draft-ietf-mpls-cosfield-def-08.txt   rfc5462.txt 
Network Working Group L. Andersson Network Working Group L. Andersson
Internet-Draft Acreo AB Request for Comments: 5462 Acreo AB
Updates: RFC 3032, RFC 3270, RFC R. Asati Updates: 3032, 3270, 3272, 3443, 3469, R. Asati
5129, RFC 3272, RFC 3443, RFC Cisco Systems 3564, 3985, 4182, 4364, 4379, Cisco Systems
3469, RFC 3564, RFC 3985, RFC December 5, 2008 4448, 4761, 5129 February 2009
4182, RFC 4364, RFC 4379, RFC Category: Standards Track
4448, RFC 4761 (if approved)
Intended status: Standards Track
Expires: June 8, 2009
Multi-Protocol Label Switching (MPLS) label stack entry: "EXP" field
renamed to "Traffic Class" field
draft-ietf-mpls-cosfield-def-08.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any Multiprotocol Label Switching (MPLS) Label Stack Entry:
applicable patent or other IPR claims of which he or she is aware "EXP" Field Renamed to "Traffic Class" Field
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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Abstract Abstract
The early Multiprotocol Label Switching (MPLS) documents defined the The early Multiprotocol Label Switching (MPLS) documents defined the
form of the MPLS Label Stack entry. This includes a three bit field form of the MPLS label stack entry. This includes a three-bit field
called the "EXP field". The exact use of this field was not defined called the "EXP field". The exact use of this field was not defined
by these documents, except to state that it was to be "reserved for by these documents, except to state that it was to be "reserved for
experimental use". experimental use".
Although the intended use of the EXP field was as a "Class of Although the intended use of the EXP field was as a "Class of
Service" (CoS) field, it was not named the CoS field by these early Service" (CoS) field, it was not named a CoS field by these early
documents because the use of such a CoS field was not considered to documents because the use of such a CoS field was not considered to
be sufficiently defined. Today a number of standards documents be sufficiently defined. Today a number of standards documents
define its usage as a CoS field. . define its usage as a CoS field.
To avoid misunderstanding about how this field may be used, it has To avoid misunderstanding about how this field may be used, it has
become increasingly necessary to rename this field. This document become increasingly necessary to rename this field. This document
changes the name of the field to the "Traffic Class field" ("TC changes the name of the field to the "Traffic Class field" ("TC
field".) In doing so it also updates documents that define the field"). In doing so, it also updates documents that define the
current use of the EXP this field. current use of the EXP field.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Details of change . . . . . . . . . . . . . . . . . . . . . . 6 2. Details of Change . . . . . . . . . . . . . . . . . . . . . . 3
2.1. RFC 3032 . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. RFC 3032 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. RFC 3270 . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. RFC 3270 . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. RFC 5129 . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3. RFC 5129 . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4. The Scope of this Change . . . . . . . . . . . . . . . . . 9 2.4. The Scope of This Change . . . . . . . . . . . . . . . . . 7
3. Use of the TC field . . . . . . . . . . . . . . . . . . . . . 11 3. Use of the TC field . . . . . . . . . . . . . . . . . . . . . 7
4. IANA considerations . . . . . . . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. Security considerations . . . . . . . . . . . . . . . . . . . 13 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 15 6.2. Informative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative references . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 18
1. Introduction 1. Introduction
The format of a MPLS label stack entry is defined by RFC 3032 The format of an MPLS label stack entry is defined by RFC 3032
[RFC3032], include a three bit field called the "EXP field". The [RFC3032] to include a three-bit field called the "EXP field". The
exact use of this field is not defined by RFC 3032 leaves, except to exact use of this field is not defined by RFC 3032, except to state
state that it is to be "reserved for experimental use". that it is to be "reserved for experimental use".
The EXP field, from the start, was intended to carry "Class of The EXP field, from the start, was intended to carry "Class of
Service" (CoS) information. The field was actually called the "Class Service" (CoS) information. The field was actually called the "Class
of Service field" in the early versions of the working group document of Service field" in early versions of the working group document
that was published as RFC 3032. However at the time that RFC 3032 that was published as RFC 3032. However, at the time that RFC 3032
was published the exact usage of this "Class of Service" field was was published, the exact usage of this "Class of Service" field was
not agreed and the field was designated as "Experimental use"; hence not agreed upon and the field was designated as "experimental use";
the name has since then been the "EXP Field". hence, the name has since been the "EXP field".
The designation "for Experimental use" has led other Standards The designation "for experimental use" has led other Standards
Development Organizations (SDO) and implementors to the assume that Development Organizations (SDOs) and implementors to assume that it
it possible to use the field for other purposes. This document is possible to use the field for other purposes. This document
changes the name of the field to clearly indicate its use as a changes the name of the field to clearly indicate its use as a
traffic classification field. traffic classification field.
At first we discussed to use the original "CoS field" as the name for At first, we discussed using the original "CoS field" as the name for
the field, but it has been pointed that this name does not cover the the field, but it has been pointed out that this name does not cover
following changes with respect to its usage, since RFC 3032 was the following changes that have occurred with respect to its usage
published. since RFC 3032 was published.
1. The use of the EXP field was first defined in RFC 3270 [RFC3270] 1. The use of the EXP field was first defined in RFC 3270 [RFC3270],
where a method to define a variant of DiffServ Label Switched where a method to define a variant of Diffserv Label Switched
Paths (LSP) called EXP-Inferred-PSC LSP (E-LSPs) was specified. Paths (LSP), called EXP-Inferred-PSC LSP (E-LSPs), was specified.
The PSC is a two stage acroynym that is expanded as Per Hop PSC is a two-stage acronym that is expanded as PHB (Per Hop
Behavior (PHB) and PHB Scheduling Class (PSC). Behavior) Scheduling Class (PSC).
2. The use of the EXP field as defined in RFC 3270 has been further 2. The use of the EXP field as defined in RFC 3270 has been further
extended in RFC 5129 [RFC5129], where methods for explicit extended in RFC 5129 [RFC5129], where methods for explicit
congestion marking in MPLS are defined. congestion marking in MPLS are defined.
This document, hence, uses the name "Traffic Class Field (TC Field)", This document, hence, uses the name "Traffic Class field (TC field)",
which better covers the potential use. The MPLS TC field relates to which better covers the potential use. The MPLS TC field relates to
an MPLS encapsulated packet the same way as the IPv6 TC field relates an MPLS encapsulated packet the same way as the IPv6 TC field relates
to an IPv6 encapsulted packet or the IPv4 Precedence field relates to to an IPv6 encapsulated packet or the IPv4 Precedence field relates
an IPv4 encapsulated packet. to an IPv4 encapsulated packet.
The definitions of how the EXP field is used are perfectly clear in The definitions of how the EXP field is used are perfectly clear in
RFC 3270 and RFC 5129. However, these RFCs do not explicitly state RFC 3270 and RFC 5129. However, these RFCs do not explicitly state
they update RFC 3032, and this fact was not captured in the RFC they update RFC 3032, and this fact was not captured in the RFC
repository until after the work on this document were started. This repository until after work on this document was started.
document updates RFC 3032, RFC 3270 and RFC 5129 to clarify the
intended usage of the TC field. Section 2 explains the changes. This document updates RFC 3032, RFC 3270, and RFC 5129 to clarify the
intended usage of the TC field. The changes to these RFCs requires
some changes to the actual text in those documents; Section 2
explains the changes.
This document also updates several other RFCs; see Section 2.4. For
these documents, the change is limited to changing the name of the
Label Stack entry field.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Details of change 2. Details of Change
The three RFCs are now updated according to the following. The three RFCs 3032, 3270, and 5129 are now updated according to the
following.
2.1. RFC 3032 2.1. RFC 3032
RFC 3032 states on page 4: RFC 3032 states on page 4:
3. Experimental Use 3. Experimental Use
This three-bit field is reserved for experimental use. This three-bit field is reserved for experimental use.
This paragraph is now changed to: This paragraph is now changed to:
3. Traffic Class (TC) field 3. Traffic Class (TC) field
This three-bit field is used to carry Traffic Class information This three-bit field is used to carry traffic class information,
and the change of the name is applicable to all places it occurs and the change of the name is applicable to all places it occurs
in IETF RFCs and other IETF documents. in IETF RFCs and other IETF documents.
RFC 3270 and RFC 5129 updates the definition of the TC field and RFC 3270 and RFC 5129 update the definition of the TC field and
describes how to use the field. describe how to use the field.
In Figure 1 on page 3 in RFC3032 the format of a label stack entry is In Figure 1 on page 3 in RFC 3032, the format of a label stack entry
specified as: is specified as:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
| Label | Exp |S| TTL | Stack | Label | Exp |S| TTL | Stack
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
Label: Label Value, 20 bits Label: Label Value, 20 bits
Exp: Experimental Use, 3 bits Exp: Experimental Use, 3 bits
S: Bottom of Stack, 1 bit S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits TTL: Time to Live, 8 bits
Figure 1 Figure 1
Figure 1 in RFC 3032 is now changed to match the change of name of Figure 1 in RFC 3032 is now changed to match the change of name to TC
the TC field to: field:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
| Label | TC |S| TTL | Stack | Label | TC |S| TTL | Stack
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
Label: Label Value, 20 bits Label: Label Value, 20 bits
CoS: Traffic Class field, 3 bits TC: Traffic Class field, 3 bits
S: Bottom of Stack, 1 bit S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits TTL: Time to Live, 8 bits
Figure 1 (new) Figure 1 (new)
Note: The designation of the picture above as "Figure 1 new" is Note: The designation of the picture above as "Figure 1 (new)" is
introduced as a way to distinguish the figures in this draft. It introduced as a way to distinguish the figures in this document. It
will still be "Figure 1." in RFC 3032. will still be "Figure 1" in RFC 3032.
2.2. RFC 3270 2.2. RFC 3270
RFC 3270 says on page 6: RFC 3270 says on page 6:
1.2 EXP-Inferred-PSC LSPs (E-LSP) 1.2 EXP-Inferred-PSC LSPs (E-LSP)
A single LSP can be used to support one or more OAs. Such LSPs A single LSP can be used to support one or more OAs. Such LSPs
can support up to eight BAs of a given FEC, regardless of how many can support up to eight BAs of a given FEC, regardless of how many
OAs these BAs span. With such LSPs, the EXP field of the MPLS OAs these BAs span. With such LSPs, the EXP field of the MPLS
skipping to change at page 8, line 5 skipping to change at page 5, line 30
field value for that packet. field value for that packet.
The mapping from the EXP field to the PHB (i.e., to PSC and drop The mapping from the EXP field to the PHB (i.e., to PSC and drop
precedence) for a given such LSP, is either explicitly signaled at precedence) for a given such LSP, is either explicitly signaled at
label set-up or relies on a pre-configured mapping. label set-up or relies on a pre-configured mapping.
Detailed operations of E-LSPs are specified in section 3 below. Detailed operations of E-LSPs are specified in section 3 below.
RFC 3270 is now updated like this: RFC 3270 is now updated like this:
a. A new paragraph is added at the end of section 1 "Introduction": a. A new paragraph is added at the end of Section 1 "Introduction":
The EXP field has been renamed to the TC field, and thus all The EXP field has been renamed the TC field, and thus all
references in RFC 3270 to EXP field SHOULD be taken to refer references in RFC 3270 to the EXP field now refer to the TC
to the TC field. field.
b. A new term is added to section 1.1 "Terminology": b. A new term is added to Section 1.1 "Terminology":
TC Traffic Class (replaces the term EXP) TC Traffic Class (replaces the term EXP)
c. In section 1.1 "Terminology" the acronym E-LSP is now understood c. In Section 1.1 "Terminology", the acronym E-LSP is now understood
to mean : to mean :
E-LSP Explicitly TC-encoded-PSC LSP E-LSP Explicitly TC-encoded-PSC LSP
Section 1.2 on page 5 in RFC 3270 is now changed to: Section 1.2 on page 6 in RFC 3270 is now changed to:
1.2 Explicitly TC-encoded-PSC LSPs (E-LSP) 1.2 Explicitly TC-encoded-PSC LSPs (E-LSP)
The EXP field has been renamed to the TC field, and thus all The EXP field has been renamed to the TC field, and thus all
references in RFC 3270 to EXP field SHOULD be taken to refer to references in RFC 3270 to EXP field now refer to the TC field.
the TC field. However, we retain the acronym E-LSP (Explicitly However, we retain the acronym E-LSP (Explicitly TC-encoded-PSC
TC-encoded-PSC LSP) as the acronym is in widespread use. LSP) as the acronym is in widespread use.
A single LSP can be used to support one or more OAs. Such LSPs A single LSP can be used to support one or more OAs. Such LSPs
can support up to eight BAs of a given FEC, regardless of how many can support up to eight BAs of a given FEC, regardless of how many
OAs these BAs span. With such LSPs, the TC field of the MPLS Shim OAs these BAs span. With such LSPs, the TC field of the MPLS Shim
Header is used by the LSR to determine the PHB to be applied to Header is used by the LSR to determine the PHB to be applied to
the packet. This includes both the PSC and the drop preference. the packet. This includes both the PSC and the drop preference.
We refer to such LSPs as "Explicitly TC-encoded-PSC LSP" (E-LSP), We refer to such LSPs as "Explicitly TC-encoded-PSC LSPs"
since the PSC of a packet transported on this LSP depends on the (E-LSPs), since the PSC of a packet transported on this LSP
TC field (previously called the EXP field) value for that packet. depends on the TC field (previously called the EXP field) value
for that packet.
The mapping from the TC field to the PHB (i.e., to PSC and drop The mapping from the TC field to the PHB (i.e., to PSC and drop
precedence) for a given such LSP, is either explicitly signaled at precedence) for a given such LSP is either explicitly signaled at
label set-up or relies on a pre-configured mapping. label set-up or relies on a pre-configured mapping.
This is an update to RFC 3032 [RFC3032] in line with the original This is an update to RFC 3032 [RFC3032], in line with the original
intent of how this field in the MPLS Shim Header should be used intent of how this field in the MPLS Shim Header should be used
(as TC field). The RFC 3270 has itself been updated by RFC 5129 (as a TC field). RFC 3270 has itself been updated by RFC 5129
[RFC5129]. [RFC5129].
Detailed operations of E-LSPs are specified in section 3 of Detailed operations of E-LSPs are specified in Section 3 of RFC
RFC3270. 3270.
2.3. RFC 5129 2.3. RFC 5129
RFC 5129 is now updated like this: RFC 5129 is now updated like this:
A new paragraph is added at the end of section 1.1 "Background": A new paragraph is added at the end of Section 1.1 "Background":
The EXP field has been renamed to the TC field, and thus all The EXP field has been renamed to the TC field, and thus all
references in RFC 5129 to EXP field SHOULD be taken to refer to references in RFC 5129 to the EXP field now refer to the TC field.
the TC field.
Section 2 (bullet 3) on page 6 of RFC 5129 says: Section 2 (bullet 5) on page 7 of RFC 5129 says:
o A third possible approach was suggested by [Shayman]. In this o A third possible approach was suggested by [Shayman]. In this
scheme, interior LSRs assume that the endpoints are ECN-capable, scheme, interior LSRs assume that the endpoints are ECN-capable,
but this assumption is checked when the final label is popped. If but this assumption is checked when the final label is popped. If
an interior LSR has marked ECN in the EXP field of the shim an interior LSR has marked ECN in the EXP field of the shim
header, but the IP header says the endpoints are not ECN-capable, header, but the IP header says the endpoints are not ECN-capable,
the edge router (or penultimate router, if using penultimate hop the edge router (or penultimate router, if using penultimate hop
popping) drops the packet. We recommend this scheme, which we popping) drops the packet. We recommend this scheme, which we
call `per-domain ECT checking', and define it more precisely in call `per-domain ECT checking', and define it more precisely in
the following section. Its chief drawback is that it can cause the following section. Its chief drawback is that it can cause
packets to be forwarded after encountering congestion only to be packets to be forwarded after encountering congestion only to be
dropped at the egress of the MPLS domain. The rationale for this dropped at the egress of the MPLS domain. The rationale for this
decision is given in Section 8.1. decision is given in Section 8.1.
Section 2 (bullet 3) of RFC 5129 is now updated changed to: Section 2 (bullet 5) of RFC 5129 is now updated to:
o A third possible approach was suggested by [Shayman]. In this o A third possible approach was suggested by [Shayman]. In this
scheme, interior LSRs assume that the endpoints are ECN-capable, scheme, interior LSRs assume that the endpoints are ECN-capable,
but this assumption is checked when the final label is popped. If but this assumption is checked when the final label is popped. If
an interior LSR has marked ECN in the TC field of the shim header, an interior LSR has marked ECN in the TC field of the shim header,
but the IP header says the endpoints are not TC-capable, the edge but the IP header says the endpoints are not TC-capable, the edge
router (or penultimate router, if using penultimate hop popping) router (or penultimate router, if using penultimate hop popping)
drops the packet. We recommend this scheme, which we call `per- drops the packet. We recommend this scheme, which we call `per-
domain ECT checking', and define it more precisely in the domain ECT checking', and define it more precisely in the
following section. Its chief drawback is that it can cause following section. Its chief drawback is that it can cause
packets to be forwarded after encountering congestion only to be packets to be forwarded after encountering congestion only to be
dropped at the egress of the MPLS domain. The rationale for this dropped at the egress of the MPLS domain. The rationale for this
decision is given in Section 8.1. This scheme is an update to RFC decision is given in Section 8.1. This scheme is an update to RFC
3032 [RFC3032] and RFC 3270 [RFC3270]. 3032 [RFC3032] and RFC 3270 [RFC3270].
2.4. The Scope of this Change 2.4. The Scope of This Change
There are several places in the RFCs that has explicitly updated by There are several places in the RFCs that are explicitly updated by
this document that reference the "Exp field", sometimes they refer to this document that reference the "Exp field", sometimes they refer to
the field as "Exp bits", "EXP bits" and "EXP". In all those the field as "Exp bits", "EXP bits", or "EXP". In all those
instances the references SHOULD be taken to reference the TC field. instances, the references now reference the TC field.
There are also other RFCs, e.g. RFC 3272 [RFC3272], RFC 3443 There are also other RFCs (e.g., RFC 3272 [RFC3272], RFC 3443
[RFC3443], RFC 3469 [RFC3469], RFC 3564 [RFC3564], RFC 3985 [RFC3443], RFC 3469 [RFC3469], RFC 3564 [RFC3564], RFC 3985
[RFC3985], RFC 4182 [RFC4182], RFC 4364 [RFC4364], RFC 4379 [RFC3985], RFC 4182 [RFC4182], RFC 4364 [RFC4364], RFC 4379
[RFC4379], RFC 4448 [RFC4448] and RFC 4761 [RFC4761] that references [RFC4379], RFC 4448 [RFC4448], and RFC 4761 [RFC4761]) that reference
the "Exp field", sometimes they refer to the field as "Exp bits", the "Exp field"; sometimes they refer to the field as "Exp bits",
"EXP bits" and "EXP". For all RFCs, including but not limited to "EXP bits", and "EXP". For all RFCs, including but not limited to
those mentioned in this paragraph, such references SHOULD be taken to those mentioned in this paragraph, such references now reference the
reference the TC field. TC field.
3. Use of the TC field 3. Use of the TC field
Due to the limited number of bits in the TC field, their use for QoS Due to the limited number of bits in the TC field, their use for QoS
and ECN functions is intended to be flexible. These funtions may and ECN (Explicit Congestion Notification) functions is intended to
rewrite all or some of the bits in the TC field. be flexible. These functions may rewrite all or some of the bits in
the TC field.
Current implementations look at the TC field with and without label Current implementations look at the TC field with and without label
context and the TC field may be copied to the label stack entries context, and the TC field may be copied to the label stack entries
that are pushed onto the label stack. This is done to avoid that that are pushed onto the label stack. This is done to avoid label
label stack entries that are pushed on to an existing label stack stack entries that are pushed onto an existing label stack having
have different TF fields from the rest of the label stack entries. different TC fields from the rest of the label stack entries.
4. IANA considerations
There are no requests for IANA allocation of code points in this
document.
5. Security considerations 4. Security Considerations
This document only changes the name of one field in the MPLS Shim This document only changes the name of one field in the MPLS shim
Header and thus does not introduce any new security considerations. header, and thus does not introduce any new security considerations.
6. Acknowledgments 5. Acknowledgments
The author would like to thank Stewart Bryant, Bruce Davie, George The authors would like to thank Stewart Bryant, Bruce Davie, George
Swallow, and Francois Le Faucheur for their input to and review of Swallow, and Francois Le Faucheur for their input to and review of
the current document. the current document.
The author also like to thanks George Swallow, Khatri Paresh and Phil The authors would also like to thank George Swallow, Khatri Paresh,
Bedard for their help with grammar and spelling, and a special thanks and Phil Bedard for their help with grammar and spelling; a special
to Adrian Farrel for a careful review and help trawling the RFC-sea thanks to Adrian Farrel for his careful review and help trawling the
for RFCs that references the EXP field. RFC-sea for RFCs that reference the EXP field.
7. References 6. References
7.1. Normative References 6.1. Normative References
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001. Encoding", RFC 3032, January 2001.
[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen, [RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi- P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
skipping to change at page 16, line 12 skipping to change at page 9, line 29
"Encapsulation Methods for Transport of Ethernet over MPLS "Encapsulation Methods for Transport of Ethernet over MPLS
Networks", RFC 4448, April 2006. Networks", RFC 4448, April 2006.
[RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
(VPLS) Using BGP for Auto-Discovery and Signaling", (VPLS) Using BGP for Auto-Discovery and Signaling",
RFC 4761, January 2007. RFC 4761, January 2007.
[RFC5129] Davie, B., Briscoe, B., and J. Tay, "Explicit Congestion [RFC5129] Davie, B., Briscoe, B., and J. Tay, "Explicit Congestion
Marking in MPLS", RFC 5129, January 2008. Marking in MPLS", RFC 5129, January 2008.
7.2. Informative references 6.2. Informative References
[Shayman] Shayman, M. and R. Jaeger, University of Michigan, "Using [Shayman] Shayman, M. and R. Jaeger, "Using ECN to Signal Congestion
ECN to Signal Congestion Within an MPLS Domain", Work in Within an MPLS Domain", Work in Progress, November 2000.
Progress, November 2000.", <http://www.watersprings.org/
pub/id/draft-shayman-mpls-ecn-00.txt/>.
Authors' Addresses Authors' Addresses
Loa Andersson Loa Andersson
Acreo AB Acreo AB
Email: loa@pi.nu EMail: loa@pi.nu
Rajiva Asati Rajiv Asati
Cisco Systems Cisco Systems
Email: rajiva@cisco.com EMail: rajiva@cisco.com
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