rfc9894v4.txt		rfc9894.txt
	skipping to change at line 86 ¶		skipping to change at line 86 ¶
	Flow control is provided using one or more logical "Credit Windows",		Flow control is provided using one or more logical "Credit Windows",
	each of which will typically be supported by an associated virtual or		each of which will typically be supported by an associated virtual or
	physical queue. A router will use traffic flow classification		physical queue. A router will use traffic flow classification
	information provided by the modem to identify which traffic is		information provided by the modem to identify which traffic is
	associated with each credit window. Credit windows may be shared or		associated with each credit window. Credit windows may be shared or
	dedicated on a per-flow basis. See [RFC9895] for an Ethernet-based		dedicated on a per-flow basis. See [RFC9895] for an Ethernet-based
	version of credit window flow control. As specified in Section 2.3.1		version of credit window flow control. As specified in Section 2.3.1
	of [RFC9892], when both Diffserv and Ethernet traffic classification		of [RFC9892], when both Diffserv and Ethernet traffic classification
	are specified for a flow, the Ethernet information takes precedence.		are specified for a flow, the Ethernet information takes precedence.
	This document uses the traffic classification and credit window		This document uses the traffic classification and credit window flow
	control mechanisms defined in [RFC9892] and [RFC9893] to provide		control mechanisms defined in [RFC9892] and [RFC9893] to provide
	credit-window-based flow control based on DLEP destinations and		credit-window-based flow control based on DLEP destinations and
	Differentiated Services Code Points (DSCPs) [RFC2475]. The defined		Differentiated Services Code Points (DSCPs) [RFC2475]. The defined
	mechanism allows for credit windows to be shared across traffic sent		mechanism allows for credit windows to be shared across traffic sent
	to multiple DLEP destinations and DSCPs, or used exclusively for		to multiple DLEP destinations and DSCPs, or used exclusively for
	traffic sent to a particular destination and/or DSCP. The extension		traffic sent to a particular destination and/or DSCP. The extension
	also supports the "wildcard" matching of any DSCP.		also supports the "wildcard" matching of any DSCP.
	The extension defined in this document is referred to as the		The extension defined in this document is referred to as the
	"Diffserv Aware Credit Window" or, more simply, the "DA Credit"		"Diffserv Aware Credit Window" or, more simply, the "DA Credit"
	extension. The reader should be familiar with both the traffic		extension. The reader should be familiar with both the traffic
	classification and credit window control mechanisms defined in		classification and credit window flow control mechanisms defined in
	[RFC9892] and [RFC9893].		[RFC9892] and [RFC9893].
	This document defines a new DLEP Extension Type Value that is used to		This document defines a new DLEP Extension Type value that is used to
	indicate support for the extension. See Section 2.		indicate support for the extension. See Section 2.
	1.1. Key Words		1.1. Key Words
	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. Extension Usage and Identification		2. Extension Usage and Identification
	The extension defined in this document is built on the mechanisms and		The extension defined in this document is built on the mechanisms and
	processing defined in [RFC9892] and [RFC9893]. To indicate that the		processing defined in [RFC9892] and [RFC9893]. To indicate that the
	Diffserv Aware Credit Window Extension is to be used, an		Diffserv Aware Credit Window Extension is to be used, an
	implementation MUST include the Diffserv Aware Credit Window		implementation MUST include the Diffserv Aware Credit Window
	Extension Type Value in the Extensions Supported Data Item (see		Extension Type value in the Extensions Supported Data Item (see
	Section 13.6 of [RFC8175]). The Extensions Supported Data Item is		Section 13.6 of [RFC8175]). The Extensions Supported Data Item is
	sent and processed according to [RFC8175]. Any implementation that		sent and processed according to [RFC8175]. Any implementation that
	indicates the use of the Diffserv Aware Credit Window Extension MUST		indicates the use of the Diffserv Aware Credit Window Extension MUST
	support all message types, Data Items, the Diffserv Traffic		support all message types, Data Items, the Diffserv Traffic
	Classification Sub-Data Item, and all related processing defined in		Classification Sub-Data Item, and all related processing defined in
	[RFC9892] and [RFC9893].		[RFC9892] and [RFC9893].
	The Diffserv Aware Credit Window Extension Type Value is 6. See		The Diffserv Aware Credit Window Extension Type value is 6. See
	Section 5.		Section 5.
	3. Management Considerations		3. Management Considerations
	This section provides several network management guidelines for		This section provides several network management guidelines for
	implementations supporting the Diffserv Aware Credit Window		implementations supporting the Diffserv Aware Credit Window
	Extension.		Extension.
	If this extension is supported, that support MUST be declared using		If this extension is supported, that support MUST be declared using
	the Extensions Supported Data Item (see Section 13.6 of [RFC8175]).		the Extensions Supported Data Item (see Section 13.6 of [RFC8175]).
	skipping to change at line 167 ¶		skipping to change at line 167 ¶
	supported. In either case, any mismatch in capabilities SHOULD be		supported. In either case, any mismatch in capabilities SHOULD be
	reported to the user via normal network management mechanisms, such		reported to the user via normal network management mechanisms, such
	as user interface messages or error logging.		as user interface messages or error logging.
	In all cases, if credit windows are in use, traffic for which credits		In all cases, if credit windows are in use, traffic for which credits
	are not available MUST NOT be sent to the modem by the router.		are not available MUST NOT be sent to the modem by the router.
	4. Security Considerations		4. Security Considerations
	This document defines a DLEP extension that uses DLEP mechanisms and		This document defines a DLEP extension that uses DLEP mechanisms and
	the credit window control and flow mechanisms defined in [RFC9892]		the credit window flow control mechanisms defined in [RFC9892] and
	and [RFC9893]. See also the Security Considerations sections of		[RFC9893]. See also the Security Considerations sections of those
	those documents.		documents.
	The defined extension is exposed to vulnerabilities similar to		The defined extension is exposed to vulnerabilities similar to
	existing DLEP messages and discussed in the Security Considerations		existing DLEP messages and discussed in the Security Considerations
	section of [RFC8175], such as an injected message resizing a credit		section of [RFC8175], such as an injected message resizing a credit
	window to a value that results in a denial of service. The security		window to a value that results in a denial of service. The security
	mechanisms documented in [RFC8175] can be applied equally to the		mechanisms documented in [RFC8175] can be applied equally to the
	mechanism defined in this document.		mechanism defined in this document.
	Wildcards for matching Priority Code Point (PCP) and VLAN Identifier		Wildcards for matching Priority Code Point (PCP) and VLAN Identifier
	(VID) fields (see [RFC9895]) are provided. Note that wildcards may		(VID) fields (see [RFC9895]) are provided. Note that wildcards may
	skipping to change at line 242 ¶		skipping to change at line 242 ¶
	Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,		Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
	<https://www.rfc-editor.org/info/rfc2475>.		<https://www.rfc-editor.org/info/rfc2475>.
	[RFC9895] Wiggins, D., Berger, L., and D. Eastlake 3rd, Ed.,		[RFC9895] Wiggins, D., Berger, L., and D. Eastlake 3rd, Ed.,
	"Dynamic Link Exchange Protocol (DLEP) IEEE 802.1Q Aware		"Dynamic Link Exchange Protocol (DLEP) IEEE 802.1Q Aware
	Credit Window Extension", RFC 9895, DOI 10.17487/RFC9895,		Credit Window Extension", RFC 9895, DOI 10.17487/RFC9895,
	November 2025, <https://www.rfc-editor.org/info/rfc9895>.		November 2025, <https://www.rfc-editor.org/info/rfc9895>.
	Acknowledgments		Acknowledgments
	The Sub-Data Item format was inspired by Rick Taylor's "Data Item		Many useful comments were received from contributors to the MANET
	Containers". He also proposed the separation of credit windows from		Working Group, notably Ronald in 't Velt.
	traffic classification at IETF 98. Many useful comments were
	received from contributors to the MANET Working Group, notably Ronald
	in 't Velt.
	We had the honor of working too briefly with David Wiggins on this		We had the honor of working too briefly with David Wiggins on this
	and related DLEP work. His contribution to the IETF and publication		and related DLEP work. His contribution to the IETF and publication
	of the first and definitive open-source DLEP implementation have been		of the first and definitive open-source DLEP implementation have been
	critical to the acceptance of DLEP. We mourn his passing on November		critical to the acceptance of DLEP. We mourn his passing on November
	26, 2023. We wish to recognize his guidance, leadership, and		26, 2023. We wish to recognize his guidance, leadership, and
	professional excellence. We were fortunate to benefit from his		professional excellence. We were fortunate to benefit from his
	leadership and friendship. He shall be missed.		leadership and friendship. He shall be missed.
	Authors' Addresses		Authors' Addresses
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