draft-ietf-rtgwg-multihomed-prefix-lfa-03.txt   draft-ietf-rtgwg-multihomed-prefix-lfa-04.txt 
Routing Area Working Group P. Sarkar, Ed. Routing Area Working Group P. Sarkar, Ed.
Internet-Draft Arrcus, Inc. Internet-Draft Arrcus, Inc.
Updates: 5286 (if approved) S. Hegde Updates: 5286 (if approved) S. Hegde
Intended status: Standards Track C. Bowers Intended status: Standards Track Juniper Networks, Inc.
Expires: May 3, 2018 Juniper Networks, Inc. Expires: June 4, 2018 U. Chunduri, Ed.
U. Chunduri, Ed.
Huawei Technologies Huawei Technologies
J. Tantsura J. Tantsura
Individual Individual
B. Decraene
Orange
H. Gredler H. Gredler
RtBrick, Inc. RtBrick, Inc.
October 30, 2017 December 1, 2017
LFA selection for Multi-Homed Prefixes LFA selection for Multi-Homed Prefixes
draft-ietf-rtgwg-multihomed-prefix-lfa-03 draft-ietf-rtgwg-multihomed-prefix-lfa-04
Abstract Abstract
This document shares experience gained from implementing algorithms This document shares experience gained from implementing algorithms
to determine Loop-Free Alternates for multi-homed prefixes. In to determine Loop-Free Alternates for multi-homed prefixes. In
particular, this document provides explicit inequalities that can be particular, this document provides explicit inequalities that can be
used to evaluate neighbors as a potential alternates for multi-homed used to evaluate neighbors as a potential alternates for multi-homed
prefixes. It also provides detailed criteria for evaluating prefixes. It also provides detailed criteria for evaluating
potential alternates for external prefixes advertised by OSPF ASBRs. potential alternates for external prefixes advertised by OSPF ASBRs.
This documents updates and expands some of the "Routing Aspects" as This documents updates and expands some of the "Routing Aspects" as
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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 June 4, 2018.
This Internet-Draft will expire on May 3, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4.2.4. RFC1583compatibility is set to enabled . . . . . . . 11 4.2.4. RFC1583compatibility is set to enabled . . . . . . . 11
4.2.5. Type 7 routes . . . . . . . . . . . . . . . . . . . . 11 4.2.5. Type 7 routes . . . . . . . . . . . . . . . . . . . . 11
4.2.6. Inequalities to be applied for alternate ASBR 4.2.6. Inequalities to be applied for alternate ASBR
selection . . . . . . . . . . . . . . . . . . . . . . 11 selection . . . . . . . . . . . . . . . . . . . . . . 11
4.2.6.1. Forwarding address set to non-zero value . . . . 11 4.2.6.1. Forwarding address set to non-zero value . . . . 11
4.2.6.2. ASBRs advertising type1 and type2 cost . . . . . 12 4.2.6.2. ASBRs advertising type1 and type2 cost . . . . . 12
5. LFA Extended Procedures . . . . . . . . . . . . . . . . . . . 13 5. LFA Extended Procedures . . . . . . . . . . . . . . . . . . . 13
5.1. Links with IGP MAX_METRIC . . . . . . . . . . . . . . . . 13 5.1. Links with IGP MAX_METRIC . . . . . . . . . . . . . . . . 13
5.2. Multi Topology Considerations . . . . . . . . . . . . . . 14 5.2. Multi Topology Considerations . . . . . . . . . . . . . . 14
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
The use of Loop-Free Alternates (LFA) for IP Fast Reroute is The use of Loop-Free Alternates (LFA) for IP Fast Reroute is
specified in [RFC5286]. Section 6.1 of [RFC5286] describes a method specified in [RFC5286]. Section 6.1 of [RFC5286] describes a method
to determine loop-free alternates for a multi-homed prefixes (MHPs). to determine loop-free alternates for a multi-homed prefixes (MHPs).
This document describes a procedure using explicit inequalities that This document describes a procedure using explicit inequalities that
can be used by a computing router to evaluate a neighbor as a can be used by a computing router to evaluate a neighbor as a
potential alternate for a multi-homed prefix. The results obtained potential alternate for a multi-homed prefix. The results obtained
are equivalent to those obtained using the method described in are equivalent to those obtained using the method described in
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the LFA principles laid out in [RFC5286] are actually applicable for the LFA principles laid out in [RFC5286] are actually applicable for
MT IS-IS [RFC5120] LFA SPF. The primary difference in this case is, MT IS-IS [RFC5120] LFA SPF. The primary difference in this case is,
identifying the eligible-set of neighbors for each LFA computation identifying the eligible-set of neighbors for each LFA computation
which is done per MT ID. The eligible-set for each MT ID is which is done per MT ID. The eligible-set for each MT ID is
determined by the presence of IGP adjacency from Source to the determined by the presence of IGP adjacency from Source to the
neighboring node on that MT-ID apart from the administrative neighboring node on that MT-ID apart from the administrative
restrictions and other checks laid out in [RFC5286]. The same is restrictions and other checks laid out in [RFC5286]. The same is
also applicable for MT-OSPF [RFC4915] or different AFs in multi also applicable for MT-OSPF [RFC4915] or different AFs in multi
instance OSPFv3 [RFC5838]. instance OSPFv3 [RFC5838].
However for MT IS-IS, if a "standart topology" is used with MT-ID #0 However for MT IS-IS, if a "standard topology" is used with MT-ID #0
[RFC5286] and both IPv4 [RFC5305] and IPv6 routes/AFs [RFC5308] are [RFC5286] and both IPv4 [RFC5305] and IPv6 routes/AFs [RFC5308] are
present, then the condition of network congruency is applicable for present, then the condition of network congruency is applicable for
LFA computation as well. Network congruency here refers to, having LFA computation as well. Network congruency here refers to, having
same address families provisioned on all the links and all the nodes same address families provisioned on all the links and all the nodes
of the network with MT-ID #0. Here with single decision process both of the network with MT-ID #0. Here with single decision process both
IPv4 and IPv6 next-hops are computed for all the prefixes in the IPv4 and IPv6 next-hops are computed for all the prefixes in the
network and similarly with one LFA computation from all eligible network and similarly with one LFA computation from all eligible
neighbors per [RFC5286], all potential alternatives can be computed. neighbors per [RFC5286], all potential alternatives can be computed.
6. Acknowledgements 6. Acknowledgements
Thanks to Alia Atlas and Salih K A for their useful feedback and Thanks to Alia Atlas and Salih K A for their useful feedback and
inputs. Thanks to Stewart Bryant for being document shepherd and inputs. Thanks to Stewart Bryant for being document shepherd and
providing detailed review comments. providing detailed review comments.
7. Security Considerations 7. Contributing Authors
The following people contributed substantially to the content of this
document and should be considered co-authors.
Chris Bowers
Juniper Networks, Inc.
1194 N. Mathilda Ave,
Sunnyvale, CA 94089, USA
Email: cbowers@juniper.ne
Bruno Decraene
Orange,
France
Email: bruno.decraene@orange.com
8. Security Considerations
This document does not introduce any change in any of the protocol This document does not introduce any change in any of the protocol
[RFC1195] [RFC5120] [RFC2328] [RFC5838] specifications discussed here [RFC1195] [RFC5120] [RFC2328] [RFC5838] specifications discussed here
and also this does not introduce any new security issues other than and also this does not introduce any new security issues other than
as noted in the LFA base specification [RFC5286]. as noted in the LFA base specification [RFC5286].
8. References 9. References
8.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for [RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
IP Fast Reroute: Loop-Free Alternates", RFC 5286, IP Fast Reroute: Loop-Free Alternates", RFC 5286,
DOI 10.17487/RFC5286, September 2008, DOI 10.17487/RFC5286, September 2008,
<https://www.rfc-editor.org/info/rfc5286>. <https://www.rfc-editor.org/info/rfc5286>.
8.2. Informative References 9.2. Informative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195, dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>. December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[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>.
[RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D. [RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D.
skipping to change at page 17, line 4 skipping to change at page 17, line 16
R. Aggarwal, "Support of Address Families in OSPFv3", R. Aggarwal, "Support of Address Families in OSPFv3",
RFC 5838, DOI 10.17487/RFC5838, April 2010, RFC 5838, DOI 10.17487/RFC5838, April 2010,
<https://www.rfc-editor.org/info/rfc5838>. <https://www.rfc-editor.org/info/rfc5838>.
Authors' Addresses Authors' Addresses
Pushpasis Sarkar (editor) Pushpasis Sarkar (editor)
Arrcus, Inc. Arrcus, Inc.
Email: pushpasis.ietf@gmail.com Email: pushpasis.ietf@gmail.com
Shraddha Hegde Shraddha Hegde
Juniper Networks, Inc. Juniper Networks, Inc.
Electra, Exora Business Park Electra, Exora Business Park
Bangalore, KA 560103 Bangalore, KA 560103
India India
Email: shraddha@juniper.net Email: shraddha@juniper.net
Chris Bowers
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: cbowers@juniper.net
Uma Chunduri (editor) Uma Chunduri (editor)
Huawei Technologies Huawei Technologies
2330 Central Expressway 2330 Central Expressway
Santa Clara, CA 95050 Santa Clara, CA 95050
USA USA
Email: uma.chunduri@huawei.com Email: uma.chunduri@huawei.com
Jeff Tantsura Jeff Tantsura
Individual Individual
Email: jefftant.ietf@gmail.com Email: jefftant.ietf@gmail.com
Bruno Decraene
Orange
Email: bruno.decraene@orange.com
Hannes Gredler Hannes Gredler
RtBrick, Inc. RtBrick, Inc.
Email: hannes@rtbrick.com Email: hannes@rtbrick.com
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