draft-ietf-ospf-segment-routing-extensions-16.txt   draft-ietf-ospf-segment-routing-extensions-17.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: November 24, 2017 Cisco Systems, Inc. Expires: December 25, 2017 Cisco Systems, Inc.
H. Gredler H. Gredler
RtBrick Inc. RtBrick Inc.
R. Shakir R. Shakir
Google, Inc. Google, Inc.
W. Henderickx W. Henderickx
Nokia Nokia
J. Tantsura J. Tantsura
Individual Individual
May 23, 2017 June 23, 2017
OSPF Extensions for Segment Routing OSPF Extensions for Segment Routing
draft-ietf-ospf-segment-routing-extensions-16 draft-ietf-ospf-segment-routing-extensions-17
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 OSPF extensions required for Segment This draft describes the OSPF extensions required for Segment
Routing. Routing.
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", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 November 24, 2017. This Internet-Draft will expire on December 25, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
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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 . . . . . . . . . . . . . . . . . . . . 3
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 . . . . . . . . . . . . . . . . . . . 6 3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6
3.3. SR Local Block Sub-TLV . . . . . . . . . . . . . . . . . 8 3.3. SR Local Block TLV . . . . . . . . . . . . . . . . . . . 8
3.4. SRMS Preference Sub-TLV . . . . . . . . . . . . . . . . . 9 3.4. SRMS Preference TLV . . . . . . . . . . . . . . . . . . . 10
4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 10 4. OSPF Extended Prefix Range TLV . . . . . . . . . . . . . . . 11
5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 12 5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 12
6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 16 6. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 16
6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 17 6.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 16
6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 18 6.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 18
6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 18 7. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 19
6.2.2. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 19 7.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 19
6.2.3. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 21 7.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 20
6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 22 7.3. Segment Routing for External Prefixes . . . . . . . . . . 21
7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 23 7.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 21
7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 23 7.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 21
7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 25 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 21
8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 26 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
8.1. Intra-area Segment routing in OSPFv2 . . . . . . . . . . 26 8.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 22
8.2. Inter-area Segment routing in OSPFv2 . . . . . . . . . . 27 8.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 22
8.3. Segment Routing for External Prefixes . . . . . . . . . . 28 8.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 22
8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 29 8.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 22
8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 29 9. Implementation Status . . . . . . . . . . . . . . . . . . . . 23
8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 29 10. Security Considerations . . . . . . . . . . . . . . . . . . . 24
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1. OSPF OSPF Router Information (RI) TLVs Registry . . . . . 29 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25
9.2. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 30 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.3. OSPF Extended Prefix LSA Sub-TLV Registry . . . . . . . . 30 13.1. Normative References . . . . . . . . . . . . . . . . . . 25
9.4. OSPF Extended Link LSA Sub-TLV Registry . . . . . . . . . 30 13.2. Informative References . . . . . . . . . . . . . . . . . 25
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
11. Security Considerations . . . . . . . . . . . . . . . . . . . 32
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
14.1. Normative References . . . . . . . . . . . . . . . . . . 32
14.2. Informative References . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
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
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). Prefix segments link-state routing protocols (IS-IS and OSPF). Prefix segments
represent an ECMP-aware shortest-path to a prefix (or a node), as per represent an ECMP-aware shortest-path to a prefix (or a node), as per
the state of the IGP topology. Adjacency segments represent a hop the state of the IGP topology. Adjacency segments represent a hop
over a specific adjacency between two nodes in the IGP. A prefix over a specific adjacency between two nodes in the IGP. A prefix
skipping to change at page 3, line 44 skipping to change at page 3, line 37
There are additional segment types, e.g., Binding SID defined in There are additional segment types, e.g., Binding SID defined in
[I-D.ietf-spring-segment-routing]. [I-D.ietf-spring-segment-routing].
This draft describes the OSPF extensions required for Segment This draft describes the OSPF extensions required for Segment
Routing. Routing.
Segment Routing architecture is described in Segment Routing architecture is described in
[I-D.ietf-spring-segment-routing]. [I-D.ietf-spring-segment-routing].
Segment Routing use cases are described in Segment Routing use cases are described in [RFC7855].
[I-D.filsfils-spring-segment-routing-use-cases].
2. Segment Routing Identifiers 2. Segment Routing Identifiers
Segment Routing defines various types of Segment Identifiers (SIDs): Segment Routing defines various types of Segment Identifiers (SIDs):
Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID. Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID.
Extended Prefix/Link Opaque LSAs defined in [RFC7684] are used for Extended Prefix/Link Opaque LSAs defined in [RFC7684] are used for
advertisements of the various SID types. advertisements of the various SID types.
2.1. SID/Label Sub-TLV 2.1. SID/Label Sub-TLV
The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined
later in this document. It is used to advertise the SID or label later in this document. It is used to advertise the SID or label
associated with a prefix or adjacency. The SID/Label TLV has associated with a prefix or adjacency. The SID/Label Sub-TLV has
following format: 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label (variable) | | SID/Label (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 4, line 49 skipping to change at page 4, line 41
advertised to other routers in the area. advertised to other routers in the area.
These SR capabilities are advertised in the Router Information Opaque These SR capabilities are advertised in the Router Information Opaque
LSA (defined in [RFC7770]). LSA (defined in [RFC7770]).
3.1. SR-Algorithm TLV 3.1. SR-Algorithm TLV
The SR-Algorithm TLV is a top-level TLV of the Router Information The SR-Algorithm TLV is a top-level TLV of the Router Information
Opaque LSA (defined in [RFC7770]). Opaque LSA (defined in [RFC7770]).
The SR-Algorithm TLV is optional. It MUST only be advertised once in The SR-Algorithm TLV is optional. It SHOULD only be advertised once
the Router Information Opaque LSA. If the SID/Label Range TLV, as in the Router Information Opaque LSA. If the SR-Algorithm TLV is not
defined in Section 3.2, is advertised, then the SR-Algorithm TLV MUST advertised by the node, such node is considered as not being segment
also be advertised. If the SR-Algorithm TLV is not advertised by the routing capable.
node, such node is considered as not being segment routing capable.
An SR Router may use various algorithms when calculating reachability An SR Router may use various algorithms when calculating reachability
to OSPF routers or prefixes in an OSPF area. Examples of these to OSPF routers or prefixes in an OSPF area. Examples of these
algorithms are metric based Shortest Path First (SPF), various algorithms are metric based Shortest Path First (SPF), various
flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a
router to advertise the algorithms currently used by the router to router to advertise the algorithms currently used by the router to
other routers in an OSPF area. The SR-Algorithm TLV has following other routers in an OSPF area. The SR-Algorithm TLV has following
format: format:
0 1 2 3 0 1 2 3
skipping to change at page 5, line 29 skipping to change at page 5, line 21
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm 1 | Algorithm... | Algorithm n | | | Algorithm 1 | Algorithm... | Algorithm n | |
+- -+ +- -+
| | | |
+ + + +
where: where:
Type: TBD, suggested value 8 Type: TBD, suggested value 8
Length: Variable Length: Variable, dependent on number of algorithms advertised.
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. If SPF path with a different path based on its local policy. If
the SR-Algorithm TLV is advertised, Algorithm 0 MUST be the SR-Algorithm TLV is advertised, Algorithm 0 MUST be
skipping to change at page 6, line 14 skipping to change at page 6, line 7
Information LSAs that have different flooding scopes, the SR- Information LSAs that have different flooding scopes, the SR-
Algorithm TLV in the Router Information LSA with the narrowest Algorithm TLV in the Router Information LSA with the narrowest
flooding scope SHOULD be used. If the SR-Algorithm TLV appears in flooding scope SHOULD be used. If the SR-Algorithm TLV appears in
multiple Router Information LSAs that have the same flooding scope, multiple Router Information LSAs that have the same flooding scope,
the SR-Algorithm TLV in the Router Information LSA with the the SR-Algorithm TLV in the Router Information LSA with the
numerically smallest Instance ID SHOULD be used and subsequent numerically smallest Instance ID SHOULD be used and subsequent
instances of the SR-Algorithm TLV SHOULD be ignored. instances of the SR-Algorithm TLV SHOULD 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
SR-Algorithm TLV advertisement, area scope flooding is required. SR-Algorithm TLV advertisement, area-scoped flooding is REQUIRED.
3.2. SID/Label Range TLV 3.2. SID/Label Range TLV
Prefix SIDs MAY be advertised in a form of an index as described in
Section 5. Such index defines the offset in the SID/Label space
advertised by the router. The SID/Label Range TLV is used to
advertise such SID/Label space.
The SID/Label Range TLV is a top-level TLV of the Router Information The SID/Label Range TLV is a top-level TLV of the Router Information
Opaque LSA (defined in [RFC7770]). Opaque LSA (defined in [RFC7770]).
The SID/Label Range TLV MAY appear multiple times and has the The SID/Label Range TLV MAY appear multiple times and has the
following format: 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
skipping to change at page 6, line 40 skipping to change at page 6, line 38
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) | | Sub-TLVs (variable) |
+- -+ +- -+
| | | |
+ + + +
where: where:
Type: TBD, suggested value 9 Type: TBD, suggested value 9
Length: Variable Length: Variable, dependent on Sub-TLVs.
Range Size: 3-octet SID/label range size (i.e., the number of SIDs Range Size: 3-octet SID/label range size (i.e., the number of SIDs
or labels in the range including the first SID/label). It MUST be or labels in the range including the first SID/label). It MUST be
greater than 0. greater than 0.
Initially, the only supported Sub-TLV is the SID/Label TLV as defined Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as
in Section 2.1. The SID/Label advertised in the SID/Label TLV defined in Section 2.1. The SID/Label Sub-TLV MUST be included in
represents the first SID/Label in the advertised range. the SID/Label Range TLV. The SID/Label advertised in the SID/Label
Sub-TLV represents the first SID/Label in the advertised range.
Only a single SID/Label Sub-TLV MAY be advertised in SID/Label Range
TLV. If more then one SID/Label Sub-TLVs are present, the SID/Label
Range TLV MUST be ignored.
Multiple occurrences of the SID/Label Range TLV MAY be advertised, in Multiple occurrences of the SID/Label Range TLV MAY be advertised, in
order to advertise multiple ranges. In such case: order to advertise multiple ranges. In such case:
o The originating router MUST encode each range into a different o The originating router MUST encode each range into a different
SID/Label Range TLV. SID/Label Range TLV.
o The originating router decides the order in which the set of SID/ o The originating router decides the order in which the set of SID/
Label Range TLVs are advertised inside the Router Information Label Range TLVs are advertised inside the Router Information
Opaque LSA. The originating router MUST ensure the order is the Opaque LSA. The originating router MUST ensure the order is the
same after a graceful restart (using checkpointing, non-volatile same after a graceful restart (using checkpointing, non-volatile
storage, or any other mechanism) in order to assure the SID/label storage, or any other mechanism) in order to assure the SID/label
range and SID index correspondence is preserved across graceful range and SID index correspondence is preserved across graceful
restarts. restarts.
o The receiving router MUST adhere to the order in which the ranges o The receiving router MUST adhere to the order in which the ranges
are advertised when calculating a SID/label from a SID index. are advertised when calculating a SID/label from a SID index.
o The originating router MUST NOT advertise overlapping ranges.
o When a router receives multiple overlapping ranges, it MUST
conform to the procedures defined in
[I-D.ietf-spring-conflict-resolution].
The following example illustrates the advertisement of multiple The following example illustrates the advertisement of multiple
ranges: ranges:
The originating router advertises the following ranges: The originating router advertises the following ranges:
Range 1: [100, 199]
Range 2: [1000, 1099] Range 1: Range Size: 100 SID/Label Sub-TLV: 199
Range 3: [500, 599] Range 1: Range Size: 100 SID/Label Sub-TLV: 1000
Range 1: Range Size: 100 SID/Label Sub-TLV: 500
The receiving routers concatenate the ranges and build the Segment The receiving routers concatenate the ranges and build the Segment
Routing Global Block (SRGB) as follows: Routing Global Block (SRGB) as follows:
SRGB = [100, 199] SRGB = [100, 199]
[1000, 1099] [1000, 1099]
[500, 599] [500, 599]
The indexes span multiple ranges: The indexes span multiple ranges:
skipping to change at page 7, line 47 skipping to change at page 8, line 31
... ...
index 99 means label 199 index 99 means label 199
index 100 means label 1000 index 100 means label 1000
index 199 means label 1099 index 199 means label 1099
... ...
index 200 means label 500 index 200 means label 500
... ...
The RI LSA can be advertised at any of the defined flooding scopes The RI LSA can be advertised at any of the defined flooding scopes
(link, area, or autonomous system (AS)). For the purpose of SID/ (link, area, or autonomous system (AS)). For the purpose of SID/
Label Range TLV advertisement, area scope flooding is required. Label Range TLV advertisement, area-scoped flooding is REQUIRED.
3.3. SR Local Block Sub-TLV 3.3. SR Local Block TLV
The SR Local Block (SRLB) Sub-TLV contains the range of labels the The SR Local Block TLV (SRLB TLV) contains the range of labels the
node has reserved for local SIDs. Local SIDs are used, e.g., for node has reserved for local SIDs. SIDs from the SRLB MAY be used for
Adjacency-SIDs, and may also be allocated by components other than Adjacency-SIDs, but also by components other than the OSPF protocol.
the OSPF protocol. As an example, an application or a controller may As an example, an application or a controller may instruct the router
instruct the router to allocate a specific local SID. Therefore, in to allocate a specific local SID. Some controllers or applications
order for such applications or controllers to know what local SIDs may use the control plane to discover the available set of local SIDs
are available on the router, it is required that the router on a particular router. In such cases, the SRLG is advertised in the
advertises its SRLB. The SRLB Sub-TLV is used for that purpose. control plane. The requirement to advertise the SRLB is further
described in [I-D.ietf-spring-segment-routing-mpls]. The SRLB TLV is
used to advertise the SRLB.
The SR Local Block (SRLB) Sub-TLV is a top-level TLV of the Router The SRLB TLV is a top-level TLV of the Router Information Opaque LSA
Information Opaque LSA (defined in [RFC7770]). (defined in [RFC7770]).
The SR Local Block Sub-TLV MAY appear multiple times in the Router The SRLB TLV MAY appear multiple times in the Router Information
Information Opaque LSA and has the following format: Opaque LSA and 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Range Size | Reserved | | Range Size | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) | | Sub-TLVs (variable) |
+- -+ +- -+
| | | |
+ + + +
where: where:
Type: TBD, suggested value 12 Type: TBD, suggested value 12
Length: Variable Length: Variable, dependent on Sub-TLVs.
Range Size: 3-octet SID/label range size (i.e., the number of SIDs Range Size: 3-octet SID/label range size (i.e., the number of SIDs
or labels in the range including the first SID/label). It MUST be or labels in the range including the first SID/label). It MUST be
greater than 0. greater than 0.
Initially, the only supported Sub-TLV is the SID/Label TLV as defined Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as
in Section 2.1. The SID/Label advertised in the SID/Label TLV defined in Section 2.1. The SID/Label Sub-TLV MUST be included in
the SRLB TLV. The SID/Label advertised in the SID/Label Sub-TLV
represents the first SID/Label in the advertised range. represents the first SID/Label in the advertised range.
Only a single SID/Label Sub-TLV MAY be advertised in the SRLB TLV.
If more then one SID/Label Sub-TLVs are present, the SRLB TLV MUST be
ignored.
The originating router MUST NOT advertise overlapping ranges. The originating router MUST NOT advertise overlapping ranges.
Each time a SID from the SRLB is allocated, it SHOULD also be Each time a SID from the SRLB is allocated, it SHOULD also be
reported to all components (e.g., controller or applications) in reported to all components (e.g., controller or applications) in
order for these components to have an up-to-date view of the current order for these components to have an up-to-date view of the current
SRLB allocation. This is required to avoid collisions between SRLB allocation. This is required to avoid collisions between
allocation instructions. allocation instructions.
Within the context of OSPF, the reporting of local SIDs is done Within the context of OSPF, the reporting of local SIDs is done
through OSPF Sub-TLVs such as the Adjacency-SID (Section 7). through OSPF Sub-TLVs such as the Adjacency-SID (Section 6).
However, the reporting of allocated local SIDs may also be done However, the reporting of allocated local SIDs may also be done
through other means and protocols which are outside the scope of this through other means and protocols which are outside the scope of this
document. document.
A router advertising the SRLB TLV may also have other label ranges, A router advertising the SRLB TLV may also have other label ranges,
outside of the SRLB, used for its local allocation purposes which are outside of the SRLB, used for its local allocation purposes which are
NOT advertised in the SRLB. For example, it is possible that an NOT advertised in the SRLB TLV. For example, it is possible that an
Adjacency-SID is allocated using a local label that is not part of Adjacency-SID is allocated using a local label that is not part of
the SRLB. the SRLB.
The RI LSA can be advertised at any of the defined flooding scopes The RI LSA can be advertised at any of the defined flooding scopes
(link, area, or autonomous system (AS)). For the purpose of SR Local (link, area, or autonomous system (AS)). For the purpose of SRLB TLV
Block Sub-TLV TLV advertisement, area scope flooding is required. advertisement, area-scoped flooding is REQUIRED.
3.4. SRMS Preference Sub-TLV 3.4. SRMS Preference TLV
The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used The Segment Routing Mapping Server Preference TLV (SRMS Preference
to advertise a preference associated with the node that acts as an SR TLV) is used to advertise a preference associated with the node that
Mapping Server. SRMS preference is defined in acts as an SR Mapping Server. The role of an SRMS is described in
[I-D.ietf-spring-conflict-resolution]. [I-D.ietf-spring-segment-routing-ldp-interop]. SRMS preference is
defined in [I-D.ietf-spring-conflict-resolution].
The SRMS Preference Sub-TLV is a top-level TLV of the Router The SRMS Preference TLV is a top-level TLV of the Router Information
Information Opaque LSA (defined in [RFC7770]). Opaque LSA (defined in [RFC7770]).
The SRMS Preference Sub-TLV MAY only be advertised once in the Router The SRMS Preference TLV MAY only be advertised once in the Router
Information Opaque LSA and has the following format: Information Opaque LSA and 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference | Reserved | | Preference | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type: TBD, suggested value 13 Type: TBD, suggested value 13
Length: 4 octets Length: 4 octets
Preference: 1 octet. SRMS preference value from 0 to 255. Preference: 1 octet. SRMS preference value from 0 to 255.
When multiple SRMS Preference sub-TLVs are received from a given When multiple SRMS Preference TLVs are received from a given router,
router, the receiver SHOULD use the first occurrence of the sub-TLV the receiver SHOULD use the first occurrence of the TLV in the Router
in the Router Information LSA. If the SRMS Preference sub-TLV Information LSA. If the SRMS Preference TLV appears in multiple
appears in multiple Router Information LSAs that have different Router Information LSAs that have different flooding scopes, the SRMS
flooding scopes, the SRLB sub-TLV in the Router Information LSA with Preference TLV in the Router Information LSA with the narrowest
the narrowest flooding scope SHOULD be used. If the SRMS Preference flooding scope SHOULD be used. If the SRMS Preference TLV appears in
sub-TLV appears in multiple Router Information LSAs that have the multiple Router Information LSAs that have the same flooding scope,
same flooding scope, the SRMS Preference sub-TLV in the Router the SRMS Preference TLV in the Router Information LSA with the
Information LSA with the numerically smallest Instance ID SHOULD be numerically smallest Instance ID SHOULD be used and subsequent
used and subsequent instances of the SRMS Preference sub-TLV SHOULD instances of the SRMS Preference TLV SHOULD be ignored.
be ignored.
The RI LSA can be advertised at any of the defined flooding scopes The RI LSA can be advertised at any of the defined flooding scopes
(link, area, or autonomous system (AS)). For the purpose of the SRMS (link, area, or autonomous system (AS)). For the purpose of the SRMS
Preference Sub-TLV advertisement, AS scope flooding is required. If Preference TLV advertisement, AS-scoped flooding is REQUIRED. This
the SRMS advertisements from the SRMS server are only used inside the is because SRMS servers can be located in a different area then
area to which the SRMS server is attached, area scope flooding may be consumers of the SRMS advertisements. If the SRMS advertisements
used. from the SRMS server are only used inside the SRMS server's area,
area-scoped flooding may be used.
4. OSPF Extended Prefix Range TLV 4. OSPF Extended Prefix Range TLV
In some cases it is useful to advertise attributes for a range of In some cases it is useful to advertise attributes for a range of
prefixes. The Segment Routing Mapping Server, which is described in prefixes. The Segment Routing Mapping Server, which is described in
[I-D.filsfils-spring-segment-routing-ldp-interop], is an example [I-D.ietf-spring-segment-routing-ldp-interop], is an example where we
where we need a single advertisement to advertise SIDs for multiple need a single advertisement to advertise SIDs for multiple prefixes
prefixes from a contiguous address range. from a contiguous address range.
The OSPF Extended Prefix Range TLV, which is a top level TLV of the The OSPF Extended Prefix Range TLV, which is a top level TLV of the
Extended Prefix LSA described in [RFC7684] is defined for this Extended Prefix LSA described in [RFC7684] is defined for this
purpose. purpose.
Multiple OSPF Extended Prefix Range TLVs MAY be advertised in each Multiple OSPF Extended Prefix Range TLVs MAY be advertised in each
OSPF Extended Prefix Opaque LSA, but all prefix ranges included in a OSPF Extended Prefix Opaque LSA, but all prefix ranges included in a
single OSPF Extended Prefix Opaque LSA MUST have the same flooding single OSPF Extended Prefix Opaque LSA MUST have the same flooding
scope. The OSPF Extended Prefix Range TLV has the following format: scope. The OSPF Extended Prefix Range TLV has the following format:
skipping to change at page 11, line 24 skipping to change at page 11, line 49
| Address Prefix (variable) | | Address Prefix (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) | | Sub-TLVs (variable) |
+- -+ +- -+
| | | |
where: where:
Type: TBD, suggested value 2. Type: TBD, suggested value 2.
Length: Variable Length: Variable, dependent on Sub-TLVs.
Prefix length: Length of the prefix Prefix length: Length of prefix in bits.
AF: Address family for the prefix. Currently, the only supported AF: Address family for the prefix. Currently, the only supported
value is 0 for IPv4 unicast. The inclusion of address family in value is 0 for IPv4 unicast. The inclusion of address family in
this TLV allows for future extension. this TLV allows for future extension.
Range size: Represents the number of prefixes that are covered by Range size: Represents the number of prefixes that are covered by
the advertisement. The Range Size MUST NOT exceed the number of the advertisement. The Range Size MUST NOT exceed the number of
prefixes that could be satisfied by the prefix length without prefixes that could be satisfied by the prefix length without
including the IPv4 multicast address range (224.0.0.0/3). including the IPv4 multicast address range (224.0.0.0/3).
skipping to change at page 12, line 16 skipping to change at page 12, line 41
over inter-area advertisements. over inter-area advertisements.
An ABR does not consider inter-area Prefix Range An ABR does not consider inter-area Prefix Range
advertisements coming from non-backbone areas. advertisements coming from non-backbone areas.
An ABR only propagates an inter-area Prefix Range An ABR only propagates an inter-area Prefix Range
advertisement from the backbone area to connected non- advertisement from the backbone area to connected non-
backbone areas if the advertisement is considered to be the backbone areas if the advertisement is considered to be the
best one. best one.
Address Prefix: The prefix, encoded as 32-bit value, padded with Address Prefix: For the address family IPv4 unicast, the prefix
zero bits as necessary. The prefix represents the first prefix in itself is encoded as a 32-bit value. The default route is
the prefix range. represented by a prefix of length 0. Prefix encoding for other
address families is beyond the scope of this specification.
5. Prefix SID Sub-TLV 5. Prefix SID Sub-TLV
The Prefix SID Sub-TLV is a Sub-TLV of the OSPF Extended Prefix TLV The Prefix SID Sub-TLV is a Sub-TLV of the OSPF Extended Prefix TLV
described in [RFC7684] and the OSPF Extended Prefix Range TLV described in [RFC7684] and the OSPF Extended Prefix Range TLV
described in Section 4. It MAY appear more than once in the parent described in Section 4. It MAY appear more than once in the parent
TLV and has the following format: TLV and 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
skipping to change at page 12, line 41 skipping to change at page 13, line 19
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved | MT-ID | Algorithm | | Flags | Reserved | MT-ID | Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Index/Label (variable) | | SID/Index/Label (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type: TBD, suggested value 2. Type: TBD, suggested value 2.
Length: Variable Length: 7 or 8 octets, dependent on the V-flag
Flags: Single octet field. The following flags are defined: Flags: Single octet field. The following flags are defined:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
| |NP|M |E |V |L | | | | |NP|M |E |V |L | | |
+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+
where: where:
NP-Flag: No-PHP flag. If set, then the penultimate hop MUST NP-Flag: No-PHP flag. If set, then the penultimate hop MUST
NOT pop the Prefix-SID before delivering packets to the node NOT pop the Prefix-SID before delivering packets to the node
that advertised the Prefix-SID. that advertised the Prefix-SID.
M-Flag: Mapping Server Flag. If set, the SID was advertised by M-Flag: Mapping Server Flag. If set, the SID was advertised by
a Segment Routing Mapping Server as described in a Segment Routing Mapping Server as described in
[I-D.filsfils-spring-segment-routing-ldp-interop]. [I-D.ietf-spring-segment-routing-ldp-interop].
E-Flag: Explicit-Null Flag. If set, any upstream neighbor of E-Flag: Explicit-Null Flag. If set, any upstream neighbor of
the Prefix-SID originator MUST replace the Prefix-SID with the the Prefix-SID originator MUST replace the Prefix-SID with the
Explicit-NULL label (0 for IPv4) before forwarding the packet. Explicit-NULL label (0 for IPv4) before forwarding the packet.
V-Flag: Value/Index Flag. If set, then the Prefix-SID carries V-Flag: Value/Index Flag. If set, then the Prefix-SID carries
an absolute value. If not set, then the Prefix-SID carries an an absolute value. If not set, then the Prefix-SID carries an
index. index.
L-Flag: Local/Global Flag. If set, then the value/index L-Flag: Local/Global Flag. If set, then the value/index
skipping to change at page 13, line 36 skipping to change at page 14, line 15
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]).
Algorithm: Single octet identifying the algorithm the Prefix-SID Algorithm: Single octet identifying the algorithm the Prefix-SID
is associated with as defined in Section 3.1. is associated with as defined in Section 3.1.
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 (Section 3.1) MUST ignore the Prefix-SID sub- SR-Algorithm Sub-TLV (Section 3.1) MUST ignore the Prefix-SID Sub-
TLV. TLV.
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.
If multiple Prefix-SIDs are advertised for the same prefix, the If an OSPF router advertises multiple Prefix-SIDs for the same
receiving router MUST use the first encoded SID and MAY use prefix, topology and algorithm, all of them MUST be ignored.
subsequent SIDs.
When propagating Prefix-SIDs between areas, if multiple prefix-SIDs
are advertised for a prefix, an implementation SHOULD preserve the
original order when advertising prefix-SIDs to other areas. This
allows implementations that only support a single Prefix-SID to have
a consistent view across areas.
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 the E and P flags advertised by the next-hop router take into account, as described below, the E, NP and M flags
if that router advertised the SID for the prefix. This MUST be done advertised by the next-hop router if that router advertised the SID
regardless of whether the next-hop router contributes to the best for the prefix. This MUST be done regardless of whether the next-hop
path to the prefix. router contributes to the best path to the prefix.
The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for
Prefix-SIDs allocated to inter-area prefixes that are originated by Prefix-SIDs allocated to inter-area prefixes that are originated by
the ABR based on intra-area or inter-area reachability between areas, the ABR based on intra-area or inter-area reachability between areas,
unless the advertised prefix is directly attached to the ABR. unless the advertised prefix is directly attached to the ABR.
The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for
Prefix-SIDs allocated to redistributed prefixes, unless the Prefix-SIDs allocated to redistributed prefixes, unless the
redistributed prefix is directly attached to the ASBR. redistributed prefix is directly attached to the ASBR.
If the NP-Flag is not set, then any upstream neighbor of the Prefix- If the NP-Flag is not set, then any upstream neighbor of the Prefix-
SID originator MUST pop the Prefix-SID. This is equivalent to the SID originator MUST pop the Prefix-SID. This is equivalent to the
penultimate hop popping mechanism used in the MPLS dataplane. In penultimate hop popping mechanism used in the MPLS dataplane. If the
such case, MPLS EXP bits of the Prefix-SID are not preserved for the NP-flag is not set, then the received E-flag is ignored.
final destination (the Prefix-SID being removed). If the NP-flag is
not set then the received E-flag is ignored.
If the NP-flag is set then: If the NP-flag is set then:
If the E-flag is not set, then any upstream neighbor of the If the E-flag is not set, then any upstream neighbor of the
Prefix-SID originator MUST keep the Prefix-SID on top of the Prefix-SID originator MUST keep the Prefix-SID on top of the
stack. This is useful when the originator of the Prefix-SID must stack. This is useful when the originator of the Prefix-SID must
stitch the incoming packet into a continuing MPLS LSP to the final stitch the incoming packet into a continuing MPLS LSP to the final
destination. This could occur at an Area Border Router (prefix destination. This could occur at an Area Border Router (prefix
propagation from one area to another) or at an AS Boundary Router propagation from one area to another) or at an AS Boundary Router
(prefix propagation from one domain to another). (prefix propagation from one domain to another).
skipping to change at page 15, line 25 skipping to change at page 15, line 43
the Extended Prefix TLV with the A-flag set for this prefix as the Extended Prefix TLV with the A-flag set for this prefix as
described in section 2.1 of [RFC7684]. described in section 2.1 of [RFC7684].
The Prefix is external type and downstream neighbor is an ASBR, The Prefix is external type and downstream neighbor is an ASBR,
which is advertising prefix reachability and is also generating which is advertising prefix reachability and is also generating
the Extended Prefix TLV with the A-flag set for this prefix as the Extended Prefix TLV with the A-flag set for this prefix as
described in section 2.1 of [RFC7684]. described in section 2.1 of [RFC7684].
When a Prefix-SID is advertised in an Extended Prefix Range TLV, then When a Prefix-SID is advertised in an Extended Prefix Range TLV, then
the value advertised in the Prefix SID Sub-TLV is interpreted as a the value advertised in the Prefix SID Sub-TLV is interpreted as a
starting SID value. starting SID/Label value.
Example 1: If the following router addresses (loopback addresses) Example 1: If the following router addresses (loopback addresses)
need to be mapped into the corresponding Prefix SID indexes: need to be mapped into the corresponding Prefix SID indexes:
Router-A: 192.0.2.1/32, Prefix-SID: Index 1 Router-A: 192.0.2.1/32, Prefix-SID: Index 1
Router-B: 192.0.2.2/32, Prefix-SID: Index 2 Router-B: 192.0.2.2/32, Prefix-SID: Index 2
Router-C: 192.0.2.3/32, Prefix-SID: Index 3 Router-C: 192.0.2.3/32, Prefix-SID: Index 3
Router-D: 192.0.2.4/32, Prefix-SID: Index 4 Router-D: 192.0.2.4/32, Prefix-SID: Index 4
then the Prefix field in the Extended Prefix Range TLV would be set then the Prefix field in the Extended Prefix Range TLV would be set
skipping to change at page 16, line 9 skipping to change at page 16, line 25
192.0.2.8/30, Prefix-SID: Index 53 192.0.2.8/30, Prefix-SID: Index 53
192.0.2.12/30, Prefix-SID: Index 54 192.0.2.12/30, Prefix-SID: Index 54
192.0.2.16/30, Prefix-SID: Index 55 192.0.2.16/30, Prefix-SID: Index 55
192.0.2.20/30, Prefix-SID: Index 56 192.0.2.20/30, Prefix-SID: Index 56
192.0.2.24/30, Prefix-SID: Index 57 192.0.2.24/30, Prefix-SID: Index 57
then the Prefix field in the Extended Prefix Range TLV would be set then the Prefix field in the Extended Prefix Range TLV would be set
to 192.0.2.0, Prefix Length would be set to 30, Range Size would be to 192.0.2.0, Prefix Length would be set to 30, Range Size would be
7, and the Index value in the Prefix-SID Sub-TLV would be set to 51. 7, and the Index value in the Prefix-SID Sub-TLV would be set to 51.
6. SID/Label Binding Sub-TLV 6. Adjacency Segment Identifier (Adj-SID)
The SID/Label Binding Sub-TLV is used to advertise a SID/Label
mapping for a path to the prefix.
The SID/Label Binding Sub-TLV MAY be originated by any router in an
OSPF domain. The router may advertise a SID/Label binding to a FEC
along with at least a single 'nexthop style' anchor. The protocol
supports more than one 'nexthop style' anchor to be attached to a
SID/Label binding, which results in a simple path description
language. Analogous to RSVP, the terminology for this is called an
'Explicit Route Object' (ERO). Since ERO-style path notation allows
anchoring SID/label bindings to both link and node IP addresses, any
Label Switched Path (LSP) can be described. Additionally, SID/Label
Bindings from external protocols can be easily re-advertised.
The SID/Label Binding Sub-TLV may be used for advertising SID/Label
Bindings and their associated Primary and Backup paths. In a single
TLV, a primary ERO Path, backup ERO Path, or both can be advertised.
If a router wants to advertise multiple parallel paths, then it can
generate several TLVs for the same Prefix/FEC. Each occurrence of a
Binding TLV for a given FEC Prefix will add a new path.
The SID/Label Binding Sub-TLV is a Sub-TLV of the OSPF Extended
Prefix TLV described in [RFC7684] and the OSPF Extended Prefix Range
TLV described in Section 4. Multiple SID/Label Binding TLVs can be
present in their parent TLV. The SID/Label Binding Sub-TLV has
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 | Reserved | MT-ID | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
+- -+
| |
where:
Type: TBD, suggested value 3
Length: Variable
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|M| |
+-+-+-+-+-+-+-+-+
where:
M-bit - When the bit is set, the binding represents a mirroring
context as defined in
[I-D.minto-rsvp-lsp-egress-fast-protection].
Other bits: Reserved. These MUST be zero when sent and are
ignored when received.
MT-ID: Multi-Topology ID (as defined in [RFC4915]).
Weight: 8 bits of weight used for load-balancing purposes. The
use of the weight is defined in [I-D.ietf-spring-segment-routing].
The SID/Label Binding Sub-TLV supports the following Sub-TLVs:
SID/Label Sub-TLV as described in Section 2.1. This Sub-TLV MUST
appear in the SID/Label Binding Sub-TLV and it SHOULD only appear
once. If the SID/Label Sub-TLV is not included in the SID/Label
Binding Sub-TLV, the SID/Label Binding Sub-TLV MUST be ignored.
If the SID/Label Sub-TLV appears in the SID/Label Binding Sub-TLV
more than once, instances other than the first SHOULD be ignored
and the condition SHOULD be logged for possible action by the
network operator.
ERO Metric Sub-TLV as defined in Section 6.1.
ERO Sub-TLVs as defined in Section 6.2.
6.1. ERO Metric Sub-TLV
The ERO Metric Sub-TLV is a Sub-TLV of the SID/Label Binding TLV.
The ERO Metric Sub-TLV advertises the cost of an ERO path. It is
used to compare the cost of a given source/destination path. ERO
Metric Sub-TLV is an option sub-TLV. The cost of the ERO Metric Sub-
TLV SHOULD be set to the cumulative IGP or TE path cost of the
advertised ERO. Since manipulation of the Metric field may attract
or repel traffic to and from the advertised segment, it MAY be
manually overridden.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ERO Metric Sub-TLV format
where:
Type: TBD, suggested value 8
Length: Always 4
Metric: A 4-octet metric representing the aggregate IGP or TE path
cost.
6.2. ERO Sub-TLVs
All ERO information represents an ordered set which describes the
segments of a path. The first ERO Sub-TLV describes the first
segment of a path. Similarly, the last ERO Sub-TLV describes the
segment closest to the egress point. If a router extends or stitches
a path, it MUST prepend the new segment's path information to the ERO
list. This applies equally to advertised backup EROs.
All ERO sub-TLVs are sub-TLVs of the SID/Label Binding TLV.
6.2.1. IPv4 ERO Sub-TLV
The IPv4 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV.
The IPv4 ERO Sub-TLV describes a path segment using IPv4 Address
style encoding. Its semantics have been borrowed from [RFC3209].
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 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 ERO Sub-TLV format
where:
Type: TBD, suggested value 4
Length: 8 octets
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L| |
+-+-+-+-+-+-+-+-+
where:
L-bit - If the L-bit is set, then the segment path is
designated as 'loose'. Otherwise, the segment path is
designated as 'strict'. The terms 'loose' and 'strict' are
defined for RSVP subobjects in [RFC3209].
Other bits: Reserved. These MUST be zero when sent and are
ignored when received.
IPv4 Address - The address of the explicit route hop.
6.2.2. Unnumbered Interface ID ERO Sub-TLV
The Unnumbered Interface ID ERO Sub-TLV is a Sub-TLV of the SID/Label
Binding Sub-TLV.
The appearance and semantics of the 'Unnumbered Interface ID' have
been borrowed from [RFC3477].
The Unnumbered Interface-ID ERO Sub-TLV describes a path segment that
includes an unnumbered interface. Unnumbered interfaces are
referenced using the interface index. Interface indices are assigned
local to the router and therefore are not unique within a domain.
All elements in an ERO path need to be unique within a domain and
hence need to be disambiguated using a domain-unique Router-ID.
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 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Unnumbered Interface ID ERO Sub-TLV format
Type: TBD, suggested value 5
Length: 12 octets
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L| |
+-+-+-+-+-+-+-+-+
where:
L-bit - If the L-bit is set, then the segment path is
designated as 'loose'. Otherwise, the segment path is
designated as 'strict'. The terms 'loose' and 'strict' are
defined for RSVP subobjects in [RFC3209]
Other bits: Reserved. These MUST be zero when sent and are
ignored when received.
Router ID: Router ID of the next-hop.
Interface ID: The identifier assigned to the link by the router
specified by the Router ID.
6.2.3. IPv4 Backup ERO Sub-TLV
IPv4 Prefix Backup ERO Sub-TLV is a Sub-TLV of the SID/Label Binding
Sub-TLV.
The IPv4 Backup ERO Sub-TLV describes a path segment using IPv4
Address style of encoding. Its semantics have been borrowed from
[RFC3209].
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 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 Backup ERO Sub-TLV format
where:
Type: TBD, suggested value 6
Length: 8 octets
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L| |
+-+-+-+-+-+-+-+-+
where:
L-bit - If the L-bit is set, then the segment path is
designated as 'loose'. Otherwise, the segment path is
designated as 'strict'. The terms 'loose' and 'strict' are
defined for RSVP subobjects in [RFC3209]
Other bits: Reserved. These MUST be zero when sent and are
ignored when received.
IPv4 Address - The address of the explicit route hop.
6.2.4. Unnumbered Interface ID Backup ERO Sub-TLV
The Unnumbered Interface ID Backup ERO Sub-TLV is a Sub-TLV of the
SID/Label Binding Sub-TLV.
The appearance and semantics of the 'Unnumbered Interface ID' have
been borrowed from [RFC3477].
The Unnumbered Interface-ID Backup ERO Sub-TLV describes a path
segment that includes an unnumbered interface. Unnumbered interfaces
are referenced using the interface index. Interface indices are
assigned local to the router and are therefore not unique within a
domain. All elements in an ERO path need to be unique within a
domain and hence need to be disambiguated with specification of the
domain-unique Router-ID.
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 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Unnumbered Interface ID Backup ERO Sub-TLV format
where:
Type: TBD, suggested value 7
Length: 12 octets
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L| |
+-+-+-+-+-+-+-+-+
where:
L-bit - If the L-bit is set, then the segment path is
designated as 'loose'. Otherwise, the segment path is
designated as 'strict'.
Other bits: Reserved. These MUST be zero when sent and are
ignored when received.
Router ID: Router ID of the next-hop.
Interface ID: The identifier assigned to the link by the router
specified by the Router ID.
7. Adjacency Segment Identifier (Adj-SID)
An Adjacency Segment Identifier (Adj-SID) represents a router An Adjacency Segment Identifier (Adj-SID) represents a router
adjacency in Segment Routing. adjacency in Segment Routing.
7.1. Adj-SID Sub-TLV 6.1. Adj-SID Sub-TLV
Adj-SID is an optional Sub-TLV of the Extended Link TLV defined in Adj-SID is an optional Sub-TLV of the Extended Link TLV defined in
[RFC7684]. It MAY appear multiple times in the Extended Link TLV. [RFC7684]. It MAY appear multiple times in the Extended Link TLV.
Examples where more than one Adj-SID may be used per neighbor are The Adj-SID Sub-TLV has the following format:
described in section 4 of
[I-D.filsfils-spring-segment-routing-use-cases]. The Adj-SID Sub-TLV
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved | MT-ID | Weight | | Flags | Reserved | MT-ID | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) | | SID/Label/Index (variable) |
+---------------------------------------------------------------+ +---------------------------------------------------------------+
where: where:
Type: TBD, suggested value 2. Type: TBD, suggested value 2.
Length: Variable. Length: 7 or 8 octets, dependent on the V flag.
Flags: Single octet field containing the following flags: Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|B|V|L|G|P| | |B|V|L|G|P| |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
where: where:
skipping to change at page 25, line 4 skipping to change at page 18, line 9
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.
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 section protection by an FRR mechanism (IP or MPLS) as described in section
3.5 of [I-D.ietf-spring-segment-routing]. 3.5 of [I-D.ietf-spring-segment-routing].
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
adjacencies adjacencies
When the P-flag is not set, the Adj-SID MAY be persistent. When the 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. P-flag is set, the Adj-SID MUST be persistent.
7.2. LAN Adj-SID Sub-TLV 6.2. LAN Adj-SID Sub-TLV
LAN Adj-SID is an optional Sub-TLV of the Extended Link TLV defined LAN Adj-SID is an optional Sub-TLV of the Extended Link TLV defined
in [RFC7684]. It MAY appear multiple times in the Extended-Link TLV. in [RFC7684]. It MAY appear multiple times in the Extended-Link TLV.
It is used to advertise a SID/Label for an adjacency to a non-DR It is used to advertise a SID/Label for an adjacency to a non-DR
router on a broadcast, NBMA, or hybrid [RFC6845] network. router on a broadcast, NBMA, or hybrid [RFC6845] network.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
skipping to change at page 25, line 33 skipping to change at page 18, line 39
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor ID | | Neighbor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) | | SID/Label/Index (variable) |
+---------------------------------------------------------------+ +---------------------------------------------------------------+
where: where:
Type: TBD, suggested value 3. Type: TBD, suggested value 3.
Length: Variable. Length: 11 or 12 octets, dependent on V-flag.
Flags: Single octet field containing the following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|B|V|L|G|P| |
+-+-+-+-+-+-+-+-+
where:
B-Flag: Backup-flag. If set, the LAN-Adj-SID refers to an
adjacency that is eligible for protection (e.g.: using IPFRR or
MPLS-FRR) as described in section 3.5 of
[I-D.ietf-spring-segment-routing].
The V-Flag: Value/Index Flag. If set, then the Prefix-SID
carries an absolute value. If not set, then the Prefix-SID
carries an index.
The L-Flag: Local/Global Flag. If set, then the value/index
carried by the Prefix-SID has local significance. If not set,
then the value/index carried by this Sub-TLV has global
significance.
The G-Flag: Group Flag. When set, the G-Flag indicates that
the LAN-Adj-SID refers to a group of adjacencies (and therefore
MAY be assigned to other adjacencies as well).
P-Flag. Persistent flag. When set, the P-Flag indicates that
the Adj-SID is persistently allocated, i.e., the Adj-SID value
remains consistent across router restart and/or interface flap.
Other bits: Reserved. These MUST be zero when sent and are Flags: same as in Section 6.1
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 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: According to the V and L flags, it contains
skipping to change at page 26, line 41 skipping to change at page 19, line 17
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.
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 7. Elements of Procedure
8.1. Intra-area Segment routing in OSPFv2 7.1. Intra-area Segment routing in OSPFv2
An OSPFv2 router that supports segment routing MAY advertise Prefix- An OSPFv2 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
loopback IP address as described in Section 5). loopback IP address as described in Section 5).
If multiple routers advertise a Prefix-SID for the same prefix, then
the Prefix-SID MUST be the same. This is required in order to allow
traffic load-balancing when multiple equal cost paths to the
destination exist in the OSPFv2 routing domain.
A Prefix-SID can also be advertised by the SR Mapping Servers (as A Prefix-SID can also be advertised by the SR Mapping Servers (as
described in [I-D.filsfils-spring-segment-routing-ldp-interop]). A described in [I-D.ietf-spring-segment-routing-ldp-interop]). A
Mapping Server advertises Prefix-SIDs for remote prefixes that exist Mapping Server advertises Prefix-SIDs for remote prefixes that exist
in the OSPFv2 routing domain. Multiple Mapping Servers can advertise in the OSPFv2 routing domain. Multiple Mapping Servers can advertise
Prefix-SIDs for the same prefix, in which case the same Prefix-SID Prefix-SIDs for the same prefix, in which case the same Prefix-SID
MUST be advertised by all of them. The flooding scope of the OSPF MUST be advertised by all of them. The flooding scope of the OSPF
Extended Prefix Opaque LSA that is generated by the SR Mapping Server Extended Prefix Opaque LSA that is generated by the SR Mapping Server
could be either area scoped or AS scoped and is determined based on could be either area-scoped or AS-scoped and is determined based on
the configuration of the SR Mapping Server. the configuration of the SR Mapping Server.
An SR Mapping Server MUST use the OSPF Extended Prefix Range TLV when An SR Mapping Server MUST use the OSPF Extended Prefix Range TLV when
advertising SIDs for prefixes. Prefixes of different route-types can advertising SIDs for prefixes. Prefixes of different route-types can
be combined in a single OSPF Extended Prefix Range TLV advertised by be combined in a single OSPF Extended Prefix Range TLV advertised by
an SR Mapping Server. an SR Mapping Server. Because the OSPF Extended Prefix Range TLV
doesn't include a Route-Type field, as in the OSPF Extended Prefix
TLV, it is possible to include adjacent prefixes from different
Route-Types in the OSPF Extended Prefix Range TLV.
Area-scoped OSPF Extended Prefix Range TLV are propagated between Area-scoped OSPF Extended Prefix Range TLVs are propagated between
areas. Similar to propagation of prefixes between areas, an ABR only areas. Similar to propagation of prefixes between areas, an ABR only
propagates the OSPF Extended Prefix Range TLV that it considers to be propagates the OSPF Extended Prefix Range TLV that it considers to be
the best from the set it received. The rules used to pick the best the best from the set it received. The rules used to pick the best
OSPF Extended Prefix Range TLV are described in Section 4. OSPF Extended Prefix Range TLV are described in Section 4.
When propagating an OSPF Extended Prefix Range TLV between areas, When propagating an OSPF Extended Prefix Range TLV between areas,
ABRs MUST set the IA-Flag, that is used to prevent redundant flooding ABRs MUST set the IA-Flag, that is used to prevent redundant flooding
of the OSPF Extended Prefix Range TLV between areas as described in of the OSPF Extended Prefix Range TLV between areas as described in
Section 4. Section 4.
8.2. Inter-area Segment routing in OSPFv2 7.2. Inter-area Segment routing in OSPFv2
In order to support SR in a multi-area environment, OSPFv2 must In order to support SR in a multi-area environment, OSPFv2 must
propagate Prefix-SID information between areas. The following propagate Prefix-SID information between areas. The following
procedure is used to propagate Prefix SIDs between areas. procedure is used to propagate Prefix SIDs between areas.
When an OSPF ABR advertises a Type-3 Summary LSA from an intra-area When an OSPF ABR advertises a Type-3 Summary LSA from an intra-area
prefix to all its connected areas, it will also originate an Extended prefix to all its connected areas, it will also originate an Extended
Prefix Opaque LSA, as described in [RFC7684]. The flooding scope of Prefix Opaque LSA, as described in [RFC7684]. The flooding scope of
the Extended Prefix Opaque LSA type will be set to area-scope. The the Extended Prefix Opaque LSA type will be set to area-local scope.
route-type in the OSPF Extended Prefix TLV is set to inter-area. The The route-type in the OSPF Extended Prefix TLV is set to inter-area.
Prefix-SID Sub-TLV will be included in this LSA and the Prefix-SID The Prefix-SID Sub-TLV will be included in this LSA and the Prefix-
value will be set as follows: SID value 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
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 when propagating the Prefix-SID for the prefix to other router when propagating the Prefix-SID for the prefix to other
areas. 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 [RFC7684]. The flooding scope of Prefix Opaque LSA, as described in [RFC7684]. The flooding scope of
the Extended Prefix Opaque LSA type will be set to area-scope. The the Extended Prefix Opaque LSA type will be set to area-local scope.
route-type in OSPF Extended Prefix TLV is set to inter-area. The 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 the Prefix-SID Prefix-SID Sub-TLV will be included in this LSA and the Prefix-SID
will be set as follows: will be set as follows:
The ABR will look at its best path to the prefix in the backbone The ABR will look at its best path to the prefix in the backbone
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 backbone If no Prefix-SID was advertised for the prefix in the backbone
area by the ABR that contributes to the best path to the prefix, area by the ABR that contributes to the best path to the prefix,
the originating ABR will use the Prefix-SID advertised by any the originating ABR will use the Prefix-SID advertised by any
other router when propagating the Prefix-SID for the prefix to other router when propagating the Prefix-SID for the prefix to
other areas. other areas.
8.3. Segment Routing for External Prefixes 7.3. Segment Routing for External Prefixes
Type-5 LSAs are flooded domain wide. When an ASBR, which supports Type-5 LSAs are flooded domain wide. When an ASBR, which supports
SR, generates Type-5 LSAs, it should also originate Extended Prefix SR, generates Type-5 LSAs, it should also originate Extended Prefix
Opaque LSAs, as described in [RFC7684]. The flooding scope of the Opaque LSAs, as described in [RFC7684]. The flooding scope of the
Extended Prefix Opaque LSA type is set to AS-scope. The route-type Extended Prefix Opaque LSA type is set to AS-wide scope. The route-
in the OSPF Extended Prefix TLV is set to external. The Prefix-SID type in the OSPF Extended Prefix TLV is set to external. The Prefix-
Sub-TLV is included in this LSA and the Prefix-SID value will be set SID Sub-TLV is included in this LSA and the Prefix-SID value will be
to the SID that has been reserved for that prefix. set to the SID that has been reserved for that prefix.
When an NSSA ABR translates Type-7 LSAs into Type-5 LSAs, it should When an NSSA ABR translates Type-7 LSAs into Type-5 LSAs, it should
also advertise the Prefix-SID for the prefix. The NSSA ABR also advertise the Prefix-SID for the prefix. The NSSA ABR
determines its best path to the prefix advertised in the translated determines its best path to the prefix advertised in the translated
Type-7 LSA and finds the advertising router associated with that Type-7 LSA and finds the advertising router associated with that
path. If the advertising router has advertised a Prefix-SID for the path. If the advertising router has advertised a Prefix-SID for the
prefix, then the NSSA ABR uses it when advertising the Prefix-SID for prefix, then the NSSA ABR uses it when advertising the Prefix-SID for
the Type-5 prefix. Otherwise, the Prefix-SID advertised by any other the Type-5 prefix. Otherwise, the Prefix-SID advertised by any other
router will be used. router will be used.
8.4. Advertisement of Adj-SID 7.4. Advertisement of Adj-SID
The Adjacency Segment Routing Identifier (Adj-SID) is advertised The Adjacency Segment Routing Identifier (Adj-SID) is advertised
using the Adj-SID Sub-TLV as described in Section 7. using the Adj-SID Sub-TLV as described in Section 6.
8.4.1. Advertisement of Adj-SID on Point-to-Point Links 7.4.1. Advertisement of Adj-SID on Point-to-Point Links
An Adj-SID MAY be advertised for any adjacency on a P2P link that is An Adj-SID MAY be advertised for any adjacency on a P2P link that is
in neighbor state 2-Way or higher. If the adjacency on a P2P link in neighbor state 2-Way or higher. If the adjacency on a P2P link
transitions from the FULL state, then the Adj-SID for that adjacency transitions from the FULL state, then the Adj-SID for that adjacency
MAY be removed from the area. If the adjacency transitions to a MAY be removed from the area. If the adjacency transitions to a
state lower then 2-Way, then the Adj-SID advertisement MUST be state lower then 2-Way, then the Adj-SID advertisement MUST be
withdrawn from the area. withdrawn from the area.
8.4.2. Adjacency SID on Broadcast or NBMA Interfaces 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces
Broadcast, NBMA, or hybrid [RFC6845] networks in OSPF are represented Broadcast, NBMA, or hybrid [RFC6845] networks in OSPF are represented
by a star topology where the Designated Router (DR) is the central by a star topology where the Designated Router (DR) is the central
point to which all other routers on the broadcast, NBMA, or hybrid point to which all other routers on the broadcast, NBMA, or hybrid
network connect. As a result, routers on the broadcast, NBMA, or network connect. As a result, routers on the broadcast, NBMA, or
hybrid network advertise only their adjacency to the DR. Routers hybrid network advertise only their adjacency to the DR. Routers
that do not act as DR do not form or advertise adjacencies with each that do not act as DR do not form or advertise adjacencies with each
other. They do, however, maintain 2-Way adjacency state with each other. They do, however, maintain 2-Way adjacency state with each
other and are directly reachable. other and are directly reachable.
When Segment Routing is used, each router on the broadcast, NBMA, or When Segment Routing is used, each router on the broadcast, NBMA, or
hybrid network MAY advertise the Adj-SID for its adjacency to the DR hybrid network MAY advertise the Adj-SID for its adjacency to the DR
using the Adj-SID Sub-TLV as described in Section 7.1. using the Adj-SID Sub-TLV as described in Section 6.1.
SR capable routers MAY also advertise a LAN-Adj-SID for other SR capable routers MAY also advertise a LAN-Adj-SID for other
neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid
network using the LAN-ADJ-SID Sub-TLV as described in Section 7.2. network using the LAN-ADJ-SID Sub-TLV as described in Section 6.2.
9. IANA Considerations 8. IANA Considerations
This specification updates several existing OSPF registries. This specification updates several existing OSPF registries.
9.1. OSPF OSPF Router Information (RI) TLVs Registry 8.1. OSPF OSPF Router Information (RI) TLVs Registry
o 8 (IANA Preallocated) - SR-Algorithm TLV o 8 (IANA Preallocated) - SR-Algorithm TLV
o 9 (IANA Preallocated) - SID/Label Range TLV o 9 (IANA Preallocated) - SID/Label Range TLV
o 12 - SR Local Block Sub-TLV o 12 - SR Local Block TLV
o 13 - SRMS Preference Sub-TLV o 13 - SRMS Preference TLV
9.2. OSPF Extended Prefix LSA TLV Registry 8.2. OSPF Extended Prefix LSA TLV Registry
Following values are allocated: Following values are allocated:
o 2 - OSPF Extended Prefix Range TLV o 2 - OSPF Extended Prefix Range TLV
9.3. OSPF Extended Prefix LSA Sub-TLV Registry 8.3. OSPF Extended Prefix LSA Sub-TLV Registry
Following values are allocated: Following values are allocated:
o 1 - SID/Label Sub-TLV o 1 - SID/Label Sub-TLV
o 2 - Prefix SID Sub-TLV o 2 - Prefix SID Sub-TLV
o 3 - SID/Label Binding Sub-TLV 8.4. OSPF Extended Link LSA Sub-TLV Registry
o 4 - IPv4 ERO Sub-TLV
o 5 - Unnumbered Interface ID ERO Sub-TLV
o 6 - IPv4 Backup ERO Sub-TLV
o 7 - Unnumbered Interface ID Backup ERO Sub-TLV
o 8 - ERO Metric Sub-TLV
9.4. OSPF Extended Link LSA Sub-TLV Registry
Following initial values are allocated: Following initial values are allocated:
o 1 - SID/Label Sub-TLV o 1 - SID/Label Sub-TLV
o 2 - Adj-SID Sub-TLV o 2 - Adj-SID Sub-TLV
o 3 - LAN Adj-SID/Label Sub-TLV o 3 - LAN Adj-SID/Label Sub-TLV
10. Implementation Status 9. Implementation Status
An implementation survey with seven questions related to the An implementation survey with seven questions related to the
implementer's support of OSPFv2 Segment Routing was sent to the OSPF implementer's support of OSPFv2 Segment Routing was sent to the OSPF
WG list and several known implementers. This section contains WG list and several known implementers. This section contains
responses from three implementers who completed the survey. No responses from three implementers who completed the survey. No
external means were used to verify the accuracy of the information external means were used to verify the accuracy of the information
submitted by the respondents. The respondents are considered experts submitted by the respondents. The respondents are considered experts
on the products they reported on. Additionally, responses were on the products they reported on. Additionally, responses were
omitted from implementers who indicated that they have not omitted from implementers who indicated that they have not
implemented the function yet. implemented the function yet.
This section will be removed before publication as an RFC.
Responses from Nokia (former Alcatel-Lucent): Responses from Nokia (former Alcatel-Lucent):
Link to a web page describing the implementation: Link to a web page describing the implementation:
https://infoproducts.alcatel-lucent.com/cgi-bin/dbaccessfilename.cgi/ https://infoproducts.alcatel-lucent.com/cgi-bin/dbaccessfilename.cgi/
3HE10799AAAATQZZA01_V1_7450%20ESS%207750%20SR%20and%207950%20XRS%20Un 3HE10799AAAATQZZA01_V1_7450%20ESS%207750%20SR%20and%207950%20XRS%20Un
icast%20Routing%20Protocols%20Guide%20R14.0.R1.pdf icast%20Routing%20Protocols%20Guide%20R14.0.R1.pdf
The implementation's level of maturity: Production. The implementation's level of maturity: Production.
Coverage: We have implemented all sections and have support for the Coverage: We have implemented all sections and have support for the
skipping to change at page 31, line 32 skipping to change at page 23, line 46
Contact information: wim.henderickx@nokia.com Contact information: wim.henderickx@nokia.com
Responses from Cisco Systems: Responses from Cisco Systems:
Link to a web page describing the implementation: Link to a web page describing the implementation:
http://www.segment-routing.net/home/tutorial http://www.segment-routing.net/home/tutorial
The implementation's level of maturity: Production. The implementation's level of maturity: Production.
Coverage: All sections, except the section 6 (SID/Label Binding Sub- Coverage: All sections have been implemented according to the latest
TLV) have been implemented according to the latest draft. draft.
Licensing: Part of a commercial software package. Licensing: Part of a commercial software package.
Implementation experience: Many aspects of the draft are result of Implementation experience: Many aspects of the draft are result of
the actual implementation experience, as the draft evolved from its the actual implementation experience, as the draft evolved from its
initial version to the current one. Interoperability testing with initial version to the current one. Interoperability testing with
Alcatel-Lucent was performed, which confirmed the draft's ability to Alcatel-Lucent was performed, which confirmed the draft's ability to
serve as a reference for the implementors. serve as a reference for the implementors.
Contact information: ppsenak@cisco.com Contact information: ppsenak@cisco.com
skipping to change at page 32, line 15 skipping to change at page 24, line 28
(second half of 2016) (second half of 2016)
Coverage: All sections implemented except Sections 4, and 6. Coverage: All sections implemented except Sections 4, and 6.
Licensing: JUNOS Licensing needed. Licensing: JUNOS Licensing needed.
Implementation experience: NA Implementation experience: NA
Contact information: shraddha@juniper.net Contact information: shraddha@juniper.net
11. Security Considerations 10. Security Considerations
Implementations must assure that malformed TLV and Sub-TLV With the OSPFv2 segment routing extensions defined herein, OSPFv2
permutations do not result in errors which cause hard OSPF failures. will now program the MPLS data plane [RFC3031] in addition to the IP
data plane. Previously, LDP [RFC5036] or another label distribution
mechanism was required to advertise MPLS labels and program the MPLS
data plane.
12. Contributors In general, the same types of attacks that can be carried out on the
IP control plane can be carried out on the MPLS control plane
resulting in traffic being misrouted in the respective data planes.
However, the latter may be more difficult to detect and isolate.
Existing security extensions as described in [RFC2328] and [RFC7684]
apply to these segment routing extensions. While OSPF is under a
single administrative domain, there may be deployments where
potential attackers have access to one or more networks in the OSPF
routing domain. In these deployments, stronger authentication
mechanisms such as those specified in [RFC7474] SHOULD be used.
Implementations must assure that malformed TLV and Sub-TLV defined in
this document are detected and do not provide a vulnerability for
attackers to crash the OSPFv2 router or routing process.
11. Contributors
The following people gave a substantial contribution to the content The following people gave a substantial contribution to the content
of this document: Acee Lindem, Ahmed Bashandy, Martin Horneffer, of this document: Acee Lindem, Ahmed Bashandy, Martin Horneffer,
Bruno Decraene, Stephane Litkowski, Igor Milojevic, Rob Shakir and Bruno Decraene, Stephane Litkowski, Igor Milojevic, Rob Shakir and
Saku Ytti. Saku Ytti.
13. Acknowledgements 12. Acknowledgements
We would like to thank Anton Smirnov for his contribution. We would like to thank Anton Smirnov for his contribution.
Many thanks to Yakov Rekhter, John Drake and Shraddha Hedge for their
contribution on earlier definition of the "Binding / MPLS Label TLV".
Thanks to Acee Lindem for the detail review of the draft, Thanks to Acee Lindem for the detail review of the draft,
corrections, as well as discussion about details of the encoding. corrections, as well as discussion about details of the encoding.
14. References 13. References
14.1. Normative References 13.1. 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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[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,
<http://www.rfc-editor.org/info/rfc3209>.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003,
<http://www.rfc-editor.org/info/rfc3477>.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007, RFC 4915, DOI 10.17487/RFC4915, June 2007,
<http://www.rfc-editor.org/info/rfc4915>. <http://www.rfc-editor.org/info/rfc4915>.
[RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast
and Point-to-Multipoint Interface Type", RFC 6845, and Point-to-Multipoint Interface Type", RFC 6845,
DOI 10.17487/RFC6845, January 2013, DOI 10.17487/RFC6845, January 2013,
<http://www.rfc-editor.org/info/rfc6845>. <http://www.rfc-editor.org/info/rfc6845>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <http://www.rfc-editor.org/info/rfc7684>. 2015, <http://www.rfc-editor.org/info/rfc7684>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <http://www.rfc-editor.org/info/rfc7770>. February 2016, <http://www.rfc-editor.org/info/rfc7770>.
14.2. Informative References 13.2. Informative References
[I-D.filsfils-spring-segment-routing-ldp-interop]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing interoperability with LDP", draft-
filsfils-spring-segment-routing-ldp-interop-03 (work in
progress), March 2015.
[I-D.filsfils-spring-segment-routing-use-cases]
Filsfils, C., Francois, P., Previdi, S., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E.
Crabbe, "Segment Routing Use Cases", draft-filsfils-
spring-segment-routing-use-cases-01 (work in progress),
October 2014.
[I-D.ietf-spring-conflict-resolution] [I-D.ietf-spring-conflict-resolution]
Ginsberg, L., Psenak, P., Previdi, S., and M. Pilka, Ginsberg, L., Psenak, P., Previdi, S., and M. Pilka,
"Segment Routing Conflict Resolution", draft-ietf-spring- "Segment Routing MPLS Conflict Resolution", draft-ietf-
conflict-resolution-03 (work in progress), April 2017. spring-conflict-resolution-04 (work in progress), May
2017.
[I-D.ietf-spring-segment-routing] [I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and R. Shakir, "Segment Routing Architecture", draft-ietf- and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-11 (work in progress), February spring-segment-routing-12 (work in progress), June 2017.
2017.
[I-D.minto-rsvp-lsp-egress-fast-protection] [I-D.ietf-spring-segment-routing-ldp-interop]
Jeganathan, J., Gredler, H., and Y. Shen, "RSVP-TE LSP Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., and
egress fast-protection", draft-minto-rsvp-lsp-egress-fast- S. Litkowski, "Segment Routing interworking with LDP",
protection-03 (work in progress), November 2013. draft-ietf-spring-segment-routing-ldp-interop-08 (work in
progress), June 2017.
[I-D.ietf-spring-segment-routing-mpls]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-10
(work in progress), June 2017.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<http://www.rfc-editor.org/info/rfc2328>.
[RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed.,
"Security Extension for OSPFv2 When Using Manual Key
Management", RFC 7474, DOI 10.17487/RFC7474, April 2015,
<http://www.rfc-editor.org/info/rfc7474>.
[RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <http://www.rfc-editor.org/info/rfc7855>.
Authors' Addresses Authors' Addresses
Peter Psenak (editor) Peter Psenak (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
Apollo Business Center Apollo Business Center
Mlynske nivy 43 Mlynske nivy 43
Bratislava 821 09 Bratislava 821 09
Slovakia Slovakia
skipping to change at page 34, line 26 skipping to change at page 27, line 4
Authors' Addresses Authors' Addresses
Peter Psenak (editor) Peter Psenak (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
Apollo Business Center Apollo Business Center
Mlynske nivy 43 Mlynske nivy 43
Bratislava 821 09 Bratislava 821 09
Slovakia Slovakia
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
Stefano Previdi (editor) Stefano Previdi (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
Via Del Serafico, 200 Via Del Serafico, 200
Rome 00142 Rome 00142
Italy Italy
Email: sprevidi@cisco.com Email: stefano@previdi.net
Clarence Filsfils Clarence Filsfils
Cisco Systems, Inc. Cisco Systems, Inc.
Brussels Brussels
Belgium Belgium
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
Hannes Gredler Hannes Gredler
RtBrick Inc. RtBrick Inc.
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