draft-ietf-isis-te-app-09.txt   draft-ietf-isis-te-app-10.txt 
Networking Working Group L. Ginsberg Networking Working Group L. Ginsberg
Internet-Draft P. Psenak Internet-Draft P. Psenak
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: May 2, 2020 S. Previdi Expires: August 9, 2020 S. Previdi
Huawei Huawei
W. Henderickx W. Henderickx
Nokia Nokia
J. Drake J. Drake
Juniper Networks Juniper Networks
October 30, 2019 February 6, 2020
IS-IS TE Attributes per application IS-IS TE Attributes per application
draft-ietf-isis-te-app-09 draft-ietf-isis-te-app-10
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.,
SRTE, LFA) have been defined which also make use of the link Segment Routing Traffic Engineering, Loop Free Alternate) have been
attribute advertisements. In cases where multiple applications wish defined which also make use of the link attribute advertisements. In
to make use of these link attributes the current advertisements do cases where multiple applications wish to make use of these link
not support application specific values for a given attribute nor do attributes the current advertisements do not support application
they support indication of which applications are using the specific values for a given attribute nor do they support indication
advertised value for a given link. of which applications are using the advertised value for a given
link. This document introduces new link attribute advertisements
This draft introduces new link attribute advertisements which address which address both of these shortcomings.
both of these shortcomings. It also discusses backwards
compatibility issues and how to minimize duplicate advertisements in
the presence of routers which do not support the extensions defined
in this document.
Requirements Language 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.
Status of This Memo Status of This Memo
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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 May 2, 2020. This Internet-Draft will expire on August 9, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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 Discussion . . . . . . . . . . . . . . . . . . . 3 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 4
3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4
3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 5
3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5
4. Advertising Application Specific Link Attributes . . . . . . 5 4. Advertising Application Specific Link Attributes . . . . . . 6
4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 6 4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 6
4.2. Application Specific Link Attributes sub-TLV . . . . . . 8 4.2. Application Specific Link Attributes sub-TLV . . . . . . 8
4.2.1. Special Considerations for Maximum Link Bandwidth . . 9 4.2.1. Special Considerations for Maximum Link Bandwidth . . 9
4.2.2. Special Considerations for Reservable/Unreserved 4.2.2. Special Considerations for Reservable/Unreserved
Bandwidth . . . . . . . . . . . . . . . . . . . . . . 9 Bandwidth . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 9 4.2.3. Considerations for Extended TE Metrics . . . . . . . 10
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 10 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 10
5.1. Use of Legacy Advertisements . . . . . . . . . . . . . . 11 5. Attribute Advertisements and Enablement . . . . . . . . . . . 11
5.2. Use of Zero Length Application Identifier Bit Masks . . . 11 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 12
6. Attribute Advertisements and Enablement . . . . . . . . . . . 12 6.1. Use of Legacy Advertisements . . . . . . . . . . . . . . 12
7. Interoperability, Backwards Compatibility and Migration 6.2. Use of Zero Length Application Identifier Bit Masks . . . 13
Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 13 6.3. Interoperability, Backwards Compatibility and Migration
7.1. Multiple Applications: Common Attributes with RSVP-TE . 13 Concerns . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2. Multiple Applications: All Attributes Not Shared w RSVP- 6.3.1. Multiple Applications: Common Attributes with RSVP-
TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 TE . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.3.2. Multiple Applications: All Attributes Not Shared with
7.3. Use of Application Specific Advertisements for RSVP-TE . 14 RSVP-TE . . . . . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 6.3.3. Interoperability with Legacy Routers . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6.3.4. Use of Application Specific Advertisements for RSVP-
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 TE . . . . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
11.1. Normative References . . . . . . . . . . . . . . . . . . 16 8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . 17 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
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], and [RFC8570]. Use of these extensions has [RFC5307], [RFC6119], and [RFC8570]. Use of these extensions has
been associated with deployments supporting Traffic Engineering over been associated with deployments supporting Traffic Engineering over
Multiprotocol Label Switching (MPLS) in the presence of Resource Multiprotocol Label Switching (MPLS) in the presence of the Resource
Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE
[RFC3209].
For the purposes of this document an application is a technology
which makes use of link attribute advertisements - examples of which
are listed in Section 3.
In recent years new applications have been introduced which have use In recent years new applications have been introduced which 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 Traffic Engineering (SRTE) Such applications include Segment Routing Traffic Engineering (SRTE)
and Loop Free Alternates (LFA). This has introduced ambiguity in [RFC8402] and Loop Free Alternates (LFA) [RFC5286]. This has
that if a deployment includes a mix of RSVP-TE support and SRTE introduced ambiguity in that if a deployment includes a mix of RSVP-
support (for example) it is not possible to unambiguously indicate TE support and SRTE support (for example) it is not possible to
which advertisements are to be used by RSVP-TE and which unambiguously indicate which advertisements are to be used by RSVP-TE
advertisements are to be used by SRTE. If the topologies are fully and which advertisements are to be used by SRTE. If the topologies
congruent this may not be an issue, but any incongruence leads to are fully congruent this may not be an issue, but any incongruence
ambiguity. leads to ambiguity.
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 which address these issues. Also, This document defines extensions which address these issues. Also,
as evolution of use cases for link attributes can be expected to as evolution of use cases for link attributes can be expected to
continue in the years to come, this document defines a solution which continue in the years to come, this document defines a solution which
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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 There are existing advertisements used in support of RSVP-TE. These
advertisements include sub-TLVs for TLVs 22, 23, 25, 141, 222, and advertisements include sub-TLVs for TLVs 22, 23, 25, 141, 222, and
223 and TLVs for SRLG advertisement. 223 and TLVs for Shared Risk Link Group(SRLG) advertisement.
Sub-TLV values are defined in https://www.iana.org/assignments/isis-
tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-
22-23-25-141-222-223 and https://www.iana.org/assignments/isis-tlv-
codepoints/isis-tlv-codepoints.xhtml .
3.1. Legacy sub-TLVs 3.1. Legacy sub-TLVs
Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223 Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223
Code Point/Attribute Name +-------------------------------------------+
-------------------------- | Type | Description |
3 Administrative group (color) +-------------------------------------------+
9 Maximum link bandwidth | 3 | Administrative group (color) |
10 Maximum reservable link bandwidth +-------------------------------------------+
11 Unreserved bandwidth | 9 | Maximum link bandwidth |
14 Extended Administrative Group +-------------------------------------------+
18 TE Default Metric | 10 | Maximum reservable link bandwidth |
33 Unidirectional Link Delay +-------------------------------------------+
34 Min/Max Unidirectional Link Delay | 11 | Unreserved bandwidth |
35 Unidirectional Delay Variation +-------------------------------------------+
36 Unidirectional Link Loss | 14 | Extended Administrative Group |
37 Unidirectional Residual Bandwidth +-------------------------------------------+
38 Unidirectional Available Bandwidth | 18 | TE Default Metric |
39 Unidirectional Utilized Bandwidth +-------------------------------------------+
| 33 | Unidirectional Link Delay |
+-------------------------------------------+
| 34 | Min/Max Unidirectional Link Delay |
+-------------------------------------------+
| 35 | Unidirectional Delay Variation |
+-------------------------------------------+
| 36 | Unidirectional Link Loss |
+-------------------------------------------+
| 37 | Unidirectional Residual Bandwidth |
+-------------------------------------------+
| 38 | Unidirectional Available Bandwidth |
+-------------------------------------------+
| 39 | Unidirectional Utilized Bandwidth |
+-------------------------------------------+
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
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given advertisement (defined in Section 4.1). given advertisement (defined in Section 4.1).
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. A second bit mask is for non-
standard User Defined Applications(UDAs). 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
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
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SABM Length + Flag (1 octet) SABM Length + Flag (1 octet)
Standard Application Identifier Bit Mask Standard Application Identifier Bit Mask
Length + Flag Length + Flag
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|L| SABM Length | |L| SABM Length |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
L-flag: When set, applications listed (both Standard L-flag: Legacy Flag.
and User Defined) MUST use the legacy advertisements See the following section for a description of how
for the corresponding link found in TLVs 22, 23, this flag is used.
25, 141, 222, and 223 or TLV 138 or TLV 139 as
appropriate.
SABM Length: Indicates the length in octets (0-127) of the SABM Length: Indicates the length in octets (0-127) of the
Bit Mask for Standard Applications. Standard Application Identifier Bit Mask. The length SHOULD
be the minimum required to send all bits which are set.
UDABM Length + Flag (1 octet) UDABM Length + Flag (1 octet)
User Defined Application Identifier Bit Mask User Defined Application Identifier Bit Mask
Length + Flag Length + Flag
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|R| UDABM Length| |R| UDABM Length|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
R: Reserved. SHOULD be transmitted as 0 and R: Reserved. SHOULD be transmitted as 0 and
MUST be ignored on receipt MUST be ignored on receipt
UDABM Length: Indicates the length in octets (0-127) of the UDABM Length: Indicates the length in octets (0-127) of the
Bit Mask for User Defined Applications. User Defined Application Identifier Bit Mask. The length SHOULD
be the minimum required to send all bits which are set.
SABM (variable length) SABM (variable length)
Standard Application Identifier Bit Mask Standard Application Identifier Bit Mask
(SABM Length * 8) bits (SABM Length * 8) bits
This 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 S-bit: Set to specify Segment Routing
Traffic Engineering (SRTE) Traffic Engineering (SRTE)
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R-bit: Set to specify RSVP-TE R-bit: Set to specify RSVP-TE
S-bit: Set to specify Segment Routing S-bit: Set to specify Segment Routing
Traffic Engineering (SRTE) Traffic Engineering (SRTE)
F-bit: Set to specify Loop Free Alternate (LFA) F-bit: Set to specify Loop Free Alternate (LFA)
(includes all LFA types) (includes all LFA types)
UDABM (variable length) UDABM (variable length)
User Defined Application Identifier Bit Mask User Defined Application Identifier Bit 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 is omitted if UDABM Length is 0. This field is omitted if UDABM Length is 0.
NOTE: If both SABM Length and UDABM Length are zero, then the
attributes associated with this Attribute Identifier Bit Mask
MAY be used by any Standard Application and any User Defined
Application.
Standard Application Identifier Bits are defined/sent starting with Standard Application Identifier Bits are defined/sent starting with
Bit 0. Additional bit definitions that may be defined in the future Bit 0. Undefined bits MUST be transmitted as 0 and MUST be ignored
SHOULD be assigned in ascending bit order so as to minimize the on receipt. Bits that are NOT transmitted MUST be treated as if they
number of octets that will need to be transmitted. Undefined bits are set to 0 on receipt. Bits that are not supported by an
MUST be transmitted as 0 and MUST be ignored on receipt. Bits that implementation MUST be ignored on receipt.
are NOT transmitted MUST be treated as if they are set to 0 on
receipt.
User Defined Application Identifier Bits have no relationship to User Defined Application Identifier Bits have no relationship to
Standard Application Identifier Bits and are NOT managed by IANA or Standard Application Identifier Bits and are NOT managed by IANA or
any other standards body. It is recommended that bits are used any other standards body. It is recommended that bits are 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.
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 which A new sub-TLV for TLVs 22, 23, 25, 141, 222, and 223 is defined which
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Length: Variable (1 octet) Length: Variable (1 octet)
Value: Value:
Application Identifier Bit Mask Application Identifier Bit Mask
(as defined in Section 4.1) (as defined in Section 4.1)
Link Attribute sub-sub-TLVs - format matches the Link Attribute sub-sub-TLVs - format matches the
existing formats defined in [RFC5305] and [RFC8570] existing formats defined in [RFC5305] and [RFC8570]
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 link the applications specified in the bit mask MUST use the legacy
attribute sub-TLV advertisements listed in Section 3.1 for the advertisements for the corresponding link found in TLVs 22, 23, 25,
corresponding link. Link attribute sub-sub-TLVs for the 141, 222, and 223 or TLV 138 or TLV 139 as appropriate. Link
corresponding link attributes MUST NOT be advertised for the set of attribute sub-sub-TLVs for the corresponding link attributes MUST NOT
applications specified in the Standard/User Application Identifier be advertised for the set of applications specified in the Standard/
Bit Masks and all such advertisements MUST be ignored on receipt. User Application Identifier Bit Masks and all such advertisements
MUST be ignored on receipt.
Multiple Application Specific Link Attribute sub-TLVs for the same Multiple Application Specific Link Attribute 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 of the same link attribute for a associated with two different values of the same link attribute for a
given link. In cases where conflicting values for the same given link. In cases where conflicting values for the same
application/attribute/link are advertised all the conflicting values application/attribute/link are advertised all the conflicting values
MUST be ignored. MUST 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.
A new registry of sub-sub-TLVs is to be created by IANA which defines A new registry of sub-sub-TLVs is to be created by IANA which defines
the link attribute sub-sub-TLV code points. This document defines a the link attribute sub-sub-TLV code points. This document defines a
sub-sub-TLV for each of the existing sub-TLVs listed in Section 3.1 sub-sub-TLV for each of the existing sub-TLVs listed in Section 3.1
except as noted below. The format of the sub-sub-TLVs matches the except as noted below. The format of the sub-sub-TLVs matches the
format of the corresponding legacy sub-TLV and IANA is requested to format of the corresponding legacy sub-TLV and IANA is requested to
assign the legacy sub-TLV identifer to the corresponding sub-sub-TLV. assign the legacy sub-TLV identifier to the corresponding sub-sub-
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 which are making use of the Mask identifies all the applications which are making use of the
value for that link. value for that link.
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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.
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. When advertised using the Application attributes specific to RSVP-TE. When advertised using the
Specific Link Attributes sub-TLV, bits other than the RSVP-TE(R-bit) Application Specific Link Attributes sub-TLV, bits other than the
MUST NOT be set in the Application Identifier Bit Mask. If an RSVP-TE (R-bit) MUST NOT be set in the Application Identifier Bit
advertisement of Maximum Reservable Link Bandwidth or Unreserved Mask. If an advertisement of Maximum Reservable Link Bandwidth or
Bandwidth is received with bits other than the RSVP-TE bit set, the Unreserved Bandwidth is received with bits other than the RSVP-TE bit
advertisement MUST be ignored. set, the advertisement MUST be ignored.
4.2.3. Considerations for Extended TE Metrics
[RFC8570] defines a number of dynamic performance metrics associated
with a link. It is conceivable that such metrics could be measured
specific to traffic associated with a specific application.
Therefore this document includes support for advertising these link
attributes specific to a given application. However, in practice it
may well be more practical to have these metrics reflect the
performance of all traffic on the link regardless of application. In
such cases, advertisements for these attributes will be associated
with all of the applications utilizing that link.
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 (defined by given link. Although similar in functionality to TLV 138 [RFC5307]
[RFC5307]) and TLV 139 (defined by [RFC6119], a single TLV provides and TLV 139 [RFC6119], a single TLV provides support for IPv4, IPv6,
support for IPv4, IPv6, and unnumbered identifiers for a link. and unnumbered identifiers for a link. Unlike TLVs 138/139, it
Unlike TLVs 138/139, it utilizes sub-TLVs to encode the link utilizes sub-TLVs to encode the link identifiers in order to provide
identifiers in order to provide the flexible formatting required to the flexible formatting required to support multiple link identifier
support multiple link identifier types. types.
Type: 238 (Temporarily assigned by IANA) Type: 238 (Temporarily assigned by IANA)
Length: Number of octets in the value field (1 octet) Length: Number of octets in the value field (1 octet)
Value: Value:
Neighbor System-ID + pseudo-node ID (7 octets) Neighbor System-ID + pseudo-node ID (7 octets)
Application Identifier Bit Mask Application Identifier Bit Mask
(as defined in Section 4.1) (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) 0 or more SRLG Values (Each value is 4 octets)
The following Link Identifier sub-TLVs are defined. The type The following Link Identifier sub-TLVs are defined.
values are suggested and will be assigned by IANA - but as The values chosen are intentionally matching the equivalent
the formats are identical to existing sub-TLVs defined for sub-TLVs from [RFC5305], [RFC5307], and [RFC6119].
TLVs 22, 23, 25, 141, 222, and 223 the use of the suggested
sub-TLV types is strongly encouraged.
Type Description Type Description
4 Link Local/Remote Identifiers (see [RFC5307]) 4 Link Local/Remote Identifiers [RFC5307]
6 IPv4 interface address (see [RFC5305]) 6 IPv4 interface address [RFC5305]
8 IPv4 neighbor address (see [RFC5305]) 8 IPv4 neighbor address [RFC5305]
12 IPv6 Interface Address (see [RFC6119]) 12 IPv6 Interface Address [RFC6119]
13 IPv6 Neighbor Address (see [RFC6119]) 13 IPv6 Neighbor Address [RFC6119]
At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST At least one set of link identifiers (IPv4, IPv6, or Link Local/
be present. TLVs which do not meet this requirement MUST be ignored. Remote) MUST be present. TLVs which do not meet this requirement
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 which are values MUST NOT be included in the TLV. Any SRLG values which are
advertised MUST be ignored. Based on the link identifiers advertised advertised MUST be ignored. Based on the link identifiers advertised
the corresponding legacy TLV (see Section 3.2) can be identified and the corresponding legacy TLV (see Section 3.2) can be identified and
the SRLG values advertised in the legacy TLV MUST be used by the set the SRLG values advertised in the legacy TLV MUST be used by the set
of applications specified in the Application Identifier Bit Mask. 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. Deployment Considerations 5. Attribute Advertisements and Enablement
This section discuss deployment considerations associated with the
use of application specific link attribute advertisements.
5.1. Use of Legacy Advertisements
Bit Identifers for Standard Applications are defined in Section 4.1.
All of the identifiers defined in this document are associated with
applications which were already deployed in some networks prior to
the writing of this document. Therefore, such applications have been
deployed using the legacy advertisements. The Standard Applications
defined in this document MAY continue to use legacy advertisements
for a given link so long as at least one of the following conditions
is true:
o The application is RSVP-TE
o The application is SRTE or LFA and RSVP-TE is not deployed
anywhere in the network
o The application is SRTE or LFA, RSVP-TE is deployed in the
network, and both the set of links on which SRTE and/or LFA
advertisements are required and the attribute values used by SRTE
and/or LFA on all such links is fully congruent with the links and
attribute values used by RSVP-TE
Under the conditions defined above, implementations which support the
extensions defined in this document have the choice of using legacy
advertisements or application specific advertisements in support of
SRTE and/or LFA. This will require implementations to provide
controls specifying which type of advertisements are to be sent/
processed on receive for these applications. Further discussion of
the associated issues can be found in Section 7.
New applications which future documents define to make use of the
advertisements defined in this document MUST NOT make use of legacy
advertisements.
5.2. Use of Zero Length Application Identifier Bit Masks
If link attributes are advertised associated with zero length
Application Identifier Bit Masks for both standard applications and
user defined applications, then that set of link attributes MAY be
used by any application. If support for a new application is
introduced on any node in a network in the presence of such
advertisements, these advertisements MAY be used by the new
application. If this is not what is intended, then existing
advertisements MUST be readvertised with an explicit set of
applications specified before a new application is introduced.
6. 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.
Whether the presence of link attribute advertisements for a given Whether the presence of link attribute advertisements for a given
application indicates that the application is enabled on that link application indicates that the application is enabled on that link
depends upon the application. Similarly, whether the absence of link depends upon the application. Similarly, whether the absence of link
attribute advertisements indicates that the application is not attribute advertisements indicates that the application is not
enabled depends upon the application. enabled depends upon the application.
skipping to change at page 13, line 5 skipping to change at page 12, line 12
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.
7. Interoperability, Backwards Compatibility and Migration Concerns 6. Deployment Considerations
This section discuss deployment considerations associated with the
use of application specific link attribute advertisements.
6.1. Use of Legacy Advertisements
Bit Identifiers for Standard Applications are defined in Section 4.1.
All of the identifiers defined in this document are associated with
applications which were already deployed in some networks prior to
the writing of this document. Therefore, such applications have been
deployed using the legacy advertisements. The Standard Applications
defined in this document may continue to use legacy advertisements
for a given link so long as at least one of the following conditions
is true:
o The application is RSVP-TE
o The application is SRTE or LFA and RSVP-TE is not deployed
anywhere in the network
o The application is SRTE or LFA, RSVP-TE is deployed in the
network, and both the set of links on which SRTE and/or LFA
advertisements are required and the attribute values used by SRTE
and/or LFA on all such links is fully congruent with the links and
attribute values used by RSVP-TE
Under the conditions defined above, implementations which support the
extensions defined in this document have the choice of using legacy
advertisements or application specific advertisements in support of
SRTE and/or LFA. This will require implementations to provide
controls specifying which type of advertisements are to be sent/
processed on receive for these applications. Further discussion of
the associated issues can be found in Section 6.3.
New applications which future documents define to make use of the
advertisements defined in this document MUST NOT make use of legacy
advertisements. This simplifies deployment of new applications by
eliminating the need to support multiple ways to advertise attributes
for the new applications.
6.2. Use of Zero Length Application Identifier Bit Masks
If link attributes are advertised associated with zero length
Application Identifier Bit Masks for both standard applications and
user defined applications, then any Standard Application and/or any
User Defined Application is permitted to use that set of link
attributes so long as there is not another set of attributes
advertised on that same link which is associated with a non-zero
length Application Identifier Bit Mask with a matching Application
Identifier Bit set. If support for a new application is introduced
on any node in a network in the presence of such advertisements,
these advertisements are permitted to be used by the new application.
If this is not what is intended, then existing advertisements MUST be
readvertised with an explicit set of applications specified before a
new application is introduced.
6.3. Interoperability, Backwards Compatibility and Migration Concerns
Existing deployments of RSVP-TE, SRTE, and/or LFA utilize the legacy Existing deployments of RSVP-TE, SRTE, and/or LFA utilize the legacy
advertisements listed in Section 3. Routers which do not support the advertisements listed in Section 3. Routers which do not support the
extensions defined in this document will only process legacy extensions defined in this document will only process legacy
advertisements and are likely to infer that RSVP-TE is enabled on the advertisements and are likely to infer that RSVP-TE is enabled on the
links for which legacy advertisements exist. It is expected that links for which legacy advertisements exist. It is expected that
deployments using the legacy advertisements will persist for a 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 must be able to co-exist with use extensions defined in this document must be able to co-exist with use
of the legacy advertisements by routers which do not support the of the legacy advertisements by routers which do not support the
extensions defined in this document. The following sub-sections extensions defined in this document. The following sub-sections
discuss interoperability and backwards compatibility concerns for a discuss interoperability and backwards compatibility concerns for a
number of deployment scenarios. number of deployment scenarios.
Note that in all cases the defined strategy can be employed on a per Note that in all cases the defined strategy can be employed on a per
link basis. link basis.
7.1. 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-bit set and no sending application specific advertisements with L-flag set and no
link attribute values. This avoids duplication of link attribute link attribute values. This avoids duplication of link attribute
advertisements. advertisements.
7.2. Multiple Applications: All Attributes Not Shared w 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 which have the L-bit clear. In cases where specific advertisements which have the L-flag clear. In cases where
some link attributes are shared with RSVP-TE, this requires duplicate some link attributes are shared with RSVP-TE, this requires duplicate
advertisements for those attributes. advertisements for those attributes.
The discussion in this section applies to cases where RSVP-TE is NOT The discussion in this section applies to cases where RSVP-TE is NOT
using any advertised attributes on a link and to cases where RSVP-TE using any advertised attributes on a link and to cases where RSVP-TE
is using some link attribute advertisements on the link but some link is using some link attribute advertisements on the link but some link
attributes cannot be shared with RSVP-TE. attributes cannot be shared with RSVP-TE.
7.3. Use of Application Specific Advertisements for RSVP-TE 6.3.3. Interoperability with Legacy Routers
For the applications defined in this document, routers which do not
support the extensions defined in this document will send and receive
only legacy link attribute advertisements. So long as there is any
legacy router in the network which has any of the applications
enabled, all routers MUST continue to advertise link attributes using
legacy advertisements. Once all legacy routers have been upgraded,
migration from legacy advertisements to application specific
advertisements can be achieved via the following steps:
1)Send application specific advertisements while continuing to
advertise using legacy (all advertisements are then duplicated).
Receiving routers continue to use legacy advertisements.
2)Enable the use of the application specific advertisements on all
routers
3)Remove legacy advertisements
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 support RSVP-TE as one of the
supported applications. This allows that RSVP-TE could eventually supported applications. This allows that RSVP-TE could eventually
utilize the application specific advertisements. This can be done in utilize the application specific advertisements. This can be done in
the following step-wise manner: the following step-wise manner:
1)Upgrade all routers to support extensions in this document 1)Upgrade all routers to support the extensions in this document
2)Readvertise all legacy link attributes using application specific 2)Advertise all legacy link attributes using application specific
advertisements with L-bit clear and R-bit set. advertisements with L-flag clear and R-bit set.
3)Remove legacy advertisements 3)Remove legacy advertisements
Migrating RSVP-TE away from legacy advertisements could result in Migrating RSVP-TE away from legacy advertisements could result in
some implementation simplification as it allows the removal of code some implementation simplification as it allows the removal of code
which encodes/decodes the legacy advertisements. Whether this is which encodes/decodes the legacy advertisements. Whether this is
seen as desirable is something for the marketplace to determine. seen as desirable is something for the marketplace to determine.
8. IANA Considerations 7. IANA Considerations
This document defines a new sub-TLV for TLVs 22, 23, 25, 141, 222, This document defines a new sub-TLV for TLVs 22, 23, 25, 141, 222,
and 223. and 223.
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 16 Application Specific y y y(s) y y y
Link Attributes Link Attributes
This document defines one new TLV: This document defines one new TLV:
skipping to change at page 15, line 27 skipping to change at page 16, line 27
19-32 Unassigned 19-32 Unassigned
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
40-255 Unassigned 40-255 Unassigned
Note to designated experts: 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 Application Specific Link Attributes sub-TLV defined
in this document, then the same numerical code should be assigned to
the link attribute whenever possible.
This document requests a new IANA registry be created, under the This document requests a new IANA registry be created, under the
category of "Interior Gateway Protocol (IGP) Parameters", to control category of "Interior Gateway Protocol (IGP) Parameters", to control
the assignment of Application Identifier Bits. The suggested name of the assignment of Application Identifier Bits. The suggested name of
the new registry is "Link Attribute Applications". The registration the new registry is "Link Attribute Applications". The registration
policy for this registry is "Standards Action" ([RFC8126] and policy for this registry is "Standards Action" ([RFC8126] and
[RFC7120]). The following assignments are made by this document: [RFC7120]). Bit definitions SHOULD be assigned in ascending bit
order beginning with Bit 0 so as to minimize the number of octets
that will need to be transmitted. The following assignments are made
by this document:
Bit # Name Bit # Name
--------------------------------------------------------- ---------------------------------------------------------
0 RSVP-TE (R-bit) 0 RSVP-TE (R-bit)
1 Segment Routing Traffic Engineering (S-bit) 1 Segment Routing Traffic Engineering (S-bit)
2 Loop Free Alternate (F-bit) 2 Loop Free Alternate (F-bit)
This document requests a new IANA registry be created to control the This document requests a new IANA registry be created to control the
assignment of sub-TLV types for the application specific SRLG TLV. assignment of sub-TLV types for the application specific SRLG TLV.
The suggested name of the new registry is "Sub-TLVs for TLV 238". The suggested name of the new registry is "Sub-TLVs for TLV 238".
skipping to change at page 16, line 18 skipping to change at page 17, line 21
4 Link Local/Remote Identifiers (see [RFC5307]) 4 Link Local/Remote Identifiers (see [RFC5307])
5 Unassigned 5 Unassigned
6 IPv4 interface address (see [RFC5305]) 6 IPv4 interface address (see [RFC5305])
7 Unassigned 7 Unassigned
8 IPv4 neighbor address (see [RFC5305]) 8 IPv4 neighbor address (see [RFC5305])
9-11 Unassigned 9-11 Unassigned
12 IPv6 Interface Address (see [RFC6119]) 12 IPv6 Interface Address (see [RFC6119])
13 IPv6 Neighbor Address (see [RFC6119]) 13 IPv6 Neighbor Address (see [RFC6119])
14-255 Unassigned 14-255 Unassigned
9. 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]. and [RFC5310].
10. Acknowledgements 9. Acknowledgements
The authors would like to thank Eric Rosen and Acee Lindem for their The authors would like to thank Eric Rosen and Acee Lindem for their
careful review and content suggestions. careful review and content suggestions.
11. References 10. References
11.1. Normative References 10.1. Normative References
[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 17, line 32 skipping to change at page 18, line 32
[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>.
11.2. Informative References 10.2. 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-03 (work in progress), ietf-spring-segment-routing-policy-06 (work in progress),
May 2019. December 2019.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
IP Fast Reroute: Loop-Free Alternates", RFC 5286,
DOI 10.17487/RFC5286, September 2008,
<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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
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 USA
Email: ginsberg@cisco.com Email: ginsberg@cisco.com
Peter Psenak Peter Psenak
Cisco Systems Cisco Systems
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