draft-ietf-isis-te-app-19.txt   rfc8919.txt 
Networking Working Group L. Ginsberg Internet Engineering Task Force (IETF) L. Ginsberg
Internet-Draft P. Psenak Request for Comments: 8919 P. Psenak
Intended status: Standards Track Cisco Systems Category: Standards Track Cisco Systems
Expires: December 31, 2020 S. Previdi ISSN: 2070-1721 S. Previdi
Huawei Huawei Technologies
W. Henderickx W. Henderickx
Nokia Nokia
J. Drake J. Drake
Juniper Networks Juniper Networks
June 29, 2020 October 2020
IS-IS Application-Specific Link Attributes IS-IS Application-Specific Link Attributes
draft-ietf-isis-te-app-19
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) that also make use of Segment Routing Policy and Loop-Free Alternates) that also make use
the link attribute advertisements have been defined . 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 that address link. This document introduces new link attribute advertisements
both of these shortcomings. that address both of these shortcomings.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on December 31, 2020. 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/rfc8919.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language
3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 5 2. Requirements Discussion
3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 5 3. Legacy Advertisements
3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 6 3.1. Legacy Sub-TLVs
4. Advertising Application-Specific Link Attributes . . . . . . 7 3.2. Legacy SRLG Advertisements
4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 7 4. Advertising Application-Specific Link Attributes
4.2. Application-Specific Link Attributes sub-TLV . . . . . . 9 4.1. Application Identifier Bit Mask
4.2.1. Special Considerations for Maximum Link Bandwidth . . 11 4.2. Application-Specific Link Attributes Sub-TLV
4.2.1. Special Considerations for Maximum Link Bandwidth
4.2.2. Special Considerations for Reservable/Unreserved 4.2.2. Special Considerations for Reservable/Unreserved
Bandwidth . . . . . . . . . . . . . . . . . . . . . . 11 Bandwidth
4.2.3. Considerations for Extended TE Metrics . . . . . . . 11 4.2.3. Considerations for Extended TE Metrics
4.3. Application-Specific SRLG TLV . . . . . . . . . . . . . . 12 4.3. Application-Specific SRLG TLV
5. Attribute Advertisements and Enablement . . . . . . . . . . . 13 5. Attribute Advertisements and Enablement
6. Deployment Considerations . . . . . . . . . . . . . . . . . . 14 6. Deployment Considerations
6.1. Use of Legacy Advertisements . . . . . . . . . . . . . . 14 6.1. Use of Legacy Advertisements
6.2. Use of Zero Length Application Identifier Bit Masks . . . 15 6.2. Use of Zero-Length Application Identifier Bit Masks
6.3. Interoperability, Backwards Compatibility and Migration 6.3. Interoperability, Backwards Compatibility, and Migration
Concerns . . . . . . . . . . . . . . . . . . . . . . . . 15 Concerns
6.3.1. Multiple Applications: Common Attributes with RSVP- 6.3.1. Multiple Applications: Common Attributes with RSVP-TE
TE . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.3.2. Multiple Applications: All Attributes Not Shared with 6.3.2. Multiple Applications: All Attributes Not Shared with
RSVP-TE . . . . . . . . . . . . . . . . . . . . . . . 15 RSVP-TE
6.3.3. Interoperability with Legacy Routers . . . . . . . . 16 6.3.3. Interoperability with Legacy Routers
6.3.4. Use of Application-Specific Advertisements for RSVP- 6.3.4. Use of Application-Specific Advertisements for RSVP-TE
TE . . . . . . . . . . . . . . . . . . . . . . . . . 16 7. IANA Considerations
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7.1. Application-Specific Link Attributes Sub-TLV
7.1. Application-Specific Link Attributes sub-TLV . . . . . . 17 7.2. Application-Specific SRLG TLV
7.2. Application-Specific SRLG TLV . . . . . . . . . . . . . . 17 7.3. Sub-sub-TLV Codepoints for Application-Specific Link
7.3. Application-Specific Link Attributes sub-sub-TLV Registry 17 Attributes Registry
7.4. Link Attribute Application Identifier Registry . . . . . 18 7.4. Link Attribute Application Identifiers Registry
7.5. SRLG sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 19 7.5. Sub-TLVs for TLV 238 Registry
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 8. Security Considerations
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 20 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 21 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses
1. Introduction 1. Introduction
Advertisement of link attributes by the Intermediate-System-to- Advertisement of link attributes by the Intermediate System to
Intermediate-System (IS-IS) protocol in support of traffic Intermediate System (IS-IS) protocol in support of traffic
engineering (TE) was introduced by [RFC5305] and extended by engineering (TE) was introduced by [RFC5305] and extended by
[RFC5307], [RFC6119], [RFC7308], and [RFC8570]. Use of these [RFC5307], [RFC6119], [RFC7308], and [RFC8570]. 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 3. are listed in Section 3.
In recent years new applications that have use cases for many of the In recent years, new applications that have use cases for many of the
link attributes historically used by RSVP-TE have been introduced. link attributes historically used by RSVP-TE have been introduced.
Such applications include Segment Routing Policy (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 where 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 a path setup set up an RSVP-TE path via that link, it will result in a path setup
failure. 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 to the introduction of new applications and new is easily extensible to the introduction of new applications and new
use cases. use cases.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. 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 IS-IS, it is only necessary to discuss beyond what already exists in IS-IS, 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.
3. Legacy Advertisements 3. Legacy Advertisements
There are existing advertisements used in support of RSVP-TE. These Existing advertisements used in support of RSVP-TE include sub-TLVs
advertisements include sub-TLVs for TLVs 22, 23, 25, 141, 222, and for TLVs 22, 23, 25, 141, 222, and 223 and TLVs for Shared Risk Link
223 and TLVs for Shared Risk Link Group (SRLG) advertisement. Group (SRLG) advertisement.
Sub-TLV values are defined in the Sub-TLVs for TLVs 22, 23, 25, 141, Sub-TLV values are defined in the "Sub-TLVs for TLVs 22, 23, 25, 141,
222, and 223 registry. 222, and 223" registry.
TLVs are defined in the TLV Codepoints Registry. TLVs are defined in the "TLV Codepoints Registry".
3.1. Legacy sub-TLVs 3.1. Legacy Sub-TLVs
Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223
+-------------------------------------------+ +======+====================================+
| Type | Description | | Type | Description |
+-------------------------------------------+ +======+====================================+
| 3 | Administrative group (color) | | 3 | Administrative group (color) |
+-------------------------------------------+ +------+------------------------------------+
| 9 | Maximum link bandwidth | | 9 | Maximum link bandwidth |
+-------------------------------------------+ +------+------------------------------------+
| 10 | Maximum reservable link bandwidth | | 10 | Maximum reservable link bandwidth |
+-------------------------------------------+ +------+------------------------------------+
| 11 | Unreserved bandwidth | | 11 | Unreserved bandwidth |
+-------------------------------------------+ +------+------------------------------------+
| 14 | Extended Administrative Group | | 14 | Extended Administrative Group |
+-------------------------------------------+ +------+------------------------------------+
| 18 | TE Default Metric | | 18 | TE Default Metric |
+-------------------------------------------+ +------+------------------------------------+
| 33 | Unidirectional Link Delay | | 33 | Unidirectional Link Delay |
+-------------------------------------------+ +------+------------------------------------+
| 34 | Min/Max Unidirectional Link Delay | | 34 | Min/Max Unidirectional Link Delay |
+-------------------------------------------+ +------+------------------------------------+
| 35 | Unidirectional Delay Variation | | 35 | Unidirectional Delay Variation |
+-------------------------------------------+ +------+------------------------------------+
| 36 | Unidirectional Link Loss | | 36 | Unidirectional Link Loss |
+-------------------------------------------+ +------+------------------------------------+
| 37 | Unidirectional Residual Bandwidth | | 37 | Unidirectional Residual Bandwidth |
+-------------------------------------------+ +------+------------------------------------+
| 38 | Unidirectional Available Bandwidth | | 38 | Unidirectional Available Bandwidth |
+-------------------------------------------+ +------+------------------------------------+
| 39 | Unidirectional Utilized Bandwidth | | 39 | Unidirectional Utilized Bandwidth |
+-------------------------------------------+ +------+------------------------------------+
Table 1: Sub-TLVs for TLVs 22, 23, 25,
141, 222, and 223
3.2. Legacy SRLG Advertisements 3.2. Legacy SRLG Advertisements
TLV 138 GMPLS-SRLG TLV 138 (GMPLS-SRLG):
Supports links identified by IPv4 addresses and Supports links identified by IPv4 addresses and unnumbered links.
unnumbered links
TLV 139 IPv6 SRLG TLV 139 (IPv6 SRLG):
Supports links identified by IPv6 addresses Supports links identified by IPv6 addresses.
Note that [RFC6119] prohibits the use of TLV 139 when it is possible Note that [RFC6119] prohibits the use of TLV 139 when it is possible
to use TLV 138. to use TLV 138.
4. Advertising Application-Specific Link Attributes 4. Advertising Application-Specific Link Attributes
Two new code points are defined in support of Application-Specific Two new codepoints are defined to support Application-Specific Link
Link Attribute (ASLA) Advertisements: Attribute (ASLA) advertisements:
1) ASLA sub-TLV for TLVs 22, 23, 25, 141, 222, and 223 (defined in 1) Application-Specific Link Attributes sub-TLV for TLVs 22, 23, 25,
Section 4.2 ). 141, 222, and 223 (defined in Section 4.2).
2)Application-Specific Shared Risk Link Group (SRLG) TLV (defined in 2) Application-Specific Shared Risk Link Group (SRLG) TLV (defined
Section 4.3). in Section 4.3).
In support of these new advertisements, an application identifier bit To support these new advertisements, an application identifier bit
mask is defined that identifies the application(s) associated with a mask is defined to identify the application(s) associated with a
given advertisement (defined in Section 4.1). given advertisement (defined in Section 4.1).
In addition to supporting the advertisement of link attributes used In addition to supporting the advertisement of link attributes used
by standardized applications, link attributes can also be advertised by standardized applications, link attributes can also be advertised
for use by user defined applications. Such applications are not for use by user-defined applications. Such applications are not
subject to standardization and are outside the scope of this subject to standardization and are outside the scope of this
document. document.
The following sections define the format of these new advertisements. The following sections define the format of these new advertisements.
4.1. Application Identifier Bit Mask 4.1. Application Identifier Bit Mask
Identification of the set of applications associated with link Identification of the set of applications associated with link
attribute advertisements utilizes two bit masks. One bit mask is for attribute advertisements utilizes two bit masks. One bit mask is for
standard applications where the definition of each bit is defined in standard applications where the definition of each bit is defined in
a new IANA controlled registry. A second bit mask is for non- a new IANA-controlled registry (see Section 7.4). A second bit mask
standard User Defined Applications (UDAs). is for non-standard user-defined applications (UDAs).
The encoding defined below is used by both the Application-Specific The encoding defined below is used by both the Application-Specific
Link Attributes sub-TLV and the Application-Specific SRLG TLV. Link Attributes sub-TLV and the Application-Specific SRLG TLV.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
| SABM Length + Flag | 1 octet | SABM Length + Flag | 1 octet
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
| UDABM Length + Flag | 1 octet | UDABM Length + Flag | 1 octet
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
| SABM ... 0 - 8 octets | SABM ... 0 - 8 octets
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
| UDABM ... 0 - 8 octets | UDABM ... 0 - 8 octets
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
SABM Length + Flag (1 octet) SABM Length + Flag (1 octet): Standard Application Identifier Bit
Standard Application Identifier Bit Mask Mask Length + Flag
Length + Flag
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L| SABM Length |
+-+-+-+-+-+-+-+-+
L-flag: Legacy Flag. 0 1 2 3 4 5 6 7
See Section 4.2 for a description of how +-+-+-+-+-+-+-+-+
this flag is used. |L| SABM Length |
+-+-+-+-+-+-+-+-+
SABM Length: Indicates the length in octets (0-8) of the L-flag: Legacy Flag. See Section 4.2 for a description of how
Standard Application Identifier Bit Mask. The length SHOULD this flag is used.
be the minimum required to send all bits that are set.
UDABM Length + Flag (1 octet) SABM Length: Indicates the length in octets (0-8) of the Standard
User Defined Application Identifier Bit Mask Application Identifier Bit Mask. The length SHOULD be the
Length + Flag minimum required to send all bits that are set.
0 1 2 3 4 5 6 7 UDABM Length + Flag (1 octet): User-Defined Application Identifier
+-+-+-+-+-+-+-+-+ Bit Mask Length + Flag
|R| UDABM Length|
+-+-+-+-+-+-+-+-+
R: Reserved. SHOULD be transmitted as 0 and 0 1 2 3 4 5 6 7
MUST be ignored on receipt +-+-+-+-+-+-+-+-+
|R| UDABM Length|
+-+-+-+-+-+-+-+-+
UDABM Length: Indicates the length in octets (0-8) of the R: Reserved. SHOULD be transmitted as 0 and MUST be ignored on
User Defined Application Identifier Bit Mask. The length SHOULD receipt.
be the minimum required to send all bits that are set.
SABM (variable length) UDABM Length: Indicates the length in octets (0-8) of the User-
Standard Application Identifier Bit Mask Defined Application Identifier Bit Mask. The length SHOULD be
the minimum required to send all bits that are set.
SABM (variable length): Standard Application Identifier Bit Mask
(SABM Length * 8) bits (SABM Length * 8) bits
This field is omitted if SABM Length is 0. This field is omitted if SABM Length is 0.
0 1 2 3 4 5 6 7 ... 0 1 2 3 4 5 6 7 ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
|R|S|F| ... |R|S|F| ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
R-bit: Set to specify RSVP-TE R-bit: Set to specify RSVP-TE.
S-bit: Set to specify Segment Routing Policy S-bit: Set to specify Segment Routing Policy.
F-bit: Set to specify Loop Free Alternate (LFA) F-bit: Set to specify Loop-Free Alternate (LFA) (includes all LFA
(includes all LFA types) types).
UDABM (variable length) UDABM (variable length): User-Defined Application Identifier Bit
User Defined Application Identifier Bit Mask Mask
(UDABM Length * 8) bits (UDABM Length * 8) bits
0 1 2 3 4 5 6 7 ... 0 1 2 3 4 5 6 7 ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
| ... | ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
This field is omitted if UDABM Length is 0. This field is omitted if UDABM Length is 0.
NOTE: SABM/UDABM Length is arbitrarily limited to 8 octets in order | Note: SABM/UDABM Length is arbitrarily limited to 8 octets in
to insure that sufficient space is left to advertise link attributes | order to ensure that sufficient space is left to advertise link
without overrunning the maximum length of a sub-TLV. | attributes without overrunning the maximum length of a sub-TLV.
Standard Application Identifier Bits are defined/sent starting with Standard Application Identifier Bits are defined and sent starting
Bit 0. with bit 0.
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 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. to advertise all UDAs.
In the case of both SABM and UDABM, the following rules apply: For both SABM and UDABM, the following rules apply:
o Undefined bits that are transmitted MUST be transmitted as 0 and * Undefined bits that are transmitted MUST be transmitted as 0 and
MUST be ignored on receipt MUST be ignored on receipt.
o Bits that are not transmitted MUST be treated as if they are set * Bits that are not transmitted MUST be treated as if they are set
to 0 on receipt. to 0 on receipt.
o Bits that are not supported by an implementation MUST be ignored * Bits that are not supported by an implementation MUST be ignored
on receipt. on receipt.
. 4.2. Application-Specific Link Attributes Sub-TLV
4.2. Application-Specific Link Attributes sub-TLV
A new sub-TLV for TLVs 22, 23, 25, 141, 222, and 223 is defined that A new sub-TLV for TLVs 22, 23, 25, 141, 222, and 223 is defined that
supports specification of the applications and application-specific supports specification of the applications and application-specific
attribute values. attribute values.
Type: 16 (temporarily assigned by IANA) Type: 16
Length: Variable (1 octet)
Value:
Application Identifier Bit Mask Length: Variable (1 octet)
(as defined in Section 4.1)
Link Attribute sub-sub-TLVs - format matches the Value:
existing formats defined in [RFC5305], [RFC7308], Application Identifier Bit Mask (as defined in Section 4.1)
and [RFC8570]
If the SABM or UDABM length in the Application Identifier Bit Mask is Link Attribute sub-sub-TLVs -- format matches the existing
formats defined in [RFC5305], [RFC7308], and [RFC8570]
If the SABM or UDABM Length in the Application Identifier Bit Mask is
greater than 8, the entire sub-TLV MUST be ignored. greater than 8, the entire sub-TLV MUST be ignored.
When the L-flag is set in the Application Identifier Bit Mask, all of When the L-flag is set in the Application Identifier Bit Mask, all of
the applications specified in the bit mask MUST use the legacy the applications specified in the bit mask MUST use the legacy
advertisements for the corresponding link found in TLVs 22, 23, 25, advertisements for the corresponding link found in TLVs 22, 23, 25,
141, 222, and 223 or TLV 138 or TLV 139 as appropriate. Link 141, 222, and 223, in TLV 138, or in TLV 139 as appropriate. Link
attribute sub-sub-TLVs for the corresponding link attributes MUST NOT attribute sub-sub-TLVs for the corresponding link attributes MUST NOT
be advertised for the set of applications specified in the Standard/ be advertised for the set of applications specified in the Standard
User Application Identifier Bit Masks and all such advertisements or User-Defined Application Identifier Bit Masks, and all such
MUST be ignored on receipt. advertisements MUST be ignored on receipt.
Multiple Application-Specific Link Attribute sub-TLVs for the same Multiple Application-Specific Link Attributes sub-TLVs for the same
link MAY be advertised. When multiple sub-TLVs for the same link are link MAY be advertised. When multiple sub-TLVs for the same link are
advertised, they SHOULD advertise non-conflicting application/ advertised, they SHOULD advertise non-conflicting application/
attribute pairs. A conflict exists when the same application is attribute pairs. A conflict exists when the same application is
associated with two different values for the same link attribute for associated with two different values for the same link attribute for
a given link. In cases where conflicting values for the same a given link. In cases where conflicting values for the same
application/attribute/link are advertised the first advertisement application/attribute/link are advertised, the first advertisement
received in the lowest numbered LSP SHOULD be used and subsequent received in the lowest-numbered LSP SHOULD be used, and subsequent
advertisements of the same attribute SHOULD be ignored. advertisements of the same attribute SHOULD be ignored.
For a given application, the setting of the L-flag MUST be the same For a given application, the setting of the L-flag MUST be the same
in all sub-TLVs for a given link. In cases where this constraint is in all sub-TLVs for a given link. In cases where this constraint is
violated, the L-flag MUST be considered set for this application. violated, the L-flag MUST be considered set for this application.
If link attributes are advertised associated with zero length If link attributes are advertised associated with zero-length
Application Identifier Bit Masks for both standard applications and Application 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 user-defined application is permitted to use that set of link
attributes so long as there is not another set of attributes attributes so long as there is not another set of attributes
advertised on that same link that is associated with a non-zero advertised on that same link that is associated with a non-zero-
length Application Identifier Bit Mask with a matching Application length Application Identifier Bit Mask with a matching Application
Identifier Bit set. Identifier Bit set.
A new registry of sub-sub-TLVs is to be created by IANA that defines IANA has created a new registry of sub-sub-TLVs to define the link
the link attribute sub-sub-TLV code points. This document defines a attribute sub-sub-TLV codepoints (see Section 7.3). This document
sub-sub-TLV for each of the existing sub-TLVs listed in Section 3.1 defines a sub-sub-TLV for each of the existing sub-TLVs listed in
except as noted below. The format of the sub-sub-TLVs matches the Section 3.1, except as noted below. The format of the sub-sub-TLVs
format of the corresponding legacy sub-TLV and IANA is requested to matches the format of the corresponding legacy sub-TLV, and IANA has
assign the legacy sub-TLV identifier to the corresponding sub-sub- assigned the legacy sub-TLV identifier to the corresponding sub-sub-
TLV. TLV.
4.2.1. Special Considerations for Maximum Link Bandwidth 4.2.1. Special Considerations for Maximum Link Bandwidth
Maximum link bandwidth is an application independent attribute of the Maximum link bandwidth is an application-independent attribute of the
link. When advertised using the Application-Specific Link Attributes link. When advertised using the Application-Specific Link Attributes
sub-TLV, multiple values for the same link MUST NOT be advertised. sub-TLV, multiple values for the same link MUST NOT be advertised.
This can be accomplished most efficiently by having a single This can be accomplished most efficiently by having a single
advertisement for a given link where the Application Identifier Bit advertisement for a given link where the Application Identifier Bit
Mask identifies all the applications that are making use of the value Mask identifies all the applications that are making use of the value
for that link. for that link.
It is also possible to advertise the same value for a given link It is also possible to advertise the same value for a given link
multiple times with disjoint sets of applications specified in the multiple times with disjoint sets of applications specified in the
Application Identifier Bit Mask. This is less efficient but still Application Identifier Bit Mask. This is less efficient but still
valid. valid.
It is also possible to advertise a single advertisement with zero It is also possible to advertise a single advertisement with zero-
length SABM and UDABM so long as the constraints discussed in length SABM and UDABM so long as the constraints discussed in
Section 4.2 and Section 6.2 are acceptable. Sections 4.2 and 6.2 are acceptable.
If different values for Maximum Link Bandwidth for a given link are If different values for maximum link bandwidth for a given link are
advertised, all values MUST be ignored. advertised, all values MUST be ignored.
4.2.2. Special Considerations for Reservable/Unreserved Bandwidth 4.2.2. Special Considerations for Reservable/Unreserved Bandwidth
Maximum Reservable Link Bandwidth and Unreserved Bandwidth are Maximum reservable link bandwidth and unreserved bandwidth are
attributes specific to RSVP-TE. When advertised using the attributes specific to RSVP-TE. When advertised using the
Application-Specific Link Attributes sub-TLV, bits other than the Application-Specific Link Attributes sub-TLV, bits other than the
RSVP-TE (R-bit) MUST NOT be set in the Application Identifier Bit RSVP-TE (R-bit) MUST NOT be set in the Application Identifier Bit
Mask. If an advertisement of Maximum Reservable Link Bandwidth or Mask. If an advertisement of maximum reservable link bandwidth or
Unreserved Bandwidth is received with bits other than the RSVP-TE bit unreserved bandwidth is received with bits other than the RSVP-TE bit
set, the advertisement MUST be ignored. set, the advertisement MUST be ignored.
4.2.3. Considerations for Extended TE Metrics 4.2.3. Considerations for Extended TE Metrics
[RFC8570] defines a number of dynamic performance metrics associated [RFC8570] 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 will be associated such cases, advertisements for these attributes will 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.
4.3. Application-Specific SRLG TLV 4.3. Application-Specific SRLG TLV
A new TLV is defined to advertise application-specific SRLGs for a A new TLV is defined to advertise application-specific SRLGs for a
given link. Although similar in functionality to TLV 138 [RFC5307] given link. Although similar in functionality to TLV 138 [RFC5307]
and TLV 139 [RFC6119], a single TLV provides support for IPv4, IPv6, and TLV 139 [RFC6119], a single TLV provides support for IPv4, IPv6,
and unnumbered identifiers for a link. Unlike TLVs 138/139, it and unnumbered identifiers for a link. Unlike TLVs 138 and 139, it
utilizes sub-TLVs to encode the link identifiers in order to provide utilizes sub-TLVs to encode the link identifiers in order to provide
the flexible formatting required to support multiple link identifier the flexible formatting required to support multiple link identifier
types. types.
Type: 238 (Temporarily assigned by IANA) Type: 238
Length: Number of octets in the value field (1 octet)
Value: Length: Number of octets in the value field (1 octet)
Neighbor System-ID + pseudo-node ID (7 octets)
Application Identifier Bit Mask Value:
(as defined in Section 4.1) Neighbor System-ID + pseudonode ID (7 octets)
Application Identifier Bit Mask (as defined in Section 4.1)
Length of sub-TLVs (1 octet) Length of sub-TLVs (1 octet)
Link Identifier sub-TLVs (variable) Link Identifier sub-TLVs (variable)
0 or more SRLG Values (Each value is 4 octets)
The following Link Identifier sub-TLVs are defined. 0 or more SRLG values (each value is 4 octets)
The values chosen are intentionally matching the equivalent
sub-TLVs from [RFC5305], [RFC5307], and [RFC6119].
Type Description The following Link Identifier sub-TLVs are defined. The values
4 Link Local/Remote Identifiers [RFC5307] chosen intentionally match the equivalent sub-TLVs from [RFC5305],
6 IPv4 interface address [RFC5305] [RFC5307], and [RFC6119].
8 IPv4 neighbor address [RFC5305]
12 IPv6 Interface Address [RFC6119] +======+=========================================+
13 IPv6 Neighbor Address [RFC6119] | Type | Description |
+======+=========================================+
| 4 | Link Local/Remote Identifiers [RFC5307] |
+------+-----------------------------------------+
| 6 | IPv4 interface address [RFC5305] |
+------+-----------------------------------------+
| 8 | IPv4 neighbor address [RFC5305] |
+------+-----------------------------------------+
| 12 | IPv6 Interface Address [RFC6119] |
+------+-----------------------------------------+
| 13 | IPv6 Neighbor Address [RFC6119] |
+------+-----------------------------------------+
Table 2
At least one set of link identifiers (IPv4, IPv6, or Link Local/ At least one set of link identifiers (IPv4, IPv6, or Link Local/
Remote) MUST be present. Multiple occurrences of the same identifier Remote) MUST be present. Multiple occurrences of the same identifier
type MUST NOT be present. TLVs that do not meet this requirement type MUST NOT be present. TLVs that do not meet this requirement
MUST be ignored. MUST be ignored.
Multiple TLVs for the same link MAY be advertised. Multiple TLVs for the same link MAY be advertised.
When the L-flag is set in the Application Identifier Bit Mask, SRLG When the L-flag is set in the Application Identifier Bit Mask, SRLG
values MUST NOT be included in the TLV. Any SRLG values that are values MUST NOT be included in the TLV. Any SRLG values that are
advertised MUST be ignored. Based on the link identifiers advertised advertised MUST be ignored. Based on the link identifiers
the corresponding legacy TLV (see Section 3.2) can be identified and advertised, the corresponding legacy TLV (see Section 3.2) can be
the SRLG values advertised in the legacy TLV MUST be used by the set identified, and the SRLG values advertised in the legacy TLV MUST be
of applications specified in the Application Identifier Bit Mask. used by the set of applications specified in the Application
Identifier Bit Mask.
For a given application, the setting of the L-flag MUST be the same For a given application, the setting of the L-flag MUST be the same
in all TLVs for a given link. In cases where this constraint is in all TLVs for a given link. In cases where this constraint is
violated, the L-flag MUST be considered set for this application. violated, the L-flag MUST be considered set for this application.
5. Attribute Advertisements and Enablement 5. 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.
skipping to change at page 13, line 28 skipping to change at line 566
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
enabled depends upon the application. enabled depends upon the application.
In the case of RSVP-TE, the advertisement of application-specific In the case of RSVP-TE, the advertisement of application-specific
link attributes implies that RSVP is enabled on that link. The link attributes implies that RSVP is enabled on that link. The
absence of RSVP-TE application-specific link attributes in absence of RSVP-TE application-specific link attributes in
combination with the absence of legacy advertisements implies that combination with the absence of legacy advertisements implies that
RSVP is not enabled on that link. RSVP is not enabled on that link.
In the case of SR Policy, advertisement of application-specific link In the case of SR Policy, the advertisement of application-specific
attributes does not indicate enablement of SR Policy on that link. link attributes does not indicate enablement of SR Policy on that
The advertisements are only used to support constraints that may be link. The advertisements are only used to support constraints that
applied when specifying an explicit path. SR Policy is implicitly may be applied when specifying an explicit path. SR Policy is
enabled on all links that are part of the Segment Routing enabled implicitly enabled on all links that are part of the SR-enabled
topology independent of the existence of link attribute topology 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 4.1). This supports Identifier Bit Mask are not present (see Section 4.1). 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.
6. Deployment Considerations 6. Deployment Considerations
This section discuss deployment considerations associated with the This section discusses deployment considerations associated with the
use of application-specific link attribute advertisements. use of application-specific link attribute advertisements.
6.1. Use of Legacy Advertisements 6.1. Use of Legacy Advertisements
Bit Identifiers for Standard Applications are defined in Section 4.1. Bit identifiers for standard applications are defined in Section 4.1.
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 legacy advertisements. The Standard Applications deployed using the legacy advertisements. The standard applications
defined in this document may continue to use legacy advertisements defined in this document may continue to use legacy advertisements
for a given link so long as at least one of the following conditions for a given link so long as at least one of the following conditions
is true: is true:
o The application is RSVP-TE * The application is RSVP-TE.
o 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.
o 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 legacy extensions defined in this document have the choice of using legacy
advertisements or application-specific advertisements in support of advertisements or application-specific advertisements in support of
SR Policy and/or LFA. This will require implementations to provide SR Policy and/or LFA. This will require implementations to provide
controls specifying which type of advertisements are to be sent/ controls specifying which types of advertisements are to be sent and
processed on receive for these applications. Further discussion of processed on receipt for these applications. Further discussion of
the associated issues can be found in Section 6.3. the associated issues can be found in Section 6.3.
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 legacy advertisements defined in this document MUST NOT make use of legacy
advertisements. This simplifies deployment of new applications by advertisements. This simplifies deployment of new applications by
eliminating the need to support multiple ways to advertise attributes eliminating the need to support multiple ways to advertise attributes
for the new applications. for the new applications.
6.2. Use of Zero Length Application Identifier Bit Masks 6.2. Use of Zero-Length Application Identifier Bit Masks
Link attribute advertisements associated with zero length Application Link attribute advertisements associated 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 are usable by any application, subject to the applications are usable by any application, subject to the
restrictions specified in Section 4.2. If support for a new restrictions specified in Section 4.2. If support for a new
application is introduced on any node in a network in the presence of application is introduced on any node in a network in the presence of
such advertisements, these advertisements are permitted to be used by such advertisements, these advertisements are permitted to be used by
the new application. If this is not what is intended, then existing the new application. If this is not what is intended, then existing
advertisements MUST be readvertised with an explicit set of advertisements MUST be readvertised with an explicit set of
applications specified before a new application is introduced. applications specified before a new application is introduced.
6.3. Interoperability, Backwards Compatibility and Migration Concerns 6.3. 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 that 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.
6.3.1. Multiple Applications: Common Attributes with RSVP-TE 6.3.1. 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 and interoperability is achieved by using legacy advertisements and
sending application-specific advertisements with L-flag set and no sending application-specific advertisements with the L-flag set and
link attribute values. This avoids duplication of link attribute no link attribute values. This avoids duplication of link attribute
advertisements. advertisements.
6.3.2. Multiple Applications: All Attributes Not Shared with RSVP-TE 6.3.2. Multiple Applications: All 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, it is necessary to use application-specific shared with RSVP-TE, it is necessary to use application-specific
advertisements as defined in this document. Attributes for advertisements as defined in this document. Attributes for
applications other than RSVP-TE MUST be advertised using application- applications other than RSVP-TE MUST be advertised using application-
specific advertisements that have the L-flag clear. In cases where specific advertisements that have the L-flag clear. In cases where
skipping to change at page 16, line 25 skipping to change at line 704
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 ASLA advertisements can be achieved via the legacy advertisements to ASLA advertisements can be achieved via the
following steps: following steps:
1)Send ASLA advertisements while continuing to advertise using legacy 1) Send ASLA advertisements while continuing to advertise using
(all advertisements are then duplicated). Receiving routers continue legacy (all advertisements are then duplicated). Receiving
to use legacy advertisements. routers continue to use legacy advertisements.
2)Enable the use of the ASLA advertisements on all routers 2) Enable the use of the ASLA advertisements on all routers.
3)Remove legacy advertisements 3) Remove legacy advertisements.
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.
Note that the use of the L-flag is of no value in the migration. Note that the use of the L-flag is of no value in the migration.
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.
6.3.4. Use of Application-Specific Advertisements for RSVP-TE 6.3.4. 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 include RSVP-TE as one of the
supported applications. This allows that RSVP-TE could eventually applications. It is therefore possible, in the future, for
utilize the application-specific advertisements. This can be done in implementations to migrate to the use of application-specific
the following step-wise manner: advertisements in support of RSVP-TE. This could be done in the
following stepwise manner:
1)Upgrade all routers to support the extensions in this document 1) Upgrade all routers to support the extensions in this document.
2)Advertise all legacy link attributes using ASLA advertisements with
L-flag clear and R-bit set. At this point both legacy and
application-specific advertisements are being sent.
3)Remove legacy advertisements 2) Advertise all legacy link attributes using ASLA advertisements
with the L-flag clear and R-bit set. At this point, both legacy
and application-specific advertisements are being sent.
3) Remove legacy advertisements.
7. IANA Considerations 7. IANA Considerations
This section lists the protocol code point changes introduced by this This section lists the protocol codepoint changes introduced by this
document and the related IANA changes required. document and the related updates made by IANA.
For new registries defined under IS-IS TLV Codepoints Registry with For the new registries defined under the "IS-IS TLV Codepoints"
registration procedure "Expert Review", guidance for designated registry with the "Expert Review" registration procedure (see
experts can be found in [RFC7370]. Sections 7.3 and 7.5), guidance for designated experts can be found
in [RFC7370].
7.1. Application-Specific Link Attributes sub-TLV 7.1. Application-Specific Link Attributes Sub-TLV
This document defines a new sub-TLV in the Sub-TLVs for TLVs 22, 23, IANA has registered the new sub-TLV defined in Section 4.2 in the
25, 141, 222, and 223 registry. See Section 4.2 "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223" registry.
Type Description 22 23 25 141 222 223 +======+======================+====+====+======+=====+=====+=====+
---- --------------------- ---- ---- ---- ---- ---- ---- | Type | Description | 22 | 23 | 25 | 141 | 222 | 223 |
16 Application-Specific y y y(s) y y y +======+======================+====+====+======+=====+=====+=====+
Link Attributes | 16 | Application-Specific | y | y | y(s) | y | y | y |
| | Link Attributes | | | | | | |
+------+----------------------+----+----+------+-----+-----+-----+
Table 3
7.2. Application-Specific SRLG TLV 7.2. Application-Specific SRLG TLV
This document defines one new TLV in the IS-IS TLV Codepoints IANA has registered the new TLV defined in Section 4.3 in the IS-IS
Registry. See Section 4.3 "TLV Codepoints Registry".
Type Description IIH LSP SNP Purge +=======+===========================+=====+=====+=====+=======+
---- --------------------- --- --- --- ----- | Value | Description | IIH | LSP | SNP | Purge |
238 Application-Specific n y n n +=======+===========================+=====+=====+=====+=======+
SRLG | 238 | Application-Specific SRLG | n | y | n | n |
+-------+---------------------------+-----+-----+-----+-------+
7.3. Application-Specific Link Attributes sub-sub-TLV Registry Table 4
This document requests a new IANA registry under the IS-IS TLV 7.3. Sub-sub-TLV Codepoints for Application-Specific Link Attributes
Codepoints Registry be created to control the assignment of sub-sub- Registry
TLV codepoints for the Application-Specific Link Attributes sub-TLV
defined in Section 7.1. The suggested name of the new registry is
"sub-sub-TLV code points for application-specific link attributes".
The registration procedure is "Expert Review" as defined in
[RFC8126]. The following assignments are made by this document:
Type Description Encoding IANA has created a new registry titled "Sub-sub-TLV Codepoints for
Reference Application-Specific Link Attributes" under the "IS-IS TLV
--------------------------------------------------------- Codepoints" registry to control the assignment of sub-sub-TLV
0-2 Unassigned codepoints for the Application-Specific Link Attributes sub-TLV
3 Administrative group (color) RFC5305 defined in Section 7.1. The registration procedure is "Expert
4-8 Unassigned Review" as defined in [RFC8126]. The initial contents of this
9 Maximum link bandwidth RFC5305 registry are as follows:
10 Maximum reservable link bandwidth RFC5305
11 Unreserved bandwidth RFC5305
12-13 Unassigned
14 Extended Administrative Group RFC7308
15-17 Unassigned
18 TE Default Metric RFC5305
19-32 Unassigned
33 Unidirectional Link Delay RFC8570
34 Min/Max Unidirectional Link Delay RFC8570
35 Unidirectional Delay Variation RFC8570
36 Unidirectional Link Loss RFC8570
37 Unidirectional Residual Bandwidth RFC8570
38 Unidirectional Available Bandwidth RFC8570
39 Unidirectional Utilized Bandwidth RFC8570
40-255 Unassigned
Note to IANA: For future codepoints, in cases where the document that +========+====================================+===========+
defines the encoding is different from the document that assigns the | Type | Description | Reference |
codepoint, the encoding reference MUST be to the document that +========+====================================+===========+
defines the encoding. | 0-2 | Unassigned | |
+--------+------------------------------------+-----------+
| 3 | Administrative group (color) | [RFC5305] |
+--------+------------------------------------+-----------+
| 4-8 | Unassigned | |
+--------+------------------------------------+-----------+
| 9 | Maximum link bandwidth | [RFC5305] |
+--------+------------------------------------+-----------+
| 10 | Maximum reservable link bandwidth | [RFC5305] |
+--------+------------------------------------+-----------+
| 11 | Unreserved bandwidth | [RFC5305] |
+--------+------------------------------------+-----------+
| 12-13 | Unassigned | |
+--------+------------------------------------+-----------+
| 14 | Extended Administrative Group | [RFC7308] |
+--------+------------------------------------+-----------+
| 15-17 | Unassigned | |
+--------+------------------------------------+-----------+
| 18 | TE Default Metric | [RFC5305] |
+--------+------------------------------------+-----------+
| 19-32 | Unassigned | |
+--------+------------------------------------+-----------+
| 33 | Unidirectional Link Delay | [RFC8570] |
+--------+------------------------------------+-----------+
| 34 | Min/Max Unidirectional Link Delay | [RFC8570] |
+--------+------------------------------------+-----------+
| 35 | Unidirectional Delay Variation | [RFC8570] |
+--------+------------------------------------+-----------+
| 36 | Unidirectional Link Loss | [RFC8570] |
+--------+------------------------------------+-----------+
| 37 | Unidirectional Residual Bandwidth | [RFC8570] |
+--------+------------------------------------+-----------+
| 38 | Unidirectional Available Bandwidth | [RFC8570] |
+--------+------------------------------------+-----------+
| 39 | Unidirectional Utilized Bandwidth | [RFC8570] |
+--------+------------------------------------+-----------+
| 40-255 | Unassigned | |
+--------+------------------------------------+-----------+
Note to designated experts: If a link attribute can be advertised Table 5
both as a sub-TLV of TLVs 22, 23, 25, 141, 222, and 223 and as a sub-
sub-TLV of the Application-Specific Link Attributes sub-TLV defined
in this document, then the same numerical code should be assigned to
the link attribute whenever possible.
7.4. Link Attribute Application Identifier Registry IANA has also added the following notes to this registry:
This document requests a new IANA registry be created, under the Note: For future codepoints, in cases where the document that
category of "Interior Gateway Protocol (IGP) Parameters", to control defines the encoding is different from the document that assigns
the assignment of Application Identifier Bits. The suggested name of the codepoint, the encoding reference MUST be to the document that
the new registry is "Link Attribute Applications". The registration defines the encoding.
policy for this registry is "Expert Review" [RFC8126]. Bit
definitions SHOULD be assigned such that all bits in the lowest
available octet are allocated before assigning bits in the next
octet. This minimizes the number of octets that will need to be
transmitted. The following assignments are made by this document:
Bit # Name Note: If a link attribute can be advertised both as a sub-TLV of
--------------------------------------------------------- TLVs 22, 23, 25, 141, 222, and 223 and as a sub-sub-TLV of the
0 RSVP-TE (R-bit) Application-Specific Link Attributes sub-TLV defined in RFC 8919,
1 Segment Routing Policy (S-bit) then the same numerical code should be assigned to the link
2 Loop Free Alternate (F-bit) attribute whenever possible.
3-63 Unassigned
7.5. SRLG sub-TLVs 7.4. Link Attribute Application Identifiers Registry
This document requests a new IANA registry be created under the IS-IS IANA has created a new registry titled "Link Attribute Application
TLV Codepoints Registry to control the assignment of sub-TLV types Identifiers" under the "Interior Gateway Protocol (IGP) Parameters"
for the application-specific SRLG TLV. The suggested name of the new registry to control the assignment of Application Identifier Bits.
registry is "Sub-TLVs for TLV 238". The registration procedure is The registration policy for this registry is "Expert Review" as
"Expert Review" as defined in [RFC8126]. The following assignments defined in [RFC8126]. Bit definitions SHOULD be assigned such that
are made by this document: all bits in the lowest available octet are allocated before assigning
bits in the next octet. This minimizes the number of octets that
will need to be transmitted. The initial contents of this registry
are as follows:
Value Description Encoding +=======+================================+
Reference | Bit # | Name |
--------------------------------------------------------- +=======+================================+
0-3 Unassigned | 0 | RSVP-TE (R-bit) |
4 Link Local/Remote Identifiers [RFC5307] +-------+--------------------------------+
5 Unassigned | 1 | Segment Routing Policy (S-bit) |
6 IPv4 interface address [RFC5305] +-------+--------------------------------+
7 Unassigned | 2 | Loop-Free Alternate (F-bit) |
8 IPv4 neighbor address [RFC5305] +-------+--------------------------------+
9-11 Unassigned | 3-63 | Unassigned |
12 IPv6 Interface Address [RFC6119] +-------+--------------------------------+
13 IPv6 Neighbor Address [RFC6119]
14-255 Unassigned
Note to IANA: For future codepoints, in cases where the document that Table 6
defines the encoding is different from the document that assigns the
codepoint, the encoding reference MUST be to the document that 7.5. Sub-TLVs for TLV 238 Registry
defines the encoding.
IANA has created a new registry titled "Sub-TLVs for TLV 238" under
the "IS-IS TLV Codepoints" registry to control the assignment of sub-
TLV types for the Application-Specific SRLG TLV. The registration
procedure is "Expert Review" as defined in [RFC8126]. The initial
contents of this registry are as follows:
+========+===============================+===========+
| Value | Description | Reference |
+========+===============================+===========+
| 0-3 | Unassigned | |
+--------+-------------------------------+-----------+
| 4 | Link Local/Remote Identifiers | [RFC5307] |
+--------+-------------------------------+-----------+
| 5 | Unassigned | |
+--------+-------------------------------+-----------+
| 6 | IPv4 interface address | [RFC5305] |
+--------+-------------------------------+-----------+
| 7 | Unassigned | |
+--------+-------------------------------+-----------+
| 8 | IPv4 neighbor address | [RFC5305] |
+--------+-------------------------------+-----------+
| 9-11 | Unassigned | |
+--------+-------------------------------+-----------+
| 12 | IPv6 Interface Address | [RFC6119] |
+--------+-------------------------------+-----------+
| 13 | IPv6 Neighbor Address | [RFC6119] |
+--------+-------------------------------+-----------+
| 14-255 | Unassigned | |
+--------+-------------------------------+-----------+
Table 7
IANA has also added the following note to this registry:
Note: For future codepoints, in cases where the document that
defines the encoding is different from the document that assigns
the codepoint, the encoding reference MUST be to the document that
defines the encoding.
8. Security Considerations 8. Security Considerations
Security concerns for IS-IS are addressed in [ISO10589], [RFC5304], Security concerns for IS-IS are addressed in [ISO10589], [RFC5304],
and [RFC5310]. While IS-IS is deployed under a single administrative and [RFC5310]. While IS-IS is deployed under a single administrative
domain, there can be deployments where potential attackers have domain, there can be deployments where potential attackers have
access to one or more networks in the IS-IS routing domain. In these access to one or more networks in the IS-IS routing domain. In these
deployments, the stronger authentication mechanisms defined in the deployments, the stronger authentication mechanisms defined in the
aforementioned documents SHOULD be used. aforementioned documents SHOULD be used.
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 as discussed in [RFC8570]. As the advertisements defined engineering as discussed in [RFC8570]. As the advertisements defined
in this document limit the scope to specific applications, the impact in this document limit the scope to specific applications, the impact
of tampering is similarly limited in scope. of tampering is similarly limited in scope.
9. Acknowledgements 9. References
The authors would like to thank Eric Rosen and Acee Lindem for their
careful review and content suggestions.
10. References
10.1. Normative References 9.1. Normative References
[ISO10589] [ISO10589] International Organization for Standardization,
International Organization for Standardization, "Information technology - Telecommunications and
"Intermediate system to Intermediate system intra-domain information exchange between systems - Intermediate System
routeing information exchange protocol for use in to Intermediate System intra-domain routing information
conjunction with the protocol for providing the exchange protocol for use in conjunction with the protocol
connectionless-mode Network Service (ISO 8473)", ISO/ for providing the connectionless-mode network service (ISO
IEC 10589:2002, Second Edition, Nov 2002. 8473)", ISO/IEC 10589:2002, Second Edition, November 2002.
[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>.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>. 2008, <https://www.rfc-editor.org/info/rfc5304>.
skipping to change at page 21, line 28 skipping to change at line 988
[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>.
[RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward, [RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE) D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
2019, <https://www.rfc-editor.org/info/rfc8570>. 2019, <https://www.rfc-editor.org/info/rfc8570>.
10.2. Informative References 9.2. Informative References
[I-D.ietf-spring-segment-routing-policy]
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>.
[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>.
[RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
Litkowski, S., Horneffer, M., and R. Shakir, "Source Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <https://www.rfc-editor.org/info/rfc7855>. 2016, <https://www.rfc-editor.org/info/rfc7855>.
[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>.
Acknowledgements
The authors would like to thank Eric Rosen and Acee Lindem for their
careful review and content suggestions.
Authors' Addresses Authors' Addresses
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
Peter Psenak Peter Psenak
Cisco Systems Cisco Systems
Apollo Business Center Mlynske nivy 43 Apollo Business Center
Bratislava 821 09 Mlynske nivy 43
821 09 Bratislava
Slovakia Slovakia
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
Stefano Previdi Stefano Previdi
Huawei Huawei Technologies
Email: stefano@previdi.net Email: stefano@previdi.net
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
John Drake John Drake
Juniper Networks Juniper Networks
Email: jdrake@juniper.net Email: jdrake@juniper.net
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