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Versions: (draft-farrel-mpls-rsvpte-attributes)
00 01 02 03 04 05 RFC 4420
Network Working Group Adrian Farrel (Editor)
Internet Draft Old Dog Consulting
Category: Standards Track
Expires: July 2004 Dimitri Papadimitriou
Alcatel
Jean-Philippe Vasseur
Cisco Systems, Inc.
Arthi Ayyangar
Juniper Networks
January 2004
Encoding of Attributes for Multiprotocol Label Switching (MPLS)
Label Switched Path (LSP) Establishment Using RSVP-TE
draft-ietf-mpls-rsvpte-attributes-02.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC 2026 [RFC2026].
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, 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
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be
accessed at http://www.ietf.org/shadow.html.
Abstract
Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs) may
be established using the Resource Reservation Protocol Traffic
Engineering extensions (RSVP-TE). This protocol includes an object
(the SESSION_ATTRIBUTE object) which carries a flags field used to
indicate options and attributes of the LSP. That flags field has
eight bits allowing for eight options to be set. Recent proposals in
many documents that extend RSVP-TE have suggested uses for each of
the previously unused bits.
This document defines a new object for RSVP-TE messages that allows
the signaling of further attribute bits and also the carriage of
arbitrary attribute parameters to make RSVP-TE easily extensible to
support new requirements. Additionally, this document defines a way
to record the attributes applied to the LSP on a hop-by-hop basis.
The object mechanisms defined in this document are equally applicable
to Generalized MPLS (GMPLS) Packet Switch Capable (PSC) LSPs and to
GMPLS non-PSC LSPs.
Farrel, Papadimitriou, Vasseur and Ayyangar Page 1
draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
0. Change History
This section to be removed before publication.
0.1 Changes from 01 to 02 Version
- Minor typographical changes.
0.2 Changes from 00 to 01 Version
- Change Attributes Flags TLV to be variable length so that more bits
can easily be added in the future.
- Define default behaviors for bits absent from the TLV and for
absence of the TLV.
- Clarify the IANA requirements for tracking Attributes Flags bits.
- Introduce RRO Attibutes Subobject and describe usage.
- Move Fast Reroute reference to informational.
- Update security considerations to handle new RRO subobject
- Remove section that explained the need for this document in
advance of any definitive bit definitions.
- Tighten rules for processing LSP_ATTRIBUTES object in cases where
TLVs are unknown or unsupported.
- Clarify that LSP Attributes apply to individual LSPs and not to
entire sessions.
1. Introduction and Problem Statement
Traffic Engineered Multiprotocol Label Switching (MPLS) Label
Switched Paths (LSPs) [RFC3031] may be set up using the Path message
of the RSVP-TE signaling protocol [RFC3209]. The Path message
includes the SESSION_ATTRIBUTE object which carries a flags field
used to indicate desired options and attributes of the LSP.
The flags field in the SESSION_ATTRIBUTE object has eight bits. Just
three of those bits are assigned in [RFC3209]. A further two bits are
assigned in [FRR] for fast re-reroute functionality leaving only
three bits available. Several recent proposals and Internet Drafts
have demonstrated that there is a high demand for the use of the
other three bits. Some, if not all, of those proposals are likely to
go forward as RFCs resulting in depletion or near depletion of the
flags field and a consequent difficulty in signaling new options and
attributes that may be developed in the future.
This document defines a new object for RSVP-TE messages that allows
the signaling of further attributes bits. The new object is
constructed from TLVs, and a new TLV is defined to carry a variable
number of attributes bits. Because of the nature of the TLV
construction the object is flexible and allows the future definition
of:
- further bit flags if further, distinct uses are discovered
- arbitrary options and attributes parameters carried as individual
TLVs.
Note that the LSP Attributes defined in this document are
specifically scoped to an LSP. They may be set differently on
separate LSPs with the same Tunnel ID between the same source and
destination (that is, within the same Session).
Farrel, Papadimitriou, Vasseur and Ayyangar Page 2
draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
It is noted that that some options and attributes do not need to be
acted on by all Label Switched Routers (LSRs) along the path of the
LSP. In particular, these options and attributes may apply only to
key LSRs on the path such as the ingress and egress. Special transit
LSRs, such as area or AS Border Routers (ABR/ASBRs) may also fall
into this category. This means that the new options and attributes
should be signaled transparently, and only examined at those points
that need to act on them.
On the other hand, other options and attributes may require action
at all transit LSRs along the path of the LSP. Inability to support
the required attributes by one of those transit LSRs may require the
LSR to refuse the establishment of the LSP.
These considerations are particularly important in the context of
backwards compatibility. In general, it should be possible to provide
new MPLS services across a legacy network without upgrading those
LSRs that do not need to participate actively in the new services.
Note that options already specified for the SESSION_ATTRIBUTE object
in pre-existing RFCs are not migrated to the new mechanisms described
in this documnet.
RSVP includes a way for unrecognized objects to be transparently
forwarded by transit nodes without them refusing the incoming
protocol messages and with the objects being stripped from the
outgoing protocol message (see [RFC2205] section 3.10). This
capability extends to RSVP-TE and provides a good way to ensure that
only those LSRs that understand a particular object examine it.
This document distinguishes between options and attributes that are
only required at key LSRs along the path of the LSP, and those that
must be acted on by every LSR along the LSP. Two LSP Attributes
objects are defined in this document: the first may be passed
transparently by LSRs that do not recognize it, the second must cause
LSP setup failure with the generation of a PathErr message with an
appropriate Error Code if an LSR does not recognize it.
1.1 Applicability to Generalized MPLS
The RSVP-TE signaling protocol also forms the basis of a signaling
protocol for Generalized MPLS (GMPLS) as described in [RFC3471] and
[RFC3473]. The extensions described in this document are intended to
be equally applicable to MPLS and GMPLS.
1.2 A Rejected Alternate Solution
A rejected alternate solution was to define a new C-Type for the
existing SESSION_ATTRIBUTE object. This new C-Type could allow a
larger Flags field and address the immediate problem.
This solution was rejected because:
- A new C-Type is not backward compatible with deployed
implementations that expect to see a C-Type of 1 or 7. It is
important that any solution be capable of carrying new attributes
transparently across legacy LSRs if those LSRs are not required to
act on the attributes.
Farrel, Papadimitriou, Vasseur and Ayyangar Page 3
draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
- Support for arbitrary attributes parameters through TLVs would
have meant a significant change of substance to the existing
object.
2. Terminology
This document uses terminology from the MPLS architecture document
[RFC3031] and from the RSVP-TE protocol specification [RFC3209] which
inherits from the RSVP specification [RFC2205].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [6].
3. Attributes TLVs
Attributes carried by the new objects defined in this document are
encoded within TLVs. One or more TLVs may be present in each object.
There are no ordering rules for TLVs and no interpretation should be
placed on the order in which TLVs are received.
Each TLV is encoded as follows.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
The identifier of the TLV.
Length
The length of the value field in bytes. Thus if no value
field is present the length field contains the value zero.
Each value field must be zero padded at the end to take it
up to a four byte boundary - the padding is not included in
the length so that a one byte value would be encoded in an
eight byte TLV with length field set to one.
Value
The data for the TLV padded as described above.
3.1 Attributes Flags TLV
This document defines only one TLV type value. Type 1 indicates the
Attributes Flags TLV. Other TLV types may be defined in future with
type values assigned by IANA.
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draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
The Attributes Flags TLV may be present in an LSP_ATTRIBUTES object
and/or an LSP_REQUIRED_ATTRIBUTES object. The bits in the TLV
represent the same attributes regardless of which object carries the
TLV. Documents that define individual bits MUST specify whether the
bit may be set in one object or the other, or both. It is not
expected that a bit will be set in both objects on a single Path
message at the same time, but this is not ruled out by this document.
The Attributes Flags TLV value field is a variable length array of
flags numbered from the MSB as bit zero. The length field for this
TLV is always a multiple of 4 bytes, regardless of the number bits
carried.
Unassigned bits are considered as reserved and MUST be set to zero
on transmission by the originator of the object. Bits not contained in the
TLV MUST be assumed to be set to zero. If the TLV is absent either
because it is not contained in the LSP_ATTRIBUTES or LSP_REQUIRED_
ATTRIBUTES object, or because those objects are themselves absent,
all processing MUST be performed as though the bits were present
and set to zero.
No bits are defined in this document. The assignment of bits is
managed by IANA.
4. LSP_ATTRIBUTES Object
The LSP_ATTRIBUTES object is used to signal attributes required in
support of an LSP, or to indicate the nature or use of an LSP where
that information is not required to be acted on by all transit LSRs.
Specifically, if an LSR does not support the object, it forwards it
unexamined and unchanged. This facilitates the exchange of attributes
across legacy networks that do not support this new object.
This object effectively extends the flags field in the SESSION_
ATTRIBUTE object and allows for the future inclusion of more complex
objects through TLVs.
Note that some function may require an LSR to inspect both the
SESSION_ATTRIBUTE object, and the LSP_ATTRIBUTES or
LSP_REQUIRED_ATTIBUTES object.
The LSP_ATTRIBUTES object class is TBD of the form 11bbbbbb. This
C-Num value (see section 7) ensures that LSRs that do not recognize
the object pass it on transparently.
One C-Type is defined, C-Type = 1 for LSP Attributes.
This object is optional and may be placed on Path messages to convey
additional information about the desired attributes of the LSP.
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4.1 Format
LSP_ATTRIBUTES class = TBD, C-Type = 1
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Attributes TLVs are encoded as described in section 3.
4.2 Generic Processing Rules
An LSR that does not support this object will pass it on unaltered
because of the C-Num.
An LSR that does support this object, but does not recognize a TLV
type code carried in this object MUST pass the TLV on unaltered
in the LSP_ATTRIBUTES object that it places in the Path message
that it sends downstream.
An LSR that does support this object and recognizes a TLV but does
not support the attribute defined by the TLV MUST act as specified in
the document that defines the TLV.
An LSR that supports the Attributes Flags TLV, but does not
recognize a bit set in the Attributes Flags TLV MUST forward the
TLV unchanged.
An LSR that supports the Attributes Flags TLV and recognizes a bit
that is set but does not support the indicated attribute MUST act as
specified in the document that defines the bit.
5. LSP_REQUIRED_ATTRIBUTES Object
The LSP_REQUIRED_ATTRIBUTES object is used to signal attributes
required in support of an LSP, or to indicate the nature or use of
an LSP where that information MUST be inspected at each transit LSR.
Specifically, each transit LSR MUST examine the attributes in the
LSP_REQUIRED_ATTRIBUTES object and MUST NOT forward the object
transparently.
This object effectively extends the flags field in the SESSION_
ATTRIBUTE object and allows for the future inclusion of more complex
objects through TLVs. It complements the LSP_ATTRIBUTES object.
The LSP_REQUIRED_ATTRIBUTES object class is TBD of the form 0bbbbbbb.
This C-Num value ensures that LSRs that do not
recognize the object reject the LSP setup effectively saying that
they do not support the attributes requested. This means that this
object SHOULD only be used for attributes that require support at
some transit LSRs and so require examination at all transit LSRs. See
section 4 for how end-to-end and selective attributes are signaled.
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One C-Type is defined, C-Type = 1 for LSP Required Attributes.
This object is optional and may be placed on Path messages to convey
additional information about the desired attributes of the LSP.
5.1 Format
LSP_REQUIRED_ATTRIBUTES class = TBD, C-Type = 1
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Attributes TLVs are encoded as described in section 3.
5.2 Generic Processing Rules
An LSR that does not support this object will use a PathErr to reject
the Path message based on the C-Num using the error code "Unknown
Object Class".
An LSR that does not recognize a TLV type code carried in this object
MUST reject the Path message using a PathErr with Error Code
"Unknown Attributes TLV" and Error Value set to the value of the
unknown TLV type code.
An LSR that does not recognize a bit set in the Attributes Flags
TLV MUST reject the Path message using a PathErr with Error Code
"Unknown Attributes Bit" and Error Value set to the bit number of
the unknown bit in the Attributes Flags.
An LSR that recognizes an attribute, however encoded, but which does
not support that attribute MUST act according to the behavior
specified in the document that defines that specific attribute.
6. Recording Attributes
6.1 Requirements
In some circumstances it is useful to determine which of the
requested LSP attributes have been applied at which LSRs along the
path of the LSP. For example, an attribute may be requested in the
LSP_ATTRIBUTES object such that LSRs that do not support the object
are not required to support the attribute or provide the requested
function. In this case, it may be useful to the ingress LSR to know
which LSRs acted on the request and which ignored it.
Additionally, there may be other qualities that need to be reported
on a hop-by-hop basis. These are currently indicated in the Flags
field of RRO subobjects. Since there are only eight bits available
in this field, and since some are already assigned and there is also
likely to be an increase in allocations in new documents, there is a
need for some other method to report per-hop attributes.
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6.2 RRO Attributes Subobject
The RRO Attributes Subobject may be carried in the RECORD_ROUTE
object if it is present. The subobject uses the standard format of
an RRO subobject.
The length is variable as for the Attributes Flags TLV. The content
is the same as the Attribute Flags TLV - that is, it is a series of
bit flags.
There is a one-to-one correspondance between bits in the Attributes
Flags TLV and the RRO Attributes Subobject. If a bit is only required
in one of the two places, it is reserved in the other place. See
the procedures sections, below, for more information.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attribute Flags //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
0x?? TBD RRO Attribute Subobject
Length
The Length contains the total length of the subobject in bytes,
including the Type and Length fields. This length must be a
multiple of 4 and must be at least 8.
Attribute Flags
The attribute flags recorded for the specific hop.
6.3 Procedures
6.3.1 Subobject Presence Rules
The Attributes subobject is pushed onto the RECORD_ROUTE object
immediately prior to pushing the node's IP address or link
identifier. Thus, if label recording is being used, the Attributes
subobject SHOULD be pushed onto the RECORD_ROUTE object after the
Record Label subobject(s).
A node MUST NOT push an Attributes subobject on to the RECORD_ROUTE
object without also pushing an IPv4, IPv6 or Unnumbered Interface ID
subobject.
This means that an Attributes subobject is bound to the LSR
identified by the subobject found in the RRO immediately before the
Attributes subobject.
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If the new subobject causes the RRO to be too big to fit in a Path
(or Resv) message, the processing MUST be as described in [RFC3209].
If more than one Attributes subobject is found between a pair of
subobjects that identify LSRs, only the first one found (that is, the
nearest to the stop of the stack) SHALL have any meaning within the
context of this document. All such subobjects MUST be forwarded
unmodified by transit LSRs.
6.3.2 Reporting Compliance with LSP Attributes
To report compliance with an attribute requested in the Attributes
Flags TLV, an LSR MAY set the corresponding bit (see section 7) in
the Attributes subobject. To report non-compliance, an LSR MAY clear
the corresponding bit in the Attributes subobject.
The requirement to report compliance MUST be specified in the
document that defines the usage of any bit. This will reduce to a
statement of whether hop-by-hop acknowledgement is required.
6.3.3 Reporting Per-Hop Attributes
To report a per-hop attribute, an LSR sets the appropriate bit in the
Attributes subobject.
The requirement to report a per-hop attribute MUST be specified in
the document that defines the usage of the bit.
6.3.4 Default Behavior
By default all bits in an Attibutes subobject SHOULD be set to zero.
If a received Attribute subobject is not long enough to include a
specific numbered bit, that bit MUST be treated as though present and
as if set to zero.
If the RRO subobject is not present for a hop in the LSP, all bits
MUST be assumed to be set to zero.
7. Summary of Attribute Bit Allocation
This document defines two uses of per-LSP attribute flag bit fields.
The bit numbering in the Attributes Flags TLV and the RRO Attributes
subobject is identical. That is, the same attribute is indicated by
the same bit in both places. This means that only a single registry
of bits is maintained.
The consequence is a degree of clarity in implementation and
registration.
Note, however, that it is not always the case that a bit will be used
in both the Attributes Flags TLV and the RRO Attributes subobject.
For example, an attribute may be requested using the Attributes Flags
TLV, but there is no requirement to report the handling of the
attribute on a hop-by-hop basis. Conversely, there may be a
requirement to report the attributes of an LSP on a hop-by-hop basis,
but there is no corresponding request attribute.
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In these cases, a single bit number is still assigned for both the
Attributes Flags TLV and the RRO Attributes subobject even though the
bit may be irrelevant in either the Attributes Flags or the RRO
Attributes subobject. The document that defines the usage of the new
bit MUST state in which places it is used and MUST handle a default
setting of zero.
8. Message Formats
The LSP_ATTRIBUTES object and the LSP_REQUIRED_ATTRIBUTES object MAY
be carried in a Path message.
The order of objects in RSVP-TE messages is recommended, but
implementations must be capable of receiving the objects in any
meaningful order. The LSP_ATTRIBUTES object and LSP_REQUIRED_
ATTRIBUTES objects are RECOMMENDED to be placed immediately after the
SESSION_ATTRIBUTE object if it is present, or otherwise immediately
after the LABEL_REQUEST object.
If both the LSP_ATTRIBUTES object and the LSP_REQUIRED_ATTRIBUTES
object are present, the LSP_REQUIRED_ATTRIBUTES object is RECOMMENDED
to be placed first.
LSRs SHOULD be prepared to receive these objects in any order in any
position within a Path message. Subsequent instances of these objects
within a Path message SHOULD be ignored and those objects MUST be
forwarded unchanged transparently.
9. IANA Considerations
9.1 New RSVP C-Nums and C-Types
Two new RSVP C-Nums are defined in this document and should be
assigned by IANA.
o LSP_ATTRIBUTES object
The C-Num should be of the form 11bbbbbb so that LSRs that do not
recognize the object will ignore the object but forward it,
unexamined and unmodified, in all messages resulting from this
message.
One C-Type is defined for this object and should be assigned by
IANA.
o LSP Attributes TLVs
Recommended C-Type value 1.
o LSP_REQUIRED_ATTRIBUTES object
The C-Num should be of the form 0bbbbbbb so that LSRs that do not
recognize the object will reject the message that carries it with
an "Unknown Object Class" error.
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One C-Type is defined for this object and should be assigned by
IANA.
o LSP Required Attributes TLVs
Recommended C-Type value 1.
9.2 New TLV Space
The two new objects referenced above are constructed from TLVs. Each
TLV includes a 16-bit type identifier (the T-field). The same T-field
values are applicable to both objects.
IANA is requested to manage TLV type identifiers as follows:
- TLV Type (T-field value)
- TLV Name
- Whether allowed on LSP_ATTRIBUTES object
- Whether allowed on LSP_REQUIRED_ATTRIBUTES object.
This document defines one TLV type as follows:
- TLV Type = 1
- TLV Name = Attributes Flags TLV
- allowed on LSP_ATTRIBUTES object
- allowed on LSP_REQUIRED_ATTRIBUTES object.
9.3 Attributes Flags
This document provides new attributes bit flags for use in other
documents that specify new RSVP-TE attributes. These flags are
present in the Attributes Flags TLV referenced in the previous
section.
IANA is requested to manage the space of attributes bit flags
numbering them in the usual IETF notation starting at zero and
continuing through 2039.
Each bit should be tracked with the following qualities:
- Bit number
- Defining RFC
- Name of bit
- Whether there is meaning in the Attibute Flags TLV (yes/no)
- Whether there is meaning in the RRO Attributes Subobject (yes/no).
Note that this means that all bits in the Attribute Flags TLV and the
RRO Attributes Subobject use the same bit number regardless of
whether they are used in one or both places. Thus, only one list of
bits is required to be maintained. (It would be meaningless in the
context of this document for a bit to have no meaning in neither the
Attribute Flags TLV nor the RRO Attributes Subobject.)
9.4 SESSION_ATTRIBUTE Flags Field
This document does not make any alterations to the definition of the
existing SESSION_ATTRIBUTE object nor to the definition of meanings
assigned to the flags in the Flags field of that object. These flags
are assigned meanings in various other RFCs and Internet Drafts.
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It is suggested that IANA manage the allocation of meaning to the
bits in the Flags field of the SESSION_ATTRIBUTE object to prevent
accidental double allocation of any one bit.
9.5 New Error Codes
This document defines the following new error codes and error values.
Numeric values should be assigned by IANA.
Error Code Error Value
"Unknown Attributes TLV" Identifies the unknown TLV type code.
"Unknown Attributes Bit" Identifies the unknown Attribute Bit.
9.6 New Record Route Subobject Identifier
A new subobject is defined for inclusion in the RECORD_ROUTE object.
The RRO Attributes subobject is identified by a Type value of TBD.
10. Security Considerations
This document adds two new objects to the RSVP Path message as used
in MPLS and GMPLS signaling, and a new subobject to the RECORD_ROUTE
object carried on may RSVP messages. It does not introduce any new
direct security issues and the reader is referred to the security
considerations expressed in [RFC2205], [RFC3209] and [RFC3473].
It is of passing note that any signaling request that indicates the
functional preferences or attributes of an MPLS LSP may provide
anyone with unauthorized access to the contents of the message with
information about the LSP that an administrator may wish to keep
secret. Although this document adds new objects for signaling desired
LSP attributes, it does not contribute to this issue which can
only be satisfactorily handled by encrypting the content of the
signaling message.
Similarly, the addition of attribute recording information to the
RRO may reveal information about the status of the LSP and the
capabilities of individual LSRs that operators wish to keep secret.
The same strategy that applies to other RRO subobjects also applies
here. Note, however, that there is a tension between notifying the
head end of the LSP status at transit LSRs, and hiding the existence
or identity of the transit LSRs.
11. Acknowledgements
Credit to the OSPF Working Group for inspiration from their solution
to a similar problem.
Thanks to Rahul Aggarwal for his careful review and support of this
work. Thanks also to Raymond Zhang, Kireeti Kompella, Philip Matthews
and Jim Gibson for their input.
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12. Intellectual Property Consideration
The IETF takes no position regarding the validity or scope
of any intellectual property or other rights that might be
claimed to pertain to the implementation or use of the
technology described in this document or the extent to
which any license under such rights might or might not be
available; neither does it represent that it has made any
effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track
and standards-related documentation can be found in BCP-11.
Copies of claims of rights made available for publication
and any assurances of licenses to be made available, or the
result of an attempt made to obtain a general license or
permission for the use of such proprietary rights by
implementors or users of this specification can be obtained
from the IETF Secretariat.
The IETF invites any interested party to bring to its
attention any copyrights, patents or patent applications, or
other proprietary rights which may cover technology that may
be required to practice this standard. Please address the
information to the IETF Executive Director.
13. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R. (Ed.), Zhang, L., Berson, S., Herzog, S.
and S. Jamin, "Resource ReserVation Protocol --
Version 1 Functional Specification", RFC 2205,
September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T.,
Srinivasan, V. and G. Swallow, "RSVP-TE: Extensions
to RSVP for LSP Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L. (Editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, January 2003.
[RFC3473] Berger, L. (Editor), "Generalized MPLS Signaling -
RSVP-TE Extensions", RFC 3473 January 2003.
14. Informative References
[RFC2026] Bradner, S., "The Internet Standards Process
-- Revision 3", RFC 2026, October 1996.
[RFC3031] Rosen, E., Viswanathan, A., and Callon, R.,
"Multiprotocol Label Switching
Architecture", RFC 3031, January 2001.
Farrel, Papadimitriou, Vasseur and Ayyangar Page 13
draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
[INTER-AS] Vasseur, JP., Zhang, R., "Inter-AS MPLS Traffic
Engineering", <draft-vasseur-inter-as-te-03.txt>,
Internet Draft, work in progress.
[FRR] Pan, P. (Ed.), "Fast Reroute Extensions to RSVP-TE for
LSP Tunnels", <draft-ietf-mpls-rsvp-lsp-fastreroute-03
.txt>, Internet Draft, work in progress.
[OSPF-CAPS] Lindem, A., Shen, N., Aggarwal, R., Shaffer, S.,
Vasseur, JP., "Extensions to OSPF for Advertising
Optional Router Capabilities", <draft-ietf-ospf-cap-
00.txt>, Internet Draft, work in progress.
[REOPT] Vasseur, JP., Ikejiri, Y., "Reoptimization of MPLS
Traffic Engineering loosely routed explicit LSP path",
<draft-vasseur-mpls-loose-path-reopt-02.txt>, Internet
Draft, work in progress.
15. Authors' Addresses
Adrian Farrel
Old Dog Consulting
Phone: +44 (0) 1978 860944
EMail: adrian@olddog.co.uk
Dimitri Papadimitriou (Alcatel)
Fr. Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491
EMail: dimitri.papadimitriou@alcatel.be
Jean Philippe Vasseur
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough , MA - 01719
USA
EMail: jpv@cisco.com
Arthi Ayyangar
Juniper Networks, Inc.
1194 N.Mathilda Ave
Sunnyvale, CA 94089
USA
EMail: arthi@juniper.net
16. Full Copyright Statement
Copyright (C) The Internet Society (2004). All Rights
Reserved.
This document and translations of it may be copied and
furnished to others, and derivative works that comment on
or otherwise explain it or assist in its implementation may
be prepared, copied, published and distributed, in whole or
in part, without restriction of any kind, provided that the
above copyright notice and this paragraph are included on
all such copies and derivative works. However, this
Farrel, Papadimitriou, Vasseur and Ayyangar Page 14
draft-ietf-mpls-rsvpte-attributes-02.txt January 2004
document itself may not be modified in any way, such as by
removing the copyright notice or references to the Internet
Society or other Internet organizations, except as needed
for the purpose of developing Internet standards in which
case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to
translate it into languages other than English.
The limited permissions granted above are perpetual and
will not be revoked by the Internet Society or its
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contained herein is provided on an "AS IS" basis and THE
INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE
DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
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PURPOSE.
Farrel, Papadimitriou, Vasseur and Ayyangar Page 15
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