< draft-ietf-lsr-ospf-prefix-originator-10.txt   draft-ietf-lsr-ospf-prefix-originator-11.txt >
LSR Working Group A. Wang LSR Working Group A. Wang
Internet-Draft China Telecom Internet-Draft China Telecom
Intended status: Standards Track A. Lindem Intended status: Standards Track A. Lindem
Expires: October 4, 2021 Cisco Systems Expires: October 9, 2021 Cisco Systems
J. Dong J. Dong
Huawei Technologies Huawei Technologies
P. Psenak P. Psenak
K. Talaulikar, Ed. K. Talaulikar, Ed.
Cisco Systems Cisco Systems
April 2, 2021 April 7, 2021
OSPF Prefix Originator Extensions OSPF Prefix Originator Extensions
draft-ietf-lsr-ospf-prefix-originator-10 draft-ietf-lsr-ospf-prefix-originator-11
Abstract Abstract
This document defines OSPF extensions to include information This document defines OSPF extensions to include information
associated with the node originating a prefix along with the prefix associated with the node originating a prefix along with the prefix
advertisement. advertisement.
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
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 4, 2021. This Internet-Draft will expire on October 9, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3
2.1. Prefix Source OSPF Router-ID Sub-TLV . . . . . . . . . . 3 2.1. Prefix Source OSPF Router-ID Sub-TLV . . . . . . . . . . 3
2.2. Prefix Source Router Address Sub-TLV . . . . . . . . . . 4 2.2. Prefix Source Router Address Sub-TLV . . . . . . . . . . 4
3. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 5 3. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. Operational Considerations . . . . . . . . . . . . . . . . . 6 5. Operational Considerations . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
Prefix attributes are advertised in OSPFv2 [RFC2328] using the Prefix attributes are advertised in OSPFv2 [RFC2328] using the
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identified by the Advertising Router field of the AS-scoped LSA used. identified by the Advertising Router field of the AS-scoped LSA used.
However, the actual originating router for the prefix may be a remote However, the actual originating router for the prefix may be a remote
router outside the OSPF domain. Similarly, when an ABR performs router outside the OSPF domain. Similarly, when an ABR performs
translation of Not-So-Stubby Area (NSSA) [RFC3101] LSAs to AS- translation of Not-So-Stubby Area (NSSA) [RFC3101] LSAs to AS-
external LSAs, the information associated with the NSSA ASBR (or the external LSAs, the information associated with the NSSA ASBR (or the
router outside the OSPF domain) is not conveyed across the OSPF router outside the OSPF domain) is not conveyed across the OSPF
domain. domain.
While typically the originator of information in OSPF is identified While typically the originator of information in OSPF is identified
by its OSPF Router ID, it does not necessarily represent a reachable by its OSPF Router ID, it does not necessarily represent a reachable
address for the router. The IPv4/IPv6 Router Address as defined in address for the router since the OSPF Router ID is a 32-bit number.
[RFC3630] and [RFC5329] for OSPFv2 and OSPFv3 respectively provide an There exists a prevalent practice to use one of the IPv4 address of
address to reach that router. the node (e.g. a loopback interface) as a OSPF Router ID in the case
of OSPFv2. However, this cannot be always assumed and this approach
does not obviously extend to IPv6 addresses with OSPFv3. The IPv4/
IPv6 Router Address as defined in [RFC3630] and [RFC5329] for OSPFv2
and OSPFv3 respectively provide an address to reach that router.
The primary use case for the extensions proposed in this document is The primary use case for the extensions proposed in this document is
to be able to identify the originator of a prefix in the network. In to be able to identify the originator of a prefix in the network. In
cases where multiple prefixes are advertised by a given router, it is cases where multiple prefixes are advertised by a given router, it is
also useful to be able to associate all these prefixes with a single also useful to be able to associate all these prefixes with a single
router even when prefixes are advertised outside of the area in which router even when prefixes are advertised outside of the area in which
they originated. It also helps to determine when the same prefix is they originated. It also helps to determine when the same prefix is
being originated by multiple routers across areas. being originated by multiple routers across areas.
This document proposes extensions to the OSPF protocol for inclusion This document proposes extensions to the OSPF protocol for inclusion
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Protocol Extensions 2. Protocol Extensions
This document defines the Prefix Source OSPF Router-ID and the Prefix This document defines the Prefix Source OSPF Router-ID and the Prefix
Source Router Address Sub-TLVs for inclusion of the Router ID and a Source Router Address Sub-TLVs. They are used, respectively, to
reachable address information for the router originating the prefix include the Router ID of, and a reachable address of, the router that
as a prefix attribute. originates the prefix as a prefix attribute.
2.1. Prefix Source OSPF Router-ID Sub-TLV 2.1. Prefix Source OSPF Router-ID Sub-TLV
For OSPFv2, the Prefix Source OSPF Router-ID Sub-TLV is an optional For OSPFv2, the Prefix Source OSPF Router-ID Sub-TLV is an optional
Sub-TLV of the OSPFv2 Extended Prefix TLV [RFC7684]. For OSPFv3, the Sub-TLV of the OSPFv2 Extended Prefix TLV [RFC7684]. For OSPFv3, the
Prefix Source OSPF Router-ID Sub-TLV is an optional Sub-TLV of the Prefix Source OSPF Router-ID Sub-TLV is an optional Sub-TLV of the
Intra-Area-Prefix TLV, Inter-Area-Prefix TLV, and External-Prefix TLV Intra-Area-Prefix TLV, Inter-Area-Prefix TLV, and External-Prefix TLV
[RFC8362] when originating either an IPv4 [RFC5838] or an IPv6 prefix [RFC8362] when originating either an IPv4 [RFC5838] or an IPv6 prefix
advertisement. advertisement.
The Prefix Source OSPF Router-ID Sub-TLV has the following format: The Prefix Source OSPF Router-ID 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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with the prefix advertisement. with the prefix advertisement.
The OSPF Router ID of the Prefix Source OSPF Router-ID is set to the The OSPF Router ID of the Prefix Source OSPF Router-ID is set to the
OSPF Router ID of the node originating the prefix in the OSPF domain. OSPF Router ID of the node originating the prefix in the OSPF domain.
If the originating node is advertising an OSPFv2 Router Address TLV If the originating node is advertising an OSPFv2 Router Address TLV
[RFC3630] or an OSPFv3 Router IPv6 Address TLV [RFC5329], then the [RFC3630] or an OSPFv3 Router IPv6 Address TLV [RFC5329], then the
same address MUST be used in the Router Address field of the Prefix same address MUST be used in the Router Address field of the Prefix
Source Router Address Sub-TLV. When the originating node is not Source Router Address Sub-TLV. When the originating node is not
advertising such an address, implementations can determine a unique advertising such an address, implementations can determine a unique
and reachable address (i.e., advertised with the N-flag set [RFC7684] and reachable address (for example, advertised with the N-flag set
or N-bit set [RFC8362]) belonging to the originating node to set in [RFC7684] or N-bit set [RFC8362]) belonging to the originating node
the Router Address field. to set in the Router Address field.
When an ABR generates inter-area prefix advertisements into its non- When an ABR generates inter-area prefix advertisements into its non-
backbone areas corresponding to an inter-area prefix advertisement backbone areas corresponding to an inter-area prefix advertisement
from the backbone area, the only way to determine the originating from the backbone area, the only way to determine the originating
node information is based on the Prefix Source OSPF Router-ID and node information is based on the Prefix Source OSPF Router-ID and
Prefix Source Router Address Sub-TLVs present in the inter-area Prefix Source Router Address Sub-TLVs present in the inter-area
prefix advertisement originated into the backbone area by an ABR from prefix advertisement originated into the backbone area by an ABR from
another non-backbone area. The ABR performs its prefix calculation another non-backbone area. The ABR performs its prefix calculation
to determine the set of nodes that contribute to the best prefix to determine the set of nodes that contribute to the best prefix
reachability. It MUST use the prefix originator information only reachability. It MUST use the prefix originator information only
from this set of nodes. The ABR MUST NOT include the Prefix Source from this set of nodes. The ABR MUST NOT include the Prefix Source
OSPF Router-ID or the Prefix Source Router Address Sub-TLVs when it OSPF Router-ID or the Prefix Source Router Address Sub-TLVs when it
is unable to determine the information of the best originating node. is unable to determine the information of the best originating nodes.
Implementations may support the propagation of the originating node Implementations may support the propagation of the originating node
information along with a redistributed prefix into the OSPF domain information along with a redistributed prefix into the OSPF domain
from another routing domain. The details of such mechanisms are from another routing domain. The details of such mechanisms are
outside the scope of this document. Such implementations may also outside the scope of this document. Such implementations may also
provide control on whether the Router Address in the Prefix Source provide control on whether the Router Address in the Prefix Source
Router Address Sub-TLV is set as the ABSR node address or as the Router Address Sub-TLV is set as the ABSR node address or as the
address of the actual node outside the OSPF domain that owns the address of the actual node outside the OSPF domain that owns the
prefix. prefix.
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4. Security Considerations 4. Security Considerations
Since this document extends the OSPFv2 Extended Prefix LSA, the Since this document extends the OSPFv2 Extended Prefix LSA, the
security considerations for [RFC7684] are applicable. Similarly, security considerations for [RFC7684] are applicable. Similarly,
since this document extends the OSPFv3 E-Intra-Area-Prefix-LSA, E- since this document extends the OSPFv3 E-Intra-Area-Prefix-LSA, E-
Inter-Area-Prefix-LSA, E-AS-External LSA and E-NSSA-LSA, the security Inter-Area-Prefix-LSA, E-AS-External LSA and E-NSSA-LSA, the security
considerations for [RFC8362] are applicable. The new sub-TLVs considerations for [RFC8362] are applicable. The new sub-TLVs
introduced in this document are optional and do not affect the OSPF introduced in this document are optional and do not affect the OSPF
route computation and therefore do not affect the security aspects of route computation and therefore do not affect the security aspects of
OSPF protocol operations. A rogue node that can inject prefix OSPF protocol operations.
advertisements may use the new extensions introduced in this document
to indicate incorrect prefix source information. A rogue node that can inject prefix advertisements may use the new
extensions introduced in this document to indicate incorrect prefix
source information.
5. Operational Considerations 5. Operational Considerations
Consideration should be given to the operation impact of the increase Consideration should be given to the operational impact of the
in the size of the OSPF Link-State Database as a result of the increase in the size of the OSPF Link-State Database as a result of
protocol extensions in this document. Based on deployment design and the protocol extensions in this document. Based on deployment design
requirements, a subset of prefixes may be identified for which the and requirements, a subset of prefixes may be identified for which
originating node information needs to be included with their prefix the originating node information needs to be included with their
advertisements. prefix advertisements.
The propagation of the prefix source node information when doing The propagation of the prefix source node information when doing
prefix advertisements across OSPF area or domain boundaries results prefix advertisements across OSPF area or domain boundaries results
in the exposure of node information outside of an area or domain in the exposure of node information outside of an area or domain
within which it is normally hidden or abstracted by the base OSPF within which it is normally hidden or abstracted by the base OSPF
protocol. Based on deployment design and requirements, a subset of protocol. Based on deployment design and requirements, a subset of
prefixes may be identified for which the propagation of the prefixes may be identified for which the propagation of the
originating node information across area boundaries is disabled at originating node information across area or domain boundaries is
the ABRs. disabled at the ABRs or ASBRs respectively.
The identification of the node that is originating a specific prefix The identification of the node that is originating a specific prefix
in the network may aid in debugging of issues related to prefix in the network may aid in debugging of issues related to prefix
reachability within an OSPF network. reachability within an OSPF network.
6. IANA Considerations 6. IANA Considerations
This document requests IANA for the allocation of the codepoints from This document requests IANA for the allocation of the codepoints from
the "OSPFv2 Extended Prefix TLV Sub-TLVs" registry under the "Open the "OSPFv2 Extended Prefix TLV Sub-TLVs" registry under the "Open
Shortest Path First v2 (OSPFv2) Parameters" registry. Shortest Path First v2 (OSPFv2) Parameters" registry.
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