Advertising Unreachable Links in OSPF
draft-ietf-lsr-ospf-ls-link-infinity-07
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
|
|
|---|---|---|---|
| Authors | Liyan Gong , Weiqiang Cheng , Changwang Lin , Acee Lindem , Ran Chen | ||
| Last updated | 2025-08-22 (Latest revision 2025-08-20) | ||
| Replaces | draft-gong-lsr-ospf-unreachable-link | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
RTGDIR Early review
by Cheng Li
Has issues
YANGDOCTORS Early review
by Ladislav Lhotka
Ready w/issues
OPSDIR Early review
by Dhruv Dhody
Has issues
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | Yingzhen Qu | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | yingzhen.ietf@gmail.com |
draft-ietf-lsr-ospf-ls-link-infinity-07
LSR Working Group L. Gong
Internet-Draft W. Cheng
Updates: 6987, 8770 (if approved) China Mobile
Intended status: Standards Track C. Lin
Expires: 23 February 2026 New H3C Technologies
A. Lindem
Arrcus, Inc.
R. Chen
ZTE Corporation
22 August 2025
Advertising Unreachable Links in OSPF
draft-ietf-lsr-ospf-ls-link-infinity-07
Abstract
In certain scenarios, it is necessary to advertise unreachable links
in OSPF, which should be explicitly excluded from the related SPF
calculation. This document specifies using LSLinkInfinity(0xffff) to
advertise an OSPF link as unreachable.
Stub Router Advertisement (RFC 6987) defines MaxLinkMetric (0xffff)
to indicate a router-LSA link should not be used for transit traffic.
This document updates RFC 6987 and RFC 8770. When an OSPFv2 router
supports the Unreachable Link support capability defined in this
document, the OSPFv2 stub router MaxLinkMetric(0xffff) MUST be
updated to MaxReachableLinkMetric(0xfffe).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 23 February 2026.
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Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Case 1: Traffic Engineering . . . . . . . . . . . . . . . 3
2.2. Case 2: Flexible Algorithm . . . . . . . . . . . . . . . 3
3. LSInfinity-Based Solution . . . . . . . . . . . . . . . . . . 5
3.1. Unreachable Link Advertisement . . . . . . . . . . . . . 5
3.2. Unreachable Link Backward Compatibility . . . . . . . . . 5
3.3. Stub Router Advertisement Backward Compatibility . . . . 6
4. Management Considerations . . . . . . . . . . . . . . . . . . 7
5. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Tree for the YANG Data Model . . . . . . . . . . . . . . 7
5.2. YANG Data Model for OSPF Advertising Unreachable Links . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
In specific scenarios, there is a requirement to advertise
unreachable links in OSPF, which MUST NOT be considered during the
standard SPF computation. For example, a link may be available for
Traffic Engineering (TE) purposes but not suitable for hop-by-hop
routing. Another example is an OSPF link with dedicated resources
for a network slice included in a Flexible Algorithm (Flex-
Algorithm) but excluded from the default topology.
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his document specifies using LSLinkInfinity(oxffff) to advertise an
OSPF link as unreachable.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Use Cases
2.1. Case 1: Traffic Engineering
A network topology is shown in Figure 1. There is a link available
for Traffic Engineering only between Node A and E. If this link is
included in the SPF calculations, best-effort traffic may be routed
over the link.
TE Link
---------
/ \
/ \
A------C------E
| | |
| | |
| | |
B------D------F
Figure 1: Network Topology
2.2. Case 2: Flexible Algorithm
A network topology is shown in Figure 2. The links between nodes A,
and B and between C and D are to be used exclusively for a flex-
algorithm devoted to specific traffic. These links have an Extended
Administrative Group (EAG) [RFC7308] attribute specifying the "Red"
color.
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******
A------C------E
|* |* |
|* |* | ******: "Red" link
|* |* |
B------D------F
******
Figure 2: Network Topology
Flex-Algorithm 128 is enabled on Nodes A, B, C, and D, with an EAG
rule including "Red" and the Metric-Type is designated to be a type
other than the IGP metric. Flex-Algorithm allows OSPF to compute the
paths along the constrained topology. The topology used by Flex-
Algorithm 128 is shown in Figure 3.
A******C
* *
* *
* *
B******D
Figure 3: Topology of Flex-Algorithm 128
Flex-Algorithm 128 is used for routing particular flows, such as
those for specific traffic. The "Red" links used by Flex-Algorithm
128 are sub-interfaces with dedicated queues for guaranteed
bandwidth. Sub-interfaces in other traffic and default topology are
omitted from the example figure for clarity. So, it is expected that
only the particular flows are routed on these links using Flex-
Algorithm 128. However, these links are also contained in the
default topology computed by the normal SPF calculation, and these
links may also be used for best-effort traffic. Therefore, it is a
problem that the dedicated links for Flex-Algorithm are still
reachable in base SPF calculation.
If the IGP metrics for all the "Red" links are advertised as
unreachable, the base topology will be as shown in Figure 4,
excluding all the "Red" links. This allows Flex-Algorithm 128 to
route only specific traffic on the "Red" links.
A------C------E
| | |
| | |
| | |
B------D------F
Figure 4: Base SPF Topology Excluding Unreachable Links
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3. LSInfinity-Based Solution
3.1. Unreachable Link Advertisement
This document specifies that if the IGP metric of a link is
advertised as LSLinkInfinity (0xffff), it MUST NOT be considered
during the related SPF computation. This applies to both the Flex-
Algorithm SPF and the base SPF as long as LSLinkInfinity is specified
for the IGP metric.
While the interpretaion of LSLinkInfinity is only required in the
base topology as other topologies are optional, OSPF routers
supporting this specification MUST consistently interpret
LSLinkInfinity as unreachable during the related SPF computation.
This applies to both the Flex- Algorithm SPF and the base SPF as long
as LSLinkInfinity is specified for the IGP metric.
An IGP metic with LSLinkInfinity indicating a link is unreachable is
applicable to the following TLVs/LSAs:
* The Router-LSA [RFC2328] and [RFC5340]
* The OSPFv2 Extended Link TLV of OSPFv2 Extended Link Opaque LSA
[RFC7684]
* The Router-Link TLV of OSPFv3 E-Router-LSA [RFC8362]
3.2. Unreachable Link Backward Compatibility
Prior to this specification, OSPF treated links advertised as
LSLinkInfinity as reachable [RFC2328]. Hence, partial deployment of
this specification may result in routing loops due to inconsistent
interpretation of LSLinkInfinity. For example in the network shown
in Figure 5, link D-F is advertised with LSLinkInfinity
(65535/0xffff). Router B supports LSLinkInfinity as unreachable, but
router A doesn't. Router A considers link D-F as reachable, and the
shortest path to F is A->B->D->F. Router B considers link D-F as
unreachable, and the shortest path to F is B->A->C->E->F. As a
result, A forwards the packets to B, but B returns them to A, which
results in a routing loop.
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40000 40000 Traffic: A->F
A------C------E A considers link D-F as reachable
| | A's shortest path: A->B->D->F
5| |5 B considers link D-F as unreachable
| | B's shortest path: B->A->C->E->F
B------D------F
5 65535
Figure 5: Inconsistent LSLinkInfinity Interpretation Causing Loops
To provide backward compatibility, this document defines that routers
supporting LSLinkInfinity for unreachable links MUST advertise a
Router Information (RI) LSA with a Router Functional Capabilities TLV
[RFC7770] including the following Router Functional Capability Bit:
+=====+==========================+
| Bit | Capabilities |
+=====+==========================+
| TBA | Unreachable Link support |
+-----+--------------------------+
Table 1
OSPF Routers MUST NOT treat links with an advertised metric of
LSLinkInfinity as unreachable unless all routers in the OSPF area
have advertised this capability. If all OSPF Routers in the area
have advertised this capability, then links with an advertised metric
of LSLinkInfinity MUST be treated as unreachable. Upon detection of
a change in the number of routers in the area not supporting the
Unreachable Link support capability changes to 0 or from 0 to greater
than 0, all OSPF routers in the area MUST recalculate their routes.
3.3. Stub Router Advertisement Backward Compatibility
Stub Router Advertisement [RFC6987] defines MaxLinkMetric (0xffff) to
indicate a router-LSA link should not be used for transit traffic.
This document updates [RFC6987] and [RFC8770]. When an OSPFv2 router
supports the Unreachable Link support capability defined in this
document, the OSPFv2 stub router MaxLinkMetric(0xffff) MUST be
updated to MaxReachableLinkMetric(0xfffe).
When an OSPFv2 router supports [RFC6987] and the Unreachable Link
support capability defined in this document, it MUST also support
advertise all its non-stub links with a link cost of
MaxReachableLinkMetric (0xfffe). Since MaxLinkMetric will not be
used to indicate a link is unreachable unless all OSPFv2 routers in
the area support this specification as specified in Section 3.2, all
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routers in the area will also support the usage of
MaxReachableLinkMetric to discourage the usage of stub router links
for transit traffic.
An OSPFv3 router can simply advertise R-bit in its router-LSA options
[RFC5340] to prevent usage stub router links for transit traffic.
Similarily, OSPFv2 routers supporting [RFC8770] can advertise the
H-bit in the router-LSA options.
4. Management Considerations
Support of the Unreachable Link support capability SHOULD be
configurable.
In some networks, the operator may still want links with maximum
metric(0xffff) to be treated as reachable. For example, when auto-
costing of links is used and there is a mix of low-speed and high-
speed links. In such cases, the updated routers can disable the
Unreachable Link support capability and still treat links with
maximum metric as reachable.
It is also RECOMMENDED that implementations supporting this document
and auto-costing limit the maximum computed cost to
MaxReachableLinkMetric (0xfffe).
5. YANG Data Model
YANG [RFC7950] is a data definition language used to define the
contents of a conceptual data store that allows networked devices to
be managed using NETCONF [RFC6241] or RESTCONF [RFC8040].
This section defines a YANG data model that can be used to configure
and manage the usage of OSPF LSLinkInfinity for unreachable links as
defined in this document, which augments the OSPF YANG data model
[RFC9129] and the YANG Data Model for Routing Management [RFC8349].
5.1. Tree for the YANG Data Model
This document uses the graphical representation of data models per
[RFC8340].
The following show the tree diagram of the module:
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augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf:
+--rw unreachable-link-advertisement
+--rw enabled? boolean
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area
/ospf:database/ospf:area-scope-lsa-type
/ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
/ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque
/ospf:ri-opaque/ospf:router-capabilities-tlv:
+--ro router-functional-capabilities
+--ro functional-capabilities* identityref
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf/ospf:database
/ospf:as-scope-lsa-type/ospf:as-scope-lsas
/ospf:as-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2
/ospf:body/ospf:opaque/ospf:ri-opaque
/ospf:router-capabilities-tlv:
+--ro router-functional-capabilities
+--ro functional-capabilities* identityref
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf/ospf:database
/ospf:as-scope-lsa-type/ospf:as-scope-lsas
/ospf:as-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3
/ospf:body/ospf:router-information
/ospf:router-capabilities-tlv:
+--ro router-functional-capabilities
+--ro functional-capabilities* identityref
augment /rt:routing/rt:control-plane-protocols
/rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area
/ospf:database/ospf:area-scope-lsa-type
/ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
/ospf:ospfv3/ospf:ospfv3/ospf:body/ospf:router-information
/ospf:router-capabilities-tlv:
+--ro router-functional-capabilities
+--ro functional-capabilities* identityref
5.2. YANG Data Model for OSPF Advertising Unreachable Links
The following is the YANG module:
<CODE BEGINS> file "ietf-ospf-unreachable-links@2025-08-20.yang"
module ietf-ospf-unreachable-links {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-ospf-unreachable-links";
prefix ospf-unreach-link;
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import ietf-routing {
prefix rt;
reference
"RFC 8349: A YANG Data Model for Routing
Management (NMDA Version)";
}
import ietf-ospf {
prefix ospf;
reference
"RFC 9129: YANG Data Model for the OSPF Protocol";
}
organization
"IETF LSR - Link State Routing Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/lsr/>
WG List: <mailto:lsr@ietf.org>
Author: Yingzhen Qu
<mailto:yqu@futurewei.com>
Author: Acee Lindem
<mailto:acee.ietf@gmail.com>";
description
"This YANG module defines the configuration and operational
state for Advertising Unreachable Links in OSPF as defined
in RFC XXXX.
Copyright (c) 2025 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX;
see the RFC itself for full legal notices.";
reference
"RFC XXXX";
revision 2025-08-20 {
description
"Initial version";
reference
"RFC XXXX: Advertising Unreachable Links in OSPF";
}
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identity functional-capability {
description
"Base identity for router informational capabilities.";
}
identity unreachable-link {
base ospf-unreach-link:functional-capability;
description
"When set, the router is capable of advertising unreachable
links.";
}
grouping router-functional-capabilities {
description
"Grouping for OSPF router capabilities TLV types.";
reference
"RFC 7770: Extensions to OSPF for Advertising Optional
Router Capabilities";
container router-functional-capabilities {
leaf-list functional-capabilities {
type identityref {
base functional-capability;
}
description
"List of functional capabilities. This list will
contain the identities for the functional
capabilities supported by the router.";
}
description
"OSPF Router Functional identity definitions.";
}
}
augment "/rt:routing/rt:control-plane-protocols"
+ "/rt:control-plane-protocol/ospf:ospf" {
when "../rt:type = 'ospf:ospfv2' or "
+ "../rt:type = 'ospf:ospfv3'" {
description
"This augments the OSPF routing protocol when used.";
}
description
"This augments OSPF protocol with unreachable link
advertisement.";
container unreachable-link-advertisement {
leaf enabled {
type boolean;
default "false";
description
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"Enable advertisement of unreachable links.";
}
description
"OSPF unreachable link advertisement configuration.";
}
}
augment "/rt:routing/"
+ "rt:control-plane-protocols/rt:control-plane-protocol/"
+ "ospf:ospf/ospf:areas/"
+ "ospf:area/ospf:database/"
+ "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
+ "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/"
+ "ospf:ospfv2/ospf:body/ospf:opaque/"
+ "ospf:ri-opaque/ospf:router-capabilities-tlv" {
when "derived-from(/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
description
"This augmentation is only valid for OSPFv2.";
}
description
"OSPFv2 Opaque Area-Scoped Router-Information LSA Router
Functional capabilities (RFC 7770).";
uses router-functional-capabilities;
}
augment "/rt:routing/"
+ "rt:control-plane-protocols/rt:control-plane-protocol/"
+ "ospf:ospf/ospf:database/"
+ "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
+ "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/"
+ "ospf:ospfv2/ospf:body/ospf:opaque/"
+ "ospf:ri-opaque/ospf:router-capabilities-tlv" {
when "derived-from(/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
description
"This augmentation is only valid for OSPFv2.";
}
description
"OSPFv2 Opaque AS-Scoped Router-Information LSA Router
Functional capabilities (RFC 7770).";
uses router-functional-capabilities;
}
augment "/rt:routing/"
+ "rt:control-plane-protocols/rt:control-plane-protocol/"
+ "ospf:ospf/ospf:database/"
+ "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
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+ "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/"
+ "ospf:ospfv3/ospf:body/ospf:router-information/"
+ "ospf:router-capabilities-tlv" {
when "derived-from(/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
description
"This augmentation is only valid for OSPFv3.";
}
description
"OSPFv3 Area-Scoped Router-Information LSA Router
Functional capabilities (RFC 7770).";
uses router-functional-capabilities;
}
augment "/rt:routing/"
+ "rt:control-plane-protocols/rt:control-plane-protocol/"
+ "ospf:ospf/ospf:areas/"
+ "ospf:area/ospf:database/"
+ "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
+ "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
+ "ospf:ospfv3/ospf:body/ospf:router-information/"
+ "ospf:router-capabilities-tlv" {
when "derived-from(/rt:routing/rt:control-plane-protocols/"
+ "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
description
"This augmentation is only valid for OSPFv3.";
}
description
"OSPFv3 AS-Scoped Router-Information LSA Router
Functional capabilities (RFC 7770).";
uses router-functional-capabilities;
}
}
<CODE ENDS>
6. Security Considerations
The document does not introduce any new security issues for the OSPF
protocol. The security considerations for [RFC2328],[RFC5340],
[RFC6987], and [RFC7770] are applicable to protocol extension.
The ietf-ospf-link-unreach YANG module defines a data model that is
designed to be accessed via YANG-based management protocols, such as
NETCONF [RFC6241] and RESTCONF [RFC8040]. These protocols have to
use a secure transport layer (e.g., SSH [RFC4252], TLS [RFC8446], and
QUIC [RFC9000]) and have to use mutual authentication.
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The NETCONF Access Control Model (NACM) [RFC8341] provides the means
to restrict access for particular NETCONF or RESTCONF users to a pre-
configured subset of all available NETCONF or RESTCONF protocol
operations and content.
The following data nodes defined in the YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). The modifications to these data nodes without proper
protection can have prevent interpreting the OSPF LSLinkInfinity
metric as unreachable.
/ospf:ospf/ospf-unreach-link:unreachable-link-advertisement/ospf-
unreach-link:enabled
Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. Exposure of
the OSPF link state database may be useful in mounting a Denial-of-
Service (DoS) attacks. These are the readable data nodes:
/ospf:ospf/ospf-unreach-link:unreachable-link-advertisement/ospf-
unreach-link:enabled
7. IANA Considerations
This document defines a new bit in the registry "OSPF Router
Functional Capability Bits":
+============+==========================+===============+
| Bit Number | Capability Name | Reference |
+============+==========================+===============+
| 0(TBD) | Unreachable Link support | This document |
+------------+--------------------------+---------------+
Table 2
The IANA is requested to assign one new URI from the IETF XML
registry ([RFC3688]). Authors are suggesting the following URI:
URI: urn:ietf:params:xml:ns:yang:ietf-ospf-unreachable-links
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace
This document also requests one new YANG module name in the YANG
Module Names registry ([RFC6020]) with the following suggestion :
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name: ietf-ospf-unreachable-links
namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-unreachable-links
prefix: ospf-unreach-link
reference: RFC XXXX
8. Contributors
The following individuals have contributed to this document:
Mengxiao Chen
New H3C Technologies
China
Email: chen.mengxiao@h3c.com
Yanrong Liang
Ruijie Networks Co., Ltd.
China
Email: liangyanrong@ruijie.com.cn
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
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[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <https://www.rfc-editor.org/info/rfc7770>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
Routing Management (NMDA Version)", RFC 8349,
DOI 10.17487/RFC8349, March 2018,
<https://www.rfc-editor.org/info/rfc8349>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC9129] Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
"YANG Data Model for the OSPF Protocol", RFC 9129,
DOI 10.17487/RFC9129, October 2022,
<https://www.rfc-editor.org/info/rfc9129>.
9.2. Informative References
[RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
January 2006, <https://www.rfc-editor.org/info/rfc4252>.
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[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D.
McPherson, "OSPF Stub Router Advertisement", RFC 6987,
DOI 10.17487/RFC6987, September 2013,
<https://www.rfc-editor.org/info/rfc6987>.
[RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8770] Patel, K., Pillay-Esnault, P., Bhardwaj, M., and S.
Bayraktar, "Host Router Support for OSPFv2", RFC 8770,
DOI 10.17487/RFC8770, April 2020,
<https://www.rfc-editor.org/info/rfc8770>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
Authors' Addresses
Liyan Gong
China Mobile
China
Email: gongliyan@chinamobile.com
Weiqiang Cheng
China Mobile
China
Email: chengweiqiang@chinamobile.com
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Changwang Lin
New H3C Technologies
China
Email: linchangwang.04414@h3c.com
Acee Lindem
Arrcus, Inc.
United States of America
Email: acee.ietf@gmail.com
Ran Chen
ZTE Corporation
China
Email: chen.ran@zte.com.cn
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