Internet DRAFT - draft-cheng-manet-dlep-da-credit-extension
draft-cheng-manet-dlep-da-credit-extension
Network Working Group B. Cheng
Internet-Draft D. Wiggins
Intended status: Standards Track Lincoln Laboratory
Expires: April 30, 2017 L. Berger
LabN Consulting, L.L.C.
October 27, 2016
DLEP DiffServ Aware Credit Windowing Extension
draft-cheng-manet-dlep-da-credit-extension-00
Abstract
This document defines an extension to the DLEP protocol that enables
a DiffServ aware credit-windowing scheme for destination-specific
flow control.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 30, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extension Overview . . . . . . . . . . . . . . . . . . . . . 3
3. Extension Usage and Identification . . . . . . . . . . . . . 4
4. Extension Messages . . . . . . . . . . . . . . . . . . . . . 4
4.1. Credit Control Message . . . . . . . . . . . . . . . . . 4
4.2. Credit Control Response Message . . . . . . . . . . . . . 5
5. Extension Data Items . . . . . . . . . . . . . . . . . . . . 5
5.1. Queue Parameters . . . . . . . . . . . . . . . . . . . . 5
5.2. DiffServ Aware (DA) Credit Grant . . . . . . . . . . . . 8
5.3. DiffServ Aware (DA) Credit Window Status . . . . . . . . 10
5.4. DiffServ Aware (DA) Credit Request . . . . . . . . . . . 11
6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.1. Extension Type Value . . . . . . . . . . . . . . . . . . 13
8.2. Message Values . . . . . . . . . . . . . . . . . . . . . 13
8.3. Data Item Values . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
The Dynamic Link Event Protocol (DLEP) is defined in
[I-D.ietf-manet-dlep]. It provides the exchange of link related
control information between DLEP peers. DLEP peers are comprised of
a modem and a router. DLEP defines a base set of mechanisms as well
as support for possible extensions. This document defines one such
extension.
The base DLEP specification does not include any flow control
capability. There are various flow control theoretically possible
with DLEP. For example, a credit-windowing scheme for destination-
specific flow control which provides aggregate flow control for both
modem and routers has been proposed in
[I-D.ietf-manet-credit-window].
This document defines a DLEP extension which provides flow control
for DiffServ [RFC2475] traffic sent from a router to a modem. Flow
control is provided for multiple DSCPs (differentiated services
codepoint), which are grouped into logical sets of logical queues.
The extension defined in this document is referred to as "DiffServ
Aware Credit Windowing" or, more simply, the "DA Credit" extension.
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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
are defined in Section 4, and four new DLEP Data Items in Section 5.
1.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14, RFC 2119 [RFC2119].
2. Extension Overview
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
be used to support DiffServ and non-DiffServ based flow control.
Both types of DLEP endpoints, i.e., a router and a modem, negotiate
the use of extension during session initialization, see Section 5.2
[I-D.ietf-manet-dlep].
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
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
otherwise identified by the modem. The modem also provides a size,
in bytes, of the logical queue for informative and, potential, future
uses. Currently, only DSCP to logical queue index value mapping is
used in flow control operation.
The DA Credit extension supports credit based flow control on a per
MAC address destination, per queue index basis. Modems provide the
initial size of the associated "Credit Window", i.e., the amount in
octets (bytes) that may be sent by the router to the modem, when a
MAC destination becomes reachable and, optionally, when its rate
information changes. "Credit Increments", i.e., increases in a
Credit Window size, are provided using new "Credit Control" messages.
A router provides its view of the Credit Window, which is known as
"status", in Destination Up Response and the new "Credit Control
Response" messages. Routers can also request credits using the new
"Credit Control" message.
Credit information, both grants and status, is provided in new credit
grant related data items. Each data item contains a single credit
value that applies to one or more queue indexes. Different (grant
and status) values for different queue indexes can be provided in a
single message by including multiple grant data items. The values
indicate a number of octets (bytes), including MAC headers on the
router to modem link, that may be sent.
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Note that credit information related to different destination MAC
addresses is always passed in different DLEP messages.
3. Extension Usage and Identification
The use of the extension defined in this document SHOULD be
configurable. To indicate that the DiffServ Aware Credit Windowing
Extension is to be used, an implementation MUST include the DiffServ
Aware Credit Windowing Type Value in the Extensions Supported Data
Item. The Extensions Supported Data Item is sent and processed
according to [I-D.ietf-manet-dlep].
The DiffServ Aware Credit Windowing Extension Type Value is TBA1, see
Section 8.
4. Extension Messages
Two new messages are defined by this extension: the Credit Control
and the Credit Control Response message. Sending and receiving both
message types MUST be supported by any implementation that advertises
use of this extension per Section 3.
4.1. Credit Control Message
Credit Control Messages are sent by modems to provide Credit
Increments. For messages sent by modems, only one message per MAC
address can be outstanding at one time. That is, a modem MUST NOT
send a second (or any subsequent) message containing the same MAC
Address until a Credit Control Response message is received from its
peer router with that MAC address.
Credit Control Messages MAY be sent by routers, e.g., to request
credits or provide window status. No specific response message is
required from a message transaction perspective.
[TBD: Should anything be said about sending, or limiting, multiple
credit requests?]
The Message Type value in the DLEP Message Header is set to TBA2.
The message MUST contain a DLEP MAC Address Data Item.
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
receiving this message MUST respond with a Credit Control Response
Message.
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A message sent by a router, MUST contain the DiffServ Aware Credit
Request data item defined below in Section 5.4. A modem receiving
this message MUST provide a Credit Increment for the indicated MAC
address and queue indexes via a new Credit Control Message.
Specific processing associated with each Credit data item is provided
below.
4.2. Credit Control Response Message
Credit Control Response Messages are sent by routers to report the
current Credit Window for a destination.
The Message Type value in the DLEP Message Header is set to TBA3.
The message MUST contain a DLEP MAC Address Data Item.
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.
Specific processing associated with the DA Credit Window Status data
item is provided below.
5. Extension Data Items
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
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
router to request additional credits. The DA Credit Window Status is
used to advertise the sender's view of number of available credits
for synchronization purposes.
The defined data items and operations are similar to those found in
[I-D.ietf-manet-credit-window]. One notable difference from this
extension is that in this document credits are never provided by the
router to the modem.
5.1. Queue Parameters
The Queue Parameters Data Item is used by a modem to indicate DSCP
values that may be independently controlled. This data item MUST be
included in a Session Initialization Response Message that also
contains the DiffServ Aware Credit Windowing Extension Type Value in
the Extensions Supported Data Item. Updates to these parameters MAY
be sent by a modem by including the data item in Session Update
Messages.
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The Queue Parameters Data Item identifies DSCPs based on groups of
logical queues. The number of logical queues is variable as is the
number of DSCPs associated with each queue. A queue size (in bytes)
is provided for informational purposes. An implementation that does
not support DSCPs would indicate 1 queue with 0 DSCPs, and the number
of bytes that may be in its associated link transmit queue.
The format of the Queue Parameters Data Item is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num Queues | Scale | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Num DSCPs Q0(0)| Queue Size Q0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num DSCPs Q1 | Queue Size Q1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num DSCPs Q2 | Queue Size Q2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num DSCPs Qn | Queue Size Qn |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DS Field Q1 | DS Field Q1 | DS Field Q1 | DS Field Q2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... | DS Field Qn |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: TBA4
Length: Variable
Per [I-D.ietf-manet-dlep] Length is the number of octets in the
data item, excluding the Type and Length fields.
Num Queues:
An 8-bit unsigned integer indicating the number of queues
represented in the data item. This field MUST contain a value of
at least one (1). Note that this number is one larger than the
largest queue index value included in the data item.
Scale:
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An 4-bit unsigned integer indicating the scale used in the Queue
Size fields. The valid values are:
Value Scale
------------
0 B - Bytes (Octets)
1 KB - Kilobytes (B/1024)
2 MB - Megabytes (KB/1024)
3 GB - Gigabytes (MB/1024)
Reserved:
MUST be set to zero by the sender (a modem) and ignored by the
receiver (a router).
Num DSCPs Qn:
An 8-bit unsigned integer indicating the number of DSCPs
associated with the indexed queue. Other than the special case
covered in the next paragraph, this field MUST contain a value of
at least one (1). Queue indexes start at zero (0) and the maximum
queue index "Qn" is one less than the value carried in the Num
Queues field. Queue indexes are implicit in the position in the
data item.
Queue index zero "Q0" is a special case. It is used for any
traffic that does not carry a DSCP value represented in the data
item. Therefore the value of the Queue index zero field, "Num
DSCPs Q0", field MUST be zero (0).
Queue Size Qn:
A 24-bit unsigned integer representing the size, in the octet
scale indicated by the Scale field, of the queue supporting
traffic with the DSCPs associated with the queue index.
DS Field Qn:
The data item contains a sequence of 8 bit DS Fields. The
position in the sequence identifies the associated queue index.
The number of DS Fields present should equal the sum of all Num
DSCPs field values.
The DS Field structure is the same as [RFC2474].
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0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| DSCP | CU |
+---+---+---+---+---+---+---+---+
DSCP: differentiated services codepoint
CU: currently unused, MUST be zero
5.2. DiffServ Aware (DA) Credit Grant
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
items MAY be carried in the DLEP Destination Up, Destination Announce
Response, Destination Update, and Credit Control messages. Multiple
DA Credit Grant data items in a single message are used to indicated
different credit values for different logical queues.
In Destination type messages, this data item provides the total
number of octets available in the Credit Window to the destination
indicated in the message for the specified logical queues. In the
Credit Control message, this data item provides an additional number
of octets to be added to the Credit Window to the destination
indicated in the message for the specified logical queues.
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
case where same credit information applies to multiple queues. As
mentioned above, multiple DA Credit Grant Data Items MAY be present
to provide different queue-specific credit information in one
message. The special Queue Index value of 255 is used to indicate
that the credit information applies to all queues.
The format of the DA Credit Grant Data Item is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Queue Index | ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... | Queue Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Data Item Type: TBA5
Length: Variable
Per [I-D.ietf-manet-dlep], Length is the number of octets in the
data item, excluding the Type and Length fields. It will equal 8
plus the number of Queue Index fields carried in the data item and
MUST be at least 9.
Credit Value:
A 64-bit unsigned integer representing the credits, in octets, to
be applied to the Credit Window. This value includes MAC headers
as seen on the link between the modem and router.
Queue Index:
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
that the information in the data item applies to all queue
indexes.
Receive processing of this data item is based on the message in which
it is carried. When this data item is received in a Destination type
message, the Credit Window of the indicated destination MAC address
and indicated queue indexes MUST be set to the value contained in the
Credit Value field.
When this data item is received in a Credit Control message, the
Credit Window of the indicated destination MAC address and indicated
queue indexes MUST be increased by the value contained in the Credit
Value field. If the increase results in a window overflow, i.e., the
Credit Window resulting after the increase is smaller than the
original Credit Window, the Credit Window must be set to its maximum
(0xFFFFFFFFFFFFFFFF).
Independent of the received message, the receiving router MUST send a
DA Credit Window Status data item or items reflecting the resulting
Credit Window value of each modified queue index. When the Credit
Grant data item is received in a Destination Up message, the DA
Credit Window Status data item(s) MUST be sent in the corresponding
Destination Up Response message. In all other cases, the a Credit
Control message MUST be sent.
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5.3. DiffServ Aware (DA) Credit Window Status
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
or more DA Credit Window Status data items MAY be carried in a
Destination Up Response message or a Credit Control Response message.
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 Credit Control Response message is sent in response to a Credit
Control message. Multiple DA Credit Window Status data items in a
single message are used to indicated different credit window values
for different logical queues.
Similar to the DA Credit Grant, 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 case where same credit information
applies to multiple queues. Multiple DA Credit Window Status Data
Items are used to provide different queue-specific credit window
information in one message. The special Queue Index value of 255 is
used to indicate that the Credit Window information applies to all
queues.
The format of the DA Credit Window Status Data Item is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Credit Window :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Credit Window |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Queue Index | ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... | Queue Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: TBA6
Length: Variable
Per [I-D.ietf-manet-dlep] Length is the number of octets in the
data item, excluding the Type and Length fields. It will equal 8
plus the number of Queue Index fields carried in the data item and
MUST be at least 9.
Credit Window:
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A 64-bit unsigned integer, indicating the current number of
credits, in octets, available for the router to send to the modem.
This is referred to as the Modem Receive Window in
[I-D.ietf-manet-credit-window].
Queue Index:
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
that the information in the data item applies to all queue
indexes.
The receiving modem SHOULD check the received Credit Window value
against the outstanding credits available at the time the last Credit
Increment associated with the indicated MAC address and Queue Indexes
were sent. If the values significantly differ, i.e., greater than
can be accounted for based on observed data frames, then the modem
SHOULD send a Destination Update message carrying a DA Credit Grant
data item to reset the associated Credit Window(s) to the data item
indicated value. Multiple values and queue indexes SHOULD be
combined into a single Destination Update Control message when
possible. Alternatively, and also in cases where there are small
differences, the modem MAY adjust the values sent in DA Credit Grant
data items to account for the reported Credit Window.
5.4. DiffServ Aware (DA) Credit Request
The DiffServ Aware, or DA, Credit Request Data Item data item is used
by a router to request additional credits for a specific destination
and Queue Index associated Credit window. DA Credit Request data
items are carried in Credit Control messages, and only one DA Credit
Request data item SHOULD be present in a message.
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
case where the credit request applies to multiple queues. The
special Queue Index value of 255 is used to indicate that a credit
request is being made across all queues.
The format of the DA Credit Request Data Item is:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Queue Index | ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... | Queue Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[LB note: a list of Queue Indexes is now supported as is special
value 255.]
Data Item Type: TBA7
Length: Variable
Per [I-D.ietf-manet-dlep] Length is the number of octets in the
data item, excluding the Type and Length fields. It will equal
the number of Queue Index fields carried in the data item and MUST
be at least 1.
Queue Index:
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
that the request applies to all queue indexes.
A modem receiving this data item MUST provide a Credit Increment for
the indicated MAC address and queue indexes via a DA Credit Grant
carried in a new Credit Control Message. Multiple values and queue
indexes SHOULD be combined into a single Credit Control message when
possible.
6. Compatibility
Sessions established with both peers identified as supporting the
DiffServ Aware Credit Windowing Extension Type, see Section 3, SHOULD
NOT use the [I-D.ietf-manet-credit-window] defined Credit data items.
If a node supporting the extension defined in this document, receives
a [I-D.ietf-manet-credit-window] defined data item, the recipient
MUST treat the received credit information as applying to Queue Index
zero (0).
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7. Security Considerations
The extension introduces a DiffServ awareness to the mechanisms
defined in [I-D.ietf-manet-credit-window]. The extension does not
inherently introduce any additional threats above those documented in
[I-D.ietf-manet-dlep]. The approach taken to Security in that
document and [I-D.ietf-manet-credit-window] apply equally when
running the extension defined in this document.
8. IANA Considerations
This document requests the assignment of 5 values by IANA. All
assignments are to registries defined by [I-D.ietf-manet-dlep].
8.1. Extension Type Value
This document requests 1 new assignment to the DLEP Extensions
Registry named "Extension Tyoe Values" in the range with the
"Specification Required" policy. The requested value is as follows:
+------+---------------------------------+
| Code | Description |
+------+---------------------------------+
| TBA1 | DiffServ Aware Credit Windowing |
+------+---------------------------------+
Table 1: Requested Extension Type Value
8.2. Message Values
This document requests 2 new assignments to the DLEP Message Registry
named "Message Values" in the range with the "Specification Required"
policy. The requested values are as follows:
+-----------+-------------------------+
| Type Code | Description |
+-----------+-------------------------+
| TBA2 | Credit Control |
| | |
| TBA3 | Credit Control Response |
+-----------+-------------------------+
Table 2: Requested Message Values
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8.3. Data Item Values
This document requests 4 new assignments to the DLEP Data Item
Registry named "Data Item Values" in the range with the
"Specification Required" policy. The requested values are as
follows:
+-----------+-------------------------+
| Type Code | Description |
+-----------+-------------------------+
| TBA4 | Queue Parameters |
| | |
| TBA5 | DA Credit Grant |
| | |
| TBA6 | DA Credit Window Status |
| | |
| TBA7 | DA Credit Request |
+-----------+-------------------------+
Table 3: Requested Data Item Values
9. References
9.1. Normative References
[I-D.ietf-manet-dlep]
Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and (.
(Unknown), "Dynamic Link Exchange Protocol (DLEP)", draft-
ietf-manet-dlep-24 (work in progress), July 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[I-D.ietf-manet-credit-window]
Ratliff, S., "Credit Windowing extension for DLEP", draft-
ietf-manet-credit-window-04 (work in progress), April
2016.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>.
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[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<http://www.rfc-editor.org/info/rfc2475>.
Authors' Addresses
Bow-Nan Cheng
Lincoln Laboratory
Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02420-9108
Email: bcheng@ll.mit.edu
David Wiggins
Lincoln Laboratory
Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02420-9108
Email: David.Wiggins@ll.mit.edu
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
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