Internet DRAFT - draft-peng-lsr-algorithm-related-adjacency-sid
draft-peng-lsr-algorithm-related-adjacency-sid
LSR Shaofu. Peng
Internet-Draft Ran. Chen
Intended status: Standards Track ZTE Corporation
Expires: November 18, 2021 Ketan. Talaulikar
Peter. Psenak
Cisco Systems
May 17, 2021
Algorithm Related IGP-Adjacency SID Advertisement
draft-peng-lsr-algorithm-related-adjacency-sid-03
Abstract
Segment Routing architecture supports the use of multiple routing
algorithms, i.e, different constraint-based shortest-path
calculations can be supported. There are two standard algorithms:
SPF and Strict-SPF, defined in Segment Routing architecture. There
are also other user defined algorithms according to Flex-algo
applicaiton. However, an algorithm identifier is often included as
part of a Prefix-SID advertisement, that maybe not satisfy some
scenarios where multiple algorithm share the same link resource.
This document complement that the algorithm identifier can be also
included as part of a Adjacency-SID advertisement
Status of This Memo
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This Internet-Draft will expire on November 18, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Use-cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Adjacency Segment Identifier per Algorithm . . . . . . . . . 4
4.1. ISIS Adjacency Segment Identifier per Algorithm . . . . . 4
4.1.1. ISIS Adjacency Segment Identifier (Adj-SID) per
Algorithm Sub-TLV . . . . . . . . . . . . . . . . . . 4
4.1.2. ISIS Adjacency Segment Identifier (LAN-Adj-SID) per
Algorithm Sub-TLV . . . . . . . . . . . . . . . . . . 5
4.2. OSPFv2 Adjacency Segment Identifier per Algorithm . . . . 6
4.2.1. OSPFv2 Adj-SID per Algorithm Sub-TLV . . . . . . . . 6
4.2.2. OSPFv2 LAN Adj-SID per Algorithm Sub-TLV . . . . . . 7
4.3. OSPFv3 Adjacency Segment Identifier per Algorithm . . . . 8
4.3.1. OSPFv3 Adj-SID per Algorithm Sub-TLV . . . . . . . . 8
4.3.2. OSPFv3 LAN Adj-SID per Algorithm Sub-TLV . . . . . . 9
5. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6.1. IANA ISIS Considerations . . . . . . . . . . . . . . . . 11
6.2. IANA OSPFv2 Considerations . . . . . . . . . . . . . . . 11
6.3. IANA OSPFv3 Considerations . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. Normative References . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
Segment Routing architecture [RFC8402] supports the use of multiple
routing algorithms, i.e, different constraint-based shortest-path
calculations can be supported. There are two standard algorithms,
i.e, SPF and Strict-SPF, that defined in Segment Routing
architecture. For SPF, the packet is forwarded along the well known
ECMP-aware Shortest Path First (SPF) algorithm employed by the IGPs.
However, it is explicitly allowed for a midpoint to implement another
forwarding based on local policy. For Strict Shortest Path First
(Strict-SPF), it mandates that the packet be forwarded according to
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the ECMP-aware SPF algorithm and instructs any router in the path to
ignore any possible local policy overriding the SPF decision.
There are also other user defined algorithms according to IGP Flex
Algorithm [I-D.ietf-lsr-flex-algo]. IGP Flex Algorithm proposes a
solution that allows IGPs themselves to compute constraint based
paths over the network, and it also specifies a way of using Segment
Routing (SR) Prefix-SIDs and SRv6 locators to steer packets along the
constraint-based paths. It specifies a set of extensions to ISIS,
OSPFv2 and OSPFv3 that enable a router to send TLVs that identify (a)
calculation-type, (b) specify a metric-type, and (c )describe a set
of constraints on the topology, that are to be used to compute the
best paths along the constrained topology. A given combination of
calculation-type, metric-type, and constraints is known as an FAD
(Flexible Algorithm Definition).
However, an algorithm identifier is often included as part of a
Prefix-SID advertisement, that maybe not satisfy some scenarios where
multiple algorithm share the same link resource. This document
complement that the algorithm identifier can be also included as part
of an Adjacency-SID advertisement for SR-MPLS.
2. 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.
3. Use-cases
There are several use-cases for the algorithm-aware Adjacency-SID:
case-1: an SR-TE policy may be instantiated within specific Flex-
algo plane, i.e., the SID list may contain algorithm related SIDs.
An algorithm-aware Adjacency-SID included in the SID list can not
only steer the traffic towards the link, but also apply specific
QoS policy for that algorithm.
case-2: a TI-LFA backup path computed in Flex-algo plane may
contain Adjacency Segments and require to contain an algorithm-
aware Adjacency-SID. An algorithm-aware Adjacency-SID included in
the TI-LFA SID list can not only steer the traffic towards the
link, but also distinguish traffic between different algorithms.
case-3: for the protected Adjacency-SID which belongs to SR-TE
path within specific Flex-algo plane, the backup path of such
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Adjacency-SID need follow the algorithm specific constraints that
is consistent with the primary SR-TE path.
4. Adjacency Segment Identifier per Algorithm
4.1. ISIS Adjacency Segment Identifier per Algorithm
[RFC8667] describes the IS-IS extensions that need to be introduced
for Segment Routing operating on an MPLS data plane. It defined
Adjacency Segment Identifier (Adj-SID) sub-TLV advertised with TLV-
22/222/23/223/141, and Adjacency Segment Identifier (LAN-Adj-SID)
Sub-TLV advetised with TLV-22/222/23/223. Accordingly, this document
defines two new optional Sub-TLVs, "ISIS Adjacency Segment Identifier
(Adj-SID) per Algorithm Sub-TLV" and "ISIS Adjacency Segment
Identifier (LAN-Adj-SID) per Algorithm Sub-TLV".
4.1.1. ISIS Adjacency Segment Identifier (Adj-SID) per Algorithm Sub-
TLV
ISIS Adjacency Segment Identifier (Adj-SID) per Algorithm Sub-TLV has
the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: ISIS Adjacency Segment Identifier (Adj-SID) per Algorithm
Format
where:
Type: TBA1.
Length: 6 or 7 depending on size of the SID.
Flags: Refer to Adjacency Segment Identifier (Adj-SID) sub-TLV.
Weight: Refer to Adjacency Segment Identifier (Adj-SID) sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
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SID/Label/Index: Refer to Adjacency Segment Identifier (Adj-SID) sub-
TLV.
For a P2P link, an SR-capable router MAY allocate different Adj-SID
for different algorithm, if this link joins different algorithm
related plane.
4.1.2. ISIS Adjacency Segment Identifier (LAN-Adj-SID) per Algorithm
Sub-TLV
ISIS Adjacency Segment Identifier (LAN-Adj-SID) per Algorithm Sub-TLV
has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor System-ID (ID length octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: ISIS Adjacency Segment Identifier (LAN-Adj-SID) per
Algorithm Format
where:
Type: TBA2.
Length: Variable.
Flags: Refer to Adjacency Segment Identifier (LAN-Adj-SID) Sub-TLV.
Weight: Refer to Adjacency Segment Identifier (LAN-Adj-SID) Sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
SID/Label/Index: Refer to Adjacency Segment Identifier (LAN-Adj-SID)
Sub-TLV.
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For a broadcast link, an SR-capable router MAY allocate different
Adj-SID for different algorithm, if this link joins different
algorithm related plane.
4.2. OSPFv2 Adjacency Segment Identifier per Algorithm
[RFC8665] describes the OSPFv2 extensions that need to be introduced
for Segment Routing operating on an MPLS data plane. It defined Adj-
SID Sub-TLV and LAN Adj-SID Sub-TLV advertised with Extended Link TLV
defined in [RFC7684]. Accordingly, this document defines two new
optional Sub-TLVs, "OSPFv2 Adj-SID per Algorithm Sub-TLV" and "OSPFv2
LAN Adj-SID per Algorithm Sub-TLV".
4.2.1. OSPFv2 Adj-SID per Algorithm Sub-TLV
OSPFv2 Adj-SID per Algorithm Sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Algorithm | MT-ID | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: OSPFv2 Adj-SID per Algorithm Format
where:
Type: TBA3
Length: 7 or 8 octets, depending on the V-Flag.
Flags: Refer to OSPFv2 Adj-SID Sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
MT-ID: Refer to OSPFv2 Adj-SID Sub-TLV.
Weight: Refer to OSPFv2 Adj-SID Sub-TLV.
SID/Index/Label: Refer to OSPFv2 Adj-SID Sub-TLV.
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For a P2P link, an SR-capable router MAY allocate different Adj-SID
for different algorithm, if this link joins different algorithm
related plane.
4.2.2. OSPFv2 LAN Adj-SID per Algorithm Sub-TLV
OSPFv2 LAN Adj-SID per Algorithm Sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Algorithm | MT-ID | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: OSPFv2 LAN Adj-SID per Algorithm Format
where:
Type: TBA4
Length: 11 or 12 octets, depending on the V-Flag.
Flags: Refer to OSPFv2 LAN Adj-SID Sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
MT-ID: Refer to OSPFv2 LAN Adj-SID Sub-TLV.
Weight: Refer to OSPFv2 LAN Adj-SID Sub-TLV.
Neighbor ID: Refer to OSPFv2 LAN Adj-SID Sub-TLV.
SID/Index/Label: Refer to OSPFv2 LAN Adj-SID Sub-TLV.
For a broadcast link, an SR-capable router MAY allocate different
Adj-SID for different algorithm, if this link joins different
algorithm related plane.
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4.3. OSPFv3 Adjacency Segment Identifier per Algorithm
[RFC8666] describes the OSPFv3 extensions that need to be introduced
for Segment Routing operating on an MPLS data plane. It defined Adj-
SID Sub-TLV and LAN Adj-SID Sub-TLV advertised with Router-Link TLV
as defined in [RFC8362]. Accordingly, this document defines two new
optional Sub-TLVs, "OSPFv3 Adj-SID per Algorithm Sub-TLV" and "OSPFv3
LAN Adj-SID per Algorithm Sub-TLV".
4.3.1. OSPFv3 Adj-SID per Algorithm Sub-TLV
OSPFv3 Adj-SID per Algorithm Sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Algorithm | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: OSPFv3 Adj-SID per Algorithm Format
where:
Type: TBA5
Length: 7 or 8 octets, depending on the V-Flag.
Flags: Refer to OSPFv3 Adj-SID Sub-TLV.
Weight: Refer to OSPFv3 Adj-SID Sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
Reserved: SHOULD be set to 0 on transmission and MUST be ignored on
reception.
SID/Index/Label: Refer to OSPFv3 Adj-SID Sub-TLV.
For a P2P link, an SR-capable router MAY allocate different Adj-SID
for different algorithm, if this link joins different algorithm
related plane.
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4.3.2. OSPFv3 LAN Adj-SID per Algorithm Sub-TLV
OSPFv3 LAN Adj-SID per Algorithm Sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Algorithm | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: OSPFv3 LAN Adj-SID per Algorithm Format
where:
Type: TBA6
Length: 11 or 12 octets, depending on the V-Flag.
Flags: Refer to OSPFv3 LAN Adj-SID Sub-TLV.
Weight: Refer to OSPFv3 LAN Adj-SID Sub-TLV.
Algorithm: The Algorithm field contains the identifier of the
algorithm the router uses to apply algorithm specific treatment
configured on the adjacency.
Reserved: SHOULD be set to 0 on transmission and MUST be ignored on
reception.
Neighbor ID: Refer to OSPFv3 LAN Adj-SID Sub-TLV.
SID/Index/Label: Refer to OSPFv3 LAN Adj-SID Sub-TLV.
For a broadcast link, an SR-capable router MAY allocate different
Adj-SID for different algorithm, if this link joins different
algorithm related plane.
5. Operations
The method introduced in this document enables the traffic of
different flex-algo plane to be distinguished on the same link, so
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that these traffic can be applied with different QoS policy per
algorithm.
The endpoint of a link shared by multiple flex-algo plane can reserve
different queue resources for different algorithms locally, and
perform priority based queue scheduling and traffic shaping. This
algorithm related reserved information can be advertised to other
nodes in the network through some mechanism, therefore it has an
impact on the constraint based path calculation of the flex-algo
plane. How to allocate algorithm related resouce and advertise it in
the network is out the scope of this document.
Depending on the implementation, operators can configure multiple
Adacency-SIDs each for different algorithm on the same link. One of
the difficulties is that during this configuration phase it is not
straightforward for a link to be included in an FA plane, as this can
only be determined after all nodes in the network have negotiated the
FAD. A simple way is that as long as an IGP instance enable an
algorithm for a level/area, all links joined to that level/area
should allocate Adjacency-SIDs for that algorithm statically.
Another way is to allocate and withdraw Adjacency-SID per algorithm
dynamically according to the result of FAD negotiation.
The following figure shows an example of Adjacency-SID per algorithm.
[S1]--------[D]--------[S2]
| | |
| | |
| | |
[A]---------[B]--------[C]
Figure 7: Flex-algo LFA Path with Adjacency-SID per Algorithm
Suppose that node S1, A, B, D and their inter-connected links belongs
to FA-id 128 plane, and S2, B, C, D and their inter-connected links
belongs to FA-id 129 plane. The IGP metric of link B-D is 100, and
all other links have IGP metric 1. Both FA-id 128 and 129 use IGP
default metric type for path calculation. In FA-id 128 plane, from
S1 to destination D, the primary path is S1-D, and the TI-LFA backup
path is segment list {node(B), adjacency(B-D)}. Similarly, In FA-id
129 plane, from S2 to destination D, the primary path is S2-D, and
the TI-LFA backup path is segment list {node(B), adjacency(B-D)}. The
above TI-LFA path of FA-id 128 plane can be translated to {node-
SID(B)@FA-id128, adjacency-SID(B-D)@FA-id128}, and TI-LFA path of FA-
id 129 plane will be translate to {node-SID(B)@FA-id129, adjacency-
SID(B-D)@FA-id129}. So that node B can distinguish the flow of FA-id
128 and FA-id 129 based on different adjacency-SID(B-D), and take
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different treatment (e.g., QoS policy) of them when they are send to
the same outgoing link B-D.
6. IANA Considerations
6.1. IANA ISIS Considerations
This document makes the following registrations in the "Sub-TLVs for
TLV 22, 23, 25, 141, 222, and 223" registry.
+------+--------------------+----+----+----+-----+-----+-----+
| Type | Description | 22 | 23 | 25 | 141 | 222 | 223 |
+======+====================+====+====+====+=====+=====+=====+
| | Adjacency Segment | | | | | | |
| TBA1 | Identifier per | y | y | n | y | y | y |
| | Algorithm | | | | | | |
+------+--------------------+----+----+----+-----+-----+-----+
| | LAN Adjacency | | | | | | |
| TBA2 | Segment Identifier | y | y | n | y | y | y |
| | per Algorithm | | | | | | |
+------+--------------------+----+----+----+-----+-----+-----+
6.2. IANA OSPFv2 Considerations
This document makes the following registrations in the OSPFv2
Extended Link TLV Sub-TLVs Registry.
+-------+------------------------------------------+---------------+
| Value | Description | Reference |
+=======+==========================================+===============+
| TBA3 | OSPFv2 Adj-SID per Algorithm Sub-TLV | This document |
+-------+------------------------------------------+---------------+
| TBA4 | OSPFv2 LAN Adj-SID per Algorithm Sub-TLV | This document |
+-------+------------------------------------------+---------------+
6.3. IANA OSPFv3 Considerations
This document makes the following registrations in the "OSPFv3
Extended-LSA Sub-TLVs" Registry.
+-------+------------------------------------------+---------------+
| Value | Description | Reference |
+=======+==========================================+===============+
| TBA5 | OSPFv3 Adj-SID per Algorithm Sub-TLV | This document |
+-------+------------------------------------------+---------------+
| TBA6 | OSPFv3 LAN Adj-SID per Algorithm Sub-TLV | This document |
+-------+------------------------------------------+---------------+
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7. Security Considerations
There are no new security issues introduced by the extensions in this
document. Refer to [RFC8665], [RFC8666], [RFC8667] for other
security considerations.
8. Acknowledgements
TBD
9. Normative References
[I-D.ietf-lsr-flex-algo]
Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-15 (work in progress), April 2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
[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>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
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[RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
December 2019, <https://www.rfc-editor.org/info/rfc8666>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
Authors' Addresses
Shaofu Peng
ZTE Corporation
China
Email: peng.shaofu@zte.com.cn
Ran Chen
ZTE Corporation
China
Email: chen.ran@zte.com.cn
Ketan Talaulikar
Cisco Systems
India
Email: ketant@cisco.com
Peter Psenak
Cisco Systems
Slovakia
Email: ppsenak@cisco.com
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