draft-ietf-ospf-link-overload-12.txt   draft-ietf-ospf-link-overload-13.txt 
Open Shortest Path First IGP S. Hegde Open Shortest Path First IGP S. Hegde
Internet-Draft Juniper Networks, Inc. Internet-Draft Juniper Networks, Inc.
Intended status: Standards Track P. Sarkar Intended status: Standards Track P. Sarkar
Expires: July 20, 2018 H. Gredler Expires: July 25, 2018 H. Gredler
Individual Individual
M. Nanduri M. Nanduri
ebay Corporation ebay Corporation
L. Jalil L. Jalil
Verizon Verizon
January 16, 2018 January 21, 2018
OSPF Graceful Link shutdown OSPF Graceful Link shutdown
draft-ietf-ospf-link-overload-12 draft-ietf-ospf-link-overload-13
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 routers in an OSPFv2 or OSPFv3 routing domain to be It is useful for routers in an OSPFv2 or OSPFv3 routing domain to be
able to advertise a link as being in a graceful-shutdown state to able to advertise a link as being in a graceful-shutdown state to
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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 July 20, 2018. This Internet-Draft will expire on July 25, 2018.
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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Flooding Scope . . . . . . . . . . . . . . . . . . . . . . . 4 3. Flooding Scope . . . . . . . . . . . . . . . . . . . . . . . 4
4. Graceful-Link-Shutdown sub-TLV . . . . . . . . . . . . . . . 4 4. Graceful-Link-Shutdown sub-TLV . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . 5 4.2. Remote IPv4 Address Sub-TLV . . . . . . . . . . . . . . . 5
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 . . . . . . . . . . . . . . . . . . 8 5.1. Point-to-point links . . . . . . . . . . . . . . . . . . 8
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is useful to be able to advertise the impending maintenance activity is useful to be able to advertise the impending maintenance activity
on the link and to have LSP re-routing policies at the ingress to on the link and to have LSP re-routing policies at the ingress to
route the LSPs away from the link. route the LSPs away from 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 pseudo-wires 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 the maintenance is
actually performed. Since the nodes in the underlying network are actually performed. Since the nodes in the underlying network are
not visible to OSPF, the existing stub router mechanism described in not visible to OSPF, the existing stub router mechanism described in
[RFC6987] cannot be used. An application specific to this use case [RFC6987] cannot be used. In a service provider's network, there may
is described in Section 7.1. be many CE-to-CE connections that run over a single PE. It is
cumbersome to change the metric on every CE-to-CE connection in both
directions. This document provides a mechanism to change metric in
other direction of the link and also use the link as a last-resort-
link if no alternate paths are available. An application specific to
this use case is described in detail in Section 7.1.
The procedures described in this draft may be used to divert the The procedures described in this draft may be used to divert the
traffic away from the link in other scenarios and is not restricted traffic away from the link in other scenarios and is not restricted
to link-shutdown or link-replacement activity. to link-shutdown or link-replacement activity.
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]. Throughout this document, OSPF is Attribute Advertisement [RFC7684]. Throughout this document, OSPF is
used when the text applies to both OSPFv2 and OSPFv3. OSPFv2 or used when the text applies to both OSPFv2 and OSPFv3. OSPFv2 or
OSPFv3 is used when the text is specific to one version of the OSPF OSPFv3 is used when the text is specific to one version of the OSPF
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