draft-ietf-manet-dlep-da-credit-extension-00.txt   draft-ietf-manet-dlep-da-credit-extension-01.txt 
Network Working Group B. Cheng Network Working Group B. Cheng
Internet-Draft D. Wiggins Internet-Draft D. Wiggins
Intended status: Standards Track Lincoln Laboratory Intended status: Standards Track Lincoln Laboratory
Expires: August 13, 2017 L. Berger Expires: September 14, 2017 L. Berger
LabN Consulting, L.L.C. LabN Consulting, L.L.C.
February 9, 2017 March 13, 2017
DLEP DiffServ Aware Credit Windowing Extension DLEP DiffServ Aware Credit Windowing Extension
draft-ietf-manet-dlep-da-credit-extension-00 draft-ietf-manet-dlep-da-credit-extension-01
Abstract Abstract
This document defines an extension to the DLEP protocol that enables This document defines an extension to the DLEP protocol that enables
a DiffServ aware credit-windowing scheme for destination-specific a DiffServ aware credit-windowing scheme for destination-specific
flow control. flow control.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 13, 2017. This Internet-Draft will expire on September 14, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extension Overview . . . . . . . . . . . . . . . . . . . . . 3 2. Extension Overview . . . . . . . . . . . . . . . . . . . . . 3
3. Extension Usage and Identification . . . . . . . . . . . . . 4 3. Extension Usage and Identification . . . . . . . . . . . . . 4
4. Extension Messages . . . . . . . . . . . . . . . . . . . . . 4 4. Data Plane Considerations . . . . . . . . . . . . . . . . . . 4
4.1. Credit Control Message . . . . . . . . . . . . . . . . . 4 5. Extension Messages . . . . . . . . . . . . . . . . . . . . . 4
4.2. Credit Control Response Message . . . . . . . . . . . . . 5 5.1. Credit Control Message . . . . . . . . . . . . . . . . . 4
5. Extension Data Items . . . . . . . . . . . . . . . . . . . . 5 5.2. Credit Control Response Message . . . . . . . . . . . . . 5
5.1. Queue Parameters . . . . . . . . . . . . . . . . . . . . 5 6. Extension Data Items . . . . . . . . . . . . . . . . . . . . 5
5.2. DiffServ Aware (DA) Credit Grant . . . . . . . . . . . . 8 6.1. Queue Parameters . . . . . . . . . . . . . . . . . . . . 6
5.3. DiffServ Aware (DA) Credit Window Status . . . . . . . . 10 6.2. DiffServ Aware (DA) Credit Grant . . . . . . . . . . . . 8
5.4. DiffServ Aware (DA) Credit Request . . . . . . . . . . . 11 6.3. DiffServ Aware (DA) Credit Window Status . . . . . . . . 10
6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 12 6.4. DiffServ Aware (DA) Credit Request . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8.1. Extension Type Value . . . . . . . . . . . . . . . . . . 13 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.2. Message Values . . . . . . . . . . . . . . . . . . . . . 13 9.1. Extension Type Value . . . . . . . . . . . . . . . . . . 13
8.3. Data Item Values . . . . . . . . . . . . . . . . . . . . 14 9.2. Message Values . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.3. Data Item Values . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Open and Resolved Issues . . . . . . . . . . . . . . 15
A.1. Merge with [I-D.ietf-manet-credit-window] . . . . . . . . 15
A.2. Credit Windows Shared Across Destinations . . . . . . . . 16
A.3. Supporting Router Limits . . . . . . . . . . . . . . . . 16
A.4. Absolute vs Increment . . . . . . . . . . . . . . . . . . 16
A.5. Alternate Format Encoding . . . . . . . . . . . . . . . . 16
A.6. Bidirectional Flow
Control (closed) . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
The Dynamic Link Event Protocol (DLEP) is defined in The Dynamic Link Event Protocol (DLEP) is defined in
[I-D.ietf-manet-dlep]. It provides the exchange of link related [I-D.ietf-manet-dlep]. It provides the exchange of link related
control information between DLEP peers. DLEP peers are comprised of control information between DLEP peers. DLEP peers are comprised of
a modem and a router. DLEP defines a base set of mechanisms as well a modem and a router. DLEP defines a base set of mechanisms as well
as support for possible extensions. This document defines one such as support for possible extensions. This document defines one such
extension. extension.
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This document defines a DLEP extension which provides flow control This document defines a DLEP extension which provides flow control
for DiffServ [RFC2475] traffic sent from a router to a modem. Flow for DiffServ [RFC2475] traffic sent from a router to a modem. Flow
control is provided for multiple DSCPs (differentiated services control is provided for multiple DSCPs (differentiated services
codepoint), which are grouped into logical sets of logical queues. codepoint), which are grouped into logical sets of logical queues.
The extension defined in this document is referred to as "DiffServ The extension defined in this document is referred to as "DiffServ
Aware Credit Windowing" or, more simply, the "DA Credit" extension. Aware Credit Windowing" or, more simply, the "DA Credit" extension.
This document defines a new DLEP Extension Type Value in Section 3 This document defines a new DLEP Extension Type Value in Section 3
which is used to indicate the use of the extension. Two new messages which is used to indicate the use of the extension. Two new messages
are defined in Section 4, and four new DLEP Data Items in Section 5. are defined in Section 5, and four new DLEP Data Items in Section 6.
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 BCP
14, RFC 2119 [RFC2119]. 14, RFC 2119 [RFC2119].
2. Extension Overview 2. Extension Overview
The DA Credit extension can be used to support credit based flow The DA Credit extension can be used to support credit based flow
control of traffic sent from a router to a modem. The extension can control of traffic sent from a router to a modem. The extension can
be used to support DiffServ and non-DiffServ based flow control. be used to support DiffServ and non-DiffServ based flow control.
Both types of DLEP endpoints, i.e., a router and a modem, negotiate Both types of DLEP endpoints, i.e., a router and a modem, negotiate
the use of extension during session initialization, see Section 5.2 the use of extension during session initialization, see Section 5.2
[I-D.ietf-manet-dlep]. [I-D.ietf-manet-dlep]. When using this extension, data is allowed to
be sent by the router to the modem only when there are credits
available.
When the extension is to be used, a modem passes to a router its When the extension is to be used, a modem passes to a router its
known DSCPs, if any. DSCPs are grouped by logical queues, each of known DSCPs, if any. DSCPs are grouped by logical queues, each of
which are given a logical queue index. The queue index zero (0) is which are given a logical queue index. The queue index zero (0) is
special and is used for any DSCP value, including 0, which is not special and is used for any DSCP value, including 0, which is not
otherwise identified by the modem. The modem also provides a size, otherwise identified by the modem. The modem also provides a size,
in bytes, of the logical queue for informative and, potential, future in bytes, of the logical queue for informative and, potential, future
uses. Currently, only DSCP to logical queue index value mapping is uses. Currently, only DSCP to logical queue index value mapping is
used in flow control operation. used in flow control operation.
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3. Extension Usage and Identification 3. Extension Usage and Identification
The use of the extension defined in this document SHOULD be The use of the extension defined in this document SHOULD be
configurable. To indicate that the DiffServ Aware Credit Windowing configurable. To indicate that the DiffServ Aware Credit Windowing
Extension is to be used, an implementation MUST include the DiffServ Extension is to be used, an implementation MUST include the DiffServ
Aware Credit Windowing Type Value in the Extensions Supported Data Aware Credit Windowing Type Value in the Extensions Supported Data
Item. The Extensions Supported Data Item is sent and processed Item. The Extensions Supported Data Item is sent and processed
according to [I-D.ietf-manet-dlep]. according to [I-D.ietf-manet-dlep].
The DiffServ Aware Credit Windowing Extension Type Value is TBA1, see The DiffServ Aware Credit Windowing Extension Type Value is TBA1, see
Section 8. Section 9.
4. Extension Messages 4. Data Plane Considerations
When the use of the extension defined in this document is agreed upon
per standard DLEP processing, see Section 3, a router MUST NOT send
data to a modem for forwarding when there are no credits available in
the associated Credit Window.
5. Extension Messages
Two new messages are defined by this extension: the Credit Control Two new messages are defined by this extension: the Credit Control
and the Credit Control Response message. Sending and receiving both and the Credit Control Response message. Sending and receiving both
message types MUST be supported by any implementation that advertises message types MUST be supported by any implementation that advertises
use of this extension per Section 3. use of this extension per Section 3.
4.1. Credit Control Message 5.1. Credit Control Message
Credit Control Messages are sent by modems to provide Credit Credit Control Messages are sent by modems to provide Credit
Increments. For messages sent by modems, only one message per MAC Increments. For messages sent by modems, only one message per MAC
address can be outstanding at one time. That is, a modem MUST NOT address can be outstanding at one time. That is, a modem MUST NOT
send a second (or any subsequent) message containing the same MAC send a second (or any subsequent) message containing the same MAC
Address until a Credit Control Response message is received from its Address until a Credit Control Response message is received from its
peer router with that MAC address. peer router with that MAC address.
Credit Control Messages MAY be sent by routers, e.g., to request Credit Control Messages MAY be sent by routers, e.g., to request
credits or provide window status. No specific response message is credits or provide window status. No specific response message is
required from a message transaction perspective. required from a message transaction perspective.
[TBD: Should anything be said about sending, or limiting, multiple [TBD: Should anything be said about sending, or limiting, multiple
credit requests?] credit requests?]
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 TBA2.
The message MUST contain a DLEP MAC Address Data Item. The message MUST contain a DLEP MAC Address Data Item.
A message sent by a modem, MUST contain one or more DiffServ Aware A message sent by a modem, MUST contain one or more DiffServ Aware
Credit Grant data items as defined below in Section 5.2. A router Credit Grant data items as defined below in Section 6.2. 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 message sent by a router, MUST contain the DiffServ Aware Credit A message sent by a router, MUST contain the DiffServ Aware Credit
Request data item defined below in Section 5.4. A modem receiving Request data item defined below in Section 6.4. A modem receiving
this message MUST provide a Credit Increment for the indicated MAC this message MUST provide a Credit Increment for the indicated MAC
address and queue indexes via a new Credit Control Message. address and queue indexes via a new Credit Control Message.
Specific processing associated with each Credit data item is provided Specific processing associated with each Credit data item is provided
below. below.
4.2. Credit Control Response Message 5.2. 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. current Credit Window for a destination.
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 TBA3.
The message MUST contain a DLEP MAC Address Data Item. The message MUST contain a DLEP MAC Address Data Item.
A message sent by a router, MUST contain one or more DiffServ Aware A message sent by a router, MUST contain one or more DiffServ Aware
Credit Window Status data items as defined below in Section 5.3. Credit Window Status data items as defined below in Section 6.3.
Specific processing associated with the DA Credit Window Status data Specific processing associated with the DA Credit Window Status data
item is provided below. item is provided below.
5. Extension Data Items 6. Extension Data Items
Four data items are defined by this extension. The Queue Parameters Four data items are defined by this extension. The Queue Parameters
Data Item is used by a modem to provide information on the DSCPs it Data Item is used by a modem to provide information on the DSCPs it
uses in forwarding. The DA Credit Grant is used by a modem to uses in forwarding. The DA Credit Grant is used by a modem to
provide credits to a router. The DA Credit Request is used by a provide credits to a router. The DA Credit Request is used by a
router to request additional credits. The DA Credit Window Status is router to request additional credits. The DA Credit Window Status is
used to advertise the sender's view of number of available credits used to advertise the sender's view of number of available credits
for synchronization purposes. for synchronization purposes.
The defined data items and operations are similar to those found in The defined data items and operations are similar to those found in
[I-D.ietf-manet-credit-window]. One notable difference from this [I-D.ietf-manet-credit-window]. One notable difference from this
extension is that in this document credits are never provided by the extension is that in this document credits are never provided by the
router to the modem. router to the modem.
5.1. Queue Parameters 6.1. Queue Parameters
The Queue Parameters Data Item is used by a modem to indicate DSCP The Queue Parameters Data Item is used by a modem to indicate DSCP
values that may be independently controlled. This data item MUST be values that may be independently controlled. This data item MUST be
included in a Session Initialization Response Message that also included in a Session Initialization Response Message that also
contains the DiffServ Aware Credit Windowing Extension Type Value in contains the DiffServ Aware Credit Windowing Extension Type Value in
the Extensions Supported Data Item. Updates to these parameters MAY the Extensions Supported Data Item. Updates to these parameters MAY
be sent by a modem by including the data item in Session Update be sent by a modem by including the data item in Session Update
Messages. Messages.
The Queue Parameters Data Item identifies DSCPs based on groups of The Queue Parameters Data Item identifies DSCPs based on groups of
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The DS Field structure is the same as [RFC2474]. The DS Field structure is the same as [RFC2474].
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
| DSCP | CU | | DSCP | CU |
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
DSCP: differentiated services codepoint DSCP: differentiated services codepoint
CU: currently unused, MUST be zero CU: currently unused, MUST be zero
5.2. DiffServ Aware (DA) Credit Grant 6.2. DiffServ Aware (DA) Credit Grant
The DiffServ Aware, or DA, Credit Grant data item is used by a modem The DiffServ Aware, or DA, Credit Grant data item is used by a modem
to provide credits to a router. One or more DA Credit Grant data to provide credits to a router. One or more DA Credit Grant data
items MAY be carried in the DLEP Destination Up, Destination Announce items MAY be carried in the DLEP Destination Up, Destination Announce
Response, Destination Update, and Credit Control messages. Multiple Response, Destination Update, and Credit Control messages. Multiple
DA Credit Grant data items in a single message are used to indicated DA Credit Grant data items in a single message are used to indicated
different credit values for different logical queues. different credit values for different logical queues.
In Destination type messages, this data item provides the total In Destination type messages, this data item provides the total
number of octets available in the Credit Window to the destination number of octets available in the Credit Window to the destination
indicated in the message for the specified logical queues. In the indicated in the message for the specified logical queues. In the
Credit Control message, this data item provides an additional number Credit Control message, this data item provides an additional number
of octets to be added to the Credit Window to the destination of octets to be added to the Credit Window to the destination
indicated in the message for the specified logical queues. indicated in the message for the specified logical queues.
Logical queues are identified using a Queue Index as defined above in Logical queues are identified using a Queue Index as defined above in
Section 5.1. Multiple Queue Indexes MAY be present to allow for the Section 6.1. Multiple Queue Indexes MAY be present to allow for the
case where same credit information applies to multiple queues. As case where same credit information applies to multiple queues. As
mentioned above, multiple DA Credit Grant Data Items MAY be present mentioned above, multiple DA Credit Grant Data Items MAY be present
to provide different queue-specific credit information in one to provide different queue-specific credit information in one
message. The special Queue Index value of 255 is used to indicate message. The special Queue Index value of 255 is used to indicate
that the credit information applies to all queues. that the credit information applies to all queues.
The format of the DA Credit Grant Data Item is: The format of the DA Credit Grant Data Item is:
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
skipping to change at page 10, line 5 skipping to change at page 10, line 38
(0xFFFFFFFFFFFFFFFF). (0xFFFFFFFFFFFFFFFF).
Independent of the received message, the receiving router MUST send a Independent of the received message, the receiving router MUST send a
DA Credit Window Status data item or items reflecting the resulting DA Credit Window Status data item or items reflecting the resulting
Credit Window value of each modified queue index. When the Credit Credit Window value of each modified queue index. When the Credit
Grant data item is received in a Destination Up message, the DA Grant data item is received in a Destination Up message, the DA
Credit Window Status data item(s) MUST be sent in the corresponding Credit Window Status data item(s) MUST be sent in the corresponding
Destination Up Response message. In all other cases, the a Credit Destination Up Response message. In all other cases, the a Credit
Control message MUST be sent. Control message MUST be sent.
5.3. DiffServ Aware (DA) Credit Window Status 6.3. DiffServ Aware (DA) Credit Window Status
The DiffServ Aware, or DA, Credit Window Status data item is used by The DiffServ Aware, or DA, Credit Window Status data item is used by
a router to report the current Credit Window to its peer modem. One a router to report the current Credit Window to its peer modem. One
or more DA Credit Window Status data items MAY be carried in a or more DA Credit Window Status data items MAY be carried in a
Destination Up Response message or a Credit Control Response message. Destination Up Response message or a Credit Control Response message.
As discussed above, the Destination Up Response message is used when As discussed above, 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 the Credit Control Response message is sent in response to a Credit
Control message. Multiple DA Credit Window Status data items in a Control message. Multiple DA Credit Window Status data items in a
single message are used to indicated different credit window values single message are used to indicated different credit window values
for different logical queues. for different logical queues.
Similar to the DA Credit Grant, logical queues are identified using a Similar to the DA Credit Grant, logical queues are identified using a
Queue Index as defined above in Section 5.1. Multiple Queue Indexes Queue Index as defined above in Section 6.1. Multiple Queue Indexes
MAY be present to allow for the case where same credit information MAY be present to allow for the case where same credit information
applies to multiple queues. Multiple DA Credit Window Status Data applies to multiple queues. Multiple DA Credit Window Status Data
Items are used to provide different queue-specific credit window Items are used to provide different queue-specific credit window
information in one message. The special Queue Index value of 255 is information in one message. The special Queue Index value of 255 is
used to indicate that the Credit Window information applies to all used to indicate that the Credit Window information applies to all
queues. queues.
The format of the DA Credit Window Status Data Item is: The format of the DA Credit Window Status Data Item is:
0 1 2 3 0 1 2 3
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were sent. If the values significantly differ, i.e., greater than were sent. If the values significantly differ, i.e., greater than
can be accounted for based on observed data frames, then the modem can be accounted for based on observed data frames, then the modem
SHOULD send a Destination Update message carrying a DA Credit Grant SHOULD send a Destination Update message carrying a DA Credit Grant
data item to reset the associated Credit Window(s) to the data item data item to reset the associated Credit Window(s) to the data item
indicated value. Multiple values and queue indexes SHOULD be indicated value. Multiple values and queue indexes SHOULD be
combined into a single Destination Update Control message when combined into a single Destination Update Control message when
possible. Alternatively, and also in cases where there are small possible. Alternatively, and also in cases where there are small
differences, the modem MAY adjust the values sent in DA Credit Grant differences, the modem MAY adjust the values sent in DA Credit Grant
data items to account for the reported Credit Window. data items to account for the reported Credit Window.
5.4. DiffServ Aware (DA) Credit Request 6.4. DiffServ Aware (DA) Credit Request
The DiffServ Aware, or DA, Credit Request Data Item data item is used The DiffServ Aware, or DA, Credit Request Data Item data item is used
by a router to request additional credits for a specific destination by a router to request additional credits for a specific destination
and Queue Index associated Credit window. DA Credit Request data and Queue Index associated Credit window. DA Credit Request data
items are carried in Credit Control messages, and only one DA Credit items are carried in Credit Control messages, and only one DA Credit
Request data item SHOULD be present in a message. Request data item SHOULD be present in a message.
Logical queues are identified using a Queue Index as defined above in Logical queues are identified using a Queue Index as defined above in
Section 5.1. Multiple Queue Indexes MAY be present to allow for the Section 6.1. Multiple Queue Indexes MAY be present to allow for the
case where the credit request applies to multiple queues. The case where the credit request applies to multiple queues. The
special Queue Index value of 255 is used to indicate that a credit special Queue Index value of 255 is used to indicate that a credit
request is being made across all queues. request is being made across all queues.
The format of the DA Credit Request Data Item is: The format of the DA Credit Request Data Item is:
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 |
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One or more 8-bit fields used to indicate a queue index defined by One or more 8-bit fields used to indicate a queue index defined by
a Queue Parameters Data Item. The special value of 255 indicates a Queue Parameters Data Item. The special value of 255 indicates
that the request applies to all queue indexes. that the request applies to all queue indexes.
A modem receiving this data item MUST provide a Credit Increment for A modem receiving this data item MUST provide a Credit Increment for
the indicated MAC address and queue indexes via a DA Credit Grant the indicated MAC address and queue indexes via a DA Credit Grant
carried in a new Credit Control Message. Multiple values and queue carried in a new Credit Control Message. Multiple values and queue
indexes SHOULD be combined into a single Credit Control message when indexes SHOULD be combined into a single Credit Control message when
possible. possible.
6. Compatibility 7. Compatibility
Sessions established with both peers identified as supporting the Sessions established with both peers identified as supporting the
DiffServ Aware Credit Windowing Extension Type, see Section 3, SHOULD DiffServ Aware Credit Windowing Extension Type, see Section 3, SHOULD
NOT use the [I-D.ietf-manet-credit-window] defined Credit data items. NOT use the [I-D.ietf-manet-credit-window] defined Credit data items.
If a node supporting the extension defined in this document, receives If a node supporting the extension defined in this document, receives
a [I-D.ietf-manet-credit-window] defined data item, the recipient a [I-D.ietf-manet-credit-window] defined data item, the recipient
MUST treat the received credit information as applying to Queue Index MUST treat the received credit information as applying to Queue Index
zero (0). zero (0).
7. Security Considerations 8. Security Considerations
The extension introduces a DiffServ awareness to the mechanisms The extension introduces a DiffServ awareness to the mechanisms
defined in [I-D.ietf-manet-credit-window]. The extension does not defined in [I-D.ietf-manet-credit-window]. The extension does not
inherently introduce any additional threats above those documented in inherently introduce any additional threats above those documented in
[I-D.ietf-manet-dlep]. The approach taken to Security in that [I-D.ietf-manet-dlep]. The approach taken to Security in that
document and [I-D.ietf-manet-credit-window] apply equally when document and [I-D.ietf-manet-credit-window] apply equally when
running the extension defined in this document. running the extension defined in this document.
8. IANA Considerations 9. IANA Considerations
This document requests the assignment of 5 values by IANA. All This document requests the assignment of 5 values by IANA. All
assignments are to registries defined by [I-D.ietf-manet-dlep]. assignments are to registries defined by [I-D.ietf-manet-dlep].
8.1. Extension Type Value 9.1. Extension Type Value
This document requests 1 new assignment to the DLEP Extensions This document requests 1 new assignment to the DLEP Extensions
Registry named "Extension Tyoe Values" in the range with the Registry named "Extension Tyoe Values" in the range with the
"Specification Required" policy. The requested value is as follows: "Specification Required" policy. The requested value is as follows:
+------+---------------------------------+ +------+---------------------------------+
| Code | Description | | Code | Description |
+------+---------------------------------+ +------+---------------------------------+
| TBA1 | DiffServ Aware Credit Windowing | | TBA1 | DiffServ Aware Credit Windowing |
+------+---------------------------------+ +------+---------------------------------+
Table 1: Requested Extension Type Value Table 1: Requested Extension Type Value
8.2. Message Values 9.2. Message Values
This document requests 2 new assignments to the DLEP Message Registry This document requests 2 new assignments to the DLEP Message Registry
named "Message Values" in the range with the "Specification Required" named "Message Values" in the range with the "Specification Required"
policy. The requested values are as follows: policy. The requested values are as follows:
+-----------+-------------------------+ +-----------+-------------------------+
| Type Code | Description | | Type Code | Description |
+-----------+-------------------------+ +-----------+-------------------------+
| TBA2 | Credit Control | | TBA2 | Credit Control |
| | | | | |
| TBA3 | Credit Control Response | | TBA3 | Credit Control Response |
+-----------+-------------------------+ +-----------+-------------------------+
Table 2: Requested Message Values Table 2: Requested Message Values
8.3. Data Item Values 9.3. Data Item Values
This document requests 4 new assignments to the DLEP Data Item This document requests 4 new assignments to the DLEP Data Item
Registry named "Data Item Values" in the range with the Registry named "Data Item Values" in the range with the
"Specification Required" policy. The requested values are as "Specification Required" policy. The requested values are as
follows: follows:
+-----------+-------------------------+ +-----------+-------------------------+
| Type Code | Description | | Type Code | Description |
+-----------+-------------------------+ +-----------+-------------------------+
| TBA4 | Queue Parameters | | TBA4 | Queue Parameters |
| | | | | |
| TBA5 | DA Credit Grant | | TBA5 | DA Credit Grant |
| | | | | |
| TBA6 | DA Credit Window Status | | TBA6 | DA Credit Window Status |
| | | | | |
| TBA7 | DA Credit Request | | TBA7 | DA Credit Request |
+-----------+-------------------------+ +-----------+-------------------------+
Table 3: Requested Data Item Values Table 3: Requested Data Item Values
9. References 10. References
9.1. Normative References 10.1. Normative References
[I-D.ietf-manet-dlep] [I-D.ietf-manet-dlep]
Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and (. Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
(Unknown), "Dynamic Link Exchange Protocol (DLEP)", draft- Berry, "Dynamic Link Exchange Protocol (DLEP)", draft-
ietf-manet-dlep-24 (work in progress), July 2016. ietf-manet-dlep-28 (work in progress), March 2017.
[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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References 10.2. Informative References
[I-D.ietf-manet-credit-window] [I-D.ietf-manet-credit-window]
Ratliff, S., "Credit Windowing extension for DLEP", draft- Ratliff, S., "Credit Windowing extension for DLEP", draft-
ietf-manet-credit-window-04 (work in progress), April ietf-manet-credit-window-07 (work in progress), November
2016. 2016.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>. <http://www.rfc-editor.org/info/rfc2474>.
[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,
<http://www.rfc-editor.org/info/rfc2475>. <http://www.rfc-editor.org/info/rfc2475>.
Appendix A. Open and Resolved Issues
This section captures issues that are open or have been addressed
since the document has become a WG draft. This section will be
removed before submission for publication.
A.1. Merge with [I-D.ietf-manet-credit-window]
There has been discussion within the WG that this document should be
merged with [I-D.ietf-manet-credit-window]. The timing of this is
TBD. The authors would like to reach closure on some of the
remaining open issues before embarking on this merge, but are open to
discussion with the WG and other authors.
A.2. Credit Windows Shared Across Destinations
The DA Credit Extension supports credit windows per mac destination.
Some media technologies share queues across all, or even some set of,
destinations and supporting an associated set of credit windows isn't
currently supported.
Supporting credit windows per modem, i.e., for a single transmit
channel, is clearly required and needs to be supported.
Credit windows for sets of mac addresses should also be considered
and discussed within the working group, both from a requirements and
support perspective.
This issue was reported by Stan Ratliff <ratliffstan@gmail.com>.
A.3. Supporting Router Limits
Routers may have limits on the number of queues that they can support
and, perhaps, if per destination queues can even be supported at all.
There is no current way for a router to communicate these limits to a
modem or for a router to indicate that the identified queue
information cannot be supported. Support for these cases clearly
needs to be addressed.
This issue was reported by Stan Ratliff <ratliffstan@gmail.com>.
A.4. Absolute vs Increment
Stan Ratliff <ratliffstan@gmail.com> suggested an approach to
simplify credit synchronization and re-synchronization by always
passing the credit window size rather than credit window increments.
This is an interesting idea that needs to be explored and perhaps
experimented with.
A.5. Alternate Format Encoding
The format of the Queue Parameters Data Item is a bit cumbersome and
there has been some discussion of a possible better way of encoding
lists and optional information elements within Data Items. There has
been some discussion of developing a generic mechanisms for use by
DLEP and future DLEP Data Items. Such a definition is beyond the
scope of this document, but if such becomes available there is every
reason for this document to leverage this improved encoding. This
issue will remain open until such a time as there is a such a
definition within the WG or this document is otherwise ready for
publication.
This issue was independently raised by both David Wiggins (co-author)
and Rick Taylor <rick@tropicalstormsoftware.com>.
A.6. Bidirectional Flow Control (closed)
One of the key differences between this draft and
[I-D.ietf-manet-credit-window] is that this document only supports
flow control in one direction, i.e., for traffic sent from a router
to a modem, while the other credit-window draft supports it in both
directions.
This was a conscious choice, made out of the desire to keep the
extension as simple as possible and to provide what is really
expected to be used. Clearly the reason for being able to control
traffic that is sent from the router to the modem/radio is pretty
easily understood. Also, while bidirectional flow control existed in
pre-dlep solutions, it wasn't really used. There is also no reason
why router to modem flow control can't be defined at a later time -
once there is an actual need.
Based on a brief discussion on the WG list, and the absence of any
advocates for bidirectional flow control, there is no current plan to
add bidirectional flow control to this document.
Authors' Addresses Authors' Addresses
Bow-Nan Cheng Bow-Nan Cheng
Lincoln Laboratory Lincoln Laboratory
Massachusetts Institute of Technology Massachusetts Institute of Technology
244 Wood Street 244 Wood Street
Lexington, MA 02420-9108 Lexington, MA 02420-9108
Email: bcheng@ll.mit.edu Email: bcheng@ll.mit.edu
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