a Flow will have a different sequence of		different packets in such a Flow will have a different sequence of
	extension header type codes.		extension header type codes.
	3. Information Elements for IPv6 Extension Headers		3. Information Elements for IPv6 Extension Headers
	3.1. ipv6ExtensionHeaderType Information Element		3.1. ipv6ExtensionHeaderType Information Element
	Name: ipv6ExtensionHeaderType		Name: ipv6ExtensionHeaderType
	skipping to change at line 277 ¶		skipping to change at line 277 ¶
	so, few octets will be needed to encode common IPv6 extension		so, few octets will be needed to encode common IPv6 extension
	headers when observed in a Flow.		headers when observed in a Flow.
	The "No Next Header" (bit 2) value (Section 4.7 of [RFC8200]) is		The "No Next Header" (bit 2) value (Section 4.7 of [RFC8200]) is
	used if there is no upper-layer header in an IPv6 packet. Even if		used if there is no upper-layer header in an IPv6 packet. Even if
	the value is not considered as an extension header as such, the		the value is not considered as an extension header as such, the
	corresponding bit is set in the ipv6ExtensionHeadersFull IE		corresponding bit is set in the ipv6ExtensionHeadersFull IE
	whenever that value is encountered in the Flow.		whenever that value is encountered in the Flow.
	Extension headers observed in a Flow with varying extension header		Extension headers observed in a Flow with varying extension header
	chain MUST NOT be grouped in the ipv6ExtensionHeadersFull IE if		chains MUST NOT be grouped in the ipv6ExtensionHeadersFull IE if
	the ipv6ExtensionHeaderChainLengthList IE is also present.		the ipv6ExtensionHeaderChainLengthList IE is also present.
	If the ipv6ExtensionHeaderChainLengthList IE is not present, then		If the ipv6ExtensionHeaderChainLengthList IE is not present, then
	extension headers observed in a Flow with varying extension header		extension headers observed in a Flow with varying extension header
	chain MAY be grouped in one single ipv6ExtensionHeadersFull IE or		chains MAY be grouped in one single ipv6ExtensionHeadersFull IE or
	be exported in separate ipv6ExtensionHeadersFull IEs, one for each		be exported in separate ipv6ExtensionHeadersFull IEs, one for each
	extension header chain.		extension header chain.
	The ipv6ExtensionHeadersFull IE MUST NOT be exported if		The ipv6ExtensionHeadersFull IE MUST NOT be exported if
	ipv6ExtensionHeaderTypeCountList IE is also present because of the		ipv6ExtensionHeaderTypeCountList IE is also present because of the
	overlapping scopes of these two IEs.		overlapping scopes of these two IEs.
	The value of ipv6ExtensionHeadersFull IE may be encoded in fewer		The value of ipv6ExtensionHeadersFull IE may be encoded in fewer
	octets per the guidelines in Section 6.2 of [RFC7011].		octets per the guidelines in Section 6.2 of [RFC7011].
	skipping to change at line 329 ¶		skipping to change at line 329 ¶
	Description: As per Section 4.1 of [RFC8200], IPv6 nodes must accept		Description: As per Section 4.1 of [RFC8200], IPv6 nodes must accept
	and attempt to process extension headers occurring any number of		and attempt to process extension headers occurring any number of
	times in the same packet. This IE echoes the order of extension		times in the same packet. This IE echoes the order of extension
	headers and number of consecutive occurrences of the same		headers and number of consecutive occurrences of the same
	extension header type in a Flow.		extension header type in a Flow.
	This IE is a subTemplateList of ipv6ExtensionHeaderType and		This IE is a subTemplateList of ipv6ExtensionHeaderType and
	ipv6ExtensionHeaderCount IEs.		ipv6ExtensionHeaderCount IEs.
	Each header chain in a Flow with varying extension header chain		Each header chain in a Flow with varying extension header chains
	MUST be exported in a separate IE.		MUST be exported in a separate IE.
	The same extension header type may appear several times in an		The same extension header type may appear several times in an
	ipv6ExtensionHeaderTypeCountList IE. For example, if an IPv6		ipv6ExtensionHeaderTypeCountList IE. For example, if an IPv6
	packet of a Flow includes a Hop-by-Hop Options header, a		packet of a Flow includes a Hop-by-Hop Options header, a
	Destination Options header, a Fragment header, and Destination		Destination Options header, a Fragment header, and Destination
	Options header, the ipv6ExtensionHeaderTypeCountList IE will		Options header, the ipv6ExtensionHeaderTypeCountList IE will
	report:		report:
	* the count of Hop-by-Hop Options headers,		* the count of Hop-by-Hop Options headers,
	skipping to change at line 424 ¶		skipping to change at line 424 ¶
	or deferred to a slow path.		or deferred to a slow path.
	The ipv6ExtensionHeadersChainLength IE is used to report, in		The ipv6ExtensionHeadersChainLength IE is used to report, in
	octets, the length of an extension header chain observed in a		octets, the length of an extension header chain observed in a
	Flow. The length is the sum of the lengths of all extension		Flow. The length is the sum of the lengths of all extension
	headers of the chain. Exporting such information might help		headers of the chain. Exporting such information might help
	identifying root causes of performance degradation, including		identifying root causes of performance degradation, including
	packet drops.		packet drops.
	Each header chain length of a Flow with varying extension header		Each header chain length of a Flow with varying extension header
	chain MUST be exported in a separate		chains MUST be exported in a separate
	ipv6ExtensionHeadersChainLength IE.		ipv6ExtensionHeadersChainLength IE.
	Abstract Data Type: unsigned32		Abstract Data Type: unsigned32
	Data Type Semantics: identifier		Data Type Semantics: identifier
	Units: octets		Units: octets
	Additional Information: See Section 4 of [RFC8200] for the general		Additional Information: See Section 4 of [RFC8200] for the general
	definition of IPv6 extension headers.		definition of IPv6 extension headers.
	skipping to change at line 448 ¶		skipping to change at line 448 ¶
	Reference: RFC 9740		Reference: RFC 9740
	3.7. ipv6ExtensionHeaderChainLengthList Information Element		3.7. ipv6ExtensionHeaderChainLengthList Information Element
	Name: ipv6ExtensionHeaderChainLengthList		Name: ipv6ExtensionHeaderChainLengthList
	ElementID: 519		ElementID: 519
	Description: This IE is used to report the chains and their lengths		Description: This IE is used to report the chains and their lengths
	as observed in a Flow with varying extension header chain.		as observed in a Flow with varying extension header chains.
	This IE is a subTemplateList of ipv6ExtensionHeadersFull and		This IE is a subTemplateList of ipv6ExtensionHeadersFull and
	ipv6ExtensionHeadersChainLength IEs.		ipv6ExtensionHeadersChainLength IEs.
	If several extension header chains are observed in a Flow, each		If several extension header chains are observed in a Flow, each
	header chain MUST be exported in a separate		header chain MUST be exported in a separate
	ipv6ExtensionHeaderChainLengthList IE.		ipv6ExtensionHeaderChainLengthList IE.
	Abstract Data Type: subTemplateList		Abstract Data Type: subTemplateList
	skipping to change at line 659 ¶		skipping to change at line 659 ¶
	Destination Options (0) header is observed. The bits are set		Destination Options (0) header is observed. The bits are set
	following the table provided in Section 8.4.1.		following the table provided in Section 8.4.1.
	MSB LSB		MSB LSB
	1 25		1 25
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
	|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|0|0|0|1|		|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|0|0|0|1|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
	Figure 1: A First Example of EH/Bit Mappings in the		Figure 1: Example of EH/Bit Mappings in the
	ipv6ExtensionHeadersFull IE		ipv6ExtensionHeadersFull IE
	The leading zeros are dropped per the reduced-size encoding guidance.		The leading zeros are dropped per the reduced-size encoding guidance.
	One octet is thus sufficient to send these observed options on the		One octet is thus sufficient to send these observed options on the
	wire. Concretely, the ipv6ExtensionHeadersFull IE will be set to		wire. Concretely, the ipv6ExtensionHeadersFull IE will be set to
	0x01 (Figure 2).		0x01 (Figure 2).
	MSB LSB		MSB LSB
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|0|0|0|0|0|0|0|1|		|0|0|0|0|0|0|0|1|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Figure 2: A First Example of ipv6ExtensionHeadersFull IE with		Figure 2: Example A of ipv6ExtensionHeadersFull IE with Reduced-
	Reduced-Size Encoding		Size Encoding
	Figure 3 provides another example of reported values in an		Figure 3 provides another example of reported values in an
	ipv6ExtensionHeadersFull IE for an IPv6 Flow in which the Destination		ipv6ExtensionHeadersFull IE for an IPv6 Flow in which the Destination
	Options (0), IPv6 Hop-by-Hop Options (1), and Routing (5) headers are		Options (0), IPv6 Hop-by-Hop Options (1), and Routing (5) headers are
	observed. One octet is sufficient to report these observed options.		observed. One octet is sufficient to report these observed options.
	Concretely, the ipv6ExtensionHeadersFull IE will be set to 0x23.		Concretely, the ipv6ExtensionHeadersFull IE will be set to 0x23.
	MSB LSB		MSB LSB
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|0|0|1|0|0|0|1|1|		|0|0|1|0|0|0|1|1|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Figure 3: A Second Example of ipv6ExtensionHeadersFull IE with		Figure 3: Example B of ipv6ExtensionHeadersFull IE with Reduced-
	Reduced-Size Encoding		Size Encoding
	Let us now consider an IPv6 Flow in which the following EH chain is		Let us now consider an IPv6 Flow in which the following EH chain is
	observed: Routing (5), Mobility (7), and Authentication (9) header.		observed: Routing (5), Mobility (7), and Authentication (9) header.
	Figure 4 shows the ipv6ExtensionHeadersFull IE (0x02A0) to report		Figure 4 shows the ipv6ExtensionHeadersFull IE (0x02A0) to report
	this individual chain.		this individual chain.
	MSB LSB		MSB LSB
	1		1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0|0|0|0|0|1|0|1|0|1|0|0|0|0|0|		|0|0|0|0|0|0|1|0|1|0|1|0|0|0|0|0|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 4: An Example of ipv6ExtensionHeadersFull IE Reported for		Figure 4: Example of ipv6ExtensionHeadersFull IE Reported for an
	an Extension Header Chain		Extension Header Chain
	6.2. TCP Options		6.2. TCP Options
	6.2.1. Reduced-Size Encoding		6.2.1. Reduced-Size Encoding
	Given TCP Kind allocation practices and the option mapping defined in		Given TCP Kind allocation practices and the option mapping defined in
	Section 4.1, fewer octets are likely to be used for Flows with common		Section 4.1, fewer octets are likely to be used for Flows with common
	TCP options.		TCP options.
	Figure 5 shows an example of Kind/bit mappings in a tcpOptionsFull IE		Figure 5 shows an example of Kind/bit mappings in a tcpOptionsFull IE
	for a TCP Flow in which End of Option List (0), Maximum Segment Size		for a TCP Flow in which End of Option List (0), Maximum Segment Size
	(2), and Window Scale (3) options are observed.		(2), and Window Scale (3) options are observed.
	MSB LSB		MSB LSB
	1 25		1 25
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
	|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|1|1|0|1|		|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|1|1|0|1|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
	Figure 5: An Example of TCP Options / Bit Mappings in a		Figure 5: Example of TCP Options / Bit Mappings in a
	tcpOptionsFull IE		tcpOptionsFull IE
	One octet is sufficient to report these observed options.		One octet is sufficient to report these observed options.
	Concretely, the tcpOptionsFull IE will be set to 0x0D (Figure 6).		Concretely, the tcpOptionsFull IE will be set to 0x0D (Figure 6).
	MSB LSB		MSB LSB
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|0|0|0|0|1|1|0|1|		|0|0|0|0|1|1|0|1|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Figure 6: An Example of tcpOptionsFull IE with Reduced-Size Encoding		Figure 6: Example of tcpOptionsFull IE with Reduced-Size Encoding
	6.2.2. Shared Options		6.2.2. Shared Options
	Let us consider a TCP Flow in which shared options with ExIDs 0x0348		Let us consider a TCP Flow in which shared options with ExIDs 0x0348
	(HOST_ID) [RFC7974], 0x454E (TCP-ENO) [RFC8547], and 0xE2D4C3D9		(HOST_ID) [RFC7974], 0x454E (TCP-ENO) [RFC8547], and 0xE2D4C3D9
	(Shared Memory Communications over RDMA protocol) [RFC7609] are		(Shared Memory Communications over RDMA protocol) [RFC7609] are
	observed. Figure 7 shows an excerpt of the Data Set encoding with a		observed. Figure 7 shows an excerpt of the Data Set encoding with a
	focus on the tcpSharedOptionExID16 and tcpSharedOptionExID32 IEs.		focus on the tcpSharedOptionExID16 and tcpSharedOptionExID32 IEs.
	The meaning of the fields is defined in [RFC6313].		The meaning of the fields is defined in [RFC6313].
End of changes. 15 change blocks.
	23 lines changed or deleted		23 lines changed or added
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