draft-ietf-ospf-link-overload-16.txt   rfc8379.txt 
Open Shortest Path First IGP S. Hegde Internet Engineering Task Force (IETF) S. Hegde
Internet-Draft Juniper Networks, Inc. Request for Comments: 8379 Juniper Networks, Inc.
Intended status: Standards Track P. Sarkar Category: Standards Track P. Sarkar
Expires: August 8, 2018 Arrcus, Inc. ISSN: 2070-1721 Arrcus, Inc.
H. Gredler H. Gredler
Individual RtBrick Inc.
M. Nanduri M. Nanduri
ebay Corporation ebay Corporation
L. Jalil L. Jalil
Verizon Verizon
February 4, 2018 May 2018
OSPF Graceful Link shutdown OSPF Graceful Link Shutdown
draft-ietf-ospf-link-overload-16
Abstract Abstract
When a link is being prepared to be taken out of service, the traffic When a link is being prepared to be taken out of service, the traffic
needs to be diverted from both ends of the link. Increasing the needs to be diverted from both ends of the link. Increasing the
metric to the highest value on one side of the link is not sufficient metric to the highest value on one side of the link is not sufficient
to divert the traffic flowing in the other direction. to divert the traffic flowing in the other direction.
It is useful for the routers in an OSPFv2 or OSPFv3 routing domain to It is useful for the routers in an OSPFv2 or OSPFv3 routing domain to
be able to advertise a link as being in a graceful-shutdown state to be able to advertise a link as being in a graceful-shutdown state to
indicate impending maintenance activity on the link. This indicate impending maintenance activity on the link. This
information can be used by the network devices to re-route the information can be used by the network devices to reroute the traffic
traffic effectively. effectively.
This document describes the protocol extensions to disseminate This document describes the protocol extensions to disseminate
graceful-link-shutdown information in OSPFv2 and OSPFv3. graceful-link-shutdown information in OSPFv2 and OSPFv3.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on August 8, 2018. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8379.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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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
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Flooding Scope . . . . . . . . . . . . . . . . . . . . . . . 4 3. Flooding Scope . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 4 4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 4
4.1. OSPFv2 graceful-link-shutdown sub-TLV . . . . . . . . . . 4 4.1. OSPFv2 Graceful-Link-Shutdown Sub-TLV . . . . . . . . . . 4
4.2. Remote IPv4 Address Sub-TLV . . . . . . . . . . . . . . . 4 4.2. Remote IPv4 Address Sub-TLV . . . . . . . . . . . . . . . 4
4.3. Local/Remote Interface ID Sub-TLV . . . . . . . . . . . . 5 4.3. Local/Remote Interface ID Sub-TLV . . . . . . . . . . . . 5
4.4. OSPFv3 Graceful-Link-Shutdown sub-TLV . . . . . . . . . . 6 4.4. OSPFv3 Graceful-Link-Shutdown Sub-TLV . . . . . . . . . . 6
4.5. BGP-LS Graceful-Link-Shutdown TLV . . . . . . . . . . . . 6 4.5. BGP-LS Graceful-Link-Shutdown TLV . . . . . . . . . . . . 6
4.6. Distinguishing parallel links . . . . . . . . . . . . . . 7 4.6. Distinguishing Parallel Links . . . . . . . . . . . . . . 7
5. Elements of procedure . . . . . . . . . . . . . . . . . . . . 8 5. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 8
5.1. Point-to-point links . . . . . . . . . . . . . . . . . . 9 5.1. Point-to-Point Links . . . . . . . . . . . . . . . . . . 8
5.2. Broadcast/NBMA links . . . . . . . . . . . . . . . . . . 9 5.2. Broadcast/NBMA Links . . . . . . . . . . . . . . . . . . 9
5.3. Point-to-multipoint links . . . . . . . . . . . . . . . . 10 5.3. Point-to-Multipoint Links . . . . . . . . . . . . . . . . 10
5.4. Unnumbered interfaces . . . . . . . . . . . . . . . . . . 10 5.4. Unnumbered Interfaces . . . . . . . . . . . . . . . . . . 10
5.5. Hybrid Broadcast and P2MP interfaces . . . . . . . . . . 10 5.5. Hybrid Broadcast and P2MP Interfaces . . . . . . . . . . 10
6. Backward compatibility . . . . . . . . . . . . . . . . . . . 10 6. Backward Compatibility . . . . . . . . . . . . . . . . . . . 10
7. Applications . . . . . . . . . . . . . . . . . . . . . . . . 11 7. Applications . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Overlay Network . . . . . . . . . . . . . . . . . . . . . 11 7.1. Overlay Network . . . . . . . . . . . . . . . . . . . . . 11
7.2. Controller based Deployments . . . . . . . . . . . . . . 12 7.2. Controller-Based Deployments . . . . . . . . . . . . . . 12
7.3. L3VPN Services and sham-links . . . . . . . . . . . . . . 13 7.3. L3VPN Services and Sham Links . . . . . . . . . . . . . . 13
7.4. Hub and spoke deployment . . . . . . . . . . . . . . . . 13 7.4. Hub and Spoke Deployment . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 14
11.1. Normative References . . . . . . . . . . . . . . . . . . 14 10.2. Informative References . . . . . . . . . . . . . . . . . 16
11.2. Informative References . . . . . . . . . . . . . . . . . 15 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
This document describes a mechanism for gracefully taking a link out This document describes a mechanism for gracefully taking a link out
of service while allowing it to be used if no other path is of service while allowing it to be used if no other path is
available.It also provides a mechanism to divert the traffic from available. It also provides a mechanism to divert the traffic from
both directions of the link. both directions of the link.
Many OSPFv2 or OSPFv3 deployments run on overlay networks provisioned Many OSPFv2 or OSPFv3 deployments run on overlay networks provisioned
by means of pseudo-wires or L2-circuits. Prior to devices in the by means of pseudowires or L2 circuits. Prior to devices in the
underlying network going offline for maintenance, it is useful to underlying network going offline for maintenance, it is useful to
divert the traffic away from the node before the maintenance is divert the traffic away from the node before maintenance is actually
actually performed. Since the nodes in the underlying network are performed. Since the nodes in the underlying network are not visible
not visible to OSPF, the existing stub router mechanism described in to OSPF, the existing stub-router mechanism described in [RFC6987]
[RFC6987] cannot be used. In a service provider's network, there may cannot be used. In a service provider's network, there may be many
be many CE-to-CE connections that run over a single PE. It is CE-to-CE connections that run over a single PE. It is cumbersome to
cumbersome to change the metric on every CE-to-CE connection in both change the metric on every CE-to-CE connection in both directions.
directions. This document provides a mechanism to change the metric This document provides a mechanism to change the metric of the link
of the link on remote side and also use the link as a last-resort- on the remote side and also use the link as a last-resort link if no
link if no alternate paths are available. An application specific to alternate paths are available. An application specific to this use
this use case is described in detail in Section 7.1. case is described in detail in Section 7.1.
This document provides mechanisms to advertise graceful-link-shutdown This document provides mechanisms to advertise graceful-link-shutdown
state in the flexible encodings provided by OSPFv2 Prefix/Link state in the flexible encodings provided by "OSPFv2 Prefix/Link
Attribute Advertisement [RFC7684] and E-Router-LSA Attribute Advertisement" [RFC7684] and the E-Router-LSA [RFC8362] for
[I-D.ietf-ospf-ospfv3-lsa-extend] fr OSPFv3. Throughout this OSPFv3. Throughout this document, OSPF is used when the text applies
document, OSPF is used when the text applies to both OSPFv2 and to both OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is
OSPFv3. OSPFv2 or OSPFv3 is used when the text is specific to one specific to one version of the OSPF protocol.
version of the OSPF protocol.
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. Motivation 2. Motivation
The motivation of this document is to reduce manual intervention The motivation of this document is to reduce manual intervention
during maintenance activities. The following objectives help to during maintenance activities. The following objectives help to
accomplish this in a range of deployment scenarios. accomplish this in a range of deployment scenarios.
1. Advertise impending maintenance activity so that traffic from 1. Advertise impending maintenance activity so that traffic from
both directions can be diverted away from the link. both directions can be diverted away from the link.
2. Allow the solution to be backward compatible so that nodes that 2. Allow the solution to be backward compatible so that nodes that
do not understand the new advertisement, do not cause routing do not understand the new advertisement do not cause routing
loops. loops.
3. Advertise the maintenance activity to other nodes in the network 3. Advertise the maintenance activity to other nodes in the network
so that LSP ingress routers/controllers can learn about the so that Label Switched Path (LSP) ingress routers/controllers can
impending maintenance activity and apply specific policies to re- learn about the impending maintenance activity and apply specific
route the LSPs for traffic-engineering based deployments. policies to reroute the LSPs for deployments based on Traffic
Engineering (TE).
4. Allow the link to be used as a last resort link to prevent 4. Allow the link to be used as a last-resort link to prevent
traffic disruption when alternate paths are not available. traffic disruption when alternate paths are not available.
3. Flooding Scope 3. Flooding Scope
The graceful-link-shutdown information is flooded in area-scoped The graceful-link-shutdown information is flooded in an area-scoped
Extended Link Opaque LSA [RFC7684] for OSPFv2 and E-Router-LSA for Extended Link Opaque LSA [RFC7684] for OSPFv2 and in an E-Router-LSA
OSPFv3 [I-D.ietf-ospf-ospfv3-lsa-extend]. The Graceful-Link-Shutdown for OSPFv3 [RFC8362]. The Graceful-Link-Shutdown sub-TLV MAY be
sub-TLV MAY be processed by the head-end nodes or the controller as processed by the head-end nodes or the controller as described in the
described in the Section 7. The procedures for processing the Section 7. The procedures for processing the Graceful-Link-Shutdown
Graceful-Link-Shutdown sub-TLV are described in Section 5. sub-TLV are described in Section 5.
4. Protocol Extensions 4. Protocol Extensions
4.1. OSPFv2 graceful-link-shutdown sub-TLV 4.1. OSPFv2 Graceful-Link-Shutdown Sub-TLV
The Graceful-Link-Shutdown sub-TLV identifies the link as being The Graceful-Link-Shutdown sub-TLV identifies the link as being
gracefully shutdown. It is advertised in extended Link TLV of the gracefully shutdown. It is advertised in the Extended Link TLV of
Extended Link Opaque LSA as defined in [RFC7684]. the Extended Link Opaque LSA as defined in [RFC7684].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Graceful-Link-Shutdown sub-TLV for OSPFv2 Figure 1: Graceful-Link-Shutdown Sub-TLV for OSPFv2
Type : TBA (suggested value 7) Type: 7
Length: 0 Length: 0
4.2. Remote IPv4 Address Sub-TLV 4.2. Remote IPv4 Address Sub-TLV
This sub-TLV specifies the IPv4 address of remote endpoint on the This sub-TLV specifies the IPv4 address of the remote endpoint on the
link. It is advertised in the Extended Link TLV as defined in link. It is advertised in the Extended Link TLV as defined in
[RFC7684]. This sub-TLV is optional and MAY be advertised in an [RFC7684]. This sub-TLV is optional and MAY be advertised in an
area-scoped Extended Link Opaque LSA to identify the link when there area-scoped Extended Link Opaque LSA to identify the link when there
are multiple parallel links between two nodes. are multiple parallel links between two nodes.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote IPv4 address | | Remote IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Remote IPv4 Address Sub-TLV Figure 2: Remote IPv4 Address Sub-TLV
Type : TBA (suggested value 8) Type: 8
Length: 4 Length: 4
Value: Remote IPv4 address. The remote IPv4 address is used to Value: Remote IPv4 address. The remote IPv4 address is used to
identify a particular link on the remote side when there are multiple identify a particular link on the remote side when there are multiple
parallel links between two nodes. parallel links between two nodes.
4.3. Local/Remote Interface ID Sub-TLV 4.3. Local/Remote Interface ID Sub-TLV
This sub-TLV specifies local and remote interface identifiers. It is This sub-TLV specifies Local and Remote Interface IDs. It is
advertised in the Extended Link TLV as defined in [RFC7684]. This advertised in the Extended Link TLV as defined in [RFC7684]. This
sub-TLV is optional and MAY be advertised in an area-scoped Extended sub-TLV is optional and MAY be advertised in an area-scoped Extended
Link Opaque LSA to identify the link when there are multiple parallel Link Opaque LSA to identify the link when there are multiple parallel
unnumbered links between two nodes. The local interface-id is unnumbered links between two nodes. The Local Interface ID is
generally readily available. One of the mechanisms to obtain remote generally readily available. One of the mechanisms to obtain the
interface-id is described in [RFC4203]. Remote Interface ID is described in [RFC4203].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface ID | | Local Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID | | Remote Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Local/Remote Interface ID Sub-TLV Figure 3: Local/Remote Interface ID Sub-TLV
Type : TBA (suggested value 9) Type: 9
Length: 8 Length: 8
Value: 4 octets of Local Interface ID followed by 4 octets of Remote Value: 4 octets of the Local Interface ID followed by 4 octets of the
interface ID. Remote Interface ID.
4.4. OSPFv3 Graceful-Link-Shutdown sub-TLV 4.4. OSPFv3 Graceful-Link-Shutdown Sub-TLV
The Graceful-Link-Shutdown sub-TLV is carried in the Router-Link TLV The Graceful-Link-Shutdown sub-TLV is carried in the Router-Link TLV
as defined in the [I-D.ietf-ospf-ospfv3-lsa-extend] for OSPFv3. The as defined in [RFC8362] for OSPFv3. The Router-Link TLV contains the
Router-Link TLV contains the neighbour interface-id and can uniquely Neighbor Interface ID and can uniquely identify the link on the
identify the link on the remote node. remote node.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Graceful-Link-Shutdown sub-TLV for OSPFv3 Figure 4: Graceful-Link-Shutdown Sub-TLV for OSPFv3
Type : TBA (Suggested value 7) Type: 8
Length: 0 Length: 0
4.5. BGP-LS Graceful-Link-Shutdown TLV 4.5. BGP-LS Graceful-Link-Shutdown TLV
BGP-LS as defined in [RFC7752] is a mechanism to distribute network BGP-LS as defined in [RFC7752] is a mechanism that distributes
information to the external entities using BGP routing protocol. network information to the external entities using the BGP routing
Graceful-link-shutdown is an important link information that the protocol. Graceful link shutdown is important link information that
external entities can use for various use cases as defined in the external entities can use for various use cases as defined in
Section 7. BGP Link NLRI is used to carry the link information. A Section 7. BGP Link Network Layer Reachability Information (NLRI) is
new TLV called Graceful-Link-Shutdown is defined to describe the link used to carry the link information. A new TLV called "Graceful-Link-
attribute corresponding to graceful-link-shutdown state. The TLV Shutdown" is defined to describe the link attribute corresponding to
format is as described in [RFC7752] sec 3.1. There is no value field graceful-link-shutdown state. The TLV format is as described in
and length field is set to zero for this TLV. Section 3.1 of [RFC7752]. There is no Value field, and the Length
field is set to zero for this TLV.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Graceful-Link-Shutdown TLV for BGP-LS Figure 5: Graceful-Link-Shutdown TLV for BGP-LS
Type : TBA (Suggested value 1121) Type: 1121
Length: 0 Length: 0
4.6. Distinguishing parallel links 4.6. Distinguishing Parallel Links
++++++++++I.w I.y +++++++++ ++++++++++I.w I.y+++++++++++
|Router A|------------------|Router B | |Router A|------------------|Router B |
| |------------------| | | |------------------| |
++++++++++I.x I.z++++++++++ ++++++++++I.x I.z+++++++++++
Figure 6: Parallel Linkls Figure 6: Parallel Links
Consider two routers A and B connected with two parallel point-to- Consider two routers, A and B, connected with two parallel
point interfaces. I.w and I.x represent the Interface address on point-to-point interfaces. I.w and I.x represent the interface
Router A's side and I.y and I.z represent Interface addresses on address on Router A's side, and I.y and I.z represent interface
Router B's side. The extended link opaque LSA as described in addresses on Router B's side. The Extended Link Opaque LSA as
[RFC7684] describes links using link-type, Link-ID and Link-data. defined in [RFC7684] describes links using Link Type, Link ID, and
For ex. Link with address I.w is described as below on Router A. Link Data. For example, a link with the address I.w is described as
below on Router A.
Link-type = Point-to-point Link Type = Point-to-point
Link-ID: Router-ID of B Link ID = Router ID of B
Link-Data = I.w Link Data = I.w
A third node (controller or head-end) in the network cannot A third node (controller or head-end) in the network cannot
distinguish the Interface on router B which is connected to this distinguish the interface on Router B, which is connected to this
particular Interface with the above information. Interface with particular Interface on Router A based on the link information
address I.y or I.z could be chosen due to this ambiguity. In such described above. The interface with address I.y or I.z could be
cases Remote-IPv4 Address sub-TLV should be originated and added to chosen due to this ambiguity. In such cases, a Remote IPv4 Address
the Extended Link TLV. The use cases as described in Section 7 sub-TLV should be originated and added to the Extended Link TLV. The
require controller or head-end nodes to interpret the graceful-link- use cases as described in Section 7 require controller or head-end
shutdown information and hence the need for the Remote IPv4 address nodes to interpret the graceful-link-shutdown information and hence
sub-TLV. I.y is carried in the Extended Link TLV which unambiguously the need for the Remote IPv4 Address sub-TLV. I.y is carried in the
identifies the interface on the remote side. OSPFv3 Router-link-TLV Extended Link TLV, which unambiguously identifies the interface on
as described in [I-D.ietf-ospf-ospfv3-lsa-extend] contains Interface the remote side. The OSPFv3 Router-Link TLV as described in
ID and neighbor's Interface-ID which can uniquely identify connecting [RFC8362] contains an Interface ID and a neighbor's Interface ID,
interface on the remote side and hence OSPFv3 does not require which can uniquely identify connecting the interface on the remote
seperate Remote-IPv6 address to be advertised along with the OSPFv3- side; hence, OSPFv3 does not require a separate remote IPv6 address
Graceful-Link-Shutdown sub-TLV. to be advertised along with the OSPFv3 Graceful-Link-Shutdown
sub-TLV.
5. Elements of procedure 5. Elements of Procedure
As defined in [RFC7684] every link on the node will have a separate As defined in [RFC7684], every link on the node will have a separate
Extended Link Opaque LSA. The node that has the link to be taken out Extended Link Opaque LSA. The node that has the link to be taken out
of service MUST advertise the Graceful-Link-Shutdown sub-TLV in the of service MUST advertise the Graceful-Link-Shutdown sub-TLV in the
Extended Link TLV of the Extended Link Opaque LSA as defined in Extended Link TLV of the Extended Link Opaque LSA for OSPFv2, as
[RFC7684] for OSPFv2 and Router-Link TLV of E-Router-LSA for OSPFv3. defined in [RFC7684], and in the Router-Link TLV of E-Router-LSA for
The Graceful-Link-Shutdown sub-TLV indicates that the link identified OSPFv3. The Graceful-Link-Shutdown sub-TLV indicates that the link
by the sub-TLV is subjected to maintenance. identified by the sub-TLV is subjected to maintenance.
For the purposes of changing the metric OSPFv2 and OSPFv3 Router-LSAs For the purposes of changing the metric OSPFv2 and OSPFv3 Router-LSAs
need to be re-orignated and for Traffic Engineering metric, TE Opaque need to be reoriginated. To change the Traffic Engineering metric,
LSAs [RFC3630] in OSPFv2 and Intra-area-TE-LSA [RFC5329]in OSPFv3 TE Opaque LSAs in OSPFv2 [RFC3630] and Intra-area-TE-LSAs in OSPFv3
need to be re-originated. [RFC5329] need to be reoriginated.
The Graceful-Link-Shutdown information is advertised as a property of The graceful-link-shutdown information is advertised as a property of
the link and is flooded through the area. This information can be the link and is flooded through the area. This information can be
used by ingress routers or controllers to take special actions. An used by ingress routers or controllers to take special actions. An
application specific to this use case is described in Section 7.2. application specific to this use case is described in Section 7.2.
When a link is ready to carry traffic, the Graceful-Lnk-Shutdown sub- When a link is ready to carry traffic, the Graceful-Link-Shutdown
TLV MUST be removed from the Extended Link TLV/Router-Link TLV and sub-TLV MUST be removed from the Extended Link TLV/Router-Link TLV,
the corresponding LSAs MUST be readvertised. Similarly, metric MUST and the corresponding LSAs MUST be readvertised. Similarly, the
be set to original values and corresponding LSAs MUST be metric MUST be set to original values, and the corresponding LSAs
readvertised. MUST be readvertised.
The procedures described in this draft may be used to divert the The procedures described in this document may be used to divert the
traffic away from the link in scenarios other than link-shutdown or traffic away from the link in scenarios other than link-shutdown or
link-replacement activity. link-replacement activity.
The precise action taken by the remote node at the other end of the The precise action taken by the remote node at the other end of the
link identified for graceful-shutdown depends on the link type. link identified for graceful-shutdown depends on the link type.
5.1. Point-to-point links 5.1. Point-to-Point Links
The node that has the link to be taken out of service MUST set metric The node that has the link to be taken out of service MUST set the
of the link to MaxLinkMetric (0xffff) and re-originate its router- metric of the link to MaxLinkMetric (0xffff) and reoriginate its
LSA. The Traffic Engineering metric of the link SHOULD be set to Router-LSA. The Traffic Engineering metric of the link SHOULD be set
(0xffffffff) and the node SHOULD re-originate the corresponding TE to (0xffffffff), and the node SHOULD reoriginate the corresponding TE
Link Opaque LSAs. When a Graceful-Link-Shutdown sub-TLV is received Link Opaque LSAs. When a Graceful-Link-Shutdown sub-TLV is received
for a point-to-point link, the remote node MUST identify the local for a point-to-point link, the remote node MUST identify the local
link which corresponds to the graceful-shutdown link and set its link that corresponds to the graceful-shutdown link and set its
metric to MaxLinkMetric (0xffff) and the remote node MUST re- metric to MaxLinkMetric (0xffff), and the remote node MUST
originate its router-LSA with the changed metric. When TE is reoriginate its Router-LSA with the changed metric. When TE is
enabled, the Traffic Engineering metric of the link SHOULD be set to enabled, the Traffic Engineering metric of the link SHOULD be set to
(0xffffffff) and follow procedures of [RFC5817]. Similarly, the (0xffffffff) and follow the procedures in [RFC5817]. Similarly, the
remote node SHOULD set the Traffic Engineering metric of the link to remote node SHOULD set the Traffic Engineering metric of the link to
0xffffffff and SHOULD re-originate the TE Link Opaque LSA for the 0xffffffff and SHOULD reoriginate the TE Link Opaque LSA for the link
link with the new value. with the new value.
The Extended link opaque LSAs and the Extended link TLV are not The Extended Link Opaque LSAs and the Extended Link TLV are not
scoped for multi-topology [RFC4915]. In multi-topology deployments scoped for multi-topology [RFC4915]. In multi-topology deployments
[RFC4915], the Graceful-Link-Shutdown sub-TLV advertised in an [RFC4915], the Graceful-Link-Shutdown sub-TLV advertised in an
Extended Link opaque LSA corresponds to all the topologies which Extended Link Opaque LSA corresponds to all the topologies that
include the link. The receiver node SHOULD change the metric in the include the link. The receiver node SHOULD change the metric in the
reverse direction for all the topologies which include the remote reverse direction for all the topologies that include the remote link
link and re-originate the router-LSA as defined in [RFC4915]. and reoriginate the Router-LSA as defined in [RFC4915].
When the originator of the Graceful-Link-Shutdown sub-TLV purges the When the originator of the Graceful-Link-Shutdown sub-TLV purges the
Extended Link Opaque LSA or re-originates it without the Graceful- Extended Link Opaque LSA or reoriginates it without the
Link-Shutdown sub-TLV, the remote node must re-originate the Graceful-Link-Shutdown sub-TLV, the remote node must reoriginate the
appropriate LSAs with the metric and TE metric values set to their appropriate LSAs with the metric and TE metric values set to their
original values. original values.
5.2. Broadcast/NBMA links 5.2. Broadcast/NBMA Links
Broadcast or NBMA networks in OSPF are represented by a star topology Broadcast or Non-Broadcast Multi-Access (NBMA) networks in OSPF are
where the Designated Router (DR) is the central point to which all represented by a star topology where the Designated Router (DR) is
other routers on the broadcast or NBMA network logically connect. As the central point to which all other routers on the broadcast or NBMA
a result, routers on the broadcast or NBMA network advertise only network logically connect. As a result, routers on the broadcast or
their adjacency to the DR. Routers that do not act as DR do not form NBMA network advertise only their adjacency to the DR. Routers that
or advertise adjacencies with each other. For the Broadcast links, do not act as DRs do not form or advertise adjacencies with each
the MaxLinkMetric on the remote link cannot be changed since all the other. For the broadcast links, the MaxLinkMetric on the remote link
neighbors are on same link. Setting the link cost to MaxLinkMetric cannot be changed since all the neighbors are on same link. Setting
would impact paths going via all neighbors. the link cost to MaxLinkMetric would impact all paths that traverse
any of the neighbors connected on that broadcast link.
The node that has the link to be taken out of service MUST set metric The node that has the link to be taken out of service MUST set the
of the link to MaxLinkMetric (0xffff) and re-originate the Router- metric of the link to MaxLinkMetric (0xffff) and reoriginate the
LSA. The Traffic Engineering metric of the link SHOULD be set to ( Router-LSA. The Traffic Engineering metric of the link SHOULD be set
0xffffffff) and the node SHOULD re-originate the corresponding TE to (0xffffffff), and the node SHOULD reoriginate the corresponding TE
Link Opaque LSAs. For a broadcast link, the two part metric as Link Opaque LSAs. For a broadcast link, the two-part metric as
described in [RFC8042] is used. The node originating the Graceful- described in [RFC8042] is used. The node originating the
Link-Shutdown sub-TLV MUST set the metric in the Network-to-Router Graceful-Link-Shutdown sub-TLV MUST set the metric in the
Metric sub-TLV to MaxLinkMetric (0xffff) for OSPFv2 and OSPFv3 and Network-to-Router Metric sub-TLV to MaxLinkMetric (0xffff) for OSPFv2
re-originate the corresponding LSAs. The nodes that receive the two- and OSPFv3 and reoriginate the corresponding LSAs. The nodes that
part metric should follow the procedures described in [RFC8042]. The receive the two-part metric should follow the procedures described in
backward compatibility procedures described in [RFC8042] should be [RFC8042]. The backward-compatibility procedures described in
followed to ensure loop free routing. [RFC8042] should be followed to ensure loop-free routing.
5.3. Point-to-multipoint links 5.3. Point-to-Multipoint Links
Operation for the point-to-multipoint links is similar to the point- Operation for the point-to-multipoint (P2MP) links is similar to the
to-point links. When a Graceful-Link-Shutdown sub-TLV is received point-to-point links. When a Graceful-Link-Shutdown sub-TLV is
for a point-to-multipoint link the remote node MUST identify the received for a point-to-multipoint link, the remote node MUST
neighbour which corresponds to the graceful-shutdown link and set its identify the neighbor that corresponds to the graceful-shutdown link
metric to MaxLinkMetric (0xffff). The remote node MUST re-originate and set its metric to MaxLinkMetric (0xffff). The remote node MUST
the router-LSA with the changed metric for the correponding neighbor. reoriginate the Router-LSA with the changed metric for the
corresponding neighbor.
5.4. Unnumbered interfaces 5.4. Unnumbered Interfaces
Unnumbered interfaces do not have a unique IP address and borrow Unnumbered interfaces do not have a unique IP address and borrow
their address from other interfaces. [RFC2328] describes procedures their address from other interfaces. [RFC2328] describes procedures
to handle unnumbered interfaces in the context of the router-LSA. We to handle unnumbered interfaces in the context of the Router-LSA. We
apply a similar procedure to the Extended Link TLV advertising the apply a similar procedure to the Extended Link TLV advertising the
Graceful-Link-Shutdown sub-TLV in order to handle unnumbered Graceful-Link-Shutdown sub-TLV in order to handle unnumbered
interfaces. The link-data field in the Extended Link TLV includes interfaces. The Link-Data field in the Extended Link TLV includes
the Local interface-id instead of the IP address. The Local/Remote the Local Interface ID instead of the IP address. The Local/Remote
Interface ID sub-TLV MUST be advertised when there are multiple Interface ID sub-TLV MUST be advertised when there are multiple
parallel unnumbered interfaces between two nodes. One of the parallel unnumbered interfaces between two nodes. One of the
mechanisms to obtain the interface-id of the remote side is defined mechanisms to obtain the Interface ID of the remote side is defined
in [RFC4203]. in [RFC4203].
5.5. Hybrid Broadcast and P2MP interfaces 5.5. Hybrid Broadcast and P2MP Interfaces
Hybrid Broadcast and P2MP interfaces represent a broadcast network Hybrid Broadcast and P2MP interfaces represent a broadcast network
modeled as P2MP interfaces. [RFC6845] describes procedures to handle modeled as P2MP interfaces. [RFC6845] describes procedures to handle
these interfaces. Operation for the Hybrid interfaces is similar to these interfaces. Operation for the Hybrid interfaces is similar to
the P2MP interfaces. When a Graceful-Link-Shutdown sub-TLV is operation for the P2MP interfaces. When a Graceful-Link-Shutdown
received for a hybrid link, the remote node MUST identify the sub-TLV is received for a hybrid link, the remote node MUST identify
neighbor which corresponds to the graceful-shutdown link and set its the neighbor that corresponds to the graceful-shutdown link and set
metric to MaxLinkMetric (0xffff). All the remote nodes connected to its metric to MaxLinkMetric (0xffff). All the remote nodes connected
originator MUST re-originate the router-LSA with the changed metric to the originator MUST reoriginate the Router-LSA with the changed
for the neighbor. metric for the neighbor.
6. Backward compatibility 6. Backward Compatibility
The mechanisms described in the document are fully backward The mechanisms described in the document are fully backward
compatible. It is required that the node adverting the Graceful- compatible. It is required that the node adverting the
Link-Shutdown sub-TLV as well as the node at the remote end of the Graceful-Link-Shutdown sub-TLV as well as the node at the remote end
graceful-shutdown link support the extensions described herein for of the graceful-shutdown link support the extensions described herein
the traffic to diverted from the graceful-shutdown link. If the for the traffic to be diverted from the graceful-shutdown link. If
remote node doesn't support the capability, it will still use the the remote node doesn't support the capability, it will still use the
graceful-shutdown link but there are no other adverse effects. In graceful-shutdown link, but there are no other adverse effects. In
the case of broadcast links using two-part metrics, the backward the case of broadcast links using two-part metrics, the backward-
compatibility procedures as described in [RFC8042] are applicable. compatibility procedures as described in [RFC8042] are applicable.
7. Applications 7. Applications
7.1. Overlay Network 7.1. Overlay Network
Many service providers offer L2 services to a customer connecting Many service providers offer L2 services to a customer connecting
different locations. The customer's IGP protocol creates a seamless different locations. The customer's IGP protocol creates a seamless
private network (overlay network) across the locations for the private network (overlay network) across the locations for the
customer. Service providers want to offer graceful-shutdown customer. Service providers want to offer graceful-shutdown
functionality when the PE device is taken-out for maintenance. There functionality when the PE device is taken out for maintenance. There
can be large number of customers attached to a PE node and the remote can be large number of customers attached to a PE node, and the
end-points for these L2 attachments circuits are spread across the remote endpoints for these L2 attachment circuits are spread across
service provider's network. It is a tedious and error-prone process the service provider's network. Changing the metric for all
to change the metric for all corresponding L2 circuits in both corresponding L2 circuits in both directions is a tedious and error-
directions. The graceful-link-shutdown feature simplifies the prone process. The graceful-link-shutdown feature simplifies the
process by increasing the metric on the CE-CE overlay link so that process by increasing the metric on the CE-CE overlay link so that
traffic in both directions is diverted away from the PE undergoing traffic in both directions is diverted away from the PE undergoing
maintenance. The Graceful-Link-Shutdown feature allows the link to maintenance. The graceful-link-shutdown feature allows the link to
be used as a last resort link so that traffic is not disrupted when be used as a last-resort link so that traffic is not disrupted when
alternate paths are not available. alternate paths are not available.
------PE3---------------PE4------CE3 ------PE3---------------PE4------CE3
/ \ / \
/ \ / \
CE1---------PE1----------PE2---------CE2 CE1---------PE1----------PE2---------CE2
\ \
\ \
------CE4 ------CE4
CE: Customer Edge
PE: Provider Edge
Figure 7: Overlay Network Figure 7: Overlay Network
In the example shown in Figure 7, when the PE1 node is going out of In the example shown in Figure 7, when the PE1 node is going out of
service for maintenance, a service provider sets the PE1 to stub- service for maintenance, a service provider sets the PE1 to stub-
router state and communicates the pending maintenance action to the router state and communicates the pending maintenance action to the
overlay customer networks. The mechanisms used to communicate overlay customer networks. The mechanisms used to communicate
between PE1 and CE1 is outside the scope of this document. CE1 sets between PE1 and CE1 is outside the scope of this document. CE1 sets
the graceful-link-shutdown state on its links connecting CE3, CE2 and the graceful-link-shutdown state on its links connecting CE3, CE2,
CE4 and changes the metric to MaxLinkMetric and re-originates the and CE4, changes the metric to MaxLinkMetric, and reoriginates the
corresponding LSA. The remote end of the link at CE3, CE2, and CE4 corresponding LSA. The remote end of the link at CE3, CE2, and CE4
also set the metric on the link to MaxLinkMetric and the traffic from also set the metric on the link to MaxLinkMetric, and the traffic
both directions gets diverted away from PE1. from both directions gets diverted away from PE1.
7.2. Controller based Deployments 7.2. Controller-Based Deployments
In controller-based deployments where the controller participates in In controller-based deployments where the controller participates in
the IGP protocol, the controller can also receive the graceful-link- the IGP protocol, the controller can also receive the
shutdown information as a warning that link maintenance is imminent. graceful-link-shutdown information as a warning that link maintenance
Using this information, the controller can find alternate paths for is imminent. Using this information, the controller can find
traffic which uses the affected link. The controller can apply alternate paths for traffic that uses the affected link. The
various policies and re-route the LSPs away from the link undergoing controller can apply various policies and reroute the LSPs away from
maintenance. If there are no alternate paths satisfying the the link undergoing maintenance. If there are no alternate paths
constraints, the controller might temporarily relax those constraints satisfying the constraints, the controller might temporarily relax
and put the service on a different path. Increasing the link metric those constraints and put the service on a different path.
alone does not specify the maintenance activity as the metric could Increasing the link metric alone does not specify the maintenance
increase in events such as LDP-IGP synchronisation. An explicit activity as the metric could increase in events such as LDP-IGP
indication from the router using the graceful-link-shutdown sub-TLV synchronization. An explicit indication from the router using the
is needed to inform the Controller or head-end routers. Graceful-Link-Shutdown sub-TLV is needed to inform the controller or
head-end routers.
_____________ _____________
| | | |
-------------| Controller |-------------- --------------| Controller |--------------
| |____________ | | | |____________ | |
| | | |
|--------- Primary Path ------------------| |--------- Primary Path ------------------|
PE1---------P1----------------P2---------PE2 PE1---------P1----------------P2---------PE2
| | | |
| | | |
|________P3________| |________P3________|
Alternate Path Alternate Path
Figure 8: Controller based Traffic Engineering Figure 8: Controller-Based Traffic Engineering
In the above example, PE1->PE2 LSP is set-up to satisfy a constraint In the above example, the PE1->PE2 LSP is set up to satisfy a
of 10 Gbps bandwidth on each link. The links P1->P3 and P3->P2 have constraint of 10 Gbps bandwidth on each link. The links P1->P3 and
only 1 Gbps capacity and there is no alternate path satisfying the P3->P2 have only 1 Gbps capacity, and there is no alternate path
bandwidth constraint of 10Gbps. When P1->P2 link is being prepared satisfying the bandwidth constraint of 10 Gbps. When the P1->P2 link
for maintenance, the controller receives the graceful-link-shutdown is being prepared for maintenance, the controller receives the
information, as there is no alternate path available which satisfies graceful-link-shutdown information, as there is no alternate path
the constraints, the controller chooses a path that is less optimal available that satisfies the constraints, and the controller chooses
and temporarily sets up an alternate path via P1->P3->P2. Once the a path that is less optimal and temporarily sets up an alternate path
traffic is diverted, the P1->P2 link can be taken out of service for via P1->P3->P2. Once the traffic is diverted, the P1->P2 link can be
maintenance/upgrade. taken out of service for maintenance/upgrade.
7.3. L3VPN Services and sham-links 7.3. L3VPN Services and Sham Links
Many service providers offer L3VPN services to customers and CE-PE Many service providers offer Layer 3 Virtual Private Network (L3VPN)
links run OSPF [RFC4577]. When PE is taken out of service for services to customers, and CE-PE links run OSPF [RFC4577]. When the
maintenance, all the links on the PE can be set to graceful-link- PE is taken out of service for maintenance, all the links on the PE
shutdown state which will gurantee that the traffic to/from dual- can be set to graceful-link-shutdown state, which will guarantee that
homed CEs gets diverted. The interaction between OSPF and BGP is the traffic to/from dual-homed CEs gets diverted. The interaction
outside the scope of this document. [RFC6987] based mechanism with between OSPF and BGP is outside the scope of this document. A
summaries and externals advertised with high metrics could also be mechanism based on [RFC6987] with summaries and externals that are
used to achieve the same functionality when implementations support advertised with high metrics could also be used to achieve the same
high metrics advertisement for summaries and externals. functionality when implementations support high metrics advertisement
for summaries and externals.
Another useful usecase is when ISPs provide sham-link services to Another useful use case is when ISPs provide sham-link services to
customers [RFC4577]. When PE goes out of service for maintenance, customers [RFC4577]. When the PE goes out of service for
all sham-links on the PE can be set to graceful-link-shutdown state maintenance, all sham links on the PE can be set to graceful-link-
and traffic can be divered from both ends without having to touch the shutdown state, and traffic can be diverted from both ends without
configurations on the remote end of the sham-links. having to touch the configurations on the remote end of the sham
links.
7.4. Hub and spoke deployment 7.4. Hub and Spoke Deployment
OSPF is largely deployed in Hub and Spoke deployments with a large OSPF is largely deployed in Hub and Spoke deployments with a large
number of spokes connecting to the Hub. It is a general practice to number of Spokes connecting to the Hub. It is a general practice to
deploy multiple Hubs with all spokes connecting to these Hubs to deploy multiple Hubs with all Spokes connecting to these Hubs to
achieve redundancy. The [RFC6987] mechanism can be used to divert achieve redundancy. The mechanism defined in [RFC6987] can be used
the spoke-to-spoke traffic from the overloaded hub router. The to divert the Spoke-to-Spoke traffic from the overloaded Hub router.
traffic that flows from spokes via the hub into an external network The traffic that flows from Spokes via the Hub into an external
may not be diverted in certain scenarios.When a Hub node goes down network may not be diverted in certain scenarios. When a Hub node
for maintenance, all links on the Hub can be set to graceful-link- goes down for maintenance, all links on the Hub can be set to
shutdown state and traffic gets divered from the spoke sites as well graceful-link-shutdown state, and traffic gets diverted from the
without having to make configuration changes on the spokes. Spoke sites as well without having to make configuration changes on
the Spokes.
8. Security Considerations 8. Security Considerations
This document utilizes the OSPF packets and LSAs described in This document utilizes the OSPF packets and LSAs described in
[RFC2328] , [RFC5340] , [RFC3630] and [RFC5329]. The authentication [RFC2328] , [RFC3630], [RFC5329], and [RFC5340]. The authentication
procedures described in [RFC2328] for OSPFv2 and [RFC4552] for OSPFv3 procedures described in [RFC2328] for OSPFv2 and [RFC4552] for OSPFv3
are applicable to this document as well. This document does not are applicable to this document as well. This document does not
introduce any further security issues other than those discussed in introduce any further security issues other than those discussed in
[RFC2328] and [RFC5340]. [RFC2328] and [RFC5340].
9. IANA Considerations 9. IANA Considerations
This specification updates one OSPF registry: IANA has registered the following in the "OSPFv2 Extended Link TLV
Sub-TLVs" registry:
OSPFv2 Extended Link TLV Sub-TLVs
i) Graceful-Link-Shutdown Sub-TLV - Suggested value 7
ii) Remote IPv4 Address Sub-TLV - Suggested value 8
iii) Local/Remote Interface ID Sub-TLV - Suggested Value 9
OSPFv3 Extended-LSA sub-TLV Registry
i) Graceful-Link-Shutdown sub-TLV - suggested value 7 7 - Graceful-Link-Shutdown Sub-TLV
BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and 8 - Remote IPv4 Address Sub-TLV
Attribute TLVs [RFC7752]
i)Graceful-Link-Shutdown TLV - Suggested 1121 9 - Local/Remote Interface ID Sub-TLV
10. Acknowledgements IANA has registered the following value in the "OSPFv3 Extended-LSA
Sub-TLVs" registry:
Thanks to Chris Bowers for valuable inputs and edits to the document. 8 - Graceful-Link-Shutdown sub-TLV
Thanks to Jeffrey Zhang, Acee Lindem and Ketan Talaulikar for inputs.
Thanks to Karsten Thomann for careful review and inputs on the
applications where graceful-link-shutdown is useful.
Thanks to Alia Atlas, Deborah Brungard, Alvaro Retana, Andrew G. IANA has registered the following value in the "BGP-LS Node
Malis and Tim Chown for valuable inputs. Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs"
registry [RFC7752]":
11. References 1121 - Graceful-Link-Shutdown TLV
11.1. Normative References 10. References
[I-D.ietf-ospf-ospfv3-lsa-extend] 10.1. Normative References
Lindem, A., Roy, A., Goethals, D., Vallem, V., and F.
Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3-
lsa-extend-23 (work in progress), January 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
skipping to change at page 15, line 44 skipping to change at page 15, line 35
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
[RFC8042] Zhang, Z., Wang, L., and A. Lindem, "OSPF Two-Part [RFC8042] Zhang, Z., Wang, L., and A. Lindem, "OSPF Two-Part
Metric", RFC 8042, DOI 10.17487/RFC8042, December 2016, Metric", RFC 8042, DOI 10.17487/RFC8042, December 2016,
<https://www.rfc-editor.org/info/rfc8042>. <https://www.rfc-editor.org/info/rfc8042>.
11.2. Informative References [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>.
[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>.
10.2. Informative References
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<https://www.rfc-editor.org/info/rfc4203>. <https://www.rfc-editor.org/info/rfc4203>.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>. <https://www.rfc-editor.org/info/rfc4552>.
[RFC4577] Rosen, E., Psenak, P., and P. Pillay-Esnault, "OSPF as the [RFC4577] Rosen, E., Psenak, P., and P. Pillay-Esnault, "OSPF as the
Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Provider/Customer Edge Protocol for BGP/MPLS IP Virtual
Private Networks (VPNs)", RFC 4577, DOI 10.17487/RFC4577, Private Networks (VPNs)", RFC 4577, DOI 10.17487/RFC4577,
June 2006, <https://www.rfc-editor.org/info/rfc4577>. June 2006, <https://www.rfc-editor.org/info/rfc4577>.
[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,
<https://www.rfc-editor.org/info/rfc4915>. <https://www.rfc-editor.org/info/rfc4915>.
Acknowledgements
Thanks to Chris Bowers for valuable input and edits to the document.
Thanks to Jeffrey Zhang, Acee Lindem, and Ketan Talaulikar for their
input. Thanks to Karsten Thomann for careful review and input on the
applications where graceful link shutdown is useful.
Thanks to Alia Atlas, Deborah Brungard, Alvaro Retana, Andrew G.
Malis, and Tim Chown for their valuable input.
Authors' Addresses Authors' Addresses
Shraddha Hegde Shraddha Hegde
Juniper Networks, Inc. Juniper Networks, Inc.
Embassy Business Park Embassy Business Park
Bangalore, KA 560093 Bangalore, KA 560093
India India
Email: shraddha@juniper.net Email: shraddha@juniper.net
Pushpasis Sarkar Pushpasis Sarkar
Arrcus, Inc. Arrcus, Inc.
Email: pushpasis.ietf@gmail.com Email: pushpasis.ietf@gmail.com
Hannes Gredler Hannes Gredler
Individual RtBrick Inc.
Email: hannes@gredler.at Email: hannes@rtbrick.com
Mohan Nanduri Mohan Nanduri
ebay Corporation ebay Corporation
2025 Hamilton Avenue 2025 Hamilton Avenue
San Jose, CA 98052 San Jose, CA 98052
US United States of America
Email: mnanduri@ebay.com Email: mnanduri@ebay.com
Luay Jalil Luay Jalil
Verizon Verizon
Email: luay.jalil@verizon.com Email: luay.jalil@verizon.com
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