rfc9895v4.txt   rfc9895.txt 
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virtual or physical queue. The router leverages traffic flow virtual or physical queue. The router leverages traffic flow
classification information provided by the modem to determine the classification information provided by the modem to determine the
appropriate credit window for a given traffic flow. Credit windows appropriate credit window for a given traffic flow. Credit windows
may be shared across multiple flows or used on a per-flow basis. For may be shared across multiple flows or used on a per-flow basis. For
a Diffserv-based approach to credit window flow control, refer to a Diffserv-based approach to credit window flow control, refer to
[RFC9894]. As specified in Section 2.3.1 of [RFC9892], when both [RFC9894]. As specified in Section 2.3.1 of [RFC9892], when both
Diffserv and Ethernet traffic classification are applied to a flow, Diffserv and Ethernet traffic classification are applied to a flow,
Ethernet-based classification takes precedence. Ethernet-based classification takes precedence.
This document leverages the traffic classification and credit window This document leverages the traffic classification and credit window
control mechanisms defined in [RFC9892] and [RFC9893] to enable flow control mechanisms defined in [RFC9892] and [RFC9893] to enable
credit-window-based flow control based on DLEP destinations, Ethernet credit-window-based flow control based on DLEP destinations, Ethernet
Virtual Local Area Networks (VLANs), and Priority Code Points (PCPs). Virtual Local Area Networks (VLANs), and Priority Code Points (PCPs).
Ethernet PCP support is specified as part of the IEEE 802.1Q tag Ethernet PCP support is specified as part of the IEEE 802.1Q tag
format [IEEE8021Q], which includes a 3-bit "PCP" field. The tag format [IEEE8021Q], which includes a 3-bit "PCP" field. The tag
format also incorporates a 12-bit "VLAN Identifier (VID)" field. format also incorporates a 12-bit "VLAN Identifier (VID)" field.
The defined mechanism allows credit windows to be shared across The defined mechanism allows credit windows to be shared across
traffic destined for multiple DLEP destinations, VLANs, and PCPs, or traffic destined for multiple DLEP destinations, VLANs, and PCPs, or
to be dedicated exclusively to traffic associated with a specific to be dedicated exclusively to traffic associated with a specific
destination, VLAN, and/or PCP. Additionally, this extension supports destination, VLAN, and/or PCP. Additionally, this extension supports
"wildcard" matching for any PCP or VID. "wildcard" matching for any PCP or VID.
The extension defined in this document is referred to as the "IEEE The extension defined in this document is referred to as the "IEEE
802.1Q Aware Credit Window" or, more simply, the "Ethernet Credit" 802.1Q Aware Credit Window" or, more simply, the "Ethernet 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
IEEE 802.1Q Aware Credit Window Extension is to be used, an IEEE 802.1Q Aware Credit Window Extension is to be used, an
implementation MUST include the IEEE 802.1Q Aware Credit Window implementation MUST include the IEEE 802.1Q 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 IEEE 802.1Q Aware Credit Window Extension indicates the use of the IEEE 802.1Q Aware Credit Window Extension
MUST support all message types, Data Items, the Ethernet Traffic MUST support all message types, Data Items, the Ethernet 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 IEEE 802.1Q Aware Credit Window Extension Type Value is 5. See The IEEE 802.1Q Aware Credit Window Extension Type value is 5. 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 IEEE 802.1Q Aware Credit Window implementations supporting the IEEE 802.1Q 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]),
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standard network management mechanisms, such as user interface standard network management mechanisms, such as user interface
notifications or error logging. notifications or error logging.
Regardless of implementation, if credit windows are in use, the Regardless of implementation, if credit windows are in use, the
router MUST NOT send traffic to the modem unless sufficient credits router MUST NOT send traffic to the modem unless sufficient credits
are available. are available.
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 PCP and VID fields are provided. Note that Wildcards for matching PCP and VID fields are provided. Note that
wildcards may be convenient for matching a number of packet flows but wildcards may be convenient for matching a number of packet flows but
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