draft-ietf-diffserv-new-terms-08.txt   rfc3260.txt 
Diffserv Working Group Dan Grossman Network Working Group D. Grossman
Internet Draft Motorola, Inc. Request for Comments: 3260 Motorola, Inc.
Expires: July, 2002 Updates: 2474, 2475, 2597 April 2002
Category: Informational
draft-ietf-diffserv-new-terms-08.txt
January, 2002
New Terminology and Clarifications for Diffserv New Terminology and Clarifications for Diffserv
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This memo provides information for the Internet community. It does
all provisions of section 10 of RFC2026. Internet-Drafts are working not specify an Internet standard of any kind. Distribution of this
documents of the Internet Engineering Task Force (IETF), its areas, memo is unlimited.
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at Copyright Notice
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at Copyright (C) The Internet Society (2002). All Rights Reserved.
http://www.ietf.org/shadow.html
Abstract Abstract
This memo captures Diffserv working group agreements concerning new This memo captures Diffserv working group agreements concerning new
and improved terminology, and also provides minor technical and improved terminology, and provides minor technical
clarifications. It is intended to update RFC 2474, RFC 2475 and RFC clarifications. It is intended to update RFC 2474, RFC 2475 and RFC
2597. When RFCs 2474 and 2597 advance on the standards track, and 2597. When RFCs 2474 and 2597 advance on the standards track, and
RFC 2475 is updated, it is intended that the revisions in this memo RFC 2475 is updated, it is intended that the revisions in this memo
will be incorporated, and that this memo will be obsoleted by the new will be incorporated, and that this memo will be obsoleted by the new
RFCs. RFCs.
Copyright Notice
Copyright (C) The Internet Society (1999, 2002). All Rights
Reserved.
1. Introduction 1. Introduction
As the Diffserv work has evolved, there have been several cases where As the Diffserv work has evolved, there have been several cases where
terminology has needed to be created or the definitions in Diffserv terminology has needed to be created or the definitions in Diffserv
standards track RFCs have needed to be refined. Some minor technical standards track RFCs have needed to be refined. Some minor technical
clarifications were also found to be needed. This memo was created clarifications were also found to be needed. This memo was created
to capture group agreements, rather than attempting to revise the to capture group agreements, rather than attempting to revise the
base RFCs and recycle them at proposed standard. It updates in part base RFCs and recycle them at proposed standard. It updates in part
RFC 2474, RFC 2475 and RFC 2597. RFC 2598 has been updated by RFC RFC 2474, RFC 2475 and RFC 2597. RFC 2598 has been obsoleted by RFC
XXXX (draft-ietf-diffserv-rfc2598bis), and clarifications agreed by 3246, and clarifications agreed by the group were incorporated in
the group were incorporated in that update. that revision.
2. Terminology Related to Service Level Agreements (SLAs) 2. Terminology Related to Service Level Agreements (SLAs)
The Diffserv Architecture [2] uses the term "Service Level Agreement" The Diffserv Architecture [2] uses the term "Service Level Agreement"
(SLA) to describe the "service contract... that specifies the (SLA) to describe the "service contract... that specifies the
forwarding service a customer should receive". The SLA may include forwarding service a customer should receive". The SLA may include
traffic conditioning rules which (at least in part) constitute a traffic conditioning rules which (at least in part) constitute a
Traffic Conditioning Agreement (TCA). A TCA is "an agreement Traffic Conditioning Agreement (TCA). A TCA is "an agreement
specifying classifier rules and any corresponding traffic profiles specifying classifier rules and any corresponding traffic profiles
and metering, marking, discarding and/or shaping rules which are to and metering, marking, discarding and/or shaping rules which are to
apply...." apply...."
As work progressed in Diffserv (as well as in the Policy WG [6]), it As work progressed in Diffserv (as well as in the Policy WG [6]), it
came to be believed that the notion of an "agreement" implied came to be believed that the notion of an "agreement" implied
considerations that were of a pricing, contractual or other business considerations that were of a pricing, contractual or other business
nature, as well as those that were strictly technical. There also nature, as well as those that were strictly technical. There also
could be other technical considerations in such an agreement (e.g., could be other technical considerations in such an agreement (e.g.,
service availability) which are not addressed by Diffserv. It was service availability) which are not addressed by Diffserv. It was
therefore agreed that the notions of SLAs and TCAs would be taken to therefore agreed that the notions of SLAs and TCAs would be taken to
represent the broader context, and that new terminology would be used represent the broader context, and that new terminology would be used
to describe those elements of service and traffic conditioning that to describe those elements of service and traffic conditioning that
are addressed by Diffserv. are addressed by Diffserv.
- A Service Level Specification (SLS) is a set of parameters and - A Service Level Specification (SLS) is a set of parameters and
their values which together define the service offered to a their values which together define the service offered to a
traffic stream by a DS domain. traffic stream by a DS domain.
- A Traffic Conditioning Specification (TCS) is a set of - A Traffic Conditioning Specification (TCS) is a set of
parameters and their values which together specify a set of parameters and their values which together specify a set of
classfier rules and a traffic profile. A TCS is an integral classifier rules and a traffic profile. A TCS is an integral
element of an SLS. element of an SLS.
Note that the definition of "Traffic stream" is unchanged from RFC Note that the definition of "Traffic stream" is unchanged from RFC
2475. A traffic stream can be an individual microflow or a group of 2475. A traffic stream can be an individual microflow or a group of
microflows (i.e., in a source or destination DS domain) or it can microflows (i.e., in a source or destination DS domain) or it can be
be a BA. Thus, an SLS may apply in the source or destination DS a BA. Thus, an SLS may apply in the source or destination DS domain
domain to a single microflow or group of microflows, as well as to a to a single microflow or group of microflows, as well as to a BA in
BA in any DS domain. any DS domain.
Also note that the definition of a "Service Provisioning Policy" is Also note that the definition of a "Service Provisioning Policy" is
unchanged from RFC 2475. RFC 2475 defines a "Service Provisioning unchanged from RFC 2475. RFC 2475 defines a "Service Provisioning
Policy as "a policy which defines how traffic conditioners are Policy as "a policy which defines how traffic conditioners are
configured on DS boundary nodes and how traffic streams are mapped to configured on DS boundary nodes and how traffic streams are mapped to
DS behavior aggregates to achieve a range of services." According to DS behavior aggregates to achieve a range of services." According to
one definition given in RFC 3198 [6], a policy is "...a set of rules one definition given in RFC 3198 [6], a policy is "...a set of rules
to administer, manage, and control access to network resources". to administer, manage, and control access to network resources".
Therefore, the relationship between an SLS and a service provisioning Therefore, the relationship between an SLS and a service provisioning
policy is that the latter is, in part, the set of rules that express policy is that the latter is, in part, the set of rules that express
skipping to change at page 3, line 26 skipping to change at page 3, line 12
Further note that this definition is more restrictive than that in Further note that this definition is more restrictive than that in
RFC 3198. RFC 3198.
3. Usage of PHB Group 3. Usage of PHB Group
RFC 2475 defines a Per-hop behavior (PHB) group to be: RFC 2475 defines a Per-hop behavior (PHB) group to be:
"a set of one or more PHBs that can only be meaningfully specified "a set of one or more PHBs that can only be meaningfully specified
and implemented simultaneously, due to a common constraint and implemented simultaneously, due to a common constraint
applying to all PHBs in the set such as a queue servicing or queue applying to all PHBs in the set such as a queue servicing or queue
management policy. A PHB group provides a service building block management policy. A PHB group provides a service building block
that allows a set of related forwarding behaviors to be specified that allows a set of related forwarding behaviors to be specified
together (e.g., four dropping priorities). A single PHB is a together (e.g., four dropping priorities). A single PHB is a
special case of a PHB group." special case of a PHB group."
One standards track PHB Group is defined in RFC 2597 [3], "Assured One standards track PHB Group is defined in RFC 2597 [3], "Assured
Forwarding PHB Group". Assured Forwarding (AF) is a type of Forwarding PHB Group". Assured Forwarding (AF) is a type of
forwarding behavior with some assigned level of queuing resources and forwarding behavior with some assigned level of queuing resources and
three drop precedences. An AF PHB Group consists of three PHBs, and three drop precedences. An AF PHB Group consists of three PHBs, and
uses three Diffserv Codepoints (DSCPs). uses three Diffserv Codepoints (DSCPs).
RFC 2597 defines twelve DSCPs, corresponding to four independent AF RFC 2597 defines twelve DSCPs, corresponding to four independent AF
classes. The AF classes are referred to as AF1x, AF2x, AF3x, and classes. The AF classes are referred to as AF1x, AF2x, AF3x, and
AF4x (where 'x' is 1, 2, or 3 to represent drop precedence). Each AF AF4x (where 'x' is 1, 2, or 3 to represent drop precedence). Each AF
class is one instance of an AF PHB Group. class is one instance of an AF PHB Group.
There has been confusion expressed that RFC 2597 refers to all four There has been confusion expressed that RFC 2597 refers to all four
AF classes with their three drop precedences as being part of a AF classes with their three drop precedences as being part of a
single PHB Group. However, since each AF class operates entirely single PHB Group. However, since each AF class operates entirely
independently of the others, (and thus there is no common constraint independently of the others, (and thus there is no common constraint
among AF classes as there is among drop precedences within an AF among AF classes as there is among drop precedences within an AF
class) this usage is inconsistent with RFC 2475. The inconsistency class) this usage is inconsistent with RFC 2475. The inconsistency
exists for historical reasons and will be removed in future exists for historical reasons and will be removed in future revisions
revisions of the AF specification. It should now be understood that of the AF specification. It should now be understood that AF is a
AF is a _type_ of PHB group, and each AF class is an _instance_ of _type_ of PHB group, and each AF class is an _instance_ of the AF
the AF type. type.
Authors of new PHB specifications should be careful to adhere to the Authors of new PHB specifications should be careful to adhere to the
RFC 2475 definition of PHB Group. RFC 2475 does not prohibit new PHB RFC 2475 definition of PHB Group. RFC 2475 does not prohibit new PHB
specifications from assigning enough DSCPs to represent multiple specifications from assigning enough DSCPs to represent multiple
independent instances of their PHB Group. However, such a set of independent instances of their PHB Group. However, such a set of
DSCPs must not be referred to as a single PHB Group. DSCPs must not be referred to as a single PHB Group.
4. Definition of the DS Field 4. Definition of the DS Field
Diffserv uses six bits of the IPV4 or IPV6 header to convey the Diffserv uses six bits of the IPV4 or IPV6 header to convey the
Diffserv Codepoint (DSCP), which selects a PHB. RFC 2474 attempts to Diffserv Codepoint (DSCP), which selects a PHB. RFC 2474 attempts to
rename the TOS octet of the IPV4 header, and Traffic Class octet of rename the TOS octet of the IPV4 header, and Traffic Class octet of
the IPV6 header, respectively, to the DS field. The DS Field has a the IPV6 header, respectively, to the DS field. The DS Field has a
six bit Diffserv Codepoint and two "currently unused" bits. six bit Diffserv Codepoint and two "currently unused" bits.
It has been pointed out that this leads to inconsistencies and It has been pointed out that this leads to inconsistencies and
ambiguities. In particular, the "Currently Unused" (CU) bits of the ambiguities. In particular, the "Currently Unused" (CU) bits of the
DS Field have not been assigned to Diffserv, and subsequent to the DS Field have not been assigned to Diffserv, and subsequent to the
publication of RFC 2474, they were assigned for explicit congestion publication of RFC 2474, they were assigned for explicit congestion
notification, as defined in RFC 3168 [4]. In the current text, a notification, as defined in RFC 3168 [4]. In the current text, a
DSCP is, depending on context, either an encoding which selects a PHB DSCP is, depending on context, either an encoding which selects a PHB
or a sub-field in the DS field which contains that encoding. or a sub-field in the DS field which contains that encoding.
The present text is also inconsistent with BCP0037, IANA Allocation The present text is also inconsistent with BCP 37, IANA Allocation
Guidelines for Values in the Internet Protocol and Related Headers Guidelines for Values in the Internet Protocol and Related Headers
[5]. The IPV4 Type-of-Service (TOS) field and the IPV6 traffic class [5]. The IPV4 Type-of-Service (TOS) field and the IPV6 traffic class
field are superseded by the 6 bit DS field and a 2 bit CU field. The field are superseded by the 6 bit DS field and a 2 bit CU field. The
IANA allocates values in the DS field following the IANA IANA allocates values in the DS field following the IANA
considerations section in RFC 2474, as clarified in section 8 of this considerations section in RFC 2474, as clarified in section 8 of this
memo. memo.
The consensus of the DiffServ working group is that BCP0037 correctly The consensus of the DiffServ working group is that BCP 37 correctly
restates the structure of the former TOS and traffic class fields. restates the structure of the former TOS and traffic class fields.
Therefore, for use in future drafts, including the next update to RFC Therefore, for use in future documents, including the next update to
2474, the following definitions should apply: RFC 2474, the following definitions should apply:
- the Differentiated Services Field (DSField) is the six most
significant bits of the (former) IPV4 TOS octet or the (former)
IPV6 Traffic Class octet.
- the Differentiated Services Codepoint (DSCP) is a value which is - the Differentiated Services Field (DSField) is the six most
encoded in the DS field, and which each DS Node MUST use to select significant bits of the (former) IPV4 TOS octet or the (former)
the PHB which is to be experienced by each packet it forwards. IPV6 Traffic Class octet.
- the Differentiated Services Codepoint (DSCP) is a value which
is encoded in the DS field, and which each DS Node MUST use to
select the PHB which is to be experienced by each packet it
forwards.
The two least significant bits of the IPV4 TOS octet and the IPV6 The two least significant bits of the IPV4 TOS octet and the IPV6
Traffic Class octet are not used by Diffserv. Traffic Class octet are not used by Diffserv.
When RFC 2474 is updated, consideration should be given to changing When RFC 2474 is updated, consideration should be given to changing
the designation "currently unused (CU)" to "explicit congestion the designation "currently unused (CU)" to "explicit congestion
notification (ECN)" and referencing RFC 3168 (or its successor). notification (ECN)" and referencing RFC 3168 (or its successor).
The update should also reference BCP0037. The update should also reference BCP 37.
5. Ordered Aggregates and PHB Scheduling Classes 5. Ordered Aggregates and PHB Scheduling Classes
Work on Diffserv support by MPLS Label Switched Routers (LSRs) led to Work on Diffserv support by MPLS Label Switched Routers (LSRs) led to
the realization that a concept was needed in Diffserv to capture the the realization that a concept was needed in Diffserv to capture the
notion of a set of BAs with a common ordering constraint. This notion of a set of BAs with a common ordering constraint. This
presently applies to AF behavior aggregates, since a DS node may not presently applies to AF behavior aggregates, since a DS node may not
reorder packets of the same microflow if they belong to the same AF reorder packets of the same microflow if they belong to the same AF
class. This would, for example, prevent an MPLS LSR which was also a class. This would, for example, prevent an MPLS LSR, which was also
DS node from discriminating between packets of an AF Behavior a DS node, from discriminating between packets of an AF Behavior
Agrregeate (BA) based on drop precedence and forwarding packets of Aggregate (BA) based on drop precedence and forwarding packets of the
the same AF class but different drop precedence over different LSPs. same AF class but different drop precedence over different LSPs. The
The following new terms are defined. following new terms are defined.
PHB Scheduling Class: A PHB group for which a common constraint is PHB Scheduling Class: A PHB group for which a common constraint is
that ordering of at least those packets belonging to the same that, ordering of at least those packets belonging to the same
microflow must be preserved. microflow must be preserved.
Ordered Aggregate (OA): A set of Behavior Aggregates that share Ordered Aggregate (OA): A set of Behavior Aggregates that share an
an ordering constraint. The set of PHBs that are applied to this ordering constraint. The set of PHBs that are applied to this set
set of Behavior Aggregates constitutes a PHB scheduling class. of Behavior Aggregates constitutes a PHB scheduling class.
6. Unknown/Improperly Mapped DSCPs 6. Unknown/Improperly Mapped DSCPs
Several implementors have pointed out ambiguities or conflicts in the Several implementors have pointed out ambiguities or conflicts in the
Diffserv RFCs concerning behavior when a DS-node recieves a packet Diffserv RFCs concerning behavior when a DS-node receives a packet
with a DSCP which it does not understand. with a DSCP which it does not understand.
RFC 2475 states: RFC 2475 states:
"Ingress nodes must condition all other inbound traffic to ensure "Ingress nodes must condition all other inbound traffic to ensure
that the DS codepoints are acceptable; packets found to have that the DS codepoints are acceptable; packets found to have
unacceptable codepoints must either be discarded or must have unacceptable codepoints must either be discarded or must have
their DS codepoints modified to acceptable values before being their DS codepoints modified to acceptable values before being
forwarded. For example, an ingress node receiving traffic from a forwarded. For example, an ingress node receiving traffic from a
domain with which no enhanced service agreement exists may reset domain with which no enhanced service agreement exists may reset
the DS codepoint to the Default PHB codepoint [DSFIELD]." the DS codepoint to the Default PHB codepoint [DSFIELD]."
On the other hand, RFC 2474 states: On the other hand, RFC 2474 states:
"Packets received with an unrecognized codepoint SHOULD be "Packets received with an unrecognized codepoint SHOULD be
forwarded as if they were marked for the Default behavior (see forwarded as if they were marked for the Default behavior (see
Sec. 4), and their codepoints should not be changed." Sec. 4), and their codepoints should not be changed."
The intent in RFC 2474 principally concerned DS-interior nodes. RFC 2474 is principally concerned with DS-interior nodes. However,
this behavior could also be performed in DS-ingress nodes AFTER the
However, this behavior could also be performed in DS-ingress nodes traffic conditioning required by RFC 2475 (in which case, an
AFTER the traffic conditioning required by RFC 2475 (in which case, unrecognized DSCP would occur only in the case of misconfiguration).
an unrecognized DSCP would occur only in the case of If a packet arrives with a DSCP that hadn't been explicitly mapped to
misconfiguration). If a packet arrives with a DSCP that hadn't been a particular PHB, it should be treated the same way as a packet
explicitly mapped to a particular PHB, it should be treated the same marked for Default. The alternatives were to assign it another PHB,
way as a packet marked for Default. The alternatives were to assign which could result in misallocation of provisioned resources, or to
it another PHB, which could result in misallocation of provisioned drop it. Those are the only alternatives within the framework of RFC
resources, or to drop it. Those are the only alternatives within the 2474. Neither alternative was considered desirable. There has been
framework of 2474. Neither alternative was considered desirable. discussion of a PHB which receives worse service than the default;
There has been discussion of a PHB which receives worse service than this might be a better alternative. Hence the imperative was
the default; this might be a better alternative. Hence the "SHOULD" rather than "SHALL".
imperative was "SHOULD" rather than "SHALL".
The intent in RFC 2475 clearly concerns DS-ingress nodes, or to be The intent of RFC 2475 clearly concerns DS-ingress nodes, or more
more precise, the ingress traffic conditioning function. This is precisely, the ingress traffic conditioning function. This is
another context where the "SHOULD" in RFC 2474 gives the flexibility another context where the "SHOULD" in RFC 2474 provides the
to do what the group intended. Such tortured readings are not flexibility to do what the group intended. Such tortured readings
desirable. are not desirable.
Therefore, the statement in RFC 2474 will be clarified to indicate Therefore, the statement in RFC 2474 will be clarified to indicate
that it is not intended to apply at the ingress traffic conditioning that it is not intended to apply at the ingress traffic conditioning
function at a DS-ingress node, and cross reference RFC 2475 for that function at a DS-ingress node, and cross reference RFC 2475 for that
case. case.
There was a similar issue, which manifested itself with the first There was a similar issue, which manifested itself with the first
incarnation of Expedited Forwarding (EF). RFC 2598 states: incarnation of Expedited Forwarding (EF). RFC 2598 states:
To protect itself against denial of service attacks, the edge of a To protect itself against denial of service attacks, the edge of a
DS domain MUST strictly police all EF marked packets to a rate DS domain MUST strictly police all EF marked packets to a rate
negotiated with the adjacent upstream domain. (This rate must be negotiated with the adjacent upstream domain. (This rate must be
<= the EF PHB configured rate.) Packets in excess of the <= the EF PHB configured rate.) Packets in excess of the
negotiated rate MUST be dropped. If two adjacent domains have not negotiated rate MUST be dropped. If two adjacent domains have not
negotiated an EF rate, the downstream domain MUST use 0 as the negotiated an EF rate, the downstream domain MUST use 0 as the
rate (i.e., drop all EF marked packets). rate (i.e., drop all EF marked packets).
The problem arose in the case of misconfiguration or routing The problem arose in the case of misconfiguration or routing
problems. An egress DS-node at the edge of one DS-domain forwards problems. An egress DS-node at the edge of one DS-domain forwards
packets to an ingress DS-node at the edge of another DS domain. packets to an ingress DS-node at the edge of another DS domain.
These packets are marked with a DSCP that the egress node understands These packets are marked with a DSCP that the egress node understands
to map to EF, but which the ingress node does not recognize. The to map to EF, but which the ingress node does not recognize. The
statement in RFC 2475 would appear to apply to this case. RFC XXXX statement in RFC 2475 would appear to apply to this case. RFC 3246
[7] (draft-ietf-diffserv-rfc2598bis) clarifies this point. [7] clarifies this point.
7. No Backward Compatibility With RFC 1349 7. No Backward Compatibility With RFC 1349
At least one implementor has expressed confusion about the At least one implementor has expressed confusion about the
relationship of the DSField, as defined in RFC 2474, to the use of relationship of the DSField, as defined in RFC 2474, to the use of
the TOS bits, as described in RFC 1349. The RFC 1349 useage was the TOS bits, as described in RFC 1349. The RFC 1349 usage was
intended to interact with OSPF extensions in RFC 1247. These were intended to interact with OSPF extensions in RFC 1247. These were
never widely deployed and thus removed by standards action when STD never widely deployed and thus removed by standards action when STD
0054 was published. The processing of the TOS bits is described as a 54, RFC 2328, was published. The processing of the TOS bits is
requirement in RFC 1812 [8], RFC 1122 [9] and RFC 1123 [10]. RFC described as a requirement in RFC 1812 [8], RFC 1122 [9] and RFC 1123
2474 states: [10]. RFC 2474 states:
"No attempt is made to maintain backwards compatibility with
the "DTR" or TOS bits of the IPv4 TOS octet, as defined in "No attempt is made to maintain backwards compatibility with the
[RFC791].", "DTR" or TOS bits of the IPv4 TOS octet, as defined in [RFC791].",
In addition, RFC 2474 obsoletes RFC 1349 by IESG action. For In addition, RFC 2474 obsoletes RFC 1349 by IESG action. For
completeness, when RFC 2474 is updated, the sentence should read: completeness, when RFC 2474 is updated, the sentence should read:
"No attempt is made to maintain backwards compatibility with the "No attempt is made to maintain backwards compatibility with the
"DTR/MBZ" or TOS bits of the IPv4 TOS octet, as defined in "DTR/MBZ" or TOS bits of the IPv4 TOS octet, as defined in
[RFC791] and [RFC1349]. This implies that TOS bit processing as [RFC791] and [RFC1349]. This implies that TOS bit processing as
described in [RFC1812], [RFC1122] and [RFC1123] is also obsoleted described in [RFC1812], [RFC1122] and [RFC1123] is also obsoleted
by this memo. Also see [RFC2780]." by this memo. Also see [RFC2780]."
8. IANA Considerations 8. IANA Considerations
IANA has requested clarification of a point in RFC 2474, concerning IANA has requested clarification of a point in RFC 2474, concerning
registration of experimental/local use DSCPs. When RFC 2474 is registration of experimental/local use DSCPs. When RFC 2474 is
skipping to change at page 7, line 25 skipping to change at page 7, line 19
"DTR/MBZ" or TOS bits of the IPv4 TOS octet, as defined in "DTR/MBZ" or TOS bits of the IPv4 TOS octet, as defined in
[RFC791] and [RFC1349]. This implies that TOS bit processing as [RFC791] and [RFC1349]. This implies that TOS bit processing as
described in [RFC1812], [RFC1122] and [RFC1123] is also obsoleted described in [RFC1812], [RFC1122] and [RFC1123] is also obsoleted
by this memo. Also see [RFC2780]." by this memo. Also see [RFC2780]."
8. IANA Considerations 8. IANA Considerations
IANA has requested clarification of a point in RFC 2474, concerning IANA has requested clarification of a point in RFC 2474, concerning
registration of experimental/local use DSCPs. When RFC 2474 is registration of experimental/local use DSCPs. When RFC 2474 is
revised, the following should be added to Section 6: revised, the following should be added to Section 6:
IANA is requested to maintain a registry of RECOMMENDED DSCP IANA is requested to maintain a registry of RECOMMENDED DSCP
values assigned by standards action. EXP/LU values are not to be values assigned by standards action. EXP/LU values are not to be
registered. registered.
9. Summary of Pending Changes 9. Summary of Pending Changes
The following standards track and informational RFCs are expected to The following standards track and informational RFCs are expected to
be updated to reflect the agreements captured in this memo. It is be updated to reflect the agreements captured in this memo. It is
intended that these updates occur when each standards track RFC intended that these updates occur when each standards track RFC
progresses to Draft (or if some issue arises that forces recycling at progresses to Draft Standard (or if some issue arises that forces
Proposed). RFC 2475 is expected to be updated at about the same time recycling at Proposed). RFC 2475 is expected to be updated at about
as RFC 2474. Those updates will also obsolete this memo. the same time as RFC 2474. Those updates will also obsolete this
memo.
RFC 2474: revise definition of DS field. Clarify that the RFC 2474: revise definition of DS field. Clarify that the
suggested default forwarding in the event of an unrecognized DSCP suggested default forwarding in the event of an unrecognized DSCP
is not intended to apply to ingress conditioning in DS-ingress is not intended to apply to ingress conditioning in DS-ingress
nodes. Clarify effects on RFC1349 and RFC1812. Clarify that only nodes. Clarify effects on RFC 1349 and RFC 1812. Clarify that
RECOMMENDED DSCPs assigned by standards action are to be only RECOMMENDED DSCPs assigned by standards action are to be
registered by IANA. registered by IANA.
RFC 2475: revise definition of DS field. Add SLS and TCS RFC 2475: revise definition of DS field. Add SLS and TCS
definitions. Update body of document to use SLS and TCS definitions. Update body of document to use SLS and TCS
appropriately. Add definitions of PHB scheduling class and appropriately. Add definitions of PHB scheduling class and
ordered aggregate. ordered aggregate.
RFC 2497: revise to reflect understanding that AF classes are RFC 2497: revise to reflect understanding that, AF classes are
instances of the AF PHB group, and are not collectively a PHB instances of the AF PHB group, and are not collectively a PHB
group. group.
In addition, RFCXXXX [7] (draft-ietf-diffserv-rfc2598bis) put a In addition, RFC 3246 [7] has added a reference to RFC 2475 in the
reference to RFC 2475 in the security considerations section to cover security considerations section to cover the case of a DS egress node
the case of a DS egress node receiving an unrecognized DSCP which receiving an unrecognized DSCP which maps to EF in the DS ingress
maps to EF in the DS ingress node. node.
10. Security Considerations 10. Security Considerations
Security considerations are addressed in RFC 2475. Security considerations are addressed in RFC 2475.
Acknowledgements Acknowledgements
This memo captures agreements of the Diffserv working
group. Many individuals contributed to the discussions on the This memo captures agreements of the Diffserv working group. Many
Diffserv list and in the meetings. The Diffserv chairs were Brian individuals contributed to the discussions on the Diffserv list and
Carpenter and Kathie Nichols. Among many who participated actively in the meetings. The Diffserv chairs were Brian Carpenter and Kathie
in these discussions were Lloyd Wood, Juha Heinanen, Grenville Nichols. Among many who participated actively in these discussions
Armitage, Scott Brim, Sharam Davari, David Black, Gerard Gastaud, were Lloyd Wood, Juha Heinanen, Grenville Armitage, Scott Brim,
Joel Halpern, John Schnizlein, Francois Le Faucheur, and Fred Baker. Sharam Davari, David Black, Gerard Gastaud, Joel Halpern, John
Mike Ayers, Mike Heard and Andrea Westerinen provided valuable Schnizlein, Francois Le Faucheur, and Fred Baker. Mike Ayers, Mike
editorial comments. Heard and Andrea Westerinen provided valuable editorial comments.
Normative References Normative References
[1] Nichols, Blake, Baker, Black, "Defintion of the Differentiated [1] Nichols, K., Blake, S., Baker, F. and D. Black, "Definition of
Services Field (DS Field) in the IPv4 and IPv6 Headers" RFC the Differentiated Services Field (DS Field) in the IPv4 and
2474, December 1998. IPv6 Headers", RFC 2474, December 1998.
[2] Blake, Black, Carlson, Davies, Wang and Weiss "An Architecture [2] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z. and W.
for Differentiated Services", RFC 2475, December 1998. Weiss, "An Architecture for Differentiated Services", RFC 2475,
December 1998.
[3] Heinanen, Baker, Weiss, Wrocklawski, "Assured Forwarding PHB [3] Heinanen, J., Baker, F., Weiss, W. and J. Wrocklawski, "Assured
Group", RFC 2597 Forwarding PHB Group", RFC 2597, June 1999.
[4] Ramakrishnan, Floyd, Black "The Addition of Explicit Congestion [4] Ramakrishnan, K., Floyd, S. and D. Black "The Addition of
Notification (ECN) to IP", RFC 3168, September 2001 Explicit Congestion Notification (ECN) to IP", RFC 3168,
September 2001.
[5] Bradner and Paxon, "IANA Allocation Guidelines for Values in the [5] Bradner, S. and V. Paxon, "IANA Allocation Guidelines for Values
Internet Protocol and Related Headers", BCP0037/RFC2780, March in the Internet Protocol and Related Headers", BCP 37, RFC2780,
2000 March 2000.
[6] Westerinen et al, "Terminology for Policy Based Management", RFC [6] Westerinen, A., Schnizlein, J., Strassner, J., Scherling, M.,
3198 Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry, J. and S.
Waldbusser, "Terminology for Policy-Based Management", RFC 3198,
November 2001.
[7] Davie et al, "An Expedited Forwarding PHB", RFC XXXX (ex-draft- [7] Davie, B., Charny, A., Baker, F., Bennett, J.C.R., Benson, K.,
ietf-rfc2598bis-02.txt) Le Boudec, J., Chiu, A., Courtney, W., Cavari, S., Firoiu, V.,
Kalmanek, C., Ramakrishnam, K. and D. Stiliadis, "An Expedited
Forwarding PHB (Per-Hop Behavior)", RFC 3246, March 2002.
[8] Baker, "Requirements for IP Version 4 Routers", RFC 1812 [8] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812,
June 1995.
[9] Braden, "Requirements for Internet Hosts -- Communications [9] Braden, R., "Requirements for Internet Hosts -- Communications
Layers", RFC1122/STD003 Layers", STD 3, RFC 1122, October 1989.
[10] Braden, "Requirements for Internet Hosts -- Application and [10] Braden, R., "Requirements for Internet Hosts -- Application and
Support", RFC1123/STD003 Support", STD 3, RFC 1123, October 1989.
Author's Address Author's Address
Dan Grossman Dan Grossman
Motorola, Inc. Motorola, Inc.
20 Cabot Blvd. 20 Cabot Blvd.
Mansfield, MA 02048 Mansfield, MA 02048
Email: dan@dma.isg.mot.com
EMail: dan@dma.isg.mot.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (1999, 2001). All Rights Copyright (C) The Internet Society (2002). All Rights Reserved.
Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain others, and derivative works that comment on or otherwise explain it
itor assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
 End of changes. 63 change blocks. 
162 lines changed or deleted 159 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/