draft-ietf-ospf-ospfv3-segment-routing-extensions-19.txt   draft-ietf-ospf-ospfv3-segment-routing-extensions-20.txt 
Open Shortest Path First IGP P. Psenak, Ed. Open Shortest Path First IGP P. Psenak, Ed.
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Previdi, Ed. Intended status: Standards Track S. Previdi, Ed.
Expires: May 24, 2019 Individual Expires: June 6, 2019 Individual
November 20, 2018 December 3, 2018
OSPFv3 Extensions for Segment Routing OSPFv3 Extensions for Segment Routing
draft-ietf-ospf-ospfv3-segment-routing-extensions-19 draft-ietf-ospf-ospfv3-segment-routing-extensions-20
Abstract Abstract
Segment Routing (SR) allows a flexible definition of end-to-end paths Segment Routing (SR) allows a flexible definition of end-to-end paths
within IGP topologies by encoding paths as sequences of topological within IGP topologies by encoding paths as sequences of topological
sub-paths, called "segments". These segments are advertised by the sub-paths, called "segments". These segments are advertised by the
link-state routing protocols (IS-IS and OSPF). link-state routing protocols (IS-IS and OSPF).
This draft describes the OSPFv3 extensions required for Segment This draft describes the OSPFv3 extensions required for Segment
Routing with MPLS data plane. Routing with MPLS data plane.
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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 24, 2019. This Internet-Draft will expire on June 6, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 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
skipping to change at page 2, line 25 skipping to change at page 2, line 25
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 4 3. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 4
3.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4 3.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4
4. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4 4. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4
5. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 5 5. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 5
6. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 7 6. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 7
7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 10 7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 10
7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 10 7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 11
7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 12 7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 12
8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 13 8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 13
8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 13 8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 13
8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 14 8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 14
8.3. Segment Routing for External Prefixes . . . . . . . . . . 15 8.3. Segment Routing for External Prefixes . . . . . . . . . . 15
8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 15 8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 16
8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 15 8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 16
8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 16 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
9.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 16 9.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 16
9.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 16 9.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 16
10. Security Considerations . . . . . . . . . . . . . . . . . . . 16 10. Security Considerations . . . . . . . . . . . . . . . . . . . 17
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
12.1. Normative References . . . . . . . . . . . . . . . . . . 18 12.1. Normative References . . . . . . . . . . . . . . . . . . 18
12.2. Informative References . . . . . . . . . . . . . . . . . 20 12.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
Segment Routing (SR) allows a flexible definition of end-to-end paths Segment Routing (SR) allows a flexible definition of end-to-end paths
within IGP topologies by encoding paths as sequences of topological within IGP topologies by encoding paths as sequences of topological
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Algorithm: Single octet identifying the algorithm the Prefix-SID Algorithm: Single octet identifying the algorithm the Prefix-SID
is associated with as defined in is associated with as defined in
[I-D.ietf-ospf-segment-routing-extensions]. [I-D.ietf-ospf-segment-routing-extensions].
A router receiving a Prefix-SID from a remote node and with an A router receiving a Prefix-SID from a remote node and with an
algorithm value that such remote node has not advertised in the algorithm value that such remote node has not advertised in the
SR-Algorithm Sub-TLV [I-D.ietf-ospf-segment-routing-extensions] SR-Algorithm Sub-TLV [I-D.ietf-ospf-segment-routing-extensions]
MUST ignore the Prefix-SID Sub-TLV. MUST ignore the Prefix-SID Sub-TLV.
SID/Index/Label: According to the V-Fag, it contains either: SID/Index/Label: According to the V-Flag and L-Flag, it contains:
A 32-bit index defining the offset in the SID/Label space V-flag is set to 0 and L-flag is set to 0: The SID/Index/Label
advertised by this router. field is a 4 octet index defining the offset in the SID/Label
space advertised by this router
A 24-bit label where the 20 rightmost bits are used for V-flag is set to 1 and L-flag is set to 1: The SID/Index/Label
encoding the label value. field is a 3 octet local label where the 20 rightmost bits are
used for encoding the label value.
All other combinations of V-flag and L-flag are invalid and any
SID advertisement received with an invalid setting for V and L
flags MUST be ignored.
If an OSPFv3 router advertises multiple Prefix-SIDs for the same If an OSPFv3 router advertises multiple Prefix-SIDs for the same
prefix, topology, and algorithm, all of them MUST be ignored. prefix, topology, and algorithm, all of them MUST be ignored.
When calculating the outgoing label for the prefix, the router MUST When calculating the outgoing label for the prefix, the router MUST
take into account, as described below, the E, NP, and M flags take into account, as described below, the E, NP, and M flags
advertised by the next-hop router if that router advertised the SID advertised by the next-hop router if that router advertised the SID
for the prefix. This MUST be done regardless of whether the next-hop for the prefix. This MUST be done regardless of whether the next-hop
router contributes to the best path to the prefix. router contributes to the best path to the prefix.
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Other bits: Reserved. These MUST be zero when sent and are Other bits: Reserved. These MUST be zero when sent and are
ignored when received. ignored when received.
Reserved: SHOULD be set to 0 on transmission and MUST be ignored Reserved: SHOULD be set to 0 on transmission and MUST be ignored
on reception. on reception.
Weight: Weight used for load-balancing purposes. The use of the Weight: Weight used for load-balancing purposes. The use of the
weight is defined in [RFC8402]. weight is defined in [RFC8402].
SID/Index/Label: According to the V-Flag, it contains either: SID/Index/Label: as described in Section 6.
A 32-bit index defining the offset in the SID/Label space
advertised by this router.
A 24-bit label where the 20 rightmost bits are used for
encoding the label value.
An SR-capable router MAY allocate an Adj-SID for each of its An SR-capable router MAY allocate an Adj-SID for each of its
adjacencies and set the B-Flag when the adjacency is eligible for adjacencies and set the B-Flag when the adjacency is eligible for
protection by an FRR mechanism (IP or MPLS) as described in protection by an FRR mechanism (IP or MPLS) as described in
[RFC8402]. [RFC8402].
An SR-capable router MAY allocate more than one Adj-SID to an An SR-capable router MAY allocate more than one Adj-SID to an
adjacency. adjacency.
An SR-capable router MAY allocate the same Adj-SID to different An SR-capable router MAY allocate the same Adj-SID to different
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Weight: Weight used for load-balancing purposes. The use of the Weight: Weight used for load-balancing purposes. The use of the
weight is defined in [RFC8402]. weight is defined in [RFC8402].
Reserved: SHOULD be set to 0 on transmission and MUST be ignored Reserved: SHOULD be set to 0 on transmission and MUST be ignored
on reception. on reception.
Neighbor ID: The Router ID of the neighbor for which the LAN-Adj- Neighbor ID: The Router ID of the neighbor for which the LAN-Adj-
SID is advertised. SID is advertised.
SID/Index/Label: According to the V and L flags, it contains SID/Index/Label: as described in Section 6.
either:
A 32-bit index defining the offset in the SID/Label space
advertised by this router.
A 24-bit label where the 20 rightmost bits are used for
encoding the label value.
When the P-flag is not set, the Adj-SID MAY be persistent. When When the P-flag is not set, the Adj-SID MAY be persistent. When
the P-flag is set, the Adj-SID MUST be persistent. the P-flag is set, the Adj-SID MUST be persistent.
8. Elements of Procedure 8. Elements of Procedure
8.1. Intra-area Segment routing in OSPFv3 8.1. Intra-area Segment routing in OSPFv3
An OSPFv3 router that supports segment routing MAY advertise Prefix- An OSPFv3 router that supports segment routing MAY advertise Prefix-
SIDs for any prefix to which it is advertising reachability (e.g., a SIDs for any prefix to which it is advertising reachability (e.g., a
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12.1. Normative References 12.1. Normative References
[ALGOREG] "IGP Algorithm Types", <https://www.iana.org/assignments/ [ALGOREG] "IGP Algorithm Types", <https://www.iana.org/assignments/
igp-parameters/igp-parameters.xhtml#igp-algorithm-types>. igp-parameters/igp-parameters.xhtml#igp-algorithm-types>.
[I-D.ietf-ospf-segment-routing-extensions] [I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment- Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-25 (work in progress), April 2018. routing-extensions-26 (work in progress), November 2018.
[I-D.ietf-spring-segment-routing-ldp-interop] [I-D.ietf-spring-segment-routing-ldp-interop]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and
S. Litkowski, "Segment Routing interworking with LDP", S. Litkowski, "Segment Routing interworking with LDP",
draft-ietf-spring-segment-routing-ldp-interop-15 (work in draft-ietf-spring-segment-routing-ldp-interop-15 (work in
progress), September 2018. progress), September 2018.
[I-D.ietf-spring-segment-routing-mpls] [I-D.ietf-spring-segment-routing-mpls]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-15 data plane", draft-ietf-spring-segment-routing-mpls-16
(work in progress), October 2018. (work in progress), November 2018.
[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>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001, DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>. <https://www.rfc-editor.org/info/rfc3031>.
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