draft-ietf-lsr-flex-algo-11.txt   draft-ietf-lsr-flex-algo-12.txt 
Network Working Group P. Psenak, Ed. Network Working Group P. Psenak, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track S. Hegde Intended status: Standards Track S. Hegde
Expires: March 14, 2021 Juniper Networks, Inc. Expires: April 10, 2021 Juniper Networks, Inc.
C. Filsfils C. Filsfils
K. Talaulikar K. Talaulikar
Cisco Systems, Inc. Cisco Systems, Inc.
A. Gulko A. Gulko
Individual Individual
September 10, 2020 October 7, 2020
IGP Flexible Algorithm IGP Flexible Algorithm
draft-ietf-lsr-flex-algo-11.txt draft-ietf-lsr-flex-algo-12
Abstract Abstract
IGP protocols traditionally compute best paths over the network based IGP protocols traditionally compute best paths over the network based
on the IGP metric assigned to the links. Many network deployments on the IGP metric assigned to the links. Many network deployments
use RSVP-TE based or Segment Routing based Traffic Engineering to use RSVP-TE based or Segment Routing based Traffic Engineering to
steer traffic over a path that is computed using different metrics or steer traffic over a path that is computed using different metrics or
constraints than the shortest IGP path. This document proposes a constraints than the shortest IGP path. This document proposes a
solution that allows IGPs themselves to compute constraint-based solution that allows IGPs themselves to compute constraint-based
paths over the network. This document also specifies a way of using paths over the network. This document also specifies a way of using
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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 March 14, 2021. This Internet-Draft will expire on April 10, 2021.
Copyright Notice Copyright Notice
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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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Flexible Algorithm . . . . . . . . . . . . . . . . . . . . . 5 4. Flexible Algorithm . . . . . . . . . . . . . . . . . . . . . 5
5. Flexible Algorithm Definition Advertisement . . . . . . . . . 6 5. Flexible Algorithm Definition Advertisement . . . . . . . . . 6
5.1. ISIS Flexible Algorithm Definition Sub-TLV . . . . . . . 6 5.1. ISIS Flexible Algorithm Definition Sub-TLV . . . . . . . 6
5.2. OSPF Flexible Algorithm Definition TLV . . . . . . . . . 7 5.2. OSPF Flexible Algorithm Definition TLV . . . . . . . . . 7
5.3. Common Handling of Flexible Algorithm Definition TLV . . 9 5.3. Common Handling of Flexible Algorithm Definition TLV . . 9
6. Sub-TLVs of ISIS FAD Sub-TLV . . . . . . . . . . . . . . . . 10 6. Sub-TLVs of ISIS FAD Sub-TLV . . . . . . . . . . . . . . . . 10
6.1. ISIS Flexible Algorithm Exclude Admin Group Sub-TLV . . . 10 6.1. ISIS Flexible Algorithm Exclude Admin Group Sub-TLV . . . 10
6.2. ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV . 11 6.2. ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV . 11
6.3. ISIS Flexible Algorithm Include-All Admin Group Sub-TLV . 12 6.3. ISIS Flexible Algorithm Include-All Admin Group Sub-TLV . 12
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17.4. OSPF IANA Considerations . . . . . . . . . . . . . . . . 30 17.4. OSPF IANA Considerations . . . . . . . . . . . . . . . . 30
17.4.1. OSPF Router Information (RI) TLVs Registry . . . . . 30 17.4.1. OSPF Router Information (RI) TLVs Registry . . . . . 30
17.4.2. OSPFv2 Extended Prefix TLV Sub-TLVs . . . . . . . . 30 17.4.2. OSPFv2 Extended Prefix TLV Sub-TLVs . . . . . . . . 30
17.4.3. OSPFv3 Extended-LSA Sub-TLVs . . . . . . . . . . . . 30 17.4.3. OSPFv3 Extended-LSA Sub-TLVs . . . . . . . . . . . . 30
17.4.4. OSPF Flexible Algorithm Definition TLV Sub-TLV 17.4.4. OSPF Flexible Algorithm Definition TLV Sub-TLV
Registry . . . . . . . . . . . . . . . . . . . . . . 31 Registry . . . . . . . . . . . . . . . . . . . . . . 31
17.4.5. Link Attribute Applications Registry . . . . . . . . 32 17.4.5. Link Attribute Applications Registry . . . . . . . . 32
18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32 18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
19. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
19.1. Normative References . . . . . . . . . . . . . . . . . . 32 19.1. Normative References . . . . . . . . . . . . . . . . . . 32
19.2. Informative References . . . . . . . . . . . . . . . . . 35 19.2. Informative References . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction 1. Introduction
An IGP-computed path based on the shortest IGP metric must often be An IGP-computed path based on the shortest IGP metric must often be
replaced by a traffic-engineered path due to the traffic requirements replaced by a traffic-engineered path due to the traffic requirements
which are not reflected by the IGP metric. Some networks engineer which are not reflected by the IGP metric. Some networks engineer
the IGP metric assignments in a way that the IGP metric reflects the the IGP metric assignments in a way that the IGP metric reflects the
link bandwidth or delay. If, for example, the IGP metric is link bandwidth or delay. If, for example, the IGP metric is
reflecting the bandwidth on the link and the application traffic is reflecting the bandwidth on the link and the application traffic is
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"Flexible Algorithm Definition". A router that sends such a set of "Flexible Algorithm Definition". A router that sends such a set of
TLVs also assigns a Flex-Algorithm value to the specified combination TLVs also assigns a Flex-Algorithm value to the specified combination
of calculation-type, metric-type, and constraints. of calculation-type, metric-type, and constraints.
This document also specifies a way for a router to use IGPs to This document also specifies a way for a router to use IGPs to
associate one or more SR Prefix-SIDs or SRv6 locators with a associate one or more SR Prefix-SIDs or SRv6 locators with a
particular Flex-Algorithm. Each such Prefix-SID or SRv6 locator then particular Flex-Algorithm. Each such Prefix-SID or SRv6 locator then
represents a path that is computed according to the identified Flex- represents a path that is computed according to the identified Flex-
Algorithm. Algorithm.
2. Requirements notation 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[BCP14] [RFC2119] [RFC8174] when, and only when, they appear in all [BCP14] [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Terminology 3. Terminology
This section defines terms that are often used in this document. This section defines terms that are often used in this document.
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received from other nodes via IGP flooding. received from other nodes via IGP flooding.
Flexible Algorithm Participation - per application configuration Flexible Algorithm Participation - per application configuration
state that expresses whether the node is participating in a state that expresses whether the node is participating in a
particular Flexible Algorithm. particular Flexible Algorithm.
IGP Algorithm - value from the the "IGP Algorithm Types" registry IGP Algorithm - value from the the "IGP Algorithm Types" registry
defined under "Interior Gateway Protocol (IGP) Parameters" IANA defined under "Interior Gateway Protocol (IGP) Parameters" IANA
registries. IGP Algorithms represents the triplet (Calculation Type, registries. IGP Algorithms represents the triplet (Calculation Type,
Metric, Constraints), where the second and third elements of the Metric, Constraints), where the second and third elements of the
triple MAY not be specified. triple MAY be unspecified.
ABR - Area Border Router. In ISIS terminology it is also known as ABR - Area Border Router. In ISIS terminology it is also known as
L1/L2 router. L1/L2 router.
ASBR - Autonomous System Border Router. ASBR - Autonomous System Border Router.
4. Flexible Algorithm 4. Flexible Algorithm
Many possible constraints may be used to compute a path over a Many possible constraints may be used to compute a path over a
network. Some networks are deployed as multiple planes. A simple network. Some networks are deployed as multiple planes. A simple
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TLV in the Router Information LSA with the area-scoped flooding scope TLV in the Router Information LSA with the area-scoped flooding scope
MUST be used. If the OSPF FAD TLV, for the same algorithm, appears MUST be used. If the OSPF FAD TLV, for the same algorithm, appears
in multiple Router Information LSAs that have the same flooding in multiple Router Information LSAs that have the same flooding
scope, the OSPF FAD TLV in the Router Information (RI) LSA with the scope, the OSPF FAD TLV in the Router Information (RI) LSA with the
numerically smallest Instance ID MUST be used and subsequent numerically smallest Instance ID MUST be used and subsequent
instances of the OSPF FAD TLV MUST be ignored. instances of the OSPF FAD TLV MUST be ignored.
The RI LSA can be advertised at any of the defined opaque flooding The RI LSA can be advertised at any of the defined opaque flooding
scopes (link, area, or Autonomous System (AS)). For the purpose of scopes (link, area, or Autonomous System (AS)). For the purpose of
OSPF FAD TLV advertisement, area-scoped flooding is REQUIRED. The OSPF FAD TLV advertisement, area-scoped flooding is REQUIRED. The
Autonomous System flooding scope SHOULD not be used by default unless Autonomous System flooding scope SHOULD NOT be used by default unless
local configuration policy on the originating router indicates domain local configuration policy on the originating router indicates domain
wide flooding. wide flooding.
5.3. Common Handling of Flexible Algorithm Definition TLV 5.3. Common Handling of Flexible Algorithm Definition TLV
This section describes the protocol-independent handling of the FAD This section describes the protocol-independent handling of the FAD
TLV (OSPF) or FAD Sub-TLV (ISIS). We will refer to it as FAD TLV in TLV (OSPF) or FAD Sub-TLV (ISIS). We will refer to it as FAD TLV in
this section, even though in case of ISIS it is a Sub-TLV. this section, even though in case of ISIS it is a Sub-TLV.
The value of the Flex-Algorithm MUST be between 128 and 255 The value of the Flex-Algorithm MUST be between 128 and 255
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where: where:
Type: 1 Type: 1
Length: variable, dependent on the size of the Extended Admin Length: variable, dependent on the size of the Extended Admin
Group. MUST be a multiple of 4 octets. Group. MUST be a multiple of 4 octets.
Extended Administrative Group: Extended Administrative Group as Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308]. defined in [RFC7308].
The ISIS FAEAG Sub-TLV MAY NOT appear more then once in an ISIS FAD The ISIS FAEAG Sub-TLV MUST NOT appear more then once in an ISIS FAD
Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST be Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST be
ignored by the receiver. ignored by the receiver.
6.2. ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV 6.2. ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV
The Flexible Algorithm definition can specify 'colors' that are used The Flexible Algorithm definition can specify 'colors' that are used
by the operator to include links during the Flex-Algorithm path by the operator to include links during the Flex-Algorithm path
computation. computation.
The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV is used The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV is used
to advertise include-any rule that is used during the Flex-Algorithm to advertise include-any rule that is used during the Flex-Algorithm
path calculation as specified in Section 12. path calculation as specified in Section 12.
The format of the ISIS Flexible Algorithm Include-Any Admin Group The format of the ISIS Flexible Algorithm Include-Any Admin Group
Sub-TLV is identical to the format of the FAEAG Sub-TLV in Sub-TLV is identical to the format of the FAEAG Sub-TLV in
Section 6.1. Section 6.1.
The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV Type is The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV Type is
2. 2.
The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV MAY NOT The ISIS Flexible Algorithm Include-Any Admin Group Sub-TLV MUST NOT
appear more then once in an ISIS FAD Sub-TLV. If it appears more appear more then once in an ISIS FAD Sub-TLV. If it appears more
then once, the ISIS FAD Sub-TLV MUST be ignored by the receiver. then once, the ISIS FAD Sub-TLV MUST be ignored by the receiver.
6.3. ISIS Flexible Algorithm Include-All Admin Group Sub-TLV 6.3. ISIS Flexible Algorithm Include-All Admin Group Sub-TLV
The Flexible Algorithm definition can specify 'colors' that are used The Flexible Algorithm definition can specify 'colors' that are used
by the operator to include link during the Flex-Algorithm path by the operator to include link during the Flex-Algorithm path
computation. computation.
The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV is used The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV is used
to advertise include-all rule that is used during the Flex-Algorithm to advertise include-all rule that is used during the Flex-Algorithm
path calculation as specified in Section 12. path calculation as specified in Section 12.
The format of the ISIS Flexible Algorithm Include-All Admin Group The format of the ISIS Flexible Algorithm Include-All Admin Group
Sub-TLV is identical to the format of the FAEAG Sub-TLV in Sub-TLV is identical to the format of the FAEAG Sub-TLV in
Section 6.1. Section 6.1.
The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV Type is The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV Type is
3. 3.
The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV MAY NOT The ISIS Flexible Algorithm Include-All Admin Group Sub-TLV MUST NOT
appear more then once in an ISIS FAD Sub-TLV. If it appears more appear more then once in an ISIS FAD Sub-TLV. If it appears more
then once, the ISIS FAD Sub-TLV MUST be ignored by the receiver. then once, the ISIS FAD Sub-TLV MUST be ignored by the receiver.
6.4. ISIS Flexible Algorithm Definition Flags Sub-TLV 6.4. ISIS Flexible Algorithm Definition Flags Sub-TLV
The ISIS Flexible Algorithm Definition Flags Sub-TLV (FADF Sub-TLV) The ISIS Flexible Algorithm Definition Flags Sub-TLV (FADF Sub-TLV)
is a Sub-TLV of the ISIS FAD Sub-TLV. It has the following format: is a Sub-TLV of the ISIS FAD Sub-TLV. It has the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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Bits are defined/sent starting with Bit 0 defined above. Additional Bits are defined/sent starting with Bit 0 defined above. Additional
bit definitions that may be defined in the future SHOULD be assigned bit definitions that may be defined in the future SHOULD be assigned
in ascending bit order so as to minimize the number of bits that will in ascending bit order so as to minimize the number of bits that will
need to be transmitted. need to be transmitted.
Undefined bits MUST be transmitted as 0. Undefined bits MUST be transmitted as 0.
Bits that are NOT transmitted MUST be treated as if they are set to 0 Bits that are NOT transmitted MUST be treated as if they are set to 0
on receipt. on receipt.
The ISIS FADF Sub-TLV MAY NOT appear more then once in an ISIS FAD The ISIS FADF Sub-TLV MUST NOT appear more then once in an ISIS FAD
Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST be Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST be
ignored by the receiver. ignored by the receiver.
If the ISIS FADF Sub-TLV is not present inside the ISIS FAD Sub-TLV, If the ISIS FADF Sub-TLV is not present inside the ISIS FAD Sub-TLV,
all the bits are assumed to be set to 0. all the bits are assumed to be set to 0.
6.5. ISIS Flexible Algorithm Exclude SRLG Sub-TLV 6.5. ISIS Flexible Algorithm Exclude SRLG Sub-TLV
The Flexible Algorithm definition can specify Shared Risk Link Groups The Flexible Algorithm definition can specify Shared Risk Link Groups
(SRLGs) that the operator wants to exclude during the Flex-Algorithm (SRLGs) that the operator wants to exclude during the Flex-Algorithm
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| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type: 5 Type: 5
Length: variable, dependent on number of SRLG values. MUST be a Length: variable, dependent on number of SRLG values. MUST be a
multiple of 4 octets. multiple of 4 octets.
Shared Risk Link Group Value: SRLG value as defined in [RFC5307]. Shared Risk Link Group Value: SRLG value as defined in [RFC5307].
The ISIS FAESRLG Sub-TLV MAY NOT appear more then once in an ISIS FAD The ISIS FAESRLG Sub-TLV MUST NOT appear more then once in an ISIS
Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST be FAD Sub-TLV. If it appears more then once, the ISIS FAD Sub-TLV MUST
ignored by the receiver. be ignored by the receiver.
7. Sub-TLVs of OSPF FAD TLV 7. Sub-TLVs of OSPF FAD TLV
7.1. OSPF Flexible Algorithm Exclude Admin Group Sub-TLV 7.1. OSPF Flexible Algorithm Exclude Admin Group Sub-TLV
The Flexible Algorithm Exclude Admin Group Sub-TLV (FAEAG Sub-TLV) is The Flexible Algorithm Exclude Admin Group Sub-TLV (FAEAG Sub-TLV) is
a Sub-TLV of the OSPF FAD TLV. It's usage is described in a Sub-TLV of the OSPF FAD TLV. It's usage is described in
Section 6.1. It has the following format: Section 6.1. It has the following format:
0 1 2 3 0 1 2 3
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where: where:
Type: 1 Type: 1
Length: variable, dependent on the size of the Extended Admin Length: variable, dependent on the size of the Extended Admin
Group. MUST be a multiple of 4 octets. Group. MUST be a multiple of 4 octets.
Extended Administrative Group: Extended Administrative Group as Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308]. defined in [RFC7308].
The OSPF FAEAG Sub-TLV MAY NOT appear more then once in an OSPF FAD The OSPF FAEAG Sub-TLV MUST NOT appear more then once in an OSPF FAD
TLV. If it appears more then once, the OSPF FAD TLV MUST be ignored TLV. If it appears more then once, the OSPF FAD TLV MUST be ignored
by the receiver. by the receiver.
7.2. OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV 7.2. OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV
The usage of this Sub-TLVs is described in Section 6.2. The usage of this Sub-TLVs is described in Section 6.2.
The format of the OSPF Flexible Algorithm Include-Any Admin Group The format of the OSPF Flexible Algorithm Include-Any Admin Group
Sub-TLV is identical to the format of the OSPF FAEAG Sub-TLV in Sub-TLV is identical to the format of the OSPF FAEAG Sub-TLV in
Section 7.1. Section 7.1.
The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV Type is The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV Type is
2. 2.
The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV MAY NOT The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV MUST NOT
appear more then once in an OSPF FAD TLV. If it appears more then appear more then once in an OSPF FAD TLV. If it appears more then
once, the OSPF FAD TLV MUST be ignored by the receiver. once, the OSPF FAD TLV MUST be ignored by the receiver.
7.3. OSPF Flexible Algorithm Include-All Admin Group Sub-TLV 7.3. OSPF Flexible Algorithm Include-All Admin Group Sub-TLV
The usage of this Sub-TLVs is described in Section 6.3. The usage of this Sub-TLVs is described in Section 6.3.
The format of the OSPF Flexible Algorithm Include-Any Admin Group The format of the OSPF Flexible Algorithm Include-Any Admin Group
Sub-TLV is identical to the format of the OSPF FAEAG Sub-TLV in Sub-TLV is identical to the format of the OSPF FAEAG Sub-TLV in
Section 7.1. Section 7.1.
The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV Type is The OSPF Flexible Algorithm Include-Any Admin Group Sub-TLV Type is
3. 3.
The OSPF Flexible Algorithm Include-All Admin Group Sub-TLV MAY NOT The OSPF Flexible Algorithm Include-All Admin Group Sub-TLV MUST NOT
appear more then once in an OSPF FAD TLV. If it appears more then appear more then once in an OSPF FAD TLV. If it appears more then
once, the OSPF FAD TLV MUST be ignored by the receiver. once, the OSPF FAD TLV MUST be ignored by the receiver.
7.4. OSPF Flexible Algorithm Definition Flags Sub-TLV 7.4. OSPF Flexible Algorithm Definition Flags Sub-TLV
The OSPF Flexible Algorithm Definition Flags Sub-TLV (FADF Sub-TLV) The OSPF Flexible Algorithm Definition Flags Sub-TLV (FADF Sub-TLV)
is a Sub-TLV of the OSPF FAD TLV. It has the following format: is a Sub-TLV of the OSPF FAD TLV. It has the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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Bits are defined/sent starting with Bit 0 defined above. Additional Bits are defined/sent starting with Bit 0 defined above. Additional
bit definitions that may be defined in the future SHOULD be assigned bit definitions that may be defined in the future SHOULD be assigned
in ascending bit order so as to minimize the number of bits that will in ascending bit order so as to minimize the number of bits that will
need to be transmitted. need to be transmitted.
Undefined bits MUST be transmitted as 0. Undefined bits MUST be transmitted as 0.
Bits that are NOT transmitted MUST be treated as if they are set to 0 Bits that are NOT transmitted MUST be treated as if they are set to 0
on receipt. on receipt.
The OSPF FADF Sub-TLV MAY NOT appear more then once in an OSPF FAD The OSPF FADF Sub-TLV MUST NOT appear more then once in an OSPF FAD
TLV. If it appears more then once, the OSPF FAD TLV MUST be ignored TLV. If it appears more then once, the OSPF FAD TLV MUST be ignored
by the receiver. by the receiver.
If the OSPF FADF Sub-TLV is not present inside the OSPF FAD TLV, all If the OSPF FADF Sub-TLV is not present inside the OSPF FAD TLV, all
the bits are assumed to be set to 0. the bits are assumed to be set to 0.
7.5. OSPF Flexible Algorithm Exclude SRLG Sub-TLV 7.5. OSPF Flexible Algorithm Exclude SRLG Sub-TLV
The OSPF Flexible Algorithm Exclude SRLG Sub-TLV (FAESRLG Sub-TLV) is The OSPF Flexible Algorithm Exclude SRLG Sub-TLV (FAESRLG Sub-TLV) is
a Sub-TLV of the OSPF FAD TLV. Its usage is described in a Sub-TLV of the OSPF FAD TLV. Its usage is described in
skipping to change at page 17, line 7 skipping to change at page 17, line 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type: 5 Type: 5
Length: variable, dependent on the number of SRLGs. MUST be a Length: variable, dependent on the number of SRLGs. MUST be a
multiple of 4 octets. multiple of 4 octets.
Shared Risk Link Group Value: SRLG value as defined in [RFC4203]. Shared Risk Link Group Value: SRLG value as defined in [RFC4203].
The OSPF FAESRLG Sub-TLV MAY NOT appear more then once in an OSPF FAD The OSPF FAESRLG Sub-TLV MUST NOT appear more then once in an OSPF
TLV. If it appears more then once, the OSPF FAD TLV MUST be ignored FAD TLV. If it appears more then once, the OSPF FAD TLV MUST be
by the receiver. ignored by the receiver.
8. ISIS Flexible Algorithm Prefix Metric Sub-TLV 8. ISIS Flexible Algorithm Prefix Metric Sub-TLV
The ISIS Flexible Algorithm Prefix Metric (FAPM) Sub-TLV supports the The ISIS Flexible Algorithm Prefix Metric (FAPM) Sub-TLV supports the
advertisement of a Flex-Algorithm specific prefix metric associated advertisement of a Flex-Algorithm specific prefix metric associated
with a given prefix advertisement. with a given prefix advertisement.
The ISIS FAPM Sub-TLV is a sub-TLV of TLVs 135, 235, 236, and 237 and The ISIS FAPM Sub-TLV is a sub-TLV of TLVs 135, 235, 236, and 237 and
has the following format: has the following format:
skipping to change at page 32, line 46 skipping to change at page 32, line 46
Thanks to Kenji Kumaki for his comments. Thanks to Kenji Kumaki for his comments.
Thanks to William Britto A J. for his suggestions. Thanks to William Britto A J. for his suggestions.
Thanks to Acee Lindem for editorial comments. Thanks to Acee Lindem for editorial comments.
19. References 19. References
19.1. Normative References 19.1. Normative References
[BCP14] , <https://tools.ietf.org/html/bcp14>. [BCP14] "Key words for use in RFCs to Indicate Requirement
Levels", <https://tools.ietf.org/html/bcp14>.
[I-D.ietf-isis-te-app] [I-D.ietf-isis-te-app]
Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
J. Drake, "IS-IS Application-Specific Link Attributes", J. Drake, "IS-IS Application-Specific Link Attributes",
draft-ietf-isis-te-app-19 (work in progress), June 2020. draft-ietf-isis-te-app-19 (work in progress), June 2020.
[I-D.ietf-lsr-isis-srv6-extensions] [I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extension to Support Segment Routing over Z. Hu, "IS-IS Extension to Support Segment Routing over
IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-09 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-10
(work in progress), September 2020. (work in progress), September 2020.
[I-D.ietf-lsr-ospf-reverse-metric]
Talaulikar, K., Psenak, P., and H. Johnston, "OSPF Reverse
Metric", draft-ietf-lsr-ospf-reverse-metric-01 (work in
progress), June 2020.
[I-D.ietf-lsr-ospfv3-srv6-extensions] [I-D.ietf-lsr-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak, Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
"OSPFv3 Extensions for SRv6", draft-ietf-lsr- "OSPFv3 Extensions for SRv6", draft-ietf-lsr-
ospfv3-srv6-extensions-01 (work in progress), August 2020. ospfv3-srv6-extensions-01 (work in progress), August 2020.
[I-D.ietf-ospf-te-link-attr-reuse] [I-D.ietf-ospf-te-link-attr-reuse]
Psenak, P., Ginsberg, L., Henderickx, W., Tantsura, J., Psenak, P., Ginsberg, L., Henderickx, W., Tantsura, J.,
and J. Drake, "OSPF Application-Specific Link Attributes", and J. Drake, "OSPF Application-Specific Link Attributes",
draft-ietf-ospf-te-link-attr-reuse-16 (work in progress), draft-ietf-ospf-te-link-attr-reuse-16 (work in progress),
June 2020. June 2020.
 End of changes. 22 change blocks. 
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