draft-ietf-ospf-segment-routing-extensions-06.txt   draft-ietf-ospf-segment-routing-extensions-07.txt 
Open Shortest Path First IGP P. Psenak, Ed. Open Shortest Path First IGP P. Psenak, Ed.
Internet-Draft S. Previdi, Ed. Internet-Draft S. Previdi, Ed.
Intended status: Standards Track C. Filsfils Intended status: Standards Track C. Filsfils
Expires: June 24, 2016 Cisco Systems, Inc. Expires: September 22, 2016 Cisco Systems, Inc.
H. Gredler H. Gredler
Individual Individual
R. Shakir R. Shakir
Jive Communications, Inc. Jive Communications, Inc.
W. Henderickx W. Henderickx
Alcatel-Lucent Alcatel-Lucent
J. Tantsura J. Tantsura
Ericsson Ericsson
December 22, 2015 March 21, 2016
OSPF Extensions for Segment Routing OSPF Extensions for Segment Routing
draft-ietf-ospf-segment-routing-extensions-06 draft-ietf-ospf-segment-routing-extensions-07
Abstract Abstract
Segment Routing (SR) allows for a flexible definition of end-to-end Segment Routing (SR) allows for a flexible definition of end-to-end
paths within IGP topologies by encoding paths as sequences of paths within IGP topologies by encoding paths as sequences of
topological sub-paths, called "segments". These segments are topological sub-paths, called "segments". These segments are
advertised by the link-state routing protocols (IS-IS and OSPF). advertised by the link-state routing protocols (IS-IS and OSPF).
This draft describes the OSPF extensions required for Segment This draft describes the OSPF extensions required for Segment
Routing. Routing.
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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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 June 24, 2016. This Internet-Draft will expire on September 22, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 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
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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. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 3 2. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 3
2.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4 2.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4
3. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4 3. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4
3.1. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . . . 4 3.1. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . . . 4
3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 5 3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6
4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 7 4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 7
5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 9 5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 9
6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 13 6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 13
6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 14 6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 14
6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 15 6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 15
6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 15 6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 15
6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 16 6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 16
6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 17 6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 17
6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 18 6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 18
7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 19 7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 19
7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 19 7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 19
7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 21 7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 21
8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 22 8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 22
8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 22 8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 22
8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 23 8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 23
8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 24 8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 24
8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 24 8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 24
8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 24 8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 25
8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 25 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 25
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 25 9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 25
9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 25 9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 25
9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 25 9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 25
9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 26 9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 26
10. Security Considerations . . . . . . . . . . . . . . . . . . . 26 10. Security Considerations . . . . . . . . . . . . . . . . . . . 26
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
13.1. Normative References . . . . . . . . . . . . . . . . . . 27 13.1. Normative References . . . . . . . . . . . . . . . . . . 27
13.2. Informative References . . . . . . . . . . . . . . . . . 27 13.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
Segment Routing (SR) allows for a flexible definition of end-to-end Segment Routing (SR) allows for a flexible definition of end-to-end
paths within IGP topologies by encoding paths as sequences of paths within IGP topologies by encoding paths as sequences of
topological sub-paths, called "segments". These segments are topological sub-paths, called "segments". These segments are
advertised by the link-state routing protocols (IS-IS and OSPF). advertised by the link-state routing protocols (IS-IS and OSPF).
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Length: variable Length: variable
Algorithm: Single octet identifying the algorithm. The following Algorithm: Single octet identifying the algorithm. The following
values are defined by this document: values are defined by this document:
0: Shortest Path First (SPF) algorithm based on link metric. 0: Shortest Path First (SPF) algorithm based on link metric.
This is the standard shortest path algorithm as computed by the This is the standard shortest path algorithm as computed by the
OSPF protocol. Consistent with the deployed practice for link- OSPF protocol. Consistent with the deployed practice for link-
state protocols, Algorithm 0 permits any node to overwrite the state protocols, Algorithm 0 permits any node to overwrite the
SPF path with a different path based on its local policy. SPF path with a different path based on its local policy. If
the SR-Algorithm Sub-TLV is advertised, Algorithm 0 MUST be
included.
1: Strict Shortest Path First (SPF) algorithm based on link 1: Strict Shortest Path First (SPF) algorithm based on link
metric. The algorithm is identical to Algorithm 0 but metric. The algorithm is identical to Algorithm 0 but
Algorithm 1 requires that all nodes along the path will honor Algorithm 1 requires that all nodes along the path will honor
the SPF routing decision. Local policy at the node claiming the SPF routing decision. Local policy at the node claiming
the support of Algorithm 1 MUST NOT alter the forwarding the support of Algorithm 1 MUST NOT alter the forwarding
decision computed by Algorithm 1. decision computed by Algorithm 1.
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
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assigned to other adjacencies as well). assigned to other adjacencies as well).
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.
MT-ID: Multi-Topology ID (as defined in [RFC4915]. MT-ID: Multi-Topology ID (as defined in [RFC4915].
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 [I-D.ietf-spring-segment-routing]. weight is defined in [I-D.ietf-spring-segment-routing].
Neighbor ID: The Router ID of the neighbor for which the Adj-SID
is advertised.
SID/Index/Label: according to the V and L flags, it contains SID/Index/Label: according to the V and L flags, it contains
either: either:
A 32 bit index defining the offset in the SID/Label space A 32 bit index defining the offset in the SID/Label space
advertised by this router. advertised by this router.
A 24 bit label where the 20 rightmost bits are used for A 24 bit label where the 20 rightmost bits are used for
encoding the label value. encoding the label value.
8. Elements of Procedure 8. Elements of Procedure
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area and find the advertising router associated with the best path area and find the advertising router associated with the best path
to that prefix. to that prefix.
The ABR will then determine if such router advertised a Prefix-SID The ABR will then determine if such router advertised a Prefix-SID
for the prefix and use it when advertising the Prefix-SID to other for the prefix and use it when advertising the Prefix-SID to other
connected areas. connected areas.
If no Prefix-SID was advertised for the prefix in the source area If no Prefix-SID was advertised for the prefix in the source area
by the router that contributes to the best path to the prefix, the by the router that contributes to the best path to the prefix, the
originating ABR will use the Prefix-SID advertised by any other originating ABR will use the Prefix-SID advertised by any other
router (e.g.: a Prefix-SID coming from an SR Mapping Server as router when propagating the Prefix-SID for the prefix to other
defined in [I-D.filsfils-spring-segment-routing-ldp-interop]) when areas.
propagating the Prefix-SID for the prefix to other areas.
When an OSPF ABR advertises Type-3 Summary LSAs from an inter-area When an OSPF ABR advertises Type-3 Summary LSAs from an inter-area
route to all its connected areas it will also originate an Extended route to all its connected areas it will also originate an Extended
Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr]. Prefix Opaque LSA, as described in [I-D.ietf-ospf-prefix-link-attr].
The flooding scope of the Extended Prefix Opaque LSA type will be set The flooding scope of the Extended Prefix Opaque LSA type will be set
to area-scope. The route-type in OSPF Extended Prefix TLV is set to to area-scope. The route-type in OSPF Extended Prefix TLV is set to
inter-area. The Prefix-SID Sub-TLV will be included in this LSA and inter-area. The Prefix-SID Sub-TLV will be included in this LSA and
the Prefix-SID will be set as follows: the Prefix-SID will be set as follows:
The ABR will look at its best path to the prefix in the source The ABR will look at its best path to the prefix in the source
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