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Versions: (draft-berger-ccamp-assoc-info) 00
01 02 03 RFC 6689
Internet Draft Lou Berger (LabN)
Updates: 2205, 3209, 3473 Francois Le Faucheur (Cisco)
Category: Standards Track Ashok Narayanan (Cisco)
Expiration Date: April 14, 2011
October 14, 2010
Usage of The RSVP Association Object
draft-ietf-ccamp-assoc-info-00.txt
Abstract
The RSVP ASSOCIATION object was defined in the context of GMPLS
(Generalized Multi-Protocol Label Switching) controlled label
switched paths (LSPs). In this context, the object is used to
associate recovery LSPs with the LSP they are protecting. This
object also has broader applicability as a mechanism to associate
RSVP state, and this document defines how the ASSOCIATION object
can be more generally applied. The document also reviews how the
association is to be provided in the context of GMPLS recovery.
No new new procedures or mechanisms are defined with respect to
GMPLS recovery.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 14, 2011
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Copyright and License Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction ........................................... 3
1.1 Conventions Used In This Document ...................... 4
2 Background ............................................. 4
2.1 LSP Association ........................................ 4
2.2 End-to-End Recovery LSP Association .................... 6
2.3 Segment Recovery LSP Association ....................... 8
2.4 Resource Sharing LSP Association ....................... 9
3 Association of GMPLS Recovery LSPs ..................... 10
4 Non-Recovery Usage ..................................... 11
4.1 Upstream Initiated Association ......................... 11
4.1.1 Path Message Format .................................... 12
4.1.2 Path Message Processing ................................ 12
4.2 Downstream Initiated Association ....................... 13
4.2.1 Resv Message Format .................................... 14
4.2.2 Resv Message Processing ................................ 14
4.3 Association Types ...................................... 15
4.3.1 Resource Sharing Association Type ...................... 15
5 Extended IPv4 and IPv6 ASSOCIATION Objects ............. 16
5.1 Extended IPv4 and IPv6 ASSOCIATION Object Format ....... 16
6 Security Considerations ................................ 18
7 IANA Considerations .................................... 18
7.1 Extended IPv4 and IPv6 ASSOCIATION Objects ............. 18
7.2 Resource Sharing Association Type ...................... 19
8 Acknowledgments ........................................ 19
9 References ............................................. 19
9.1 Normative References ................................... 19
9.2 Informative References ................................. 20
10 Authors' Addresses ..................................... 20
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1. Introduction
End-to-end and segment recovery are defined for GMPLS (Generalized
Multi-Protocol Label Switching) controlled label switched paths
(LSPs) in [RFC4872] and [RFC4873] respectively. Both definitions use
the ASSOCIATION object to associate recovery LSPs with the LSP they
are protecting. This document provides additional narrative on how
such associations are to be identified. In the context of GMPLS
recovery, this document does not define any new procedures or
mechanisms and is strictly informative in nature. In this context,
this document formalizes the explanation provided in an e-mail to the
Common Control and Measurement Plane (CCAMP) working group authored
by Adrian Farrel, see [AF-EMAIL]. This document in no way modifies
the normative definitions of end-to-end and segment recovery, see
[RFC4872] or [RFC4873].
In addition to the narrative, this document also explicitly expands
the possible usage of the ASSOCIATION object in other contexts. In
Section 4, this document reviews how association should be made in
the case where the object is carried in a Path message and defines
usage with Resv messages. This section also discusses usage of the
ASSOCIATION object outside the context of GMPLS LSPs.
Some examples of non-LSP association in order to enable resource
sharing are:
o Voice Call-Waiting:
A bidirectional voice call between two endpoints A and B is
signaled using two separate unidirectional RSVP reservations for
the flows A->B and B->A. If endpoint A wishes to put the A-B call
on hold and join a separate A-C call, it is desirable that
network resources on common links be shared between the A-B and
A-C calls. The B->A and C->A subflows of the call can share
resources using existing RSVP sharing mechanisms, but only if
they use the same destination IP addresses and ports. However,
there is no way in RSVP today to share the resources between the
A->B and A->C subflows of the call since by definition the RSVP
reservations for these subflows must have different IP addresses
in the SESSION objects.
o Voice Shared Line:
A single number that rings multiple endpoints (which may be
geographically diverse), such as phone lines on a manager's desk
and their assistant. A VoIP system that models these calls as
multiple P2P unicast pre-ring reservations would result in
significantly over-counting bandwidth on shared links, since
today unicast reservations to different endpoints cannot share
bandwidth.
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o Symmetric NAT:
RSVP permits sharing of resources between multiple flows
addressed to the same destination D, even from different senders
S1 and S2. However, if D is behind a NAT operating in symmetric
mode [RFC5389], it is possible that the destination port of the
flows S1->D and S2->D may be different outside the NAT. In this
case, these flows cannot share resources using RSVP today, since
the SESSION objects for these two flows outside the NAT would
have different ports.
1.1. Conventions Used In This Document
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].
2. Background
This section reviews the definition of LSP association in the
contexts of end-to-end and segment recovery as defined in [RFC4872]
and [RFC4873]. This section merely reiterates what has been defined,
if differences exist between this text and [RFC4872] or [RFC4873],
the earlier RFCs provide the authoritative text.
2.1. LSP Association
[RFC4872] introduces the concept and mechanisms to support the
association of one LSP to another LSP across different RSVP-TE
sessions. Such association is enabled via the introduction of the
ASSOCIATION object. The ASSOCIATION object is defined in Section 16
of [RFC4872]. It is explicitly defined as having both general
application and specific use within the context of recovery. End-to-
end recovery usage is defined in [RFC4872] and is covered in Section
2.2. Segment recovery usage is defined in [RFC4873] and is covered
in Section 2.3. Resource sharing LSP association is also defined in
[RFC4873], while strictly speaking such association is beyond the
scope of this document, for completeness it is covered in Section
2.4. The remainder of this section covers generic usage of the
ASSOCIATION object.
In general, LSP association using the ASSOCIATION object can take
place based on the values carried in the ASSOCIATION object. This
means that association between LSPs can take place independent from
and across different sessions. This is a significant enhancement
from the association of LSPs that is possible in base MPLS [RFC3209]
and GMPLS [RFC3473].
When using ASSOCIATION object, LSP association is always initiated by
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an upstream node that inserts appropriate ASSOCIATION objects in the
Path message of LSPs that are to be associated. Downstream nodes
then correlate LSPs based on received ASSOCIATION objects. Multiple
types of LSP association is supported by the ASSOCIATION object, and
downstream correlation is made based on the type.
[RFC4872] defines C-Types 1 and 2 of the ASSOCIATION object. Both
objects have essentially the same semantics, only differing in the
type of address carried (IPv4 and IPv6). The defined objects carry
three fields. The three fields taken together enable the
identification of which LSPs are association with one another. The
three defined fields are:
o Association Type:
This field identifies the usage, or application, of the
association object. The currently defined values are Recovery
[RFC4872] and Resource Sharing [RFC4873]. This field also scopes
the interpretation of the object. In other words, the type field
is included when matching LSPs (i.e., the type fields must
match), and the way associations are identified may be type
dependent.
o Association Source:
This field is used to provide global scope (within the address
space) to the identified association. There are no specific
rules in the general case for which address should be used by a
node creating an ASSOCIATION object beyond that the address is
"associated to the node that originated the association", see
[RFC4872].
o Association ID:
This field provides an "identifier" that further scopes an
association. Again, this field is combined with the other
ASSOCIATION object fields to support identification of associated
LSPs. The generic definition does not provide any specific rules
on how matching is to be done, so such rules are governed by the
Association Type. Note that the definition permits the
association of an arbitrary number of LSPs.
As defined, the ASSOCIATION object may only be carried in a Path
message, so LSP association takes place based on Path state. The
definition permits one or more objects to be present. The support
for multiple objects enables an LSP to be associated with other LSPs
in more than one way at a time. For example, an LSP may carry one
ASSOCIATION object to associate the LSP with another LSP for end-to-
end recovery, and at the same time carry a second ASSOCIATION object
to associate the LSP with another LSP for segment recovery, and at
the same time carry a third ASSOCIATION object to associate the LSP
with yet another LSP for resource sharing.
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2.2. End-to-End Recovery LSP Association
The association of LSPs in support of end-to-end LSP recovery is
defined in Section 16.2 of [RFC4872]. There are also several
additional related conformance statements (i.e., use of [RFC2119]
defined key words) in Sections 7.3, 8.3, 9.3, 11.1. When analyzing
the definition, as with any Standards Track RFC, it is critical to
note and differentiate which statements are made using [RFC2119]
defined key words, which relate to conformance, and which statements
are made without such key words, which are only informative in
nature.
As defined in Section 16.2, end-to-end recovery related LSP
association may take place in two distinct forms:
a. Between multiple (one or more) working LSPs and a single shared
(associated) recovery LSP. This form essentially matches the
shared 1:N (N >= 1) recovery type described in the other
sections of [RFC4872].
b. Between a single working LSP and multiple (one or more)
recovery LSPs. This form essentially matches all other
recovery types described in [RFC4872].
Both forms share the same Association Type (Recovery) and the same
Association Source (the working LSP's tunnel sender address). They
also share the same definition of the Association ID, which is
(quoting [RFC4872]):
"The Association ID MUST be set to the LSP ID of the LSP being
protected by this LSP or the LSP protecting this LSP. If unknown,
this value is set to its own signaled LSP ID value (default).
Also, the value of the Association ID MAY change during the
lifetime of the LSP."
The interpretation of the above is fairly straightforward. The
Association ID carries one of 3 values:
- The LSP ID of the LSP being protected.
- The LSP ID of the LSP protecting an LSP.
- In the case where the matching LSP is not yet known (i.e.,
initiated), the LSP ID value of the LSP itself.
The text also explicitly allows for changing the Association ID
during the lifetime of an LSP. But this is only an option, and is
neither required (i.e., "MUST") nor recommended (i.e., "SHOULD"). It
should be noted that the document does not describe when such a
change should be initiated, or the procedures for such a change.
Clearly care needs to be taken when changing the Association ID to
ensure that the old association is not lost during the transition to
a new association.
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The text does not preclude, and it is therefore assumed, that one or
more ASSOCIATION objects may also be added to an LSP that was
originated without any ASSOCIATION objects. Again this is a case
that is not explicitly discussed in [RFC4872].
From the above, this means that the following combinations may occur:
Case 1. When the ASSOCIATION object of the LSP being protected is
initialized before the ASSOCIATION objects of any recovery
LSPs are initialized, the Association ID in the LSP being
protected and any recovery LSPs will carry the same value
and this value will be the LSP ID value of the LSP being
protected.
Case 2. When the ASSOCIATION object of a recovery LSP is
initialized before the ASSOCIATION object of any protected
LSP is initialized, the Association ID in the recovery LSP
and any LSPs being protected by that LSP will carry the
same value and this value will be the LSP ID value of the
recovery LSP.
Case 3. When the ASSOCIATION objects of both the LSP being
protected and the recovery LSP are concurrently
initialized, the value of the Association ID carried in
the LSP being protected is the LSP ID value of the
recovery LSP, and the value of the Association ID carried
in the recovery LSP is the LSP ID value of the LSP being
protected. As this case can only be applied to LSPs with
matching tunnel sender addresses, the scope of this case
is limited to end-to-end recovery. Note that this is
implicit in [RFC4872] as its scope is limited to end-to-
end recovery.
In practical terms, case 2 will only occur when using the shared 1:N
(N >= 1) end-to-end recovery type and case 1 will occur with all
other end-to-end recovery types. Case 3 is allowed, and it is
subject to interpretation how often it will occur. Some believe that
this case is the common case and, furthermore, that working and
recovery LSPs will often first be initiated without any ASSOCIATION
objects and then case 3 objects will be added once the LSPs are
established. Others believe that case 3 will rarely if ever occur.
Such perspectives have little impact on interoperability as a
[RFC4872] compliant implementation needs to properly handle (identify
associations for) all three cases.
It is important to note that Section 16.2 of [RFC4872] provides no
further requirements on how or when the Association ID value is to be
selected. The other sections of the document do provide further
narrative and 3 additional requirements. In general, the narrative
highlights case 3 identified above but does not preclude the other
cases. The 3 additional requirements are, by [RFC4872] Section
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number:
o Section 7.3 -- "The Association ID MUST be set by default to the
LSP ID of the protected LSP corresponding to N = 1."
When considering this statement together with the 3 cases
enumerated above, it can be seen that this statement clarifies
which LSP ID value should be used when a single shared protection
LSP is established simultaneously with (case 3), or after (case
2), more than one LSP to be protected.
o Section 8.3 -- "Secondary protecting LSPs are signaled by setting
in the new PROTECTION object the S bit and the P bit to 1, and in
the ASSOCIATION object, the Association ID to the associated
primary working LSP ID, which MUST be known before signaling of
the secondary LSP."
This requirement clarifies that the Rerouting without Extra-
Traffic type of recovery is required to follow either case 1 or
3, but not 2, as enumerated above.
o Section 9.3 -- "Secondary protecting LSPs are signaled by setting
in the new PROTECTION object the S bit and the P bit to 1, and in
the ASSOCIATION object, the Association ID to the associated
primary working LSP ID, which MUST be known before signaling of
the secondary LSP."
This requirement clarifies that the Shared-Mesh Restoration type
of recovery is required to follow either case 1 or 3, but not 2,
as enumerated above.
o Section 11.1 -- "In both cases, the Association ID of the
ASSOCIATION object MUST be set to the LSP ID value of the
signaled LSP."
This requirement clarifies that when using the LSP Rerouting type
of recovery is required to follow either case 1 or 3, but not 2,
as enumerated above.
2.3. Segment Recovery LSP Association
GMPLS segment recovery is defined in [RFC4873]. Segment recovery
reuses the LSP association mechanisms, including the Association Type
field value, defined in [RFC4872]. The primary text to this effect
in [RFC4873] is:
3.2.1. Recovery Type Processing
Recovery type processing procedures are the same as those
defined in [RFC4872], but processing and identification occur
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with respect to segment recovery LSPs. Note that this means
that multiple ASSOCIATION objects of type recovery may be
present on an LSP.
This statement means that case 2 as enumerated above is to be
followed and furthermore that Association Source is set to the tunnel
sender address of the segment recovery LSPs. The explicit exclusion
of case 3 is not listed as its non-applicability was considered
obvious to the informed reader. (Perhaps having this exclusion
explicitly identified would have obviated the need for this
document.)
2.4. Resource Sharing LSP Association
Section 3.2.2 of [RFC4873] defines an additional type of LSP
association which is used for "Resource Sharing". Resource sharing
enables the sharing of resources across LSPs with different SESSION
objects. Without this object only sharing across LSPs with a shared
SESSION object was possible, see [RFC3209].
Resource sharing is indicated using a new Association Type value. As
the Association Type field value is not the same as is used in
Recovery LSP association, the semantics used for the association of
LSPs using an ASSOCIATION object containing the new type differs from
Recovery LSP association.
Section 3.2.2 of [RFC4873] states the following rules for the
construction of an ASSOCIATION object in support of resource sharing
LSP association:
- The Association Type value is set to "Resource Sharing".
- Association Source is set to the originating node's router
address.
- The Association ID is set to a value that uniquely identifies the
set of LSPs to be associated.
The setting of the Association ID value to the working LSP's LSP
ID value is mentioned, but using the "MAY" key word. Per
[RFC2119], this translates to the use of LSP ID value as being
completely optional and that the choice of Association ID is
truly up to the originating node.
Additionally, the identical ASSOCIATION object is used for all LSPs
that should be associated using Resource Sharing. This differs from
recovery LSP association where it is possible for the LSPs to carry
different Association ID fields and still be associated (see case 3
in Section 2.2).
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3. Association of GMPLS Recovery LSPs
The previous section reviews the construction of an ASSOCIATION
object, including the selection of the value used in the Association
ID field, as defined in [RFC4872] and [RFC4873]. This section reviews
how a downstream receiver identifies that one LSP is associated
within another LSP based on ASSOCIATION objects. Note that in no way
does this section modify the normative definitions of end-to-end and
segment recovery, see [RFC4872] or [RFC4873].
As the ASSOCIATION object is only carried in Path messages, such
identification only takes place based on Path state. In order to
support the identification of the recovery type association between
LSPs, a downstream receiver needs to be able to handle all three
cases identified in Section 2.2. Cases 1 and 2 are simple as the
associated LSPs will carry the identical ASSOCIATION object. This is
also always true for resource sharing type LSP association, see
Section 2.4. Case 3 is more complicated as it is possible for the
LSPs to carry different Association ID fields and still be
associated. The receiver also needs to allow for changes in the set
of ASSOCIATION objects included in an LSP.
Based on the [RFC4872] and [RFC4873] definitions related to the
ASSOCIATION object, the following behavior can be followed to ensure
that a receiver always properly identifies the association between
LSPs:
o Covering cases 1 and 2 and resource sharing type LSP association:
For ASSOCIATION objects with the Association Type field values of
"Recovery" (1) and "Resource Sharing" (2), the association
between LSPs is identified by comparing all fields of each of the
ASSOCIATION objects carried in the Path messages associated with
each LSP. An association is deemed to exist when the same values
are carried in all three fields of an ASSOCIATION object carried
in each LSP's Path message. As more than one association may
exist (e.g., in support of different association types or end-to-
end and segment recovery), all carried ASSOCIATION objects need
to be examined.
o Covering case 3:
Any ASSOCIATION object with the Association Type field value of
"Recovery" (1) that does not yield an association in the prior
comparison needs to be checked to see if a case 3 association is
indicated. As this case only applies to end-to-end recovery, the
first step is to locate any other LSPs with the identical SESSION
object fields and the identical tunnel sender address fields as
the LSP carrying the ASSOCIATION object. If such LSPs exist, a
case 3 association is identified by comparing the value of the
Association ID field with the LSP ID field of the other LSP. If
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the values are identical, then an end-to-end recovery association
exists. As this behavior only applies to end-to-end recovery,
this check need only be performed at the egress.
No additional behavior is needed in order to support changes in the
set of ASSOCIATION objects included in an LSP, as long as the change
represents either a new association or a change in identifiers made
as described in Section 2.2.
4. Non-Recovery Usage
While the ASSOCIATION object, [RFC4872], is defined in the context of
Recovery, the object can have wider application. [RFC4872] defines
the object to be used to "associate LSPs with each other", and then
defines an Association Type field to identify the type of association
being identified. It also defines that the Association Type field is
to be considered when determining association, i.e., there may be
type-specific association rules. As discussed above, this is the
case for Recovery type association objects. The text above, notably
the text related to resource sharing types, can also be used as the
foundation for a generic method for associating LSPs when there is no
type-specific association defined.
The remainder of this section defines the general rules to be
followed when processing ASSOCIATION objects. Object usage in both
Path and Resv messages is discussed. The usage applies equally to
GMPLS LSPs [RFC3473], MPLS LSPs [RFC3209] and non-LSP RSVP sessions
[RFC2205], [RFC2207], [RFC3175] and [RFC4860]. As described below
association is always done based on matching either Path state or
Resv state, but not Path state to Resv State.
4.1. Upstream Initiated Association
Upstream initiated association is represented in ASSOCIATION objects
carried in Path messages and can be used to associate RSVP Path state
across MPLS Tunnels / RSVP sessions. (Note, per [RFC3209] an MPLS
tunnel is represented by a RSVP SESSION object, and multiple LSPs may
be represented within a single tunnel.) Cross-session association
based on Path state is defined in [RFC4872]. This definition is
extended by this section, which defined generic association rules and
usage for non-LSP uses. This section does not modify processing
required to support [RFC4872] and [RFC4873], which is reviewed above
in Section 3.
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4.1.1. Path Message Format
This section provides the Backus-Naur Form (BNF), see [RFC5511], for
Path messages containing ASSOCIATION objects. BNF is provided for
both MPLS and for non-LSP session usage. Unmodified RSVP message
formats and some optional objects are not listed.
The format for MPLS and GMPLS sessions is unmodified from [RFC4872],
and can be represented based on the BNF in [RFC3209] as:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <EXPLICIT_ROUTE> ]
<LABEL_REQUEST>
[ <SESSION_ATTRIBUTE> ]
[ <ASSOCIATION> ... ]
[ <POLICY_DATA> ... ]
<sender descriptor>
The format for non-LSP sessions as based on the BNF in [RFC2205] is:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <ASSOCIATION> ... ]
[ <POLICY_DATA> ... ]
[ <sender descriptor> ]
In general, relative ordering of ASSOCIATION objects with respect to
each other as well as with respect to other objects is not
significant. Relative ordering of ASSOCIATION objects of the same
type SHOULD be preserved by transit nodes. Association type specific
ordering requirements MAY be defined in the future.
4.1.2. Path Message Processing
This section is based on the processing rules described in [RFC4872]
and [RFC4873], which is reviewed above. These procedures apply
equally to GMPLS LSPs, MPLS LSPs and non-LSP session state.
A node that wishes to allow downstream nodes to associate Path state
across RSVP sessions MUST include an ASSOCIATION object in the
outgoing Path messages corresponding to the RSVP sessions to be
associated. In the absence of Association Type-specific rules for
identifying association, the included ASSOCIATION objects MUST be
identical. When there is an Association Type-specific definition of
association rules, the definition SHOULD allow for association based
on identical ASSOCIATION objects. This document does not define any
Association Type-specific rules. (See Section 3 for a discussion of
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an example of Association Type-specific rules which are derived from
[RFC4872].)
When creating an ASSOCIATION object, the originator MUST format the
object as defined in Section 16.1 of [RFC4872]. The originator MUST
set the Association Type field based on the type of association being
identified. The Association ID field MUST be set to a value that
uniquely identifies the sessions to be associated within the context
of the Association Source field. The Association Source field MUST
be set to a unique address assigned to the node originating the
association.
A downstream node can identify an upstream initiated association by
performing the following checks. When a node receives a Path message
it MUST check each ASSOCIATION object received in the Path message to
see if it contains an Association Type field value supported by the
node. For each ASSOCIATION object containing a supported association
type, the node MUST then check to see if the object matches an
ASSOCIATION object received in any other Path message. To perform
this matching, a node MUST examine the Path state of all other
sessions and compare the fields contained in the newly received
ASSOCIATION object with the fields contained in the Path state's
ASSOCIATION objects. An association is deemed to exist when the same
values are carried in all three fields of the ASSOCIATION objects
being compared. Processing once an association is identified is type
specific and is outside the scope of this document.
Note that as more than one association may exist, all ASSOCIATION
objects carried in a received Path message which have supported
association types MUST be compared against all Path state.
Unless there is are type-specific processing rules, downstream nodes
MUST forward all ASSOCIATION objects received in a Path message with
any corresponding outgoing Path messages.
4.2. Downstream Initiated Association
Downstream initiated association is represented in ASSOCIATION
objects carried in Resv messages and can be used to associate RSVP
Resv state across MPLS Tunnels / RSVP sessions. Cross-session
association based on Path state is defined in [RFC4872]. This section
defines cross-session association based on Resv state. This section
places no additional requirements on implementations supporting
[RFC4872] and [RFC4873].
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4.2.1. Resv Message Format
This section provides the Backus-Naur Form (BNF), see [RFC5511], for
Resv messages containing ASSOCIATION objects. BNF is provided for
both MPLS and for non-LSP session usage. Unmodified RSVP message
formats and some optional objects are not listed.
The format for MPLS, GMPLS and non-LSP sessions are identical, and is
represented based on the BNF in [RFC2205] and [RFC3209]:
<Resv Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <RESV_CONFIRM> ] [ <SCOPE> ]
[ <ASSOCIATION> ... ]
[ <POLICY_DATA> ... ]
<STYLE> <flow descriptor list>
Relative ordering of ASSOCIATION objects with respect to each other
as well as with respect to other objects is not currently
significant. Relative ordering of ASSOCIATION objects of the same
type MUST be preserved by transit nodes. Association type specific
ordering requirements MAY be defined in the future.
4.2.2. Resv Message Processing
This section apply equally to GMPLS LSPs, MPLS LSPs and non-LSP
session state.
A node that wishes to allow upstream nodes to associate Resv state
across RSVP sessions MUST include an ASSOCIATION object in the
outgoing Resv messages corresponding to the RSVP sessions to be
associated. In the absence of Association Type-specific rules for
identifying association, the included ASSOCIATION objects MUST be
identical. When there is an Association Type-specific definition of
association rules, the definition SHOULD allow for association based
on identical ASSOCIATION objects. This document does not define any
Association Type-specific rules.
When creating an ASSOCIATION object, the originator MUST format the
object as defined in Section 16.1 of [RFC4872]. The originator MUST
set the Association Type field based on the type of association being
identified. The Association ID field MUST be set to a value that
uniquely identifies the sessions to be associated within the context
of the Association Source field. The Association Source field MUST
be set to a unique address assigned to the node originating the
association.
An upstream node can identify a downstream initiated association by
performing the following checks. When a node receives a Resv message
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it MUST check each ASSOCIATION object received in the Resv message to
see if it contains an Association Type field value supported by the
node. For each ASSOCIATION object containing a supported association
type, the node MUST then check to see if the object matches an
ASSOCIATION object received in any other Resv message. To perform
this matching, a node MUST examine the Resv state of all other
sessions and compare the fields contained in the newly received
ASSOCIATION object with the fields contained in the Resv state's
ASSOCIATION objects. An association is deemed to exist when the same
values are carried in all three fields of the ASSOCIATION objects
being compared. Processing once an association is identified is type
specific and is outside the scope of this document.
Note that as more than one association may exist, all ASSOCIATION
objects with support Association Types carried in a received Resv
message MUST be compared against all Resv state.
Unless there is are type-specific processing rules, upstream nodes
MUST forward all ASSOCIATION objects received in a Resv message with
any corresponding outgoing Resv messages.
4.3. Association Types
Two association types are currently defined: recovery and resource
sharing. Recovery type association is only applicable within the
context of recovery, [RFC4872] and [RFC4873]. Resource sharing is
generally useful and its general use is defined in this section.
4.3.1. Resource Sharing Association Type
The resource sharing association type was defined in [RFC4873] and
was defined within the context of GMPLS and upstream initiated
association. This section presents a definition of the resource
sharing association that allows for its use with any RSVP session
type and in both Path and Resv messages. This definition is
consistent with the definition of the resource sharing association
type in [RFC4873] and no changes are required by this section in
order to support [RFC4873]. The Resource Sharing Association Type
MUST be supported by any implementation compliant with this document.
The Resource Sharing Association Type is used to enable resource
sharing across RSVP sessions. Per [RFC4873], Resource Sharing uses
the Association Type field value of 2. ASSOCIATION objects with an
Association Type with the value Resource Sharing MAY be carried in
Path and Resv messages. Association for the Resource Sharing type
MUST follow the procedures defined in Section 4.1.2 for upstream
(Path message) initiated association and Section 4.2.1 for downstream
(Resv message) initiated association. There are no type-specific
association rules, processing rules, or ordering requirements. Note
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that as is always the case with association as enabled by this
document, no associations are made across Path and Resv state.
Once an association is identified, resources should be shared across
the identified sessions. Resource sharing is discussed in general in
[RFC2205] and within the context of LSPs in [RFC3209].
5. Extended IPv4 and IPv6 ASSOCIATION Objects
[RFC4872] defines the IPv4 ASSOCIATION object and the IPv6
ASSOCIATION object. As defined, these objects each contain an
Association Source field and a 16-bit Association ID field. The
combination of the Association Source and the Association ID uniquely
identifies the association. Because the association-ID field is a
16-bit field, an association source can allocate up to 65536
different associations and no more. There are scenarios where this
number is insufficient. (For example where the association
identification is best known and identified by a fairly centralized
entity, which therefore may be involved in a large number of
associations.)
This sections defines new ASSOCIATION objects to address this
limitation. Specifically, the Extended IPv4 ASSOCIATION object and
Extended IPv6 ASSOCIATION object are defined below. Both new objects
include an extended association ID field, which allows identification
of a larger number of associations scoped within a given association
source IP address.
The Extended IPv4 ASSOCIATION object and Extended IPv6 ASSOCIATION
object SHOULD be supported by an implementation compliant with this
document. The processing rules for the Extended IPv4 and IPv6
ASSOCIATION object are identical to those of the existing IPv4 and
IPv6 ASSOCIATION objects.
5.1. Extended IPv4 and IPv6 ASSOCIATION Object Format
The Extended IPv4 ASSOCIATION object (Class-Num of the form 11bbbbbb
with value = 199, C-Type = TBA) has the format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(199)| C-Type (TBA) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association Type | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association ID (Continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Association Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Extended IPv6 ASSOCIATION object (Class-Num of the form 11bbbbbb
with value = 199, C-Type = TBA) has the format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(199)| C-Type (TBA) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association Type | Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association ID (Continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Association Source |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Association Type: 16 bits
Same as for IPv4 and IPv6 ASSOCIATION objects, see [RFC4872].
Association ID: 48 bits
Same as for IPv4 and IPv6 ASSOCIATION objects, see [RFC4872].
(Only the size of this field differs from the [RFC4872]
definition.)
Association Source: 4 or 16 bytes
Same as for IPv4 and IPv6 ASSOCIATION objects, see [RFC4872].
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6. Security Considerations
A portion of this document reviews procedures defined in [RFC4872]
and [RFC4873] and does not define any new procedures. As such, no
new security considerations are introduced in this portion.
Section 4 defines broader usage of the ASSOCIATION object, but does
not fundamentally expand on the association function that was
previously defined in [RFC4872] and [RFC4873]. Section 5 increases
the number of bits that are carried in an ASSOCIATION object (by 32),
and similarly does not expand on the association function that was
previously defined. This broader definition does allow for
additional information to be conveyed, but this information is not
fundamentally different from the information that is already carried
in RSVP. Therefore there are no new risks or security considerations
introduced by this document.
For a general discussion on MPLS and GMPLS related security issues,
see the MPLS/GMPLS security framework [RFC5920].
7. IANA Considerations
IANA is requested to administer assignment of new values for
namespaces defined in this document and summarized in this section.
7.1. Extended IPv4 and IPv6 ASSOCIATION Objects
Upon approval of this document, IANA will make the assignment of two
new C-Types (which are defined in section 5.1) for the existing
ASSOCIATION object in the "Class Names, Class Numbers, and Class
Types" section of the "Resource Reservation Protocol (RSVP)
Parameters" registry located at http://www.iana.org/assignments/rsvp-
parameters:
199 ASSOCIATION [RFC4872]
Class Types or C-Types
3 Type 3 Extended IPv4 Association [this document]
4 Type 4 Extended IPv6 Association [this document]
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7.2. Resource Sharing Association Type
This document also broadens the potential usage of the Resource
Sharing Association Type defined in [RFC4873]. As such, IANA is
requested to change the Reference of the Resource Sharing Association
Type included in the associate registry. This document also directs
IANA to correct the duplicate usage of '(R)' in this Registry. In
particular, the Association Type registry found at
http://www.iana.org/assignments/gmpls-sig-parameters/ should be
updated as follows:
OLD:
2 Resource Sharing (R) [RFC4873]
NEW
2 Resource Sharing (S) [RFC4873][this-document]
There are no other IANA considerations introduced by this document.
8. Acknowledgments
This document formalizes the explanation provided in an e-mail to the
working group authored by Adrian Farrel, see [AF-EMAIL]. The document
was written in response to questions raised in the CCAMP working
group by Nic Neate <nhn@dataconnection.com>. Valuable comments and
input was also received from Dimitri Papadimitriou.
We thank Subha Dhesikan for her contribution to the early work on
sharing of resources across RSVP reservations.
9. References
9.1. Normative References
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S. and
S. Jamin, "Resource ReSerVation Protocol (RSVP) --
Version 1, Functional Specification", RFC 2205,
September 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4872] Lang, J., Rekhter, Y., and Papadimitriou, D., "RSVP-TE
Extensions in Support of End-to-End Generalized Multi-
Protocol Label Switching (GMPLS) Recovery", RFC 4872,
May 2007.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., Farrel, A.,
"GMPLS Segment Recovery", RFC 4873, May 2007.
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[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.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January
2003.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, April 2009
9.2. Informative References
[AF-EMAIL] Farrel, A. "Re: Clearing up your misunderstanding of
the Association ID", CCAMP working group mailing list,
http://www.ietf.org/mail-archive/web/ccamp/current/msg00644.html,
November 18, 2008.
[RFC2207] Berger., L., O'Malley., T., "RSVP Extensions for IPSEC
RSVP Extensions for IPSEC Data Flows", RFC 2207, September
1997.
[RFC3175] Baker, F., Iturralde, C., Le, F., Davie, B., "Aggregation
of RSVP for IPv4 and IPv6 Reservations", RFC 3175,
September 2001.
[RFC4860] Le, F., Davie, B., Bose, P., Christou, C., Davenport, M.,
"Generic Aggregate Resource ReSerVation Protocol (RSVP)
Reservations", RFC 4860, May 2007.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., Wing, D., "Session
Traversal Utilities for NAT (STUN)", RFC 5389, October
2008.
[RFC5920] Fang, L., et al, "Security Framework for MPLS and
GMPLS Networks", work in progress, RFC 5920, July 2010.
10. Authors' Addresses
Lou Berger
LabN Consulting, L.L.C.
Phone: +1-301-468-9228
Email: lberger@labn.net
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Francois Le Faucheur
Cisco Systems
Greenside, 400 Avenue de Roumanille
Sophia Antipolis 06410
France
Email: flefauch@cisco.com
Ashok Narayanan
Cisco Systems
300 Beaver Brook Road
Boxborough, MA 01719
United States
Email: ashokn@cisco.com
Berger, et al Standards Track [Page 21]
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