draft-ietf-ospf-te-link-attr-reuse-15.txt   draft-ietf-ospf-te-link-attr-reuse-16.txt 
LSR Working Group P. Psenak, Ed. LSR Working Group P. Psenak, Ed.
Internet-Draft L. Ginsberg Internet-Draft L. Ginsberg
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: December 24, 2020 W. Henderickx Expires: January 1, 2021 W. Henderickx
Nokia Nokia
J. Tantsura J. Tantsura
Apstra Apstra
J. Drake J. Drake
Juniper Networks Juniper Networks
June 22, 2020 June 30, 2020
OSPF Application-Specific Link Attributes OSPF Application-Specific Link Attributes
draft-ietf-ospf-te-link-attr-reuse-15.txt 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, Loop Free Alternate) have been defined that
also make use of the link attribute advertisements. In cases where also make use of the link attribute advertisements. In cases where
multiple applications wish to make use of these link attributes the multiple applications wish to make use of these link attributes the
current advertisements do not support application specific values for current advertisements do not support application specific values for
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 24, 2020. This Internet-Draft will expire on January 1, 2021.
Copyright Notice Copyright Notice
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Existing Advertisement of Link Attributes . . . . . . . . . . 4 3. Requirements Discussion . . . . . . . . . . . . . . . . . . . 4
4. Advertisement of Link Attributes . . . . . . . . . . . . . . 4 4. Existing Advertisement of Link Attributes . . . . . . . . . . 5
4.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA . 4 5. Advertisement of Link Attributes . . . . . . . . . . . . . . 5
5. Advertisement of Application-Specific Values . . . . . . . . 5 5.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA . 5
6. Reused TE link attributes . . . . . . . . . . . . . . . . . . 9 6. Advertisement of Application-Specific Values . . . . . . . . 6
6.1. Shared Risk Link Group (SRLG) . . . . . . . . . . . . . . 9 7. Reused TE link attributes . . . . . . . . . . . . . . . . . . 9
6.2. Extended Metrics . . . . . . . . . . . . . . . . . . . . 9 7.1. Shared Risk Link Group (SRLG) . . . . . . . . . . . . . . 10
6.3. Administrative Group . . . . . . . . . . . . . . . . . . 10 7.2. Extended Metrics . . . . . . . . . . . . . . . . . . . . 10
6.4. Traffic Engineering Metric . . . . . . . . . . . . . . . 10 7.3. Administrative Group . . . . . . . . . . . . . . . . . . 11
7. Maximum Link Bandwidth . . . . . . . . . . . . . . . . . . . 11 7.4. Traffic Engineering Metric . . . . . . . . . . . . . . . 11
8. Considerations for Extended TE Metrics . . . . . . . . . . . 11 8. Maximum Link Bandwidth . . . . . . . . . . . . . . . . . . . 11
9. Local Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 11 9. Considerations for Extended TE Metrics . . . . . . . . . . . 12
10. Remote Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12 10. Local Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12
11. Attribute Advertisements and Enablement . . . . . . . . . . . 12 11. Remote Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12
12. Deployment Considerations . . . . . . . . . . . . . . . . . . 13 12. Attribute Advertisements and Enablement . . . . . . . . . . . 13
12.1. Use of Legacy RSVP-TE LSA Advertisements . . . . . . . . 13 13. Deployment Considerations . . . . . . . . . . . . . . . . . . 14
12.2. Interoperability, Backwards Compatibility and Migration 13.1. Use of Legacy RSVP-TE LSA Advertisements . . . . . . . . 14
Concerns . . . . . . . . . . . . . . . . . . . . . . . . 14 13.2. Interoperability, Backwards Compatibility and Migration
12.2.1. Multiple Applications: Common Attributes with RSVP- Concerns . . . . . . . . . . . . . . . . . . . . . . . . 15
TE . . . . . . . . . . . . . . . . . . . . . . . . . 14 13.2.1. Multiple Applications: Common Attributes with RSVP-
12.2.2. Multiple Applications: Some Attributes Not Shared
with RSVP-TE . . . . . . . . . . . . . . . . . . . . 14
12.2.3. Interoperability with Legacy Routers . . . . . . . . 15
12.2.4. Use of Application-Specific Advertisements for RSVP-
TE . . . . . . . . . . . . . . . . . . . . . . . . . 15 TE . . . . . . . . . . . . . . . . . . . . . . . . . 15
13. Security Considerations . . . . . . . . . . . . . . . . . . . 16 13.2.2. Multiple Applications: Some Attributes Not Shared
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 with RSVP-TE . . . . . . . . . . . . . . . . . . . . 15
14.1. OSPFv2 . . . . . . . . . . . . . . . . . . . . . . . . . 16 13.2.3. Interoperability with Legacy Routers . . . . . . . . 15
14.2. OSPFv3 . . . . . . . . . . . . . . . . . . . . . . . . . 17 13.2.4. Use of Application-Specific Advertisements for RSVP-
TE . . . . . . . . . . . . . . . . . . . . . . . . . 16
15. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 14. Security Considerations . . . . . . . . . . . . . . . . . . . 16
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 15.1. OSPFv2 . . . . . . . . . . . . . . . . . . . . . . . . . 17
17.1. Normative References . . . . . . . . . . . . . . . . . . 19 15.2. OSPFv3 . . . . . . . . . . . . . . . . . . . . . . . . . 18
17.2. Informative References . . . . . . . . . . . . . . . . . 20 16. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
18.1. Normative References . . . . . . . . . . . . . . . . . . 19
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 to as RSVP-TE [RFC3209]. referred 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 that
makes use of link attribute advertisements, examples of which are makes use of link attribute advertisements, examples of which are
listed in Section 5. listed in Section 6.
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 [I-D.ietf-spring-segment-routing-policy] and Loop Free Alternates
(LFA) [RFC5286]. This has introduced ambiguity in that if a (LFA) [RFC5286]. This has introduced ambiguity in that if a
deployment includes a mix of RSVP-TE support and SR Policy support deployment includes a mix of RSVP-TE support and SR Policy support
(for example) it is not possible to unambiguously indicate which (for example) it is not possible to unambiguously indicate which
advertisements are to be used by RSVP-TE and which advertisements are advertisements are to be used by RSVP-TE and which advertisements are
to be used by SR Policy. If the topologies are fully congruent this to be used by SR Policy. If the topologies are fully congruent this
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use cases. use cases.
2. Requirements Language 2. 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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Existing Advertisement of Link Attributes 3. Requirements Discussion
As stated previously, evolution of use cases for link attributes can
be expected to continue. Therefore, any discussion of existing use
cases is limited to requirements that are known at the time of this
writing. However, in order to determine the functionality required
beyond what already exists in OSPF, it is only necessary to discuss
use cases that justify the key points identified in the introduction,
which are:
1. Support for indicating which applications are using the link
attribute advertisements on a link
2. Support for advertising application-specific values for the same
attribute on a link
[RFC7855] discusses use cases/requirements for Segment Routing (SR).
Included among these use cases is SR Policy which is defined in
[I-D.ietf-spring-segment-routing-policy]. If both RSVP-TE and SR
Policy are deployed in a network, link attribute advertisements can
be used by one or both of these applications. As there is no
requirement for the link attributes advertised on a given link used
by SR Policy to be identical to the link attributes advertised on
that same link used by RSVP-TE, there is a clear requirement to
indicate independently which link attribute advertisements are to be
used by each application.
As the number of applications that may wish to utilize link
attributes may grow in the future, an additional requirement is that
the extensions defined allow the association of additional
applications to link attributes without altering the format of the
advertisements or introducing new backwards compatibility issues.
Finally, there may still be many cases where a single attribute value
can be shared among multiple applications, so the solution must
minimize advertising duplicate link/attribute pairs whenever
possible.
4. 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 LSA [RFC3630] and
OSPFv3 Intra-Area-TE-LSA [RFC5329]. Additional RSVP-TE link OSPFv3 Intra-Area-TE-LSA [RFC5329]. Additional RSVP-TE link
attributes have been defined by [RFC4203], [RFC7308] and [RFC7471]. 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
Extended Router-LSAs [RFC8362] for OSPFv3 are used to advertise link Extended 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 a generic containers for
distribution of the extended link attributes. distribution of the extended link attributes.
4. Advertisement of Link Attributes 5. 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.
4.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA 5.1. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA
Advantages of Extended Link Opaque LSAs as defined in [RFC7684] for Advantages of Extended Link Opaque LSAs as defined in [RFC7684] for
OSPFv2 and Extended Router-LSAs [RFC8362] for OSPFv3 with respect to OSPFv2 and Extended Router-LSAs [RFC8362] for OSPFv3 with respect to
advertisement of link attributes originally defined for RSVP-TE when advertisement of link attributes originally defined for RSVP-TE when
used in packet networks and in GMPLS: 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].
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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 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 6). Section 7).
TE link attributes used for RSVP-TE/GMPLS continue to use OSPFv2 TE TE link attributes used for RSVP-TE/GMPLS continue to use OSPFv2 TE
Opaque LSA [RFC3630] and OSPFv3 Intra-Area-TE-LSA [RFC5329]. 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 code points 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-TLV
Registry [RFC7684] and from the OSPFv3 Extended-LSA Sub-TLV Registry Registry [RFC7684] and from the OSPFv3 Extended-LSA Sub-TLV Registry
[RFC8362], as specified in Section 14. [RFC8362], as specified in Section 15.
5. Advertisement of Application-Specific Values 6. 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 On top of 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
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use the link attributes advertised in the ASLA sub-TLV. use the link attributes advertised in the ASLA sub-TLV.
Application Bit Masks apply to all link attributes that support Application Bit Masks apply to all link attributes that support
application-specific values and are advertised in the ASLA sub-TLV. 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 Bit Masks part of the
attribute advertisement itself is that the format of any previously attribute advertisement itself is that the format of any previously
defined link attributes can be kept and reused when advertising them defined link attributes can be kept and reused when advertising them
in the ASLA sub-TLV. in the ASLA sub-TLV.
If the same attribute is advertised in more than single 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 Bit Masks, the
application SHOULD use the first instance of advertisement and ignore application SHOULD use the first instance of advertisement and ignore
any subsequent advertisements of that attribute. any subsequent advertisements of that attribute.
If link attributes are advertised associated with zero length If link attributes are advertised with zero length Application
Application Identifier Bit Masks for both standard applications and Identifier Bit Masks for both standard applications and user defined
user defined applications, then any Standard Application and/or any applications, then any Standard Application and/or any User Defined
User Defined Application is permitted to use that set of link Application is permitted to use that set of link attributes. If
attributes. If support for a new application is introduced on any support for a new application is introduced on any node in a network
node in a network in the presence of such advertisements, these in the presence of such advertisements, these advertisements are
advertisements are permitted to be used by the new application. If permitted to be used by the new application. If this is not what is
this is not what is intended, then existing advertisements MUST be intended, then existing advertisements MUST be readvertised with an
readvertised with an explicit set of applications specified before a explicit set of applications specified before a new application is
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 which define new link
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- 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]
6. Reused TE link attributes 7. Reused TE link attributes
This section defines the use case and indicates the code points This section defines the use case and indicates the code points
(Section 14) from the OSPFv2 Extended Link TLV Sub-TLV Registry and (Section 15) from the OSPFv2 Extended Link TLV Sub-TLV Registry and
OSPFv3 Extended-LSA Sub-TLV Registry for some of the link attributes OSPFv3 Extended-LSA Sub-TLV Registry for some of the link attributes
that have been originally defined for RSVP-TE or GMPLS. that have been originally defined for RSVP-TE or GMPLS.
6.1. Shared Risk Link Group (SRLG) 7.1. 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 and TLV type 11 is used. Similarly, for OSPFv3 to advertise
the SRLG in the OSPFv3 Router-Link TLV, TLV type 12 is used. the SRLG in the OSPFv3 Router-Link TLV, TLV type 12 is used.
6.2. Extended Metrics 7.2. 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:
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15 - Unidirectional Delay Variation 15 - Unidirectional Delay Variation
16 - Unidirectional Link Loss 16 - Unidirectional Link Loss
17 - Unidirectional Residual Bandwidth 17 - Unidirectional Residual Bandwidth
18 - Unidirectional Available Bandwidth 18 - Unidirectional Available Bandwidth
19 - Unidirectional Utilized Bandwidth 19 - Unidirectional Utilized Bandwidth
6.3. Administrative Group 7.3. 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
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To advertise Administrative Group and Extended Administrative Group To advertise Administrative Group and Extended Administrative Group
in the OSPFv3 Router-Link TLV, the same format for the sub-TLVs 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
6.4. Traffic Engineering Metric 7.4. Traffic Engineering Metric
[RFC3630] defines Traffic Engineering Metric. [RFC3630] defines 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 and TLV type 22 is used. 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.
7. Maximum Link Bandwidth 8. Maximum Link Bandwidth
Maximum link bandwidth is an application independent attribute of the Maximum link bandwidth is an application independent attribute of the
link that is defined in [RFC3630]. Because it is an application link that is defined in [RFC3630]. Because it is an application
independent attribute, it MUST NOT be advertised in ASLA sub-TLV. independent attribute, it MUST NOT be advertised in ASLA sub-TLV.
Instead, it MAY be advertised as a sub-TLV of the Extended Link Instead, it MAY be advertised as a sub-TLV of the Extended Link
Opaque LSA Extended Link TLV in OSPFv2 [RFC7684] or sub-TLV of OSPFv3 Opaque LSA Extended Link TLV in OSPFv2 [RFC7684] or sub-TLV of OSPFv3
E-Router-LSA Router-Link TLV in OSPFv3 [RFC8362]. 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 sub-TLV defined in [RFC3630] is used with
TLV type 23. 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 sub-TLV defined in [RFC3630] is used with
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E-Router-LSA Router-Link TLV in OSPFv3 [RFC8362]. 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 sub-TLV defined in [RFC3630] is used with
TLV type 23. 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 sub-TLV defined in [RFC3630] is used with
TLV type 23. TLV type 23.
8. Considerations for Extended TE Metrics 9. 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.
9. Local Interface IPv6 Address Sub-TLV 10. 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 OSPFv3 E-Router-LSA Router-Link TLV [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 sub-TLV defined in [RFC5329] is
used with TLV type 24. used with TLV type 24.
10. Remote Interface IPv6 Address Sub-TLV 11. 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 OSPFv3 E-Router-LSA Router-Link TLV [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 sub-TLV defined in [RFC5329] is
used with TLV type 25. used with TLV type 25.
11. Attribute Advertisements and Enablement 12. 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 - e.g., RSVP-TE - one needs to make sure that RSVP is
enabled on the link before sending a RSVP-TE signaling message over enabled on the link before sending a RSVP-TE signaling message over
it. it.
There are applications where the enablement of the application on the There are applications where the enablement of the application on the
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Enablement is controlled by local configuration. Enablement is controlled by local configuration.
If, in the future, additional standard applications are defined to If, in the future, additional standard applications are defined to
use this mechanism, the specification defining this use MUST define use this mechanism, the specification defining this use MUST define
the relationship between application-specific link attribute the 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 5). This supports Identifier Bit Mask are not present (See Section 6). 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 attribute
advertisements is used to infer the enablement of an application on advertisements is used to infer the enablement of an application on
that link (e.g., RSVP-TE), the absence of the application identifier that link (e.g., RSVP-TE), the absence of the application identifier
leaves ambiguous whether that application is enabled on such a link. leaves ambiguous whether that application is enabled on such a link.
This needs to be considered when making use of the "any application" This needs to be considered when making use of the "any application"
encoding. encoding.
12. Deployment Considerations 13. Deployment Considerations
12.1. Use of Legacy RSVP-TE LSA Advertisements 13.1. Use of Legacy RSVP-TE LSA Advertisements
Bit Identifiers for Standard Applications are defined in Section 5. Bit Identifiers for Standard Applications are defined in Section 6.
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
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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 is 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 type of advertisements are to be
sent/ processed on receive for these applications. Further sent/ processed on receive for these applications. Further
discussion of the associated issues can be found in Section 12.2. discussion of the associated issues can be found in Section 13.2.
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.
12.2. Interoperability, Backwards Compatibility and Migration Concerns 13.2. 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 3. Routers which do not legacy advertisements listed in Section 4. Routers which 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 sub-sections discuss interoperability and backwards
compatibility concerns for a number of deployment scenarios. compatibility concerns for a number of deployment scenarios.
12.2.1. Multiple Applications: Common Attributes with RSVP-TE 13.2.1. 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.
12.2.2. Multiple Applications: Some Attributes Not Shared with RSVP-TE 13.2.2. 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
12.2.3. Interoperability with Legacy Routers 13.2.3. 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
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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.
12.2.4. Use of Application-Specific Advertisements for RSVP-TE 13.2.4. 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 backward
compatibility. RSVP-TE can eventually utilize the application- compatibility. RSVP-TE can eventually utilize the application-
specific advertisements for newly defined link attributes, that are specific advertisements for newly defined link attributes, that are
defined as application-specific. 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 ASLA Sub-
TLV. TLV.
13. Security Considerations 14. Security Considerations
Existing security extensions as described in [RFC2328], [RFC5340] and Existing security extensions as described in [RFC2328], [RFC5340] and
[RFC8362] apply to extensions defined in this document. While OSPF [RFC8362] apply to extensions defined in this document. While OSPF
is under a single administrative domain, there can be deployments is under a single administrative domain, there can be deployments
where potential attackers have access to one or more networks in the where potential attackers have access to one or more networks in the
OSPF routing domain. In these deployments, stronger authentication OSPF routing domain. In these deployments, stronger authentication
mechanisms such as those specified in [RFC5709], [RFC7474], [RFC4552] mechanisms such as those specified in [RFC5709], [RFC7474], [RFC4552]
or [RFC7166] SHOULD be used. or [RFC7166] SHOULD be used.
Implementations must assure that malformed TLV and Sub-TLV defined in Implementations must assure that malformed TLV and Sub-TLV defined in
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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 that 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.
14. IANA Considerations 15. IANA Considerations
This specifications updates two existing registries: This specifications updates two existing registries:
- OSPFv2 Extended Link TLV Sub-TLVs Registry - OSPFv2 Extended Link TLV Sub-TLVs Registry
- OSPFv3 Extended-LSA Sub-TLV Registry - OSPFv3 Extended-LSA Sub-TLV Registry
New values are allocated using the IETF Review procedure as described New values are allocated using the IETF Review procedure as described
in [RFC5226]. in [RFC5226].
14.1. OSPFv2 15.1. OSPFv2
The OSPFv2 Extended Link TLV Sub-TLVs Registry [RFC7684] defines sub- The OSPFv2 Extended Link TLV Sub-TLVs Registry [RFC7684] defines sub-
TLVs at any level of nesting for OSPFv2 Extended Link TLVs. IANA has TLVs at any level of nesting for OSPFv2 Extended Link TLVs. IANA has
assigned the following Sub-TLV types from the OSPFv2 Extended Link assigned the following Sub-TLV types from the OSPFv2 Extended Link
TLV Sub-TLVs Registry: TLV Sub-TLVs Registry:
10 - Application-Specific Link Attributes 10 - Application-Specific Link Attributes
11 - Shared Risk Link Group 11 - Shared Risk Link Group
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
19 - Administrative Group 19 - Administrative Group
20 - Extended Administrative Group 20 - Extended Administrative Group
22 - TE Metric 22 - TE Metric
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18 - Unidirectional Utilized Bandwidth 18 - Unidirectional Utilized Bandwidth
19 - Administrative Group 19 - Administrative Group
20 - Extended Administrative Group 20 - Extended Administrative Group
22 - TE Metric 22 - TE Metric
23 - Maximum Link Bandwidth 23 - Maximum Link Bandwidth
14.2. OSPFv3 15.2. OSPFv3
The OSPFv3 Extended-LSA Sub-TLV Registry [RFC8362] defines sub-TLVs The OSPFv3 Extended-LSA Sub-TLV Registry [RFC8362] defines sub-TLVs
at any level of nesting for OSPFv3 Extended LSAs. IANA has assigned at any level of nesting for OSPFv3 Extended LSAs. IANA has assigned
the following Sub-TLV types from the OSPFv3 Extended-LSA Sub-TLV the following Sub-TLV types from the OSPFv3 Extended-LSA Sub-TLV
Registry: Registry:
11 - Application-Specific Link Attributes 11 - Application-Specific Link Attributes
12 - Shared Risk Link Group 12 - Shared Risk Link Group
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21 - Extended Administrative Group 21 - Extended Administrative Group
22 - TE Metric 22 - TE Metric
23 - Maximum Link Bandwidth 23 - Maximum Link Bandwidth
24 - Local Interface IPv6 Address Sub-TLV 24 - Local Interface IPv6 Address Sub-TLV
25 - Remote Interface IPv6 Address Sub-TLV 25 - Remote Interface IPv6 Address Sub-TLV
15. Contributors 16. Contributors
The following people contributed to the content of this document and The following people contributed to the content of this document and
should be considered as co-authors: should be considered as co-authors:
Acee Lindem Acee Lindem
Cisco Systems Cisco Systems
301 Midenhall Way 301 Midenhall Way
Cary, NC 27513 Cary, NC 27513
USA USA
skipping to change at page 18, line 39 skipping to change at page 19, line 30
India India
Email: ketant@cisco.com Email: ketant@cisco.com
Hannes Gredler Hannes Gredler
RtBrick Inc. RtBrick Inc.
Austria Austria
Email: hannes@rtbrick.com Email: hannes@rtbrick.com
16. Acknowledgments 17. Acknowledgments
Thanks to Chris Bowers for his review and comments. Thanks to Chris Bowers for his review and comments.
Thanks to Alvaro Retana for his detailed review and comments. Thanks to Alvaro Retana for his detailed review and comments.
17. References 18. References
17.1. Normative References 18.1. Normative References
[I-D.ietf-isis-te-app] [I-D.ietf-isis-te-app]
Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS TE Attributes per application", draft- J. Drake, "IS-IS Application-Specific Link Attributes",
ietf-isis-te-app-17 (work in progress), June 2020. 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 20, line 19 skipping to change at page 21, line 5
[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>.
17.2. Informative References 18.2. Informative References
[I-D.ietf-spring-segment-routing-policy] [I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft- P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-07 (work in progress), ietf-spring-segment-routing-policy-07 (work in progress),
May 2020. 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,
 End of changes. 51 change blocks. 
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