rfc9893.original   rfc9893.txt 
Network Working Group B. Cheng Internet Engineering Task Force (IETF) B. Cheng
Internet-Draft MIT Lincoln Laboratory Request for Comments: 9893 MIT Lincoln Laboratory
Intended status: Standards Track D. Wiggins Category: Standards Track D. Wiggins
Expires: 26 September 2025 ISSN: 2070-1721
S. Ratliff S. Ratliff
L. Berger L. Berger
E. Kinzie, Ed. E. Kinzie, Ed.
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
25 March 2025 November 2025
Dynamic Link Exchange Protocol (DLEP) Credit-Based Flow Control Messages Dynamic Link Exchange Protocol (DLEP) Credit-Based Flow Control Messages
and Data Items and Data Items
draft-ietf-manet-dlep-credit-flow-control-19
Abstract Abstract
This document defines new Dynamic Link Exchange Protocol (DLEP) Data This document defines new Dynamic Link Exchange Protocol (DLEP) Data
Items that are used to support credit-based flow control. Credit Items that are used to support credit-based flow control. Credit
window control is used to regulate when data may be sent to an window control is used to regulate when data may be sent to an
associated virtual or physical queue. The Data Items are extensible associated virtual or physical queue. These Data Items are
and reusable. extensible and reusable.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9893.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Key Words
2. Credit Window Control . . . . . . . . . . . . . . . . . . . . 4 2. Credit Window Control
2.1. Data Plane Considerations . . . . . . . . . . . . . . . . 6 2.1. Data Plane Considerations
2.2. Credit Window Messages . . . . . . . . . . . . . . . . . 6 2.2. Credit Window Messages
2.2.1. Credit Control Message . . . . . . . . . . . . . . . 7 2.2.1. Credit Control Message
2.2.2. Credit Control Response Message . . . . . . . . . . . 7 2.2.2. Credit Control Response Message
2.3. Credit Window Control Data Items . . . . . . . . . . . . 8 2.3. Credit Window Control Data Items
2.3.1. Credit Window Initialization . . . . . . . . . . . . 8 2.3.1. Credit Window Initialization
2.3.2. Credit Window Association . . . . . . . . . . . . . . 11 2.3.2. Credit Window Association
2.3.3. Credit Window Grant . . . . . . . . . . . . . . . . . 12 2.3.3. Credit Window Grant
2.3.4. Credit Window Status . . . . . . . . . . . . . . . . 13 2.3.4. Credit Window Status
2.3.5. Credit Window Request . . . . . . . . . . . . . . . . 15 2.3.5. Credit Window Request
2.4. Management Considerations . . . . . . . . . . . . . . . . 16 2.4. Management Considerations
3. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 17 3. Compatibility
4. Security Considerations . . . . . . . . . . . . . . . . . . . 17 4. Security Considerations
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 5. IANA Considerations
5.1. Message Type Values . . . . . . . . . . . . . . . . . . . 17 5.1. Message Type Values
5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 18 5.2. Data Item Values
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 6. References
6.1. Normative References . . . . . . . . . . . . . . . . . . 18 6.1. Normative References
6.2. Informative References . . . . . . . . . . . . . . . . . 19 6.2. Informative References
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 20 Appendix A. Example DLEP Credit Flow Control and Traffic
Appendix B. Example DLEP Credit Flow Control and Traffic Classification Data Item Exchange
Classification Data Item Exchange . . . . . . . . . . . . 21 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses
1. Introduction 1. Introduction
The Dynamic Link Exchange Protocol (DLEP), defined in [RFC8175], The Dynamic Link Exchange Protocol (DLEP), defined in [RFC8175],
provides the exchange of link related control information between provides the exchange of link-related control information between
DLEP peers. DLEP peers are comprised of a modem and a router. DLEP DLEP peers. DLEP peers are comprised of a modem and a router. DLEP
defines a base set of mechanisms as well as support for future defines a base set of mechanisms as well as support for future
extensions. DLEP defines Data Items which are sets of information extensions. DLEP defines Data Items, which are sets of information
that can be reused in DLEP messaging. The DLEP specification does that can be reused in DLEP messaging. The DLEP specification does
not include any flow identification beyond DLEP endpoints nor flow not include any flow identification beyond DLEP endpoints, nor does
control capability. There are various flow control techniques it address flow control capability. Various flow control techniques
theoretically possible with DLEP. For example, a credit-window are theoretically possible with DLEP. For example, a credit-window
scheme for destination-specific flow control which provides aggregate scheme for destination-specific flow control that provides aggregate
flow control for both modem and routers has been proposed in flow control for both modems and routers has been proposed in
[I-D.ietf-manet-credit-window], and a control plane pause based [Credit-Window-Extension], and a mechanism referred to as the
mechanism is defined in [RFC8651]. The use of other flow control Control-Plane-Based Pause Extension is defined in [RFC8651]. The use
mechanisms simultaneously with Credit-Based Flow Control is not of other flow control mechanisms simultaneously with credit-based
within the scope of this document. flow control is not within the scope of this document.
Credit-Based Flow Control, as a result of its proactive nature, may Credit-based flow control, as a result of its proactive nature, may
offer some advantages over a pause mechanism. Packet loss resulting offer some advantages over a pause mechanism. Packet loss resulting
from insufficient buffer space is less likely, as a transmitter does from insufficient buffer space is less likely, as a transmitter does
not send packets until the receiver has indicated that there is not send packets until the receiver has indicated that there is
sufficient buffer available. sufficient buffer space available.
Figure 1 illustrates a local node consisting of a router and a modem Figure 1 illustrates a local node consisting of a router and a modem
with a DLEP. DLEP messages optionally contain a number of Data Items implementing DLEP. DLEP messages optionally contain a number of Data
and Sub-data Items. Traffic flow classification Data Items provided Items and Sub-Data Items. Traffic Classification Data Items provided
by the modem, are defined in by the modem are defined in [RFC9892]. In this case, a flow is
[I-D.ietf-manet-dlep-traffic-classification]. In this case, a flow identified based on information found in a data plane header, and one
is identified based on information found in a data plane header and or more matches are associated with a single flow. Refer to
one or more matches are associated with a single flow. Refer to
Section 2.3 of [RFC2475] for general background on traffic Section 2.3 of [RFC2475] for general background on traffic
classification. classification.
|--------------------Local Node--------------------| |--------------------Local Node--------------------|
| | | |
+-----------------------------+ +-------+ +-----------------------------+ +-------+
| Router | |Modem | | Router | |Modem |
| | |Device |{~~~~~~~~} Remote | | |Device |{~~~~~~~~} Remote
| | | | Link Nodes | | | | Link Nodes
| Traffic Classification: | | | Protocol | Traffic Classification: | | | Protocol
| Per TID: | | | (e.g., | Per TID: | | | (e.g.,
| DSCPs to FID / PCPs to FID | | | 802.11) | DSCPs to FID / PCPs to FID | | | 802.11)
| | Data Items | | | | Data Items | |
| Per Modem: (list of TIDs) |<---------->| | | Per Modem: (list of TIDs) |<---------->| |
| FID to Credit Window Queues |============| | | FID to Credit Window Queues |============| |
| | | | | | | |
+-----------------------------+ +-------+ +-----------------------------+ +-------+
| | | |
|----DLEP--- | |----DLEP--- |
DSCP: Differentiated Services Code Point
FID: Flow Identifier
PCP: Priority Code Point
TID: Traffic Classification Identifier
Figure 1: Router and Modem DLEP Exchange Figure 1: Router and Modem DLEP Exchange
This document defines DLEP Data Items which provide a flow control This document defines DLEP Data Items that provide a flow control
mechanism for traffic sent from a router to a modem. Flow control is mechanism for traffic sent from a router to a modem. Flow control is
provided using one or more logical "Credit Windows", each of which provided using one or more logical "Credit Windows", each of which
will typically be supported by an associated virtual or physical will typically be supported by an associated virtual or physical
queue. Credit windows may be shared or dedicated on a per flow queue. Credit windows may be shared or dedicated on a per-flow
basis. The Data Items are structured to allow for reuse of the basis. The Data Items are structured to allow for the reuse of the
defined credit window based flow control with different traffic defined credit-window-based flow control with different traffic
classification techniques. A router logically consumes credits for classification techniques. A router logically consumes credits for
each credit window matching packet sent. each credit window matching packet sent.
Note that this document defines common Messages, Data Items and Note that this document defines common messages, Data Items, and
mechanisms that are reusable. They are expected to be required by mechanisms that are reusable. They are expected to be required by
DLEP extensions defined in other documents such as found in DLEP extensions defined in other documents, such as the extension
[I-D.ietf-manet-dlep-da-credit-extension]. defined in [RFC9894].
This document introduces support for credit window control by This document introduces support for credit window control by
defining two new DLEP messages in Section 2.2, and five new DLEP Data defining two new DLEP messages (Section 2.2) and five new DLEP Data
Items in Section 2.3. Items (Section 2.3).
Various conditions described in this document cause a message to be Various conditions described in this document cause a message to be
logged. In all cases, the log message results from the contents of a logged. In all cases, the log message results from the contents of a
received Data Item defined here. No messages are logged in response received Data Item defined here. No messages are logged in response
to activity in the data plane. to activity in the data plane.
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 BCP "OPTIONAL" in this document are to be interpreted as described in
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. Credit Window Control 2. Credit Window Control
This section defines additions to DLEP used in credit based flow This section defines additions to DLEP used in credit-based flow
control. The use of credit window control impacts the data plane. control. The use of credit window control impacts the data plane.
The credit window control mechanisms defined in this document support The credit window control mechanisms defined in this document support
credit based flow control of traffic sent from a router to a modem. credit-based flow control of traffic sent from a router to a modem.
The mapping of specific flows to a particular credit window is based The mapping of specific flows to a particular credit window is based
on the Traffic Classification Data Item defined in on the Traffic Classification Data Item defined in [RFC9892]. Both
[I-D.ietf-manet-dlep-traffic-classification]. Both types of DLEP types of DLEP peers -- router and modem -- negotiate the use of an
peers, router and modem, negotiate the use of an extension employing extension employing this mechanism during session initialization as
this mechanism during session initialization as required, for required; for example, see [RFC9894]. When using credit windows,
example, by [I-D.ietf-manet-dlep-da-credit-extension]. When using data traffic is only allowed to be sent by the router to the modem
credit windows, data traffic is only allowed to be sent by the router when there are credits available.
to the modem when there are credits available.
Credits are managed on a per logical "Credit Window" basis. Each Credits are managed on a 'per logical "Credit Window"' basis. Each
credit window can be thought of as corresponding to a queue within a credit window can be thought of as corresponding to a queue within a
modem. Credit windows may be shared across, or dedicated to, modem. Credit windows may be shared across, or dedicated to,
destinations and data plane identifiers, for example, DSCPs, at a destinations and data plane identifiers -- for example, DSCPs -- at a
granularity that is appropriate for a modem's implementation and its granularity that is appropriate for a modem's implementation and its
attached transmission technology. As defined below in Section 2.3.1, attached transmission technology. As specified in Section 2.3.1,
there is a direct one-for-one mapping of credit windows to flows as there is a direct one-to-one mapping of credit windows to flows as
identified by Flow Identifiers (FIDs) carried within the Traffic identified by Flow Identifiers (FIDs) carried within the Traffic
Classification Data Item. Modems pass to the router information on Classification Data Item. Modems pass to the router information on
their credit windows and FIDs prior to a router being able to send their credit windows and FIDs prior to a router being able to send
data when an extension requiring the use of credit window control is data when an extension requiring the use of credit window control is
used. Note that TID and FID values are significant only to the used. Note that Traffic Classification Identifier (TID) values and
issuing modem. There is no relationship implied by the same TID or FID values are significant only to the issuing modem. There is no
FID value being issued by more than one modem. In addition to the relationship implied by the same TID or FID value being issued by
traffic classification information associated with a FID, modems more than one modem. In addition to the traffic classification
provide an initial credit window size, as well as the maximum size of information associated with a FID, modems provide an initial credit
the logical queue associated with each credit window. The maximum window size, as well as the maximum size of the logical queue
size is included for informative and potential future uses. associated with each credit window. The maximum size is included for
informative and potential future uses.
Modems provide an initial credit window size at the time of "Credit Modems provide an initial credit window size at the time of "Credit
Window Initialization". Such initialization can take place during Window Initialization". Such initialization can take place during
session initiation or any point thereafter. It can also take place session initiation or any point thereafter. It can also take place
when rate information changes. An increment to a Credit Window size, when rate information changes. An increment to a credit window size,
specified in a Credit Grant Data Item, is provided in a Destination specified in a Credit Grant Data Item, is provided in a Destination
Up or the new "Credit Control" Message. A router provides its view Up Message (Section 2.3.2) or Credit Control Message (Section 2.2.1).
of the Credit Window, which is known as "Status", in Destination Up A router provides its view of the Credit Window, which is known as
Response and the new "Credit Control Response" Messages. Routers can "Status", in Destination Up Response Messages (Section 2.3.3) and
also request credits using the new "Credit Control" Message. Credit Control Response Messages (Section 2.2.2). Routers can also
request credits using the Credit Control Message.
When modems provide credits to a router, they will need to take into When modems provide credits to a router, they will need to take into
account any overhead of their attached transmission technology and account any overhead of their attached transmission technology and
map it into the credit semantics defined in this document. In map it into the credit semantics defined in this document. In
particular, the credit window is defined below to include per frame particular, the credit window is defined below to include per-frame
(packet) MAC headers, and this may not match the actual overhead of (per-packet) Media Access Control (MAC) headers, and this may not
the modem attached transmission technology. In that case a direct match the actual overhead of the modems' attached transmission
mapping, or an approximation will need to be made by the modem to technology. In that case, a direct mapping or an approximation will
provide appropriate credit values. need to be made by the modem to provide appropriate credit values.
Actual flows of traffic are mapped to credit windows based on flow Actual flows of traffic are mapped to credit windows based on flow
identification information provided by modems in the Traffic identification information provided by modems in the Traffic
Classification Data Item defined in Classification Data Item defined in [RFC9892]. This Data Item
[I-D.ietf-manet-dlep-traffic-classification]. This data item supports traffic classification on a per-destination or more fine-
supports traffic classification on a per destination or more fine grained level. Routers use the combination of the DLEP-identified
grain level. Routers use the combination of the DLEP identified
destination and flow information associated with a credit window in destination and flow information associated with a credit window in
order to match traffic they send to specific credit windows. In some order to match traffic they send to specific credit windows. In some
cases, the Traffic Classification Data Item allows the modem to cases, the Traffic Classification Data Item allows the modem to
specify a wildcard to match any packets that do not match other data specify a wildcard to match any packets that do not match other Data
items, for example see [I-D.ietf-manet-dlep-ether-credit-extension]. Items; for example, see [RFC9895]. In the absence of a wildcard, a
In the absence of a wildcard, a packet may not match any of the data packet may not match any of the Data Items and, in this case, MUST be
items and, in this case, MUST be dropped by the router. dropped by the router.
When a destination becomes reachable, a modem "associates" When a destination becomes reachable, a modem "associates"
(identifies) the appropriate traffic classification information via (identifies) the appropriate traffic classification information via
the Traffic Class Identifier (TID) to be used for traffic sent by the the TID to be used for traffic sent by the router to that
router to that destination. This is supported by the Credit Window destination. This is supported by the Credit Window Association Data
Association Data Item which is carried in Destination Up and Update Item, which is carried in Destination Up and Destination Update
messages, see Section 2.3.2. The TID provides the information to Messages; see Section 2.3.2. The TID provides the information to
support router traffic classification, based on the FIDs contained in support router traffic classification, based on the FIDs contained in
the TID, see [I-D.ietf-manet-dlep-traffic-classification]. As the TID; see [RFC9892]. As defined, each credit window has a
defined, each credit window has a corresponding FID, so traffic is corresponding FID, so traffic is mapped to a credit window by
mapped to a credit window by locating a matching FID that is locating a matching FID that is contained in the TID that is
contained in the TID that is associated with the traffic's associated with the traffic's destination. This means that the use
destination. This means that the use of FIDs, TIDs and the of FIDs and TIDs, and the association of a TID to a DLEP destination,
association of a TID to a DLEP destination enables a modem to share enable a modem to share or dedicate resources as needed to match the
or dedicate resources as needed to match the specifics of its specifics of its implementation and its attached transmission
implementation and its attached transmission technology. technology.
The defined credit window control has similar objectives as the Credit window control as defined in this document has objectives
control found in [I-D.ietf-manet-credit-window]. One notable similar to the control technique described in
difference from that credit control is that in this document, credits [Credit-Window-Extension]. One notable difference from that type of
are never provided by the router to the modem. credit control is that in this document, credits are never provided
by the router to the modem.
2.1. Data Plane Considerations 2.1. Data Plane Considerations
When credit windowing is used, a router MUST NOT send data traffic to When credit windowing is used, a router MUST NOT send data traffic to
a modem for forwarding if there is no matching classifier. If a a modem for forwarding if there is no matching classifier. If a
matching classifier is found, a router MUST NOT send data traffic to matching classifier is found, a router MUST NOT send data traffic to
a modem when there are no credits available in the associated Credit a modem when there are no credits available in the associated Credit
Window. Section 2 describes how classifiers are associated with Window. Section 2 describes how classifiers are associated with
destinations and how credit windows are associated with classifiers. destinations and how credit windows are associated with classifiers.
Additionally, a router MUST ensure sufficient credits are available Additionally, a router MUST ensure that sufficient credits are
in the associated Credit Window for the current data packet before available in the associated Credit Window for the current data packet
sending that data packet to the modem. The count of octets in the before sending that data packet to the modem. The count of octets in
packet includes MAC overhead. In the example of Ethernet, framing, the packet includes MAC overhead. Taking Ethernet as an example,
header and trailer are all included in this count. This document framing, header, and trailer are all included in this count. This
defines credit windows in octets and the credit window is decremented document defines credit windows in octets, and the credit window is
by the number of sent octets. decremented by the number of sent octets.
A router MUST identify the credit window associated with traffic to A router MUST identify the credit window associated with traffic to
be sent to a modem based on the traffic classification information be sent to a modem based on the traffic classification information
provided in the Data Items defined in this document. provided in the Data Items defined in this document.
2.2. Credit Window Messages 2.2. Credit Window Messages
Two new messages are defined in support for credit window control: This document defines two new messages that support credit window
the Credit Control and the Credit Control Response Messages. Sending control: Credit Control Messages and Credit Control Response
and receiving both message types is REQUIRED to support the credit Messages. Sending and receiving both message types is REQUIRED to
window control defined in this document. support the credit window control mechanisms defined in this
document.
2.2.1. Credit Control Message 2.2.1. Credit Control Message
Credit Control Messages are sent by modems and routers. Each sender Credit Control Messages are sent by modems and routers. Each sender
is only permitted to have one message outstanding at one time. That is only permitted to have one message outstanding at one time. That
is, a sender (either modem or router) MUST NOT send any subsequent is, a sender (either modem or router) MUST NOT send a subsequent
Credit Control Message until a Credit Control Response Message is Credit Control Message until a Credit Control Response Message has
received from its peer. been received from its peer.
Credit Control Messages are sent by modems to provide credit window Credit Control Messages are sent by modems to provide credit window
increases. Modems send credit increases when there is transmission increases. Modems send credit increases when their transmission or
or local queue availability that exceeds the credit window value local queue availability exceeds the credit window value previously
previously provided to the router. Modems will need to balance the provided to the router. Modems will need to balance the load
load generated by sending and processing credit window increases generated by sending and processing credit window increases against a
against a router having data traffic available to send, but no router having data traffic available to send, but no credits
credits available. available.
Credit Control Messages MAY be sent by routers to request credits and Credit Control Messages MAY be sent by routers to request credits and
provide window status. Routers will need to balance the load provide window status. Routers will need to balance the load
generated by sending and processing credit window requests against generated by sending and processing credit window requests against
having data traffic available to send, but no credits available. having data traffic available to send, but no credits available.
The Message Type value in the DLEP Message Header is set to TBA2. The Message Type value in the DLEP Message Header is set to 17.
A Credit Control message sent by a modem, MUST contain one or more A Credit Control Message sent by a modem MUST contain one or more
Credit Window Grant Data Items as defined in Section 2.3.3. A router Credit Window Grant Data Items as defined in Section 2.3.3. A router
receiving this message MUST respond with a Credit Control Response receiving this message MUST respond with a Credit Control Response
Message. Message.
A Credit Control message sent by a router, MUST contain one or more A Credit Control Message sent by a router MUST contain one or more
Credit Window Request Data Items defined in Section 2.3.5 and SHOULD Credit Window Request Data Items as defined in Section 2.3.5 and
contain a Credit Window Status Data Item, defined in Section 2.3.4, SHOULD contain a Credit Window Status Data Item, defined in
corresponding to each credit window request. A modem receiving this Section 2.3.4, corresponding to each credit window request. A modem
message MUST respond with a Credit Control Response Message based on receiving this message MUST respond with a Credit Control Response
the received message and Data Item and the processing defined in Message based on the received message and Data Item and the
Section 2.2.2, which will typically result in credit window processing defined in Section 2.2.2, which will typically result in
increments being provided. credit window increments being provided.
Specific processing associated with each Credit Data Item is provided Specific processing associated with each Credit Data Item is provided
in Section 2.3. in Section 2.3.
2.2.2. Credit Control Response Message 2.2.2. Credit Control Response Message
Credit Control Response Messages are sent by routers to report the Credit Control Response Messages are sent by routers to report the
current Credit Window for a destination. A Credit Control Response current Credit Window for a destination. A Credit Control Response
message sent by a router, MUST contain one or more Credit Window Message sent by a router MUST contain one or more Credit Window
Status Data Items as defined below in Section 2.3.4. Specific Status Data Items as defined in Section 2.3.4. Specific receive
receive processing associated with the Credit Window Status Data Item processing associated with the Credit Window Status Data Item is
is provided in Section 2.3.4. provided in Section 2.3.4.
Credit Control Response Messages sent by modems MUST contain one or Credit Control Response Messages sent by modems MUST contain one or
more Credit Window Grant Data Items. A Data Item for every Credit more Credit Window Grant Data Items. A Data Item for every Credit
Window Request Data Item contained in the corresponding Credit Window Request Data Item contained in the corresponding Credit
Control Message received by the modem MUST be included. Each Credit Control Message received by the modem MUST be included. Each Credit
Grant Data Item MAY provide zero or more additional credits based on Grant Data Item MAY provide zero or more additional credits based on
the modem's transmission or local queue availability. Specific the modem's transmission or local queue availability. Specific
receive processing associated with each Grant Data Item is provided receive processing associated with each Grant Data Item is provided
in Section 2.3.3. in Section 2.3.3.
The Message Type value in the DLEP Message Header is set to TBA3. The Message Type value in the DLEP Message Header is set to 18.
2.3. Credit Window Control Data Items 2.3. Credit Window Control Data Items
Five new Data Items are defined to support credit window control. Five new Data Items are defined to support credit window control:
The Credit Window Initialization Data Item is used by a modem to
identify a credit window and set its size. The Credit Window * The Credit Window Initialization Data Item (Section 2.3.1) is used
Association Data Item is used by a modem to identify which traffic by a modem to identify a credit window and set its size.
classification identifiers (flows) should be used when sending
traffic to a particular DLEP identified destination. The Credit * The Credit Window Association Data Item (Section 2.3.2) is used by
Window Grant Data Item is used by a modem to provide additional a modem to identify which TIDs (flows) should be used when sending
credits to a router. The Credit Window Request Data Item is used by traffic to a particular DLEP-identified destination.
a router to request additional credits. The Credit Window Status
Data Item is used to advertise the sender's view of number of * The Credit Window Grant Data Item (Section 2.3.3) is used by a
available credits for state synchronization purposes. modem to provide additional credits to a router.
* The Credit Window Status Data Item (Section 2.3.4) is used to
advertise the sender's view of the number of available credits for
state synchronization purposes.
* The Credit Window Request Data Item (Section 2.3.5) is used by a
router to request additional credits.
Any errors or inconsistencies encountered in parsing Data Items are Any errors or inconsistencies encountered in parsing Data Items are
handled in the same fashion as any other data item parsing error handled in the same fashion as any other Data Item parsing error
encountered in DLEP, see [RFC8175]. In particular, the node parsing encountered in DLEP; see [RFC8175]. In particular, the node parsing
the Data Item MUST terminate the session with a Status Data Item the Data Item MUST terminate the session with a Status Data Item
indicating Invalid Data. indicating "Invalid Data".
2.3.1. Credit Window Initialization 2.3.1. Credit Window Initialization
The Credit Window Initialization Data Item is used by a modem to As noted above, the Credit Window Initialization Data Item is used by
identify a credit window and set its size. In order to avoid errors a modem to identify a credit window and set its size. In order to
caused by the use of undefined FIDs or uninitialized credit windows, avoid errors caused by the use of undefined FIDs or uninitialized
this Data Item SHOULD be included in any Session Initialization credit windows, this Data Item SHOULD be included in any Session
Response Message that indicates support for any such extension. Initialization Response Message that indicates support for any such
Updates to previously identified credit windows or new credit windows extension. Updates to previously identified credit windows or new
MAY be sent by a modem by including the Data Item in Session Update credit windows MAY be sent by a modem by including the Data Item in
Messages. More than one data item MAY be included in a message to Session Update Messages. More than one Data Item MAY be included in
provide information on multiple credit windows. a message to provide information on multiple credit windows.
The Credit Window Initialization Data Item identifies a credit window The Credit Window Initialization Data Item identifies a credit window
using a Flow Identifier, or FID. It also provides the size of the using a FID. It also provides the size of the identified credit
identified credit window. To be used, a FID must be defined within a window. To be used, a FID must be defined within a Traffic
Traffic Classification Data Item and the associated TID must be Classification Data Item, and the associated TID must be provided via
provided via a Credit Window Association Data Item. a Credit Window Association Data Item.
The format of the Credit Window Initialization Data Item is: The format of the Credit Window Initialization Data Item is as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length (16) | | Data Item Type | Length (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Identifier (FID) | Reserved | | Flow Identifier (FID) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit Value | | Credit Value |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scale | Credit Window Max Size | | Scale | Credit Window Max Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: Data Item Type:
Data Item Type (TBA4) 30
Length: Length:
16 16
As specified in [RFC8175], Length is the number of octets in the As specified in [RFC8175], Length is the number of octets in the
Data Item. It MUST be equal to sixteen (16). If it is some other Data Item. It MUST be equal to sixteen (16). If it is some other
value, the Data Item is corrupt so the message in which it appears value, the Data Item is corrupt, so the message in which it
cannot be reliably parsed and is ignored. appears cannot be reliably parsed and is ignored.
Flow Identifier (FID): Flow Identifier (FID):
A two-octet flow identifier as defined by the Traffic A 2-octet flow identifier as defined by the Traffic Classification
Classification Data Item Data Item [RFC9892]. The FID also uniquely identifies a credit
[I-D.ietf-manet-dlep-traffic-classification]. The FID also window for a specific DLEP session.
uniquely identifies a credit window for a specific DLEP session.
Reserved: Reserved:
For the Credit Window Initialization Data Item this reserved field For the Credit Window Initialization Data Item, this reserved
is currently unused. It MUST set to all zeros for this version of field is currently unused. It MUST be set to all zeros for this
the Data Item and it is currently ignored on reception. This version of the Data Item and is currently ignored on reception.
allows for future extensions of the Data Item if needed. This allows for future extensions of the Data Item if needed.
Credit Value: Credit Value:
A 64-bit unsigned integer representing the credits, in octets, to A 64-bit unsigned integer representing the credits, in octets, to
be added to the Credit Window. This value includes MAC headers as be added to the Credit Window. This value includes MAC headers as
seen on the link between the modem and router. seen on the link between the modem and router.
Scale: Scale:
An 8-bit unsigned integer indicating the scale used in the Credit An 8-bit unsigned integer indicating the scale used in the Credit
Window Max Size field. The valid values are: Window Max Size field. The valid values are as follows:
Value Scale +=======+=========================+
------------ | Value | Scale |
0 B - Bytes (Octets) +=======+=========================+
1 KB - Kilobytes (B/1024) | 0 | B: Bytes (Octets) |
2 MB - Megabytes (KB/1024) +-------+-------------------------+
3 GB - Gigabytes (MB/1024) | 1 | KB: Kilobytes (B/1024) |
+-------+-------------------------+
| 2 | MB: Megabytes (KB/1024) |
+-------+-------------------------+
| 3 | GB: Gigabytes (MB/1024) |
+-------+-------------------------+
Table 1: Valid Scale Field Values
Credit Window Max Size: Credit Window Max Size:
A 24-bit unsigned integer representing the maximum size, in the A 24-bit unsigned integer representing the maximum size, in the
octet scale indicated by the Scale field, of the associated credit octet scale indicated by the Scale field, of the associated credit
window. window.
A router that receives a Credit Window Initialization Data Item MUST A router that receives a Credit Window Initialization Data Item MUST
ensure that the FID field value has been provided by the modem in a ensure that the FID field value has been provided by the modem in a
Traffic Classification Data Item carried in either the current or a Traffic Classification Data Item carried in either the current
previous message. If the FID cannot be found the router SHOULD log message or a previous message. If the FID cannot be found, the
this information. The method of logging is left to the router router SHOULD log this information. The method of logging is left to
implementation. Note that no traffic will be associated with the the router implementation. Note that no traffic will be associated
credit window in this case. After FID validation, the router MUST with the credit window in this case. After FID validation, the
locate the credit window that is associated with the FID indicated in router MUST locate the credit window that is associated with the FID
each received Data Item. If no associated credit window is found, indicated in each received Data Item. If no associated credit window
the router MUST initialize a new credit window using the values is found, the router MUST initialize a new credit window using the
carried in the Data Item. When an associated credit window is found, values carried in the Data Item. When an associated credit window is
the router MUST update the credit window and associated data plane found, the router MUST update the credit window and associated data
state using the values carried in the Data Item. If the resulting plane state using the values carried in the Data Item. If the
Credit Value results in the credit window exceeding the represented resultant Credit Value in turn results in the credit window exceeding
Credit Window Max Size, the Credit Window Max Size field value is the represented Credit Window Max Size, the Credit Window Max Size
used as the new credit window size. field value is used as the new credit window size.
It is worth noting, that such updates can result in a credit window It is worth noting that such updates can result in a credit window
size being reduced, for example, due to a transmission rate change on size being reduced -- for example, due to a transmission rate change
the modem. After sending the Session Update Message with one or more on the modem. After sending the Session Update Message with one or
Credit Window Initialization Data Items that decrease the Credit more Credit Window Initialization Data Items that decrease the Credit
Window Max Size, the modem SHOULD continue processing received Window Max Size, the modem SHOULD continue processing received
packets that match the indicated FIDs, fit within the window for the packets that match the indicated FIDs, fit within the window for the
unmodified Credit Window Max Size and arrive before the modem unmodified Credit Window Max Size, and arrive before the modem
receives the corresponding Session Update Response Message. The receives the corresponding Session Update Response Message. The
modem SHOULD NOT issue additional credits for any affected FID until modem SHOULD NOT issue additional credits for any affected FID until
that FID's associated Window has drained to be less than the new that FID's associated window has drained to be less than the new
Credit Window Max Size, regardless of when the corresponding Session Credit Window Max Size, regardless of when the corresponding Session
Update Response Message is received. Update Response Message is received.
2.3.2. Credit Window Association 2.3.2. Credit Window Association
The Credit Window Association Data Item is used by a modem to The Credit Window Association Data Item is used by a modem to
associate traffic classification information with a destination. The associate traffic classification information with a destination. The
traffic classification information is identified using a TID value traffic classification information is identified using a TID value
that has previously been sent by the modem or is listed in a Traffic that has been previously sent by the modem or is listed in a Traffic
Classification Data Item carried in the same message as the Credit Classification Data Item carried in the same message as the Credit
Window Association Data Item. TIDs in different Credit windows must Window Association Data Item. TIDs in different credit windows must
not overlap. not overlap.
A single Credit Window Association Data Item MUST be included in A single Credit Window Association Data Item MUST be included in
every Destination Up and Destination Update Message sent by a modem every Destination Up and Destination Update Message sent by a modem
when the credit window control defined in this document is used. when a credit window control mechanism defined in this document is
Note that a TID will not be used unless it is listed in a Credit used. Note that a TID will not be used unless it is listed in a
Window Association Data Item. Credit Window Association Data Item.
The format of the Credit Window Association Data Item is: The format of the Credit Window Association Data Item is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length (2) | | Data Item Type | Length (2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Traffic Class. Identifier (TID)| |Traffic Class. Identifier (TID)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: Data Item Type:
Data Item Type (TBA5) 31
Length: Length:
2 2
As specified in [RFC8175], Length is the number of octets in the As specified in [RFC8175], Length is the number of octets in the
Data Item. It MUST be equal to two (2). If it is some other Data Item. It MUST be equal to two (2). If it is some other
value, the Data Item is corrupt so the message in which it appears value, the Data Item is corrupt, so the message in which it
cannot be reliably parsed and is ignored. appears cannot be reliably parsed and is ignored.
Traffic Classification Identifier (TID): Traffic Classification Identifier (TID):
A 16-bit unsigned integer identifying a traffic classification set A 16-bit unsigned integer identifying a traffic classification set
that has been identified in a Traffic Classification Data Item, that has been identified in a Traffic Classification Data Item;
see [I-D.ietf-manet-dlep-traffic-classification]. see [RFC9892].
A router that receives a Credit Window Association Data Item MUST A router that receives a Credit Window Association Data Item MUST
locate the traffic classification information indicated by the locate the traffic classification information indicated by the
received TID. If no corresponding information is found, the Credit received TID. If no corresponding information is found, the Credit
Window Association Data Item MUST be treated as an error as described Window Association Data Item MUST be treated as an error as described
above. If the traffic classification information is located, the above. If the traffic classification information is located, the
router MUST ensure that any data plane state that is associated with router MUST ensure that any data plane state that is associated with
the TID and its corresponding FIDs are updated as needed (per the TID and its corresponding FIDs is updated as needed (per
Section 2.1). If a router determines that a newly received Data Item Section 2.1). If a router determines that a newly received Data Item
results in credit windows with overlapping TIDs, the Data Item MUST results in credit windows with overlapping TIDs, the Data Item MUST
be treated as an error as described above. be treated as an error as described above.
2.3.3. Credit Window Grant 2.3.3. Credit Window Grant
The Credit Window Grant Data Item is used by a modem to provide The Credit Window Grant Data Item is used by a modem to provide
credits to a router. One or more Credit Window Grant Data Items MAY credits to a router. One or more Credit Window Grant Data Items MAY
be carried in the DLEP Destination Up, Destination Announce Response, be carried in the DLEP Destination Up, Destination Announce Response,
Destination Update, Credit Control Messages, and Credit Control Destination Update, Credit Control, and Credit Control Response
Response Messages. Multiple Credit Window Grant Data Items may be Messages. Multiple Credit Window Grant Data Items may be present in
present in a single message. Each item grants credits to a different a single message. Each item grants credits to a different credit
credit window and, therefor, references a different FID. In all window and therefore references a different FID. In all message
message types, this Data Item provides an additional number of octets types, this Data Item provides an additional number of octets to be
to be added to the indicated credit window. Credit windows are added to the indicated credit window. Credit windows are identified
identified using FID values that have been previously been sent by using FID values that have been previously sent by the modem or are
the modem or are listed in a Credit Window Initialization Data Item listed in a Credit Window Initialization Data Item carried in the
carried in the same message as the Data Item. same message as the Data Item.
The format of the Credit Window Grant Data Item is: The format of the Credit Window Grant Data Item is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length (12) | | Data Item Type | Length (12) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Identifier (FID) | Reserved | | Flow Identifier (FID) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Credits | | Additional Credits |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: Data Item Type:
Data Item Type (TBA6) 32
Length: Length:
12 12
As specified in [RFC8175], Length is the number of octets in the As specified in [RFC8175], Length is the number of octets in the
Data Item. It MUST be equal to twelve (12). If it is some other Data Item. It MUST be equal to twelve (12). If it is some other
value, the Data Item is corrupt so the message in which it appears value, the Data Item is corrupt, so the message in which it
cannot be reliably parsed and is ignored. appears cannot be reliably parsed and is ignored.
Flow Identifier (FID): Flow Identifier (FID):
A two-octet flow identifier as defined by the Traffic A 2-octet flow identifier as defined by the Traffic Classification
Classification Data Item. The FID also uniquely indicates a Data Item. The FID also uniquely indicates a credit window.
credit window.
Reserved: Reserved:
For the Credit Window Grant Data Item this reserved field is For the Credit Window Grant Data Item, this reserved field is
currently unused. It MUST set to all zeros for this version of currently unused. It MUST be set to all zeros for this version of
the Data Item and it is currently ignored on reception. This the Data Item and is currently ignored on reception. This allows
allows for future extensions of the Data Item if needed. for future extensions of the Data Item if needed.
Additional Credit: Additional Credits:
A 64-bit unsigned integer representing the credits, in octets, to A 64-bit unsigned integer representing the credits, in octets, to
be added to the Credit Window. This value includes MAC headers as be added to the Credit Window. This value includes MAC headers as
seen on the link between the modem and router. A value of zero seen on the link between the modem and router. A value of zero
indicates that no additional credits are being provided. indicates that no additional credits are being provided.
When receiving this Data Item, a router MUST identify the credit When receiving this Data Item, a router MUST identify the credit
window indicated by the FID. If the FID is not known to the router, window indicated by the FID. If the FID is not known to the router,
it SHOULD log this information and discard the Data Item. The method it SHOULD log this information and discard the Data Item. The method
of logging is left to the router implementation. It is important to of logging is left to the router implementation. It is important to
note that while this Data Item can be received in a destination note that while this Data Item can be received in a destination-
specific message, credit windows are managed independently from the specific message, credit windows are managed independently of the
destination identified in the message carrying this Data Item, and destination identified in the message carrying this Data Item, and
the indicated FID MAY even be disjoint from the identified the indicated FID MAY even be disjoint from the identified
destination. destination.
Once the credit window is identified, the credit window size MUST be Once the credit window is identified, the credit window size MUST be
increased by the value contained in the Additional Credits field. If increased by the value contained in the Additional Credits field. If
the increase results in a window overflow, the Credit Window must be the increase results in a window overflow, the Credit Window must be
set to its maximum as defined by the Credit Window Max Size carried set to its maximum as defined by the Credit Window Max Size carried
in the Credit Window Initialization Data Item. in the Credit Window Initialization Data Item.
No response is sent by the router to a modem after processing a No response is sent by the router to a modem after processing a
Credit Window Grant Data Item received in a Credit Control Response Credit Window Grant Data Item received in a Credit Control Response
Message. When a Credit Window Grant Data Item is received in other Message. When a Credit Window Grant Data Item is received in other
message types, the receiving router MUST send a Credit Window Status message types, the receiving router MUST send a Credit Window Status
Data Item or items reflecting the resulting Credit Window value of Data Item or items reflecting the resultant Credit Window value of
the updated credit window. When the Credit Grant Data Item is the updated credit window. When the Credit Grant Data Item is
received in a Destination Up Message, the Credit Window Status Data received in a Destination Up Message, the Credit Window Status Data
Item(s) MUST be sent in the corresponding Destination Up Response Item(s) MUST be sent in the corresponding Destination Up Response
Message. Otherwise, a Credit Control Message MUST be sent. Message. Otherwise, a Credit Control Message MUST be sent.
2.3.4. Credit Window Status 2.3.4. Credit Window Status
The Credit Window Status Data Item is used by a router to report the The Credit Window Status Data Item is used by a router to report the
current credit window size to its peer modem. One or more Credit current credit window size to its peer modem. One or more Credit
Window Status Data Items MAY be carried in a Destination Up Response Window Status Data Items MAY be carried in a Destination Up Response
Message or a Credit Control Response Message. As discussed in Message or a Credit Control Response Message. As discussed in
Section 2.3.3, the Destination Up Response Message is used when the Section 2.3.3, the Destination Up Response Message is used when the
Data Item is sent in response to a Destination Up Message, and the Data Item is sent in response to a Destination Up Message, and the
Credit Control Response Message is sent in response to a Credit Credit Control Response Message is sent in response to a Credit
Control Message. Multiple Credit Window Status Data Items in a Control Message. Multiple Credit Window Status Data Items in a
single message are used to indicate different sizes of different single message are used to indicate different sizes of different
credit windows. Similar to the Credit Window Grant, credit windows credit windows. Similar to the Credit Window Grant Data Item, credit
are identified using FID values that have been previously been sent windows are identified using FID values that have been previously
by the modem. sent by the modem.
The format of the Credit Window Status Data Item is: The format of the Credit Window Status Data Item is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length (12) | | Data Item Type | Length (12) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Identifier (FID) | Reserved | | Flow Identifier (FID) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Current Credit Window Size | | Current Credit Window Size |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: Data Item Type:
Data Item Type (TBA7) 33
Length: Length:
12 12
As specified in [RFC8175], Length is the number of octets in the As specified in [RFC8175], Length is the number of octets in the
Data Item. It MUST be equal to twelve (12). If it is some other Data Item. It MUST be equal to twelve (12). If it is some other
value, the Data Item is corrupt so the message in which it appears value, the Data Item is corrupt, so the message in which it
cannot be reliably parsed and is ignored. appears cannot be reliably parsed and is ignored.
Flow Identifier (FID): Flow Identifier (FID):
A two-octet flow identifier as defined by the Traffic A 2-octet flow identifier as defined by the Traffic Classification
Classification Data Item. The FID also uniquely identifies a Data Item. The FID also uniquely identifies a credit window.
credit window.
Reserved: Reserved:
For the Credit Window Status Data Item this reserved field is For the Credit Window Status Data Item, this reserved field is
currently unused. It MUST set to all zeros for this version of currently unused. It MUST be set to all zeros for this version of
the Data Item and it is currently ignored on reception. This the Data Item and is currently ignored on reception. This allows
allows for future extensions of the Data Item if needed. for future extensions of the Data Item if needed.
Current Credit Window Size: Current Credit Window Size:
A 64-bit unsigned integer, indicating the current number of A 64-bit unsigned integer indicating the current number of
credits, in octets, available for the router to send to the modem. credits, in octets, available for the router to send to the modem.
This is referred to as the Modem Receive Window in This is referred to as the Modem Receive Window in
[I-D.ietf-manet-credit-window]. [Credit-Window-Extension].
When receiving this Data Item, a modem MUST identify the credit When receiving this Data Item, a modem MUST identify the credit
window indicated by the FID. If the FID is not known to the modem, window indicated by the FID. If the FID is not known to the modem,
it SHOULD log this information and discard the Data Item. The method it SHOULD log this information and discard the Data Item. The method
of logging is left to the modem implementation. As with the Credit of logging is left to the modem implementation. As with the Credit
Window Grant Data Item, the FID MAY be unrelated to the Destination Window Grant Data Item, the FID MAY be unrelated to the destination
indicated in the message carrying the Data Item. indicated in the message carrying the Data Item.
Once the credit window is identified, the modem SHOULD check the Once the credit window is identified, the modem SHOULD check the
received Current Credit Window Size field value against the received Current Credit Window Size field value against the
outstanding credit window's available credits at the time the most outstanding credit window's available credits at the time the most
recent Credit Window Initialization or Grant Data Item associated recent Credit Window Initialization or Grant Data Item associated
with the indicated FID was sent. If the difference in values is with the indicated FID was sent. If the difference in values is
greater than can be accounted for based on observed data frames, then greater than what can be accounted for based on observed data frames,
the modem SHOULD send a Credit Window Initialization Data Item to then the modem SHOULD send a Credit Window Initialization Data Item
reset the associated credit window size to the modem's current view to reset the associated credit window size to the modem's current
of the available credits. As defined in Section 2.3.1, Credit Window view of the available credits. As specified in Section 2.3.1, Credit
Initialization Data Items are sent in Session Update Messages. When Window Initialization Data Items are sent in Session Update Messages.
multiple Data Items need to be sent, they SHOULD be combined into a When multiple Data Items need to be sent, they SHOULD be combined
single message when possible. Alternatively, and also in cases where into a single message when possible. Alternatively, and also in
there are small differences, the modem MAY adjust the values sent in cases where there are small differences, the modem MAY adjust the
Credit Window Grant Data Items to account for the reported Credit values sent in Credit Window Grant Data Items to account for the
Window. reported Credit Window.
2.3.5. Credit Window Request 2.3.5. Credit Window Request
The Credit Window Request Data Item is used by a router to request The Credit Window Request Data Item is used by a router to request
additional credits for particular credit windows. Credit Window additional credits for particular credit windows. Credit Window
Request Data Items are carried in Credit Control Messages, and one or Request Data Items are carried in Credit Control Messages, and one or
more Credit Window Request Data Items MAY be present in a message. more Credit Window Request Data Items MAY be present in a message.
Credit windows are identified using a FID as defined in Credit windows are identified using a FID as defined in
Section 2.3.1. Multiple FIDs MAY be present to allow for the case Section 2.3.1. Multiple FIDs MAY be present to allow for the case
where the router identifies that credits are needed in multiple where the router determines that credits are needed in multiple
credit windows. A special FID value, as defined below, is used to credit windows. A special FID value, as defined below, is used to
indicate that a credit request is being made across all queues. indicate that a credit request is being made across all queues.
The format of the Credit Window Request Data Item is: The format of the Credit Window Request Data Item is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length | | Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Identifier (FID) [1] | Flow Identifier (FID) [2] | | Flow Identifier (FID) [1] | Flow Identifier (FID) [2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Flow Identifier (FID) [n] | | ... | Flow Identifier (FID) [n] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: Data Item Type:
Data Item Type (TBA8) 34
Length: Length:
Variable Variable
As specified in [RFC8175], Length is the number of octets in the As specified in [RFC8175], Length is the number of octets in the
Data Item, excluding the Type and Length fields. It is equal to Data Item, excluding the Type and Length fields. It is equal to
the number of FID fields carried in the Data Item times 2 and MUST the number of FID fields carried in the Data Item times 2 and MUST
be at least 2. If it is less than 2, the Data Item is corrupt so be at least 2. If it is less than 2, the Data Item is corrupt, so
the message in which it appears cannot be reliably parsed and is the message in which it appears cannot be reliably parsed and is
ignored. ignored.
Flow Identifier (FID): Flow Identifier (FID):
A two-octet flow identifier as defined by the Traffic A 2-octet flow identifier as defined by the Traffic Classification
Classification Data Item. The FID also uniquely identifies a Data Item. The FID also uniquely identifies a credit window. The
credit window. The special value of 0xFFFF indicates that the special value 0xFFFF indicates that the request applies to all
request applies to all FIDs. When this special value is included, FIDs. When this special value is included, all other FID values
all other FID values included in the Data Item are redundant as included in the Data Item are redundant, as the special value
the special value indicates all FIDs. indicates all FIDs.
A modem receiving this Data Item MUST provide a Credit Increment for A modem receiving this Data Item MUST provide a credit window
the indicated credit windows via Credit Window Grant Data Items increment for the indicated credit windows via Credit Window Grant
carried in a new Credit Control Message. Multiple values and queue Data Items carried in a new Credit Control Message. Multiple values
indexes SHOULD be combined into a single Credit Control Message when and queue indexes SHOULD be combined into a single Credit Control
possible. Unknown FID values SHOULD be logged and then ignored by Message when possible. Unknown FID values SHOULD be logged and then
the modem. The method of logging is left to the modem ignored by the modem. The method of logging is left to the modem
implementation. implementation.
2.4. Management Considerations 2.4. Management Considerations
This section provides several network management guidelines to This section provides several network management guidelines for
implementations supporting the credit window mechanisms defined in implementations supporting the credit window mechanisms defined in
this document. this document.
Modems MAY support the configuration of the number of credit windows Modems MAY support the configuration of the number of credit windows
(queues) to advertise to a router. (queues) to advertise to a router.
Routers may have limits on the number of queues that they can Routers may have limits on the number of queues that they can
support. They may even have limits on supported credit window support. They may even have limits on supported credit window
combinations. For example, per destination queues may not be combinations. For example, per-destination queues may not be
supported at all. When modem-provided credit window information supported at all. When credit window information provided by a modem
exceeds the capabilities of a router, the router SHOULD use a subset exceeds the capabilities of a router, the router SHOULD use a subset
of the provided credit windows. Alternatively, a router MAY reset of the provided credit windows. Alternatively, a router MAY reset
the session and indicate that the extension is not supported. In the session and indicate that the extension is not supported. In
either case, the mismatch of capabilities SHOULD be reported to the either case, any mismatch in capabilities SHOULD be reported to the
user via normal network management mechanisms, such as the user user via normal network management mechanisms, such as the user
interface or error logging. interface 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.
3. Compatibility 3. Compatibility
The messages and Data Items defined in this document will only be The messages and Data Items defined in this document will only be
used when extensions require their use. used when extensions require their use.
The DLEP specification [RFC8175] defines handling of unexpected The DLEP specification [RFC8175] defines the handling of unexpected
appearances of any Data Items, including those defined in this appearances of any Data Items, including those defined in this
document. document.
4. Security Considerations 4. Security Considerations
This document introduces credit window control and flow mechanisms to This document introduces credit window control and flow mechanisms
DLEP. These mechanisms expose vulnerabilities similar to existing for DLEP. These mechanisms expose vulnerabilities similar to
DLEP messages. An example of a threat to which flow control might be existing DLEP messages. An example of a threat to which flow control
susceptible is a malicious actor masquerading as a DLEP peer could might be susceptible is where a malicious actor masquerading as a
inject a Credit Window Initialization Data Item, which resizes a DLEP peer could inject a Credit Window Initialization Data Item that
credit window to a value that results in a denial of service. Other resizes a credit window to a value that results in a denial of
possible threats are given in the Security Considerations of service. Other possible threats are discussed in the Security
[RFC8175] and are also applicable to, but not specific to, flow Considerations section of [RFC8175] and are also applicable, but not
control. The transport layer security mechanisms documented in specific, to flow control. The transport-layer security mechanisms
[RFC8175], with some updated references to external documents listed documented in [RFC8175], with some updated references to external
below, can be applied to this document. Implementations following documents listed below, can be applied to this document.
the "networked deployment" model described in the "Implementation Implementations following the "networked deployment" model described
Scenarios" of [RFC8175] SHOULD refer to [BCP195] for additional in Section 4 ("Implementation Scenarios") of [RFC8175] SHOULD refer
details. The Layer 2 security mechanisms documented in [RFC8175] can to [BCP195] for additional details. The Layer 2 security mechanisms
also, with some updates, be applied to the mechanism defined in this documented in [RFC8175] can also, with some updates, be applied to
document. Examples of technologies that can be deployed to secure the mechanisms defined in this document. Examples of technologies
the Layer 2 link include [IEEE-802.1AE] and [IEEE-8802-1X]. that can be deployed to secure the Layer 2 link include
[IEEE-802.1AE] and [IEEE-8802-1X].
5. IANA Considerations 5. IANA Considerations
This document requests the assignment of several values by IANA. All
assignments are to registries defined by [RFC8175].
5.1. Message Type Values 5.1. Message Type Values
This document requests 2 new assignments to the DLEP Message Registry IANA has assigned two new values from the "Specification Required"
named "Message Values" in the range with the "Specification Required" range [RFC8126] in the DLEP "Message Type Values" registry:
policy. The requested values are as follows:
+===========+=========================+ +===========+=========================+
| Type Code | Description | | Type Code | Description |
+===========+=========================+ +===========+=========================+
| TBA2 | Credit Control | | 17 | Credit Control |
+-----------+-------------------------+ +-----------+-------------------------+
| TBA3 | Credit Control Response | | 18 | Credit Control Response |
+-----------+-------------------------+ +-----------+-------------------------+
Table 1: Requested Message Type Values Table 2: Message Type Values
5.2. Data Item Values 5.2. Data Item Values
This document requests the following new assignments to the DLEP Data IANA has assigned the following values from the "Specification
Item Registry named "Data Item Type Values" in the range with the Required" range [RFC8126] in the DLEP "Data Item Type Values"
"Specification Required" policy. The requested values are as registry:
follows:
+===========+==============================+ +===========+==============================+
| Type Code | Description | | Type Code | Description |
+===========+==============================+ +===========+==============================+
| TBA4 | Credit Window Initialization | | 30 | Credit Window Initialization |
+-----------+------------------------------+ +-----------+------------------------------+
| TBA5 | Credit Window Association | | 31 | Credit Window Association |
+-----------+------------------------------+ +-----------+------------------------------+
| TBA6 | Credit Window Grant | | 32 | Credit Window Grant |
+-----------+------------------------------+ +-----------+------------------------------+
| TBA7 | Credit Window Status | | 33 | Credit Window Status |
+-----------+------------------------------+ +-----------+------------------------------+
| TBA8 | Credit Window Request | | 34 | Credit Window Request |
+-----------+------------------------------+ +-----------+------------------------------+
Table 2: Requested Data Item Values Table 3: Data Item Values
6. References 6. References
6.1. Normative References 6.1. Normative References
[I-D.ietf-manet-dlep-traffic-classification]
Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, "Dynamic
Link Exchange Protocol (DLEP) Traffic Classification Data
Item", Work in Progress, Internet-Draft, draft-ietf-manet-
dlep-traffic-classification, 19 November 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
traffic-classification>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B. [RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175, Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017, DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>. <https://www.rfc-editor.org/info/rfc8175>.
[RFC9892] Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, Ed.,
"Dynamic Link Exchange Protocol (DLEP) Traffic
Classification Data Item", RFC 9892, DOI 10.17487/RFC9892,
November 2025, <https://www.rfc-editor.org/info/rfc9892>.
6.2. Informative References 6.2. Informative References
[BCP195] Best Current Practice 195, [BCP195] Best Current Practice 195,
<https://www.rfc-editor.org/info/bcp195>. <https://www.rfc-editor.org/info/bcp195>.
At the time of writing, this BCP comprises the following: At the time of writing, this BCP comprises the following:
Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
<https://www.rfc-editor.org/info/rfc8996>.
Sheffer, Y., Saint-Andre, P., and T. Fossati, Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>. 2022, <https://www.rfc-editor.org/info/rfc9325>.
Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS [Credit-Window-Extension]
1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
<https://www.rfc-editor.org/info/rfc8996>.
[I-D.ietf-manet-credit-window]
Ratliff, S., "Credit Windowing extension for DLEP", Work Ratliff, S., "Credit Windowing extension for DLEP", Work
in Progress, Internet-Draft, draft-ietf-manet-credit- in Progress, Internet-Draft, draft-ietf-manet-credit-
window-07, 13 November 2016, window-07, 13 November 2016,
<https://datatracker.ietf.org/doc/html/draft-ietf-manet- <https://datatracker.ietf.org/doc/html/draft-ietf-manet-
credit-window-07>. credit-window-07>.
[I-D.ietf-manet-dlep-da-credit-extension]
Cheng, B., Wiggins, D., Berger, L., and D. E. Eastlake,
"DLEP DiffServ Aware Credit Window Extension", Work in
Progress, Internet-Draft, draft-ietf-manet-dlep-da-credit-
extension, 15 December 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
da-credit-extension/>.
[I-D.ietf-manet-dlep-ether-credit-extension]
Wiggins, D., Berger, L., and D. E. Eastlake, "DLEP IEEE
802.1Q Aware Credit Window Extension", Work in Progress,
Internet-Draft, draft-ietf-manet-dlep-ether-credit-
extension, 15 December 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
ether-credit-extension/>.
[IEEE-802.1AE] [IEEE-802.1AE]
"IEEE Standard for Local and metropolitan area networks- IEEE, "IEEE Standard for Local and metropolitan area
Media Access Control (MAC) Security Amendment 4: MAC networks-Media Access Control (MAC) Security Amendment 4:
Privacy protection", MAC Privacy protection", DOI 10.1109/IEEESTD.2018.8585421,
December 2018,
<https://ieeexplore.ieee.org/document/8585421>. <https://ieeexplore.ieee.org/document/8585421>.
[IEEE-8802-1X] [IEEE-8802-1X]
"8802-1X-2021 - IEEE/ISO/IEC International Standard- IEEE, "IEEE/ISO/IEC International Standard-
Telecommunications and exchange between information Telecommunications and exchange between information
technology systems--Requirements for local and technology systems--Requirements for local and
metropolitan area networks--Part 1X:Port-based network metropolitan area networks--Part 1X:Port-based network
access control", access control", DOI 10.1109/IEEESTD.2021.9650828, IEEE
Std 8802-1X-2021, December 2021,
<https://ieeexplore.ieee.org/document/9650828>. <https://ieeexplore.ieee.org/document/9650828>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated and W. Weiss, "An Architecture for Differentiated
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>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8651] Cheng, B., Wiggins, D., and L. Berger, Ed., "Dynamic Link [RFC8651] Cheng, B., Wiggins, D., and L. Berger, Ed., "Dynamic Link
Exchange Protocol (DLEP) Control-Plane-Based Pause Exchange Protocol (DLEP) Control-Plane-Based Pause
Extension", RFC 8651, DOI 10.17487/RFC8651, October 2019, Extension", RFC 8651, DOI 10.17487/RFC8651, October 2019,
<https://www.rfc-editor.org/info/rfc8651>. <https://www.rfc-editor.org/info/rfc8651>.
Appendix A. Acknowledgments [RFC9894] Cheng, B., Wiggins, D., Berger, L., and D. Eastlake 3rd,
Ed., "Dynamic Link Exchange Protocol (DLEP) Diffserv Aware
We mourn the loss of Stan Ratliff who passed away on October 22, Credit Window Extension", RFC 9894, DOI 10.17487/RFC9894,
2019. His guidance, leadership and personal contributions were November 2025, <https://www.rfc-editor.org/info/rfc9894>.
critical in the development of this work and DLEP as a whole. His
leadership and friendship shall be missed.
We had the honor of working too briefly with David Wiggins on this
and related DLEP work. His contribution to the IETF and publication
of the first and definitive open source DLEP implementation have been
critical to the acceptance of DLEP. We morn his passing on November
23, 2023. We wish to recognize his guidance, leadership and
professional excellence. We were fortunate to benefit from his
leadership and friendship. He shall be missed.
Many useful comments were received from contributors to the MANET [RFC9895] Wiggins, D., Berger, L., and D. Eastlake 3rd, Ed.,
working group, notably Rick Taylor, Ronald in't Velt, David Black and "Dynamic Link Exchange Protocol (DLEP) IEEE 802.1Q Aware
Donald E. Eastlake. This document was derived from Credit Window Extension", RFC 9895, DOI 10.17487/RFC9895,
[I-D.ietf-manet-dlep-da-credit-extension] as a result of discussions November 2025, <https://www.rfc-editor.org/info/rfc9895>.
at IETF 101.
Appendix B. Example DLEP Credit Flow Control and Traffic Classification Appendix A. Example DLEP Credit Flow Control and Traffic Classification
Data Item Exchange Data Item Exchange
Below Figure 2 illustrates a credit flow control and traffic Figure 2 illustrates a credit flow control and traffic classification
classification exchange between a Router and a Modem. The Modem will exchange between a router and a modem. The modem will initialize a
initialize a number of queues with Credit Window Initialization Data number of queues with Credit Window Initialization Data Items, Credit
Items, Window Association Data Item(s) and Traffic Classification Window Association Data Item(s), and Traffic Classification Data
Item(s) included in DLEP messages as outlined in this document. If Item(s) included in DLEP messages as outlined in this document. If
the Data Items are successfully validated, traffic is mapped to the the Data Items are successfully validated, traffic is mapped to the
corresponding credit window on the router and forwarded when there corresponding credit window on the router and forwarded when there
are sufficient credits. Routers can periodically report the status are sufficient credits. Routers can periodically report the status
of the credit window. Modems will send periodic updates with more of the credit window. Modems will send periodic updates with more
credits as packets are transmitted. Routers may request more credits credits as packets are transmitted. If a router requires more
for a particular window if the router requires more credits. This credits for a particular window, it may request them. This document
document defines window credit flow information for flow Identifiers defines credit window flow information for FIDs that map to the
(FIDs) that map to the queues. queues. [RFC9892] defines the Traffic Classification Sub-Data Items,
[I-D.ietf-manet-dlep-traffic-classification] defines the traffic such as DSCPs, that map to the FIDs.
classification data sub items such as DiffServ code points that map
to the FIDs.
Router Modem Router Modem
|<----------------DLEP Messages---------------| |<----------------DLEP Messages---------------|
| Traffic Classification Data Item(s) | | Traffic Classification Data Item(s) |
| Window Association Data Item(s) | | Credit Window Association Data Item(s) |
| Credit Window Initialization Data Item(s) | | Credit Window Initialization Data Item(s) |
| | | |
|============================================>| |============================================>|
| Traffic | | Traffic |
| | | |
|<----------------DLEP Messages---------------| |<----------------DLEP Messages---------------|
| Credit Window Grant Data Item(s) | T | Credit Window Grant Data Item(s) | T
|============================================>| i |============================================>| i
| Traffic | m | Traffic | m
| | e | | e
|----------------DLEP Messages--------------->| |----------------DLEP Messages--------------->|
| Credit Window Status Data Item(s) | | | Credit Window Status Data Item(s) | |
| | V | | V
|============================================>| |============================================>|
| Traffic | | Traffic |
| | | |
|----------------DLEP Messages--------------->| |----------------DLEP Messages--------------->|
| Credit Window Request Data Item(s) | | Credit Window Request Data Item(s) |
| | | |
|<------------------------------------------- | |<------------------------------------------- |
| Credit Window Grant Data Item(s) | | Credit Window Grant Data Item(s) |
| | | |
|============================================>| |============================================>|
| Traffic | | Traffic |
| | | |
Figure 2: Example DLEP Traffic Classification/Credit Flow Exchange Figure 2: Example DLEP Traffic Classification / Credit Flow Exchange
Acknowledgments
We mourn the loss of Stan Ratliff, who passed away on October 22,
2019. His guidance, leadership, and personal contributions were
critical in the development of this work and DLEP as a whole. His
leadership and friendship shall be missed.
We had the honor of working too briefly with David Wiggins on this
and related DLEP work. His contribution to the IETF and publication
of the first and definitive open-source DLEP implementation have been
critical to the acceptance of DLEP. We mourn his passing on November
26, 2023. We wish to recognize his guidance, leadership, and
professional excellence. We were fortunate to benefit from his
leadership and friendship. He shall be missed.
Many useful comments were received from contributors to the MANET
Working Group, notably Rick Taylor, Ronald in 't Velt, David Black,
and Donald E. Eastlake. This document was derived from [RFC9894] as
a result of discussions at IETF 101.
Authors' Addresses Authors' Addresses
Bow-Nan Cheng Bow-Nan Cheng
MIT Lincoln Laboratory MIT Lincoln Laboratory
Massachusetts Institute of Technology Massachusetts Institute of Technology
244 Wood Street 244 Wood Street
Lexington Lexington, MA 02421-6426
United States of America
Email: bcheng@ll.mit.edu Email: bcheng@ll.mit.edu
David Wiggins David Wiggins
Email: david@none.org
Stan Ratliff Stan Ratliff
Email: stan@none.org
Lou Berger Lou Berger
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
Email: lberger@labn.net Email: lberger@labn.net
Eric Kinzie (editor) Eric Kinzie (editor)
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
Email: ekinzie@labn.net Email: ekinzie@labn.net
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