draft-ietf-ospf-te-link-attr-reuse-16.txt   rfc8920.txt 
LSR Working Group P. Psenak, Ed. Internet Engineering Task Force (IETF) P. Psenak, Ed.
Internet-Draft L. Ginsberg Request for Comments: 8920 L. Ginsberg
Intended status: Standards Track Cisco Systems Category: Standards Track Cisco Systems
Expires: January 1, 2021 W. Henderickx ISSN: 2070-1721 W. Henderickx
Nokia Nokia
J. Tantsura J. Tantsura
Apstra Apstra
J. Drake J. Drake
Juniper Networks Juniper Networks
June 30, 2020 October 2020
OSPF Application-Specific Link Attributes OSPF Application-Specific Link Attributes
draft-ietf-ospf-te-link-attr-reuse-16.txt
Abstract Abstract
Existing traffic engineering related link attribute advertisements Existing traffic-engineering-related link attribute advertisements
have been defined and are used in RSVP-TE deployments. Since the have been defined and are used in RSVP-TE deployments. Since the
original RSVP-TE use case was defined, additional applications (e.g., original RSVP-TE use case was defined, additional applications (e.g.,
Segment Routing Policy, Loop Free Alternate) have been defined that Segment Routing Policy and Loop-Free Alternates) that also make use
also make use of the link attribute advertisements. In cases where of the link attribute advertisements have been defined. In cases
multiple applications wish to make use of these link attributes the where multiple applications wish to make use of these link
current advertisements do not support application specific values for attributes, the current advertisements do not support application-
a given attribute nor do they support indication of which specific values for a given attribute, nor do they support indication
applications are using the advertised value for a given link. This of which applications are using the advertised value for a given
document introduces new link attribute advertisements in OSPFv2 and link. This document introduces new link attribute advertisements in
OSPFv3 that address both of these shortcomings. OSPFv2 and OSPFv3 that address both of these shortcomings.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on January 1, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8920.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language
3. Requirements Discussion . . . . . . . . . . . . . . . . . . . 4 2. Requirements Discussion
4. Existing Advertisement of Link Attributes . . . . . . . . . . 5 3. Existing Advertisement of Link Attributes
5. Advertisement of Link Attributes . . . . . . . . . . . . . . 5 4. Advertisement of Link Attributes
5.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA . 5 4.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA
6. Advertisement of Application-Specific Values . . . . . . . . 6 5. Advertisement of Application-Specific Values
7. Reused TE link attributes . . . . . . . . . . . . . . . . . . 9 6. Reused TE Link Attributes
7.1. Shared Risk Link Group (SRLG) . . . . . . . . . . . . . . 10 6.1. Shared Risk Link Group (SRLG)
7.2. Extended Metrics . . . . . . . . . . . . . . . . . . . . 10 6.2. Extended Metrics
7.3. Administrative Group . . . . . . . . . . . . . . . . . . 11 6.3. Administrative Group
7.4. Traffic Engineering Metric . . . . . . . . . . . . . . . 11 6.4. Traffic Engineering Metric
8. Maximum Link Bandwidth . . . . . . . . . . . . . . . . . . . 11 7. Maximum Link Bandwidth
9. Considerations for Extended TE Metrics . . . . . . . . . . . 12 8. Considerations for Extended TE Metrics
10. Local Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12 9. Local Interface IPv6 Address Sub-TLV
11. Remote Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12 10. Remote Interface IPv6 Address Sub-TLV
12. Attribute Advertisements and Enablement . . . . . . . . . . . 13 11. Attribute Advertisements and Enablement
13. Deployment Considerations . . . . . . . . . . . . . . . . . . 14 12. Deployment Considerations
13.1. Use of Legacy RSVP-TE LSA Advertisements . . . . . . . . 14 12.1. Use of Legacy RSVP-TE LSA Advertisements
13.2. Interoperability, Backwards Compatibility and Migration 12.2. Interoperability, Backwards Compatibility, and Migration
Concerns . . . . . . . . . . . . . . . . . . . . . . . . 15 Concerns
13.2.1. Multiple Applications: Common Attributes with RSVP- 12.2.1. Multiple Applications: Common Attributes with RSVP-TE
TE . . . . . . . . . . . . . . . . . . . . . . . . . 15 12.2.2. Multiple Applications: Some Attributes Not Shared with
13.2.2. Multiple Applications: Some Attributes Not Shared RSVP-TE
with RSVP-TE . . . . . . . . . . . . . . . . . . . . 15 12.2.3. Interoperability with Legacy Routers
13.2.3. Interoperability with Legacy Routers . . . . . . . . 15 12.2.4. Use of Application-Specific Advertisements for RSVP-TE
13.2.4. Use of Application-Specific Advertisements for RSVP- 13. Security Considerations
TE . . . . . . . . . . . . . . . . . . . . . . . . . 16 14. IANA Considerations
14. Security Considerations . . . . . . . . . . . . . . . . . . . 16 14.1. OSPFv2
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 14.2. OSPFv3
15.1. OSPFv2 . . . . . . . . . . . . . . . . . . . . . . . . . 17 15. References
15.2. OSPFv3 . . . . . . . . . . . . . . . . . . . . . . . . . 18 15.1. Normative References
16. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 15.2. Informative References
17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 Acknowledgments
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 Contributors
18.1. Normative References . . . . . . . . . . . . . . . . . . 19 Authors' Addresses
18.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
Advertisement of link attributes by the OSPFv2 [RFC2328] and OSPFv3 Advertisement of link attributes by the OSPFv2 [RFC2328] and OSPFv3
[RFC5340] protocols in support of traffic engineering (TE) was [RFC5340] protocols in support of traffic engineering (TE) was
introduced by [RFC3630] and [RFC5329] respectively. It has been introduced by [RFC3630] and [RFC5329], respectively. It has been
extended by [RFC4203], [RFC7308] and [RFC7471]. Use of these extended by [RFC4203], [RFC7308], and [RFC7471]. Use of these
extensions has been associated with deployments supporting Traffic extensions has been associated with deployments supporting Traffic
Engineering over Multiprotocol Label Switching (MPLS) in the presence Engineering over Multiprotocol Label Switching (MPLS) in the presence
of the Resource Reservation Protocol (RSVP) - more succinctly of the Resource Reservation Protocol (RSVP), more succinctly referred
referred to as RSVP-TE [RFC3209]. to as RSVP-TE [RFC3209].
For the purposes of this document an application is a technology that For the purposes of this document, an application is a technology
makes use of link attribute advertisements, examples of which are that makes use of link attribute advertisements, examples of which
listed in Section 6. are listed in Section 5.
In recent years new applications have been introduced that have use In recent years, new applications have been introduced that have use
cases for many of the link attributes historically used by RSVP-TE. cases for many of the link attributes historically used by RSVP-TE.
Such applications include Segment Routing (SR) Policy Such applications include Segment Routing (SR) Policy
[I-D.ietf-spring-segment-routing-policy] and Loop Free Alternates [SEGMENT-ROUTING] and Loop-Free Alternates (LFAs) [RFC5286]. This
(LFA) [RFC5286]. This has introduced ambiguity in that if a has introduced ambiguity in that if a deployment includes a mix of
deployment includes a mix of RSVP-TE support and SR Policy support RSVP-TE support and SR Policy support, for example, it is not
(for example) it is not possible to unambiguously indicate which possible to unambiguously indicate which advertisements are to be
advertisements are to be used by RSVP-TE and which advertisements are used by RSVP-TE and which advertisements are to be used by SR Policy.
to be used by SR Policy. If the topologies are fully congruent this If the topologies are fully congruent, this may not be an issue, but
may not be an issue, but any incongruence leads to ambiguity. any incongruence leads to ambiguity.
An example where this ambiguity causes a problem is a network in that An example of where this ambiguity causes a problem is a network
RSVP-TE is enabled only on a subset of its links. A link attribute where RSVP-TE is enabled only on a subset of its links. A link
is advertised for the purpose of another application (e.g. SR attribute is advertised for the purpose of another application (e.g.,
Policy) for a link that is not enabled for RSVP-TE. As soon as the SR Policy) for a link that is not enabled for RSVP-TE. As soon as
router that is an RSVP-TE head-end sees the link attribute being the router that is an RSVP-TE head end sees the link attribute being
advertised for that link, it assumes RSVP-TE is enabled on that link, advertised for that link, it assumes RSVP-TE is enabled on that link,
even though it is not. If such RSVP-TE head-end router tries to even though it is not. If such an RSVP-TE head-end router tries to
setup an RSVP-TE path via that link, it will result in the path setup set up an RSVP-TE path via that link, it will result in the path
failure. setup failure.
An additional issue arises in cases where both applications are An additional issue arises in cases where both applications are
supported on a link but the link attribute values associated with supported on a link but the link attribute values associated with
each application differ. Current advertisements do not support each application differ. Current advertisements do not support
advertising application-specific values for the same attribute on a advertising application-specific values for the same attribute on a
specific link. specific link.
This document defines extensions that address these issues. Also, as This document defines extensions that address these issues. Also, as
evolution of use cases for link attributes can be expected to evolution of use cases for link attributes can be expected to
continue in the years to come, this document defines a solution that continue in the years to come, this document defines a solution that
is easily extensible for the introduction of new applications and new is easily extensible for the introduction of new applications and new
use cases. use cases.
2. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Requirements Discussion 2. Requirements Discussion
As stated previously, evolution of use cases for link attributes can As stated previously, evolution of use cases for link attributes can
be expected to continue. Therefore, any discussion of existing use be expected to continue. Therefore, any discussion of existing use
cases is limited to requirements that are known at the time of this cases is limited to requirements that are known at the time of this
writing. However, in order to determine the functionality required writing. However, in order to determine the functionality required
beyond what already exists in OSPF, it is only necessary to discuss beyond what already exists in OSPF, it is only necessary to discuss
use cases that justify the key points identified in the introduction, use cases that justify the key points identified in the introduction,
which are: which are:
1. Support for indicating which applications are using the link 1. Support for indicating which applications are using the link
attribute advertisements on a link attribute advertisements on a link
2. Support for advertising application-specific values for the same 2. Support for advertising application-specific values for the same
attribute on a link attribute on a link
[RFC7855] discusses use cases/requirements for Segment Routing (SR). [RFC7855] discusses use cases and requirements for Segment Routing
Included among these use cases is SR Policy which is defined in (SR). Included among these use cases is SR Policy, which is defined
[I-D.ietf-spring-segment-routing-policy]. If both RSVP-TE and SR in [SEGMENT-ROUTING]. If both RSVP-TE and SR Policy are deployed in
Policy are deployed in a network, link attribute advertisements can a network, link attribute advertisements can be used by one or both
be used by one or both of these applications. As there is no of these applications. There is no requirement for the link
requirement for the link attributes advertised on a given link used attributes advertised on a given link used by SR Policy to be
by SR Policy to be identical to the link attributes advertised on identical to the link attributes advertised on that same link used by
that same link used by RSVP-TE, there is a clear requirement to RSVP-TE; thus, there is a clear requirement to indicate independently
indicate independently which link attribute advertisements are to be which link attribute advertisements are to be used by each
used by each application. application.
As the number of applications that may wish to utilize link As the number of applications that may wish to utilize link
attributes may grow in the future, an additional requirement is that attributes may grow in the future, an additional requirement is that
the extensions defined allow the association of additional the extensions defined allow the association of additional
applications to link attributes without altering the format of the applications to link attributes without altering the format of the
advertisements or introducing new backwards compatibility issues. advertisements or introducing new backwards-compatibility issues.
Finally, there may still be many cases where a single attribute value Finally, there may still be many cases where a single attribute value
can be shared among multiple applications, so the solution must can be shared among multiple applications, so the solution must
minimize advertising duplicate link/attribute pairs whenever minimize advertising duplicate link/attribute pairs whenever
possible. possible.
4. Existing Advertisement of Link Attributes 3. Existing Advertisement of Link Attributes
There are existing advertisements used in support of RSVP-TE. These There are existing advertisements used in support of RSVP-TE. These
advertisements are carried in the OSPFv2 TE Opaque LSA [RFC3630] and advertisements are carried in the OSPFv2 TE Opaque Link State
OSPFv3 Intra-Area-TE-LSA [RFC5329]. Additional RSVP-TE link Advertisement (LSA) [RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329].
attributes have been defined by [RFC4203], [RFC7308] and [RFC7471]. Additional RSVP-TE link attributes have been defined by [RFC4203],
[RFC7308], and [RFC7471].
Extended Link Opaque LSAs as defined in [RFC7684] for OSPFv2 and Extended Link Opaque LSAs as defined in [RFC7684] for OSPFv2 and E-
Extended Router-LSAs [RFC8362] for OSPFv3 are used to advertise link Router-LSAs [RFC8362] for OSPFv3 are used to advertise link
attributes that are used by applications other than RSVP-TE or GMPLS attributes that are used by applications other than RSVP-TE or GMPLS
[RFC4203]. These LSAs were defined as a generic containers for [RFC4203]. These LSAs were defined as generic containers for
distribution of the extended link attributes. distribution of the extended link attributes.
5. Advertisement of Link Attributes 4. Advertisement of Link Attributes
This section outlines the solution for advertising link attributes This section outlines the solution for advertising link attributes
originally defined for RSVP-TE or GMPLS when they are used for other originally defined for RSVP-TE or GMPLS when they are used for other
applications. applications.
5.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA 4.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA
Advantages of Extended Link Opaque LSAs as defined in [RFC7684] for The following are the advantages of Extended Link Opaque LSAs as
OSPFv2 and Extended Router-LSAs [RFC8362] for OSPFv3 with respect to defined in [RFC7684] for OSPFv2 and E-Router-LSAs [RFC8362] for
advertisement of link attributes originally defined for RSVP-TE when OSPFv3 with respect to the advertisement of link attributes
used in packet networks and in GMPLS: originally defined for RSVP-TE when used in packet networks and in
GMPLS:
1. Advertisement of the link attributes does not make the link part 1. Advertisement of the link attributes does not make the link part
of the RSVP-TE topology. It avoids any conflicts and is fully of the RSVP-TE topology. It avoids any conflicts and is fully
compatible with [RFC3630] and [RFC5329]. compatible with [RFC3630] and [RFC5329].
2. The OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA remains 2. The OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA remain
truly opaque to OSPFv2 and OSPFv3 as originally defined in truly opaque to OSPFv2 and OSPFv3 as originally defined in
[RFC3630] and [RFC5329] respectively. Their contents are not [RFC3630] and [RFC5329], respectively. Their contents are not
inspected by OSPF, which instead acts as a pure transport. inspected by OSPF, which instead acts as a pure transport.
3. There is a clear distinction between link attributes used by 3. There is a clear distinction between link attributes used by
RSVP-TE and link attributes used by other OSPFv2 or OSPFv3 RSVP-TE and link attributes used by other OSPFv2 or OSPFv3
applications. applications.
4. All link attributes that are used by other applications are 4. All link attributes that are used by other applications are
advertised in a single LSA, the Extended Link Opaque LSA in advertised in the Extended Link Opaque LSA in OSPFv2 [RFC7684] or
OSPFv2 or the OSPFv3 E-Router-LSA [RFC8362] in OSPFv3. the OSPFv3 E-Router-LSA [RFC8362] in OSPFv3.
The disadvantage of this approach is that in rare cases, the same The disadvantage of this approach is that in rare cases, the same
link attribute is advertised in both the TE Opaque and Extended Link link attribute is advertised in both the TE Opaque and Extended Link
Attribute LSAs in OSPFv2 or the Intra-Area-TE-LSA and E-Router-LSA in Attribute LSAs in OSPFv2 or the Intra-Area-TE-LSA and E-Router-LSA in
OSPFv3. OSPFv3.
Extended Link Opaque LSA [RFC7684] and E-Router-LSA [RFC8362] are The Extended Link Opaque LSA [RFC7684] and E-Router-LSA [RFC8362] are
used to advertise any link attributes used for non-RSVP-TE used to advertise any link attributes used for non-RSVP-TE
applications in OSPFv2 or OSPFv3 respectively, including those that applications in OSPFv2 or OSPFv3, respectively, including those that
have been originally defined for RSVP-TE applications (See have been originally defined for RSVP-TE applications (see
Section 7). Section 6).
TE link attributes used for RSVP-TE/GMPLS continue to use OSPFv2 TE TE link attributes used for RSVP-TE/GMPLS continue to use the OSPFv2
Opaque LSA [RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329]. TE Opaque LSA [RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329].
The format of the link attribute TLVs that have been defined for The format of the link attribute TLVs that have been defined for
RSVP-TE applications will be kept unchanged even when they are used RSVP-TE applications will be kept unchanged even when they are used
for non-RSVP-TE applications. Unique code points are allocated for for non-RSVP-TE applications. Unique codepoints are allocated for
these link attribute TLVs from the OSPFv2 Extended Link TLV Sub-TLV these link attribute TLVs from the "OSPFv2 Extended Link TLV Sub-
Registry [RFC7684] and from the OSPFv3 Extended-LSA Sub-TLV Registry TLVs" registry [RFC7684] and from the "OSPFv3 Extended-LSA Sub-TLVs"
[RFC8362], as specified in Section 15. registry [RFC8362], as specified in Section 14.
6. Advertisement of Application-Specific Values 5. Advertisement of Application-Specific Values
To allow advertisement of the application-specific values of the link To allow advertisement of the application-specific values of the link
attribute, a new Application-Specific Link Attributes (ASLA) sub-TLV attribute, a new Application-Specific Link Attributes (ASLA) sub-TLV
is defined. The ASLA sub-TLV is a sub-TLV of the OSPFv2 Extended is defined. The ASLA sub-TLV is a sub-TLV of the OSPFv2 Extended
Link TLV [RFC7684] and OSPFv3 Router-Link TLV [RFC8362]. Link TLV [RFC7684] and OSPFv3 Router-Link TLV [RFC8362].
On top of advertising the link attributes for standardized In addition to advertising the link attributes for standardized
applications, link attributes can be advertised for the purpose of applications, link attributes can be advertised for the purpose of
applications that are not standardized. We call such an application applications that are not standardized. We call such an application
a "User Defined Application" or "UDA". These applications are not a "user-defined application" or "UDA". These applications are not
subject to standardization and are outside of the scope of this subject to standardization and are outside of the scope of this
specification. specification.
The ASLA sub-TLV is an optional sub-TLV of OSPFv2 Extended Link TLV The ASLA sub-TLV is an optional sub-TLV of the OSPFv2 Extended Link
and OSPFv3 Router-Link TLV. Multiple ASLA sub-TLVs can be present in TLV and OSPFv3 Router-Link TLV. Multiple ASLA sub-TLVs can be
its parent TLV when different applications want to control different present in a parent TLV when different applications want to control
link attributes or when different value of the same attribute needs different link attributes or when a different value of the same
to be advertised by multiple applications. The ASLA sub-TLV MUST be attribute needs to be advertised by multiple applications. The ASLA
used for advertisement of the link attributes listed at the end on sub-TLV MUST be used for advertisement of the link attributes listed
this section if these are advertised inside OSPFv2 Extended Link TLV at the end of this section if these are advertised inside the OSPFv2
and OSPFv3 Router-Link TLV. It has the following format: Extended Link TLV and OSPFv3 Router-Link TLV. It has the following
format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SABM Length | UDABM Length | Reserved | | SABM Length | UDABM Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Standard Application Identifier Bit Mask | | Standard Application Identifier Bit Mask |
+- -+ +- -+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User Defined Application Identifier Bit Mask | | User-Defined Application Identifier Bit Mask |
+- -+ +- -+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Attribute sub-sub-TLVs | | Link Attribute sub-sub-TLVs |
+- -+ +- -+
| ... | | ... |
where: where:
Type: 10 (OSPFv2), 11 (OSPFv3) Type: 10 (OSPFv2), 11 (OSPFv3)
Length: variable Length: Variable
SABM Length: Standard Application Identifier Bit Mask Length in SABM Length: Standard Application Identifier Bit Mask Length in
octets. The value MUST be 0, 4 or 8. If the Standard Application octets. The value MUST be 0, 4, or 8. If the Standard
Bit Mask is not present, the Standard Application Bit Mask Length Application Identifier Bit Mask is not present, the SABM Length
MUST be set to 0. MUST be set to 0.
UDABM Length: User Defined Application Identifier Bit Mask Length UDABM Length: User-Defined Application Identifier Bit Mask Length in
in octets. The value MUST be 0, 4 or 8. If the User Defined octets. The value MUST be 0, 4, or 8. If the User-Defined
Application Bit Mask is not present, the User Defined Application Application Identifier Bit Mask is not present, the UDABM Length
Bit Mask Length MUST be set to 0. MUST be set to 0.
Standard Application Identifier Bit Mask: Optional set of bits, Standard Application Identifier Bit Mask: Optional set of bits,
where each bit represents a single standard application. Bits are where each bit represents a single standard application. Bits are
defined in the Link Attribute Application Identifier Registry, defined in the "Link Attribute Applications" registry, which is
which has been defined in [I-D.ietf-isis-te-app]. Current defined in [RFC8919]. Current assignments are repeated here for
assignments are repeated here for informational purpose: informational purposes:
0 1 2 3 4 5 6 7 ... 0 1 2 3 4 5 6 7 ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
|R|S|F| ... |R|S|F| ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
Bit-0 (R-bit): RSVP-TE Bit 0 (R-bit): RSVP-TE.
Bit-1 (S-bit): Segment Routing Policy
Bit-2 (F-bit): Loop Free Alternate (LFA). Includes all LFA Bit 1 (S-bit): Segment Routing Policy.
types
User Defined Application Identifier Bit Mask: Optional set of Bit 2 (F-bit): Loop-Free Alternate (LFA). Includes all LFA
bits, where each bit represents a single user defined application. types.
If the SABM or UDABM length is other than 0, 4, or 8, the ASLA sub- User-Defined Application Identifier Bit Mask: Optional set of bits,
where each bit represents a single user-defined application.
If the SABM or UDABM Length is other than 0, 4, or 8, the ASLA sub-
TLV MUST be ignored by the receiver. TLV MUST be ignored by the receiver.
Standard Application Identifier Bits are defined/sent starting with Standard Application Identifier Bits are defined and sent starting
Bit 0. Undefined bits that are transmitted MUST be transmitted as 0 with bit 0. Undefined bits that are transmitted MUST be transmitted
and MUST be ignored on receipt. Bits that are not transmitted MUST as 0 and MUST be ignored on receipt. Bits that are not transmitted
be treated as if they are set to 0 on receipt. Bits that are not MUST be treated as if they are set to 0 on receipt. Bits that are
supported by an implementation MUST be ignored on receipt. not supported by an implementation MUST be ignored on receipt.
User Defined Application Identifier Bits have no relationship to User-Defined Application Identifier Bits have no relationship to
Standard Application Identifier Bits and are not managed by IANA or Standard Application Identifier Bits and are not managed by IANA or
any other standards body. It is recommended that bits are used any other standards body. It is recommended that these bits be used
starting with Bit 0 so as to minimize the number of octets required starting with bit 0 so as to minimize the number of octets required
to advertise all UDAs. Undefined bits which are transmitted MUST be to advertise all UDAs. Undefined bits that are transmitted MUST be
transmitted as 0 and MUST be ignored on receipt. Bits that are not transmitted as 0 and MUST be ignored on receipt. Bits that are not
transmitted MUST be treated as if they are set to 0 on receipt. Bits transmitted MUST be treated as if they are set to 0 on receipt. Bits
that are not supported by an implementation MUST be ignored on that are not supported by an implementation MUST be ignored on
receipt. receipt.
If the link attribute advertisement is intended to be only used by a If the link attribute advertisement is intended to be only used by a
specific set of applications, corresponding Bit Masks MUST be present specific set of applications, corresponding bit masks MUST be
and application-specific bit(s) MUST be set for all applications that present, and application-specific bit(s) MUST be set for all
use the link attributes advertised in the ASLA sub-TLV. applications that use the link attributes advertised in the ASLA sub-
TLV.
Application Bit Masks apply to all link attributes that support Application Identifier Bit Masks apply to all link attributes that
application-specific values and are advertised in the ASLA sub-TLV. support application-specific values and are advertised in the ASLA
sub-TLV.
The advantage of not making the Application Bit Masks part of the The advantage of not making the Application Identifier Bit Masks part
attribute advertisement itself is that the format of any previously of the attribute advertisement itself is that the format of any
defined link attributes can be kept and reused when advertising them previously defined link attributes can be kept and reused when
in the ASLA sub-TLV. advertising them in the ASLA sub-TLV.
If the same attribute is advertised in more than one ASLA sub-TLVs If the same attribute is advertised in more than one ASLA sub-TLVs
with the application listed in the Application Bit Masks, the with the application listed in the Application Identifier Bit Masks,
application SHOULD use the first instance of advertisement and ignore the application SHOULD use the first instance of advertisement and
any subsequent advertisements of that attribute. ignore any subsequent advertisements of that attribute.
If link attributes are advertised with zero length Application If link attributes are advertised with zero-length Application
Identifier Bit Masks for both standard applications and user defined Identifier Bit Masks for both standard applications and user-defined
applications, then any Standard Application and/or any User Defined applications, then any standard application and/or any user-defined
Application is permitted to use that set of link attributes. If application is permitted to use that set of link attributes. If
support for a new application is introduced on any node in a network support for a new application is introduced on any node in a network
in the presence of such advertisements, these advertisements are in the presence of such advertisements, these advertisements are
permitted to be used by the new application. If this is not what is permitted to be used by the new application. If this is not what is
intended, then existing advertisements MUST be readvertised with an intended, then existing advertisements MUST be readvertised with an
explicit set of applications specified before a new application is explicit set of applications specified before a new application is
introduced. introduced.
An application-specific advertisement (Application Identifier Bit An application-specific advertisement (Application Identifier Bit
Mask with a matching Application Identifier Bit set) for an attribute Mask with a matching Application Identifier Bit set) for an attribute
MUST always be preferred over the advertisement of the same attribute MUST always be preferred over the advertisement of the same attribute
with the zero length Application Identifier Bit Masks for both with the zero-length Application Identifier Bit Masks for both
standard applications and user defined applications on the same link. standard applications and user-defined applications on the same link.
This document defines the initial set of link attributes that MUST This document defines the initial set of link attributes that MUST
use the ASLA sub-TLV if advertised in the OSPFv2 Extended Link TLV or use the ASLA sub-TLV if advertised in the OSPFv2 Extended Link TLV or
in the OSPFv3 Router-Link TLV. Documents which define new link in the OSPFv3 Router-Link TLV. Documents that define new link
attributes MUST state whether the new attributes support application- attributes MUST state whether the new attributes support application-
specific values and as such are advertised in an ASLA sub-TLV. The specific values and, as such, are advertised in an ASLA sub-TLV. The
standard link attributes that are advertised in ASLA sub-TLVs are: standard link attributes that are advertised in ASLA sub-TLVs are:
- Shared Risk Link Group [RFC4203] * Shared Risk Link Group [RFC4203]
- Unidirectional Link Delay [RFC7471] * Unidirectional Link Delay [RFC7471]
- Min/Max Unidirectional Link Delay [RFC7471] * Min/Max Unidirectional Link Delay [RFC7471]
- Unidirectional Delay Variation [RFC7471] * Unidirectional Delay Variation [RFC7471]
- Unidirectional Link Loss [RFC7471] * Unidirectional Link Loss [RFC7471]
- Unidirectional Residual Bandwidth [RFC7471] * Unidirectional Residual Bandwidth [RFC7471]
- Unidirectional Available Bandwidth [RFC7471] * Unidirectional Available Bandwidth [RFC7471]
- Unidirectional Utilized Bandwidth [RFC7471] * Unidirectional Utilized Bandwidth [RFC7471]
- Administrative Group [RFC3630] * Administrative Group [RFC3630]
- Extended Administrative Group [RFC7308] * Extended Administrative Group [RFC7308]
- TE Metric [RFC3630] * TE Metric [RFC3630]
7. Reused TE link attributes 6. Reused TE Link Attributes
This section defines the use case and indicates the code points This section defines the use case and indicates the codepoints
(Section 15) from the OSPFv2 Extended Link TLV Sub-TLV Registry and (Section 14) from the "OSPFv2 Extended Link TLV Sub-TLVs" registry
OSPFv3 Extended-LSA Sub-TLV Registry for some of the link attributes and "OSPFv3 Extended-LSA Sub-TLVs" registry for some of the link
that have been originally defined for RSVP-TE or GMPLS. attributes that have been originally defined for RSVP-TE or GMPLS.
7.1. Shared Risk Link Group (SRLG) 6.1. Shared Risk Link Group (SRLG)
The SRLG of a link can be used in OSPF calculated IPFRR (IP Fast The SRLG of a link can be used in OSPF-calculated IPFRR (IP Fast
Reroute) [RFC5714] to compute a backup path that does not share any Reroute) [RFC5714] to compute a backup path that does not share any
SRLG group with the protected link. SRLG group with the protected link.
To advertise the SRLG of the link in the OSPFv2 Extended Link TLV, To advertise the SRLG of the link in the OSPFv2 Extended Link TLV,
the same format for the sub-TLV defined in section 1.3 of [RFC4203] the same format for the sub-TLV defined in Section 1.3 of [RFC4203]
is used and TLV type 11 is used. Similarly, for OSPFv3 to advertise is used with TLV type 11. Similarly, for OSPFv3 to advertise the
the SRLG in the OSPFv3 Router-Link TLV, TLV type 12 is used. SRLG in the OSPFv3 Router-Link TLV, TLV type 12 is used.
7.2. Extended Metrics 6.2. Extended Metrics
[RFC3630] defines several link bandwidth types. [RFC7471] defines [RFC3630] defines several link bandwidth types. [RFC7471] defines
extended link metrics that are based on link bandwidth, delay and extended link metrics that are based on link bandwidth, delay, and
loss characteristics. All of these can be used to compute primary loss characteristics. All of these can be used to compute primary
and backup paths within an OSPF area to satisfy requirements for and backup paths within an OSPF area to satisfy requirements for
bandwidth, delay (nominal or worst case) or loss. bandwidth, delay (nominal or worst case), or loss.
To advertise extended link metrics in the OSPFv2 Extended Link TLV, To advertise extended link metrics in the OSPFv2 Extended Link TLV,
the same format for the sub-TLVs defined in [RFC7471] is used with the same format for the sub-TLVs defined in [RFC7471] is used with
the following TLV types: the following TLV types:
12 - Unidirectional Link Delay 12: Unidirectional Link Delay
13 - Min/Max Unidirectional Link Delay 13: Min/Max Unidirectional Link Delay
14 - Unidirectional Delay Variation 14: Unidirectional Delay Variation
15 - Unidirectional Link Loss 15: Unidirectional Link Loss
16 - Unidirectional Residual Bandwidth 16: Unidirectional Residual Bandwidth
17 - Unidirectional Available Bandwidth 17: Unidirectional Available Bandwidth
18 - Unidirectional Utilized Bandwidth 18: Unidirectional Utilized Bandwidth
To advertise extended link metrics in the OSPFv3 Extended-LSA Router- To advertise extended link metrics in the Router-Link TLV inside the
Link TLV, the same format for the sub-TLVs defined in [RFC7471] is OSPFv3 E-Router-LSA, the same format for the sub-TLVs defined in
used with the following TLV types: [RFC7471] is used with the following TLV types:
13 - Unidirectional Link Delay 13: Unidirectional Link Delay
14 - Min/Max Unidirectional Link Delay 14: Min/Max Unidirectional Link Delay
15 - Unidirectional Delay Variation
16 - Unidirectional Link Loss 15: Unidirectional Delay Variation
17 - Unidirectional Residual Bandwidth 16: Unidirectional Link Loss
18 - Unidirectional Available Bandwidth 17: Unidirectional Residual Bandwidth
19 - Unidirectional Utilized Bandwidth 18: Unidirectional Available Bandwidth
7.3. Administrative Group 19: Unidirectional Utilized Bandwidth
6.3. Administrative Group
[RFC3630] and [RFC7308] define the Administrative Group and Extended [RFC3630] and [RFC7308] define the Administrative Group and Extended
Administrative Group sub-TLVs respectively. Administrative Group sub-TLVs, respectively.
To advertise the Administrative Group and Extended Administrative To advertise the Administrative Group and Extended Administrative
Group in the OSPFv2 Extended Link TLV, the same format for the sub- Group in the OSPFv2 Extended Link TLV, the same format for the sub-
TLVs defined in [RFC3630] and [RFC7308] is used with the following TLVs defined in [RFC3630] and [RFC7308] is used with the following
TLV types: TLV types:
19 - Administrative Group 19: Administrative Group
20 - Extended Administrative Group 20: Extended Administrative Group
To advertise Administrative Group and Extended Administrative Group To advertise the Administrative Group and Extended Administrative
in the OSPFv3 Router-Link TLV, the same format for the sub-TLVs Group in the OSPFv3 Router-Link TLV, the same format for the sub-TLVs
defined in [RFC3630] and [RFC7308] is used with the following TLV defined in [RFC3630] and [RFC7308] is used with the following TLV
types: types:
20 - Administrative Group 20: Administrative Group
21 - Extended Administrative Group 21: Extended Administrative Group
7.4. Traffic Engineering Metric 6.4. Traffic Engineering Metric
[RFC3630] defines Traffic Engineering Metric. [RFC3630] defines the Traffic Engineering Metric.
To advertise the Traffic Engineering Metric in the OSPFv2 Extended To advertise the Traffic Engineering Metric in the OSPFv2 Extended
Link TLV, the same format for the sub-TLV defined in section 2.5.5 of Link TLV, the same format for the sub-TLV defined in Section 2.5.5 of
[RFC3630] is used and TLV type 22 is used. Similarly, for OSPFv3 to [RFC3630] is used with TLV type 22. Similarly, for OSPFv3 to
advertise the Traffic Engineering Metric in the OSPFv3 Router-Link advertise the Traffic Engineering Metric in the OSPFv3 Router-Link
TLV, TLV type 22 is used. TLV, TLV type 22 is used.
8. Maximum Link Bandwidth 7. Maximum Link Bandwidth
Maximum link bandwidth is an application independent attribute of the
link that is defined in [RFC3630]. Because it is an application
independent attribute, it MUST NOT be advertised in ASLA sub-TLV.
Instead, it MAY be advertised as a sub-TLV of the Extended Link Maximum link bandwidth is an application-independent attribute of the
Opaque LSA Extended Link TLV in OSPFv2 [RFC7684] or sub-TLV of OSPFv3 link that is defined in [RFC3630]. Because it is an application-
E-Router-LSA Router-Link TLV in OSPFv3 [RFC8362]. independent attribute, it MUST NOT be advertised in the ASLA sub-TLV.
Instead, it MAY be advertised as a sub-TLV of the Extended Link TLV
in the Extended Link Opaque LSA in OSPFv2 [RFC7684] or as a sub-TLV
of the Router-Link TLV in the E-Router-LSA Router-Link TLV in OSPFv3
[RFC8362].
To advertise the Maximum link bandwidth in the OSPFv2 Extended Link To advertise the maximum link bandwidth in the OSPFv2 Extended Link
TLV, the same format for sub-TLV defined in [RFC3630] is used with TLV, the same format for the sub-TLV defined in [RFC3630] is used
TLV type 23. with TLV type 23.
To advertise the Maximum link bandwidth in the OSPFv3 Router-Link To advertise the maximum link bandwidth in the OSPFv3 Router-Link
TLV, the same format for sub-TLV defined in [RFC3630] is used with TLV, the same format for the sub-TLV defined in [RFC3630] is used
TLV type 23. with TLV type 23.
9. Considerations for Extended TE Metrics 8. Considerations for Extended TE Metrics
[RFC7471] defines a number of dynamic performance metrics associated [RFC7471] defines a number of dynamic performance metrics associated
with a link. It is conceivable that such metrics could be measured with a link. It is conceivable that such metrics could be measured
specific to traffic associated with a specific application. specific to traffic associated with a specific application.
Therefore this document includes support for advertising these link Therefore, this document includes support for advertising these link
attributes specific to a given application. However, in practice it attributes specific to a given application. However, in practice, it
may well be more practical to have these metrics reflect the may well be more practical to have these metrics reflect the
performance of all traffic on the link regardless of application. In performance of all traffic on the link regardless of application. In
such cases, advertisements for these attributes can be associated such cases, advertisements for these attributes can be associated
with all of the applications utilizing that link. This can be done with all of the applications utilizing that link. This can be done
either by explicitly specifying the applications in the Application either by explicitly specifying the applications in the Application
Identifier Bit Mask or by using a zero length Application Identifier Identifier Bit Mask or by using a zero-length Application Identifier
Bit Mask. Bit Mask.
10. Local Interface IPv6 Address Sub-TLV 9. Local Interface IPv6 Address Sub-TLV
The Local Interface IPv6 Address Sub-TLV is an application The Local Interface IPv6 Address sub-TLV is an application-
independent attribute of the link that is defined in [RFC5329]. independent attribute of the link that is defined in [RFC5329].
Because it is an application independent attribute, it MUST NOT be Because it is an application-independent attribute, it MUST NOT be
advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a
sub-TLV of the OSPFv3 E-Router-LSA Router-Link TLV [RFC8362]. sub-TLV of the Router-Link TLV inside the OSPFv3 E-Router-LSA
[RFC8362].
To advertise the Local Interface IPv6 Address Sub-TLV in the OSPFv3 To advertise the Local Interface IPv6 Address sub-TLV in the OSPFv3
Router-Link TLV, the same format for sub-TLV defined in [RFC5329] is Router-Link TLV, the same format for the sub-TLV defined in [RFC5329]
used with TLV type 24. is used with TLV type 24.
11. Remote Interface IPv6 Address Sub-TLV 10. Remote Interface IPv6 Address Sub-TLV
The Remote Interface IPv6 Address Sub-TLV is an application The Remote Interface IPv6 Address sub-TLV is an application-
independent attribute of the link that is defined in [RFC5329]. independent attribute of the link that is defined in [RFC5329].
Because it is an application independent attribute, it MUST NOT be Because it is an application-independent attribute, it MUST NOT be
advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a
sub-TLV of the OSPFv3 E-Router-LSA Router-Link TLV [RFC8362]. sub-TLV of the Router-Link TLV inside the OSPFv3 E-Router-LSA
[RFC8362].
To advertise the Remote Interface IPv6 Address Sub-TLV in the OSPFv3 To advertise the Remote Interface IPv6 Address sub-TLV in the OSPFv3
Router-Link TLV, the same format for sub-TLV defined in [RFC5329] is Router-Link TLV, the same format for the sub-TLV defined in [RFC5329]
used with TLV type 25. is used with TLV type 25.
12. Attribute Advertisements and Enablement 11. Attribute Advertisements and Enablement
This document defines extensions to support the advertisement of This document defines extensions to support the advertisement of
application-specific link attributes. application-specific link attributes.
There are applications where the application enablement on the link There are applications where the application enablement on the link
is relevant - e.g., RSVP-TE - one needs to make sure that RSVP is is relevant; for example, with RSVP-TE, one needs to make sure that
enabled on the link before sending a RSVP-TE signaling message over RSVP is enabled on the link before sending an RSVP-TE signaling
it. message over it.
There are applications where the enablement of the application on the There are applications where the enablement of the application on the
link is irrelevant and has nothing to do with the fact that some link link is irrelevant and has nothing to do with the fact that some link
attributes are advertised for the purpose of such application. An attributes are advertised for the purpose of such application. An
example of this is LFA. example of this is LFA.
Whether the presence of link attribute advertisements for a given Whether the presence of link attribute advertisements for a given
application indicates that the application is enabled on that link application indicates that the application is enabled on that link
depends upon the application. Similarly, whether the absence of link depends upon the application. Similarly, whether the absence of link
attribute advertisements indicates that the application is not attribute advertisements indicates that the application is not
skipping to change at page 13, line 40 skipping to change at line 607
In the case of RSVP-TE, the advertisement of application-specific In the case of RSVP-TE, the advertisement of application-specific
link attributes has no implication of RSVP-TE being enabled on that link attributes has no implication of RSVP-TE being enabled on that
link. The RSVP-TE enablement is solely derived from the information link. The RSVP-TE enablement is solely derived from the information
carried in the OSPFv2 TE Opaque LSA [RFC3630] and OSPFv3 Intra-Area- carried in the OSPFv2 TE Opaque LSA [RFC3630] and OSPFv3 Intra-Area-
TE-LSA [RFC5329]. TE-LSA [RFC5329].
In the case of SR Policy, advertisement of application-specific link In the case of SR Policy, advertisement of application-specific link
attributes does not indicate enablement of SR Policy. The attributes does not indicate enablement of SR Policy. The
advertisements are only used to support constraints that may be advertisements are only used to support constraints that may be
applied when specifying an explicit path. SR Policy is implicitly applied when specifying an explicit path. SR Policy is implicitly
enabled on all links that are part of the Segment Routing enabled enabled on all links that are part of the SR-enabled topology
topology independent of the existence of link attribute independent of the existence of link attribute advertisements.
advertisements
In the case of LFA, advertisement of application-specific link In the case of LFA, the advertisement of application-specific link
attributes does not indicate enablement of LFA on that link. attributes does not indicate enablement of LFA on that link.
Enablement is controlled by local configuration. Enablement is controlled by local configuration.
If, in the future, additional standard applications are defined to In the future, if additional standard applications are defined to use
use this mechanism, the specification defining this use MUST define this mechanism, the specification defining this use MUST define the
the relationship between application-specific link attribute relationship between application-specific link attribute
advertisements and enablement for that application. advertisements and enablement for that application.
This document allows the advertisement of application-specific link This document allows the advertisement of application-specific link
attributes with no application identifiers i.e., both the Standard attributes with no application identifiers, i.e., both the Standard
Application Identifier Bit Mask and the User Defined Application Application Identifier Bit Mask and the User-Defined Application
Identifier Bit Mask are not present (See Section 6). This supports Identifier Bit Mask are not present (see Section 5). This supports
the use of the link attribute by any application. In the presence of the use of the link attribute by any application. In the presence of
an application where the advertisement of link attribute an application where the advertisement of link attributes is used to
advertisements is used to infer the enablement of an application on infer the enablement of an application on that link (e.g., RSVP-TE),
that link (e.g., RSVP-TE), the absence of the application identifier the absence of the application identifier leaves ambiguous whether
leaves ambiguous whether that application is enabled on such a link. that application is enabled on such a link. This needs to be
This needs to be considered when making use of the "any application" considered when making use of the "any application" encoding.
encoding.
13. Deployment Considerations 12. Deployment Considerations
13.1. Use of Legacy RSVP-TE LSA Advertisements 12.1. Use of Legacy RSVP-TE LSA Advertisements
Bit Identifiers for Standard Applications are defined in Section 6. Bit identifiers for standard applications are defined in Section 5.
All of the identifiers defined in this document are associated with All of the identifiers defined in this document are associated with
applications that were already deployed in some networks prior to the applications that were already deployed in some networks prior to the
writing of this document. Therefore, such applications have been writing of this document. Therefore, such applications have been
deployed using the RSVP-TE LSA advertisements. The Standard deployed using the RSVP-TE LSA advertisements. The standard
Applications defined in this document may continue to use RSVP-TE LSA applications defined in this document may continue to use RSVP-TE LSA
advertisements for a given link so long as at least one of the advertisements for a given link so long as at least one of the
following conditions is true: following conditions is true:
The application is RSVP-TE * The application is RSVP-TE.
The application is SR Policy or LFA and RSVP-TE is not deployed * The application is SR Policy or LFA, and RSVP-TE is not deployed
anywhere in the network anywhere in the network.
The application is SR Policy or LFA, RSVP-TE is deployed in the * The application is SR Policy or LFA, RSVP-TE is deployed in the
network, and both the set of links on which SR Policy and/or LFA network, and both the set of links on which SR Policy and/or LFA
advertisements are required and the attribute values used by SR advertisements are required and the attribute values used by SR
Policy and/or LFA on all such links is fully congruent with the Policy and/or LFA on all such links are fully congruent with the
links and attribute values used by RSVP-TE links and attribute values used by RSVP-TE.
Under the conditions defined above, implementations that support the Under the conditions defined above, implementations that support the
extensions defined in this document have the choice of using RSVP-TE extensions defined in this document have the choice of using RSVP-TE
LSA advertisements or application-specific advertisements in support LSA advertisements or application-specific advertisements in support
of SR Policy and/or LFA. This will require implementations to of SR Policy and/or LFA. This will require implementations to
provide controls specifying which type of advertisements are to be provide controls specifying which types of advertisements are to be
sent/ processed on receive for these applications. Further sent and processed on receipt for these applications. Further
discussion of the associated issues can be found in Section 13.2. discussion of the associated issues can be found in Section 12.2.
New applications that future documents define to make use of the New applications that future documents define to make use of the
advertisements defined in this document MUST NOT make use of RSVP-TE advertisements defined in this document MUST NOT make use of RSVP-TE
LSA advertisements. This simplifies deployment of new applications LSA advertisements. This simplifies deployment of new applications
by eliminating the need to support multiple ways to advertise by eliminating the need to support multiple ways to advertise
attributes for the new applications. attributes for the new applications.
13.2. Interoperability, Backwards Compatibility and Migration Concerns 12.2. Interoperability, Backwards Compatibility, and Migration Concerns
Existing deployments of RSVP-TE, SR Policy, and/or LFA utilize the Existing deployments of RSVP-TE, SR Policy, and/or LFA utilize the
legacy advertisements listed in Section 4. Routers which do not legacy advertisements listed in Section 3. Routers that do not
support the extensions defined in this document will only process support the extensions defined in this document will only process
legacy advertisements and are likely to infer that RSVP-TE is enabled legacy advertisements and are likely to infer that RSVP-TE is enabled
on the links for which legacy advertisements exist. It is expected on the links for which legacy advertisements exist. It is expected
that deployments using the legacy advertisements will persist for a that deployments using the legacy advertisements will persist for a
significant period of time. Therefore deployments using the significant period of time. Therefore, deployments using the
extensions defined in this document in the presence of routers that extensions defined in this document in the presence of routers that
do not support these extensions need to be able to interoperate with do not support these extensions need to be able to interoperate with
the use of legacy advertisements by the legacy routers. The the use of legacy advertisements by the legacy routers. The
following sub-sections discuss interoperability and backwards following subsections discuss interoperability and backwards-
compatibility concerns for a number of deployment scenarios. compatibility concerns for a number of deployment scenarios.
13.2.1. Multiple Applications: Common Attributes with RSVP-TE 12.2.1. Multiple Applications: Common Attributes with RSVP-TE
In cases where multiple applications are utilizing a given link, one In cases where multiple applications are utilizing a given link, one
of the applications is RSVP-TE, and all link attributes for a given of the applications is RSVP-TE, and all link attributes for a given
link are common to the set of applications utilizing that link, link are common to the set of applications utilizing that link,
interoperability is achieved by using legacy advertisements for RSVP- interoperability is achieved by using legacy advertisements for RSVP-
TE. Attributes for applications other than RSVP-TE MUST be TE. Attributes for applications other than RSVP-TE MUST be
advertised using application-specific advertisements. This results advertised using application-specific advertisements. This results
in duplicate advertisements for those attributes. in duplicate advertisements for those attributes.
13.2.2. Multiple Applications: Some Attributes Not Shared with RSVP-TE 12.2.2. Multiple Applications: Some Attributes Not Shared with RSVP-TE
In cases where one or more applications other than RSVP-TE are In cases where one or more applications other than RSVP-TE are
utilizing a given link and one or more link attribute values are not utilizing a given link and one or more link attribute values are not
shared with RSVP-TE, interoperability is achieved by using legacy shared with RSVP-TE, interoperability is achieved by using legacy
advertisements for RSVP-TE. Attributes for applications other than advertisements for RSVP-TE. Attributes for applications other than
RSVP-TE MUST be advertised using application-specific advertisements. RSVP-TE MUST be advertised using application-specific advertisements.
In cases where some link attributes are shared with RSVP-TE, this In cases where some link attributes are shared with RSVP-TE, this
requires duplicate advertisements for those attributes requires duplicate advertisements for those attributes.
13.2.3. Interoperability with Legacy Routers 12.2.3. Interoperability with Legacy Routers
For the applications defined in this document, routers that do not For the applications defined in this document, routers that do not
support the extensions defined in this document will send and receive support the extensions defined in this document will send and receive
only legacy link attribute advertisements. So long as there is any only legacy link attribute advertisements. So long as there is any
legacy router in the network that has any of the applications legacy router in the network that has any of the applications
enabled, all routers MUST continue to advertise link attributes using enabled, all routers MUST continue to advertise link attributes using
legacy advertisements. In addition, the link attribute values legacy advertisements. In addition, the link attribute values
associated with the set of applications supported by legacy routers associated with the set of applications supported by legacy routers
(RSVP-TE, SR Policy, and/or LFA) are always shared since legacy (RSVP-TE, SR Policy, and/or LFA) are always shared since legacy
routers have no way of advertising or processing application-specific routers have no way of advertising or processing application-specific
values. Once all legacy routers have been upgraded, migration from values. Once all legacy routers have been upgraded, migration from
legacy advertisements to application specific advertisements can be legacy advertisements to application-specific advertisements can be
achieved via the following steps: achieved via the following steps:
1)Send new application-specific advertisements while continuing to 1) Send new application-specific advertisements while continuing to
advertise using the legacy advertisement (all advertisements are then advertise using the legacy advertisement (all advertisements are
duplicated). Receiving routers continue to use legacy then duplicated). Receiving routers continue to use legacy
advertisements. advertisements.
2)Enable the use of the application-specific advertisements on all 2) Enable the use of the application-specific advertisements on all
routers routers.
3)Keep legacy advertisements if needed for RSVP-TE purposes. 3) Keep legacy advertisements if needed for RSVP-TE purposes.
When the migration is complete, it then becomes possible to advertise When the migration is complete, it then becomes possible to advertise
incongruent values per application on a given link. incongruent values per application on a given link.
Documents defining new applications that make use of the application- Documents defining new applications that make use of the application-
specific advertisements defined in this document MUST discuss specific advertisements defined in this document MUST discuss
interoperability and backwards compatibility issues that could occur interoperability and backwards-compatibility issues that could occur
in the presence of routers that do not support the new application. in the presence of routers that do not support the new application.
13.2.4. Use of Application-Specific Advertisements for RSVP-TE 12.2.4. Use of Application-Specific Advertisements for RSVP-TE
The extensions defined in this document support RSVP-TE as one of the The extensions defined in this document support RSVP-TE as one of the
supported applications. It is however RECOMMENDED to advertise all supported applications. It is, however, RECOMMENDED to advertise all
link-attributes for RSVP-TE in the existing OSPFv2 TE Opaque LSA link attributes for RSVP-TE in the existing OSPFv2 TE Opaque LSA
[RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329] to maintain backward [RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329] to maintain
compatibility. RSVP-TE can eventually utilize the application- backwards compatibility. RSVP-TE can eventually utilize the
specific advertisements for newly defined link attributes, that are application-specific advertisements for newly defined link attributes
defined as application-specific. that are defined as application specific.
Link attributes that are not allowed to be advertised in the ASLA Link attributes that are not allowed to be advertised in the ASLA
Sub-TLV, such as Maximum Reservable Link Bandwidth and Unreserved sub-TLV, such as maximum reservable link bandwidth and unreserved
Bandwidth MUST use the OSPFv2 TE Opaque LSA [RFC3630] and OSPFv3 bandwidth, MUST use the OSPFv2 TE Opaque LSA [RFC3630] and OSPFv3
Intra-Area-TE-LSA [RFC5329] and MUST NOT be advertised in ASLA Sub- Intra-Area-TE-LSA [RFC5329] and MUST NOT be advertised in the ASLA
TLV. sub-TLV.
14. Security Considerations 13. Security Considerations
Existing security extensions as described in [RFC2328], [RFC5340] and Existing security extensions as described in [RFC2328], [RFC5340],
[RFC8362] apply to extensions defined in this document. While OSPF and [RFC8362] apply to extensions defined in this document. While
is under a single administrative domain, there can be deployments OSPF is under a single administrative domain, there can be
where potential attackers have access to one or more networks in the deployments where potential attackers have access to one or more
OSPF routing domain. In these deployments, stronger authentication networks in the OSPF routing domain. In these deployments, stronger
mechanisms such as those specified in [RFC5709], [RFC7474], [RFC4552] authentication mechanisms such as those specified in [RFC5709],
or [RFC7166] SHOULD be used. [RFC7474], [RFC4552], or [RFC7166] SHOULD be used.
Implementations must assure that malformed TLV and Sub-TLV defined in Implementations must ensure that if any of the TLVs and sub-TLVs
this document are detected and do not provide a vulnerability for defined in this document are malformed, they are detected and do not
attackers to crash the OSPF router or routing process. Reception of facilitate a vulnerability for attackers to crash the OSPF router or
a malformed TLV or Sub-TLV SHOULD be counted and/or logged for routing process. Reception of a malformed TLV or sub-TLV SHOULD be
further analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be counted and/or logged for further analysis. Logging of malformed
rate-limited to prevent a Denial of Service (DoS) attack (distributed TLVs and sub-TLVs SHOULD be rate-limited to prevent a denial-of-
or otherwise) from overloading the OSPF control plane. service (DoS) attack (distributed or otherwise) from overloading the
OSPF control plane.
This document defines a new way to advertise link attributes. This document defines a new way to advertise link attributes.
Tampering with the information defined in this document may have an Tampering with the information defined in this document may have an
effect on applications using it, including impacting Traffic effect on applications using it, including impacting traffic
Engineering that uses various link attributes for its path engineering, which uses various link attributes for its path
computation. This is similar in nature to the impacts associated computation. This is similar in nature to the impacts associated
with (for example) [RFC3630]. As the advertisements defined in this with, for example, [RFC3630]. As the advertisements defined in this
document limit the scope to specific applications, the impact of document limit the scope to specific applications, the impact of
tampering is similarly limited in scope. tampering is similarly limited in scope.
15. IANA Considerations 14. IANA Considerations
This specifications updates two existing registries:
- OSPFv2 Extended Link TLV Sub-TLVs Registry
- OSPFv3 Extended-LSA Sub-TLV Registry
New values are allocated using the IETF Review procedure as described
in [RFC5226].
15.1. OSPFv2
The OSPFv2 Extended Link TLV Sub-TLVs Registry [RFC7684] defines sub-
TLVs at any level of nesting for OSPFv2 Extended Link TLVs. IANA has
assigned the following Sub-TLV types from the OSPFv2 Extended Link
TLV Sub-TLVs Registry:
10 - Application-Specific Link Attributes
11 - Shared Risk Link Group
12 - Unidirectional Link Delay
13 - Min/Max Unidirectional Link Delay
14 - Unidirectional Delay Variation
15 - Unidirectional Link Loss This specification updates two existing registries:
16 - Unidirectional Residual Bandwidth * the "OSPFv2 Extended Link TLV Sub-TLVs" registry
17 - Unidirectional Available Bandwidth
18 - Unidirectional Utilized Bandwidth * the "OSPFv3 Extended-LSA Sub-TLVs" registry
19 - Administrative Group The new values defined in this document have been allocated using the
IETF Review procedure as described in [RFC8126].
20 - Extended Administrative Group 14.1. OSPFv2
22 - TE Metric The "OSPFv2 Extended Link TLV Sub-TLVs" registry [RFC7684] defines
sub-TLVs at any level of nesting for OSPFv2 Extended Link TLVs. IANA
has assigned the following sub-TLV types from the "OSPFv2 Extended
Link TLV Sub-TLVs" registry:
23 - Maximum Link Bandwidth 10: Application-Specific Link Attributes
15.2. OSPFv3 11: Shared Risk Link Group
The OSPFv3 Extended-LSA Sub-TLV Registry [RFC8362] defines sub-TLVs 12: Unidirectional Link Delay
at any level of nesting for OSPFv3 Extended LSAs. IANA has assigned
the following Sub-TLV types from the OSPFv3 Extended-LSA Sub-TLV
Registry:
11 - Application-Specific Link Attributes 13: Min/Max Unidirectional Link Delay
12 - Shared Risk Link Group 14: Unidirectional Delay Variation
13 - Unidirectional Link Delay 15: Unidirectional Link Loss
14 - Min/Max Unidirectional Link Delay 16: Unidirectional Residual Bandwidth
15 - Unidirectional Delay Variation 17: Unidirectional Available Bandwidth
16 - Unidirectional Link Loss 18: Unidirectional Utilized Bandwidth
17 - Unidirectional Residual Bandwidth 19: Administrative Group
18 - Unidirectional Available Bandwidth 20: Extended Administrative Group
19 - Unidirectional Utilized Bandwidth 22: TE Metric
20 - Administrative Group 23: Maximum link bandwidth
21 - Extended Administrative Group 14.2. OSPFv3
22 - TE Metric The "OSPFv3 Extended-LSA Sub-TLVs" registry [RFC8362] defines sub-
TLVs at any level of nesting for OSPFv3 Extended LSAs. IANA has
assigned the following sub-TLV types from the "OSPFv3 Extended-LSA
Sub-TLVs" registry:
23 - Maximum Link Bandwidth 11: Application-Specific Link Attributes
24 - Local Interface IPv6 Address Sub-TLV 12: Shared Risk Link Group
25 - Remote Interface IPv6 Address Sub-TLV 13: Unidirectional Link Delay
16. Contributors 14: Min/Max Unidirectional Link Delay
The following people contributed to the content of this document and 15: Unidirectional Delay Variation
should be considered as co-authors:
Acee Lindem 16: Unidirectional Link Loss
Cisco Systems
301 Midenhall Way
Cary, NC 27513
USA
Email: acee@cisco.com 17: Unidirectional Residual Bandwidth
Ketan Talaulikar 18: Unidirectional Available Bandwidth
Cisco Systems, Inc.
India
Email: ketant@cisco.com 19: Unidirectional Utilized Bandwidth
Hannes Gredler 20: Administrative Group
RtBrick Inc.
Austria
Email: hannes@rtbrick.com 21: Extended Administrative Group
17. Acknowledgments 22: TE Metric
Thanks to Chris Bowers for his review and comments. 23: Maximum link bandwidth
Thanks to Alvaro Retana for his detailed review and comments. 24: Local Interface IPv6 Address
18. References 25: Remote Interface IPv6 Address
18.1. Normative References 15. References
[I-D.ietf-isis-te-app] 15.1. Normative References
Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS Application-Specific Link Attributes",
draft-ietf-isis-te-app-19 (work in progress), June 2020.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
skipping to change at page 21, line 5 skipping to change at line 917
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA) F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>. 2018, <https://www.rfc-editor.org/info/rfc8362>.
18.2. Informative References [RFC8919] Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS Application-Specific Link Attributes",
RFC 8919, DOI 10.17487/RFC8919, October 2020,
<https://www.rfc-editor.org/info/rfc8919>.
[I-D.ietf-spring-segment-routing-policy] 15.2. Informative References
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-07 (work in progress),
May 2020.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>. <https://www.rfc-editor.org/info/rfc4552>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for [RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
IP Fast Reroute: Loop-Free Alternates", RFC 5286, IP Fast Reroute: Loop-Free Alternates", RFC 5286,
DOI 10.17487/RFC5286, September 2008, DOI 10.17487/RFC5286, September 2008,
<https://www.rfc-editor.org/info/rfc5286>. <https://www.rfc-editor.org/info/rfc5286>.
[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <https://www.rfc-editor.org/info/rfc5709>. 2009, <https://www.rfc-editor.org/info/rfc5709>.
skipping to change at page 22, line 5 skipping to change at line 957
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166, Authentication Trailer for OSPFv3", RFC 7166,
DOI 10.17487/RFC7166, March 2014, DOI 10.17487/RFC7166, March 2014,
<https://www.rfc-editor.org/info/rfc7166>. <https://www.rfc-editor.org/info/rfc7166>.
[RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed., [RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed.,
"Security Extension for OSPFv2 When Using Manual Key "Security Extension for OSPFv2 When Using Manual Key
Management", RFC 7474, DOI 10.17487/RFC7474, April 2015, Management", RFC 7474, DOI 10.17487/RFC7474, April 2015,
<https://www.rfc-editor.org/info/rfc7474>. <https://www.rfc-editor.org/info/rfc7474>.
[RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <https://www.rfc-editor.org/info/rfc7855>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[SEGMENT-ROUTING]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", Work in
Progress, Internet-Draft, draft-ietf-spring-segment-
routing-policy-08, 8 July 2020,
<https://tools.ietf.org/html/draft-ietf-spring-segment-
routing-policy-08>.
Acknowledgments
Thanks to Chris Bowers for his review and comments.
Thanks to Alvaro Retana for his detailed review and comments.
Contributors
The following people contributed to the content of this document and
should be considered as coauthors:
Acee Lindem
Cisco Systems
301 Midenhall Way
Cary, NC 27513
United States of America
Email: acee@cisco.com
Ketan Talaulikar
Cisco Systems, Inc.
India
Email: ketant@cisco.com
Hannes Gredler
RtBrick Inc.
Austria
Email: hannes@rtbrick.com
Authors' Addresses Authors' Addresses
Peter Psenak (editor) Peter Psenak (editor)
Cisco Systems Cisco Systems
Eurovea Centre, Central 3 Eurovea Centre, Central 3
Pribinova Street 10 Pribinova Street 10
Bratislava 81109 81109 Bratislava
Slovakia Slovakia
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
Les Ginsberg Les Ginsberg
Cisco Systems Cisco Systems
821 Alder Drive 821 Alder Drive
MILPITAS, CA 95035 Milpitas, CA 95035
USA United States of America
Email: ginsberg@cisco.com Email: ginsberg@cisco.com
Wim Henderickx Wim Henderickx
Nokia Nokia
Copernicuslaan 50 Copernicuslaan 50
Antwerp, 2018 94089 2018 94089 Antwerp
Belgium Belgium
Email: wim.henderickx@nokia.com Email: wim.henderickx@nokia.com
Jeff Tantsura Jeff Tantsura
Apstra Apstra
US United States of America
Email: jefftant.ietf@gmail.com Email: jefftant.ietf@gmail.com
John Drake John Drake
Juniper Networks Juniper Networks
1194 N. Mathilda Ave 1194 N. Mathilda Ave
Sunnyvale, California 94089 Sunnyvale, California 94089
USA United States of America
Email: jdrake@juniper.net Email: jdrake@juniper.net
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