rfc9792v1.txt		rfc9792.txt
	skipping to change at line 63 ¶		skipping to change at line 63 ¶
	Table of Contents		Table of Contents
	1. Introduction		1. Introduction
	1.1. Requirements Language		1.1. Requirements Language
	2. Variable-Length Prefix Attribute Flags Sub-TLV		2. Variable-Length Prefix Attribute Flags Sub-TLV
	3. Backward Compatibility		3. Backward Compatibility
	4. IANA Considerations		4. IANA Considerations
	4.1. OSPFv2		4.1. OSPFv2
	4.1.1. OSPFv2 Prefix Attribute Flags Sub-TLV		4.1.1. OSPFv2 Prefix Attribute Flags Sub-TLV
	4.1.2. OSPFv2 Prefix Extended Flag Field Registry		4.1.2. OSPFv2 Prefix Attribute Flags Registry
	4.2. OSPFv3		4.2. OSPFv3
	4.2.1. OSPFv3 Prefix Attribute Flags Sub-TLV		4.2.1. OSPFv3 Prefix Attribute Flags Sub-TLV
	4.2.2. OSPFv3 Prefix Extended Flag Field Registry		4.2.2. OSPFv3 Prefix Attribute Flags Registry
	5. Security Considerations		5. Security Considerations
	6. References		6. References
	6.1. Normative References		6.1. Normative References
	6.2. Informative References		6.2. Informative References
	Acknowledgements		Acknowledgements
	Authors' Addresses		Authors' Addresses
	1. Introduction		1. Introduction
	Each OSPF prefix can be advertised with an 8-bit field to indicate		Each OSPF prefix can be advertised with an 8-bit field to indicate
	skipping to change at line 105 ¶		skipping to change at line 105 ¶
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
	BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	2. Variable-Length Prefix Attribute Flags Sub-TLV		2. Variable-Length Prefix Attribute Flags Sub-TLV
	This document defines a variable-length Prefix Attribute Flags sub-		This document defines a variable-length Prefix Attribute Flags sub-
	TLV for OSPFv2 and OSPFv3. The sub-TLV specifies the variable-flag		TLV for OSPFv2 and OSPFv3. The sub-TLV specifies the variable-length
	fields to advertise additional attributes associated with OSPF		Prefix Attribute Flags field to advertise additional attributes
	prefixes. The advertisement and processing of the existing fixed-		associated with OSPF prefixes. The advertisement and processing of
	size prefix attribute flags remain unchanged.		the existing fixed-size prefix attribute flags remain unchanged.
	The format of the OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV is		The format of the OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV is
	shown in Figure 1.		shown in Figure 1.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length |		| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
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	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: Format of OSPFv2/OSPFv3 Prefix Attribute Flags Sub-TLV		Figure 1: Format of OSPFv2/OSPFv3 Prefix Attribute Flags Sub-TLV
	where:		where:
	Type (2 octets): 11 for OSPFv2 and 37 for OSPFv3		Type (2 octets): 11 for OSPFv2 and 37 for OSPFv3
	Length (2 octets): Variable, dependent on the included Prefix		Length (2 octets): Variable, dependent on the included Prefix
	Attribute Flags. This indicates the length of the prefix		Attribute Flags field. This indicates the length of the Prefix
	attribute flags in octets. The length MUST be a multiple of 4		Attribute Flags field in octets. The length MUST be a multiple of
	octets. If the length is not a multiple of 4 octets, the Link		4 octets. If the length is not a multiple of 4 octets, the Link
	State Advertisement (LSA) is malformed and MUST be ignored.		State Advertisement (LSA) is malformed and MUST be ignored.
	Prefix Attribute Flags (Variable): The extended flag field. This		Prefix Attribute Flags (Variable): The extended flag field. This
	field contains a variable number of flags, grouped in 4-octet		field contains a variable number of flags, grouped in 4-octet
	blocks. The bits are numbered starting from bit 0 as the most		blocks. The bits are numbered starting from bit 0 as the most
	significant bit of the first 32-bit block. If the length of the		significant bit of the first 32-bit block. If the length of the
	Prefix Attribute Flags field exceeds 4 octets, numbering for the		Prefix Attribute Flags field exceeds 4 octets, numbering for the
	additional bits picks up where the previous 4-octet block left		additional bits picks up where the previous 4-octet block left
	off. For example, the most significant bit in the fifth octet of		off. For example, the most significant bit in the fifth octet of
	an 8-octet Prefix Attribute Flags is referred to as bit 32.		an 8-octet Prefix Attribute Flags field is referred to as bit 32.
	Currently, no bits are defined in this document.		Currently, no bits are defined in this document.
	Unassigned bits MUST be set to zero on transmission and MUST be		Unassigned bits MUST be set to zero on transmission and MUST be
	ignored on receipt.		ignored on receipt.
	An implementation MUST limit the length of the sub-TLV so as to		An implementation MUST limit the length of the sub-TLV so as to
	signal the bits that are set to 1. Defined prefix flags that are not		signal the bits that are set to 1. Defined prefix flags that are not
	transmitted due to being beyond the transmitted length MUST be		transmitted due to being beyond the transmitted length MUST be
	treated as being set to 0.		treated as being set to 0.
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	only the first occurrence of the sub-TLV and MUST ignore all		only the first occurrence of the sub-TLV and MUST ignore all
	subsequent instances of the sub-TLV. Errors SHOULD be logged subject		subsequent instances of the sub-TLV. Errors SHOULD be logged subject
	to rate limiting.		to rate limiting.
	3. Backward Compatibility		3. Backward Compatibility
	The OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV does not introduce		The OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV does not introduce
	any backward compatibility issues. An implementation that does not		any backward compatibility issues. An implementation that does not
	recognize the OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV would		recognize the OSPFv2/OSPFv3 Prefix Attribute Flags sub-TLV would
	ignore the sub-TLV as per normal TLV processing operations (refer to		ignore the sub-TLV as per normal TLV processing operations (refer to
	Section 6.3 of [RFC3630] and Section 2.3.2 of [RFC8362]).		Section 2.3.2 of [RFC3630] and Section 6.3 of [RFC8362]).
	4. IANA Considerations		4. IANA Considerations
	4.1. OSPFv2		4.1. OSPFv2
	4.1.1. OSPFv2 Prefix Attribute Flags Sub-TLV		4.1.1. OSPFv2 Prefix Attribute Flags Sub-TLV
	IANA has allocated the following codepoint in the "OSPFv2 Extended		IANA has allocated the following codepoint in the "OSPFv2 Extended
	Prefix TLV Sub-TLVs" registry:		Prefix TLV Sub-TLVs" registry:
	+=======+===============================+===========+		+=======+===============================+===========+
	| Value | Description | Reference |		| Value | Description | Reference |
	+=======+===============================+===========+		+=======+===============================+===========+
	| 11 | OSPFv2 Prefix Attribute Flags | RFC 9792 |		| 11 | OSPFv2 Prefix Attribute Flags | RFC 9792 |
	+-------+-------------------------------+-----------+		+-------+-------------------------------+-----------+
	Table 1		Table 1
	4.1.2. OSPFv2 Prefix Extended Flag Field Registry		4.1.2. OSPFv2 Prefix Attribute Flags Registry
	IANA has created the "OSPFv2 Prefix Extended Flag Field" registry		IANA has created the "OSPFv2 Prefix Attribute Flags" registry within
	within the "Open Shortest Path First v2 (OSPFv2) Parameters" registry		the "Open Shortest Path First v2 (OSPFv2) Parameters" registry group.
	group. The registry defines the bits in the Prefix Attribute Flags		The registry defines the bits in the Prefix Attribute Flags field in
	field in the OSPFv2 Prefix Attribute Flags sub-TLV as specified in		the OSPFv2 Prefix Attribute Flags sub-TLV as specified in Section 2.
	Section 2. The bits are to be allocated via IETF Review [RFC8126].		The bits are to be allocated via IETF Review [RFC8126]. Each bit
	Each bit definition will include:		definition will include:
	* Bit number (counting from bit 0 as the most significant bit of the		* Bit number (counting from bit 0 as the most significant bit of the
	first block)		first block)
	* Description		* Description
	* Reference		* Reference
	No bits are currently defined. Bits 0-31 are to be initially marked		No bits are currently defined. Bits 0-31 are to be initially marked
	as "Unassigned". The flags defined in this document may use either a		as "Unassigned". The flags defined in this document may use either a
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	LSA Sub-TLVs" registry:		LSA Sub-TLVs" registry:
	+=======+===============================+===========+		+=======+===============================+===========+
	| Value | Description | Reference |		| Value | Description | Reference |
	+=======+===============================+===========+		+=======+===============================+===========+
	| 37 | OSPFv3 Prefix Attribute Flags | RFC 9792 |		| 37 | OSPFv3 Prefix Attribute Flags | RFC 9792 |
	+-------+-------------------------------+-----------+		+-------+-------------------------------+-----------+
	Table 2		Table 2
	4.2.2. OSPFv3 Prefix Extended Flag Field Registry		The entry in the "L2BM" field is "X".
	IANA has created the "OSPFv3 Prefix Extended Flag Field" registry		4.2.2. OSPFv3 Prefix Attribute Flags Registry
	within the "Open Shortest Path First v3 (OSPFv3) Parameters" registry
	group. The registry defines the bits in the Prefix Attribute Flags		IANA has created the "OSPFv3 Prefix Attribute Flags" registry within
	field in the OSPFv2 Prefix Attribute Flags sub-TLV as specified in		the "Open Shortest Path First v3 (OSPFv3) Parameters" registry group.
	Section 2. The bits are to be allocated via IETF Review [RFC8126].		The registry defines the bits in the Prefix Attribute Flags field in
	Each bit definition will include:		the OSPFv2 Prefix Attribute Flags sub-TLV as specified in Section 2.
			The bits are to be allocated via IETF Review [RFC8126]. Each bit
			definition will include:
	* Bit number (counting from bit 0 as the most significant bit of the		* Bit number (counting from bit 0 as the most significant bit of the
	first block)		first block)
	* Description		* Description
	* Reference		* Reference
	No bits are currently defined. Bits 0-31 are to be initially marked		No bits are currently defined. Bits 0-31 are to be initially marked
	as "Unassigned". The flags defined in this document may use either a		as "Unassigned". The flags defined in this document may use either a
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