--- 1/draft-ietf-rtgwg-multihomed-prefix-lfa-00.txt 2017-01-17 12:13:07.736322705 -0800 +++ 2/draft-ietf-rtgwg-multihomed-prefix-lfa-01.txt 2017-01-17 12:13:07.772323547 -0800 @@ -1,28 +1,28 @@ Routing Area Working Group P. Sarkar, Ed. Internet-Draft Individual Intended status: Informational S. Hegde -Expires: February 5, 2017 C. Bowers +Expires: July 20, 2017 C. Bowers Juniper Networks, Inc. U. Chunduri, Ed. - Ericsson Inc. + Huawei Technologies J. Tantsura Individual B. Decraene Orange H. Gredler - Unaffiliated - August 4, 2016 + RtBrick, Inc. + January 16, 2017 LFA selection for Multi-Homed Prefixes - draft-ietf-rtgwg-multihomed-prefix-lfa-00 + draft-ietf-rtgwg-multihomed-prefix-lfa-01 Abstract This document shares experience gained from implementing algorithms to determine Loop-Free Alternates for multi-homed prefixes. In particular, this document provides explicit inequalities that can be used to evaluate neighbors as a potential alternates for multi-homed prefixes. It also provides detailed criteria for evaluating potential alternates for external prefixes advertised by OSPF ASBRs. @@ -39,25 +39,25 @@ 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 http://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 February 5, 2017. + This Internet-Draft will expire on July 20, 2017. Copyright Notice - Copyright (c) 2016 IETF Trust and the persons identified as the + Copyright (c) 2017 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -74,21 +74,21 @@ 4. LFA selection for the multi-homed external prefixes . . . . . 8 4.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. Rules to select alternate ASBR . . . . . . . . . . . 8 4.2.2. Multiple ASBRs belonging different area . . . . . . . 9 4.2.3. Type 1 and Type 2 costs . . . . . . . . . . . . . . . 10 4.2.4. RFC1583compatibility is set to enabled . . . . . . . 10 4.2.5. Type 7 routes . . . . . . . . . . . . . . . . . . . . 10 4.2.6. Inequalities to be applied for alternate ASBR selection . . . . . . . . . . . . . . . . . . . . . . 10 - 4.2.6.1. Forwarding address set to non zero value . . . . 10 + 4.2.6.1. Forwarding address set to non-zero value . . . . 10 4.2.6.2. ASBRs advertising type1 and type2 cost . . . . . 11 5. LFA Extended Procedures . . . . . . . . . . . . . . . . . . . 12 5.1. Links with IGP MAX_METRIC . . . . . . . . . . . . . . . . 12 5.2. Multi Topology Considerations . . . . . . . . . . . . . . 13 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . 15 @@ -198,21 +198,21 @@ for P with the N as the alternate neighbor. 1.a. If LFA inequality condition is met, select N as a LFA for prefix P. 1.b. Else, N is not a LFA for prefix P. Node-Protection : ================= 1. If alternate neighbor N is also prefix-originator of P, 1.a. Select N as a LFA for prefix P (irrespective of the metric advertised by N for the prefix P). - 2. Else, evaluate the apporpriate node-protecting LFA inequality + 2. Else, evaluate the appropriate node-protecting LFA inequality for P with the N as the alternate neighbor. 2.a. If LFA inequality condition is met, select N as a LFA for prefix P. 2.b. Else, N is not a LFA for prefix P. Figure 2: Rules for selecting LFA for MHPs In case an alternate neighbor N is also one of the prefix-originators of prefix P, N MAY be selected as a valid LFA for P. @@ -447,21 +447,21 @@ Type 7 routes, routes with p-bit and forwarding address set have higher preference than routes without these attributes. Alternate ASBRs selected for LFA comparison should have same p-bit and forwarding address attributes. 4.2.6. Inequalities to be applied for alternate ASBR selection The alternate ASBRs selected using above mechanism described in 3.2.1, are evaluated for Loop free criteria using below inequalities. -4.2.6.1. Forwarding address set to non zero value +4.2.6.1. Forwarding address set to non-zero value Link-Protection: F_opt(N,PO_i)+ cost(PO_i,P) < D_opt(N,S) + F_opt(S,PO_best) + cost(PO_best,P) Link-Protection + Downstream-paths-only: F_opt(N,PO_i)+ cost(PO_i,P) < F_opt(S,PO_best) + cost(PO_best,P) Node-Protection: F_opt(N,PO_i)+ cost(PO_i,P) < D_opt(N,E) + F_opt(E,PO_best) + cost(PO_best,P) @@ -610,26 +610,20 @@ dual environments", RFC 1195, DOI 10.17487/RFC1195, December 1990, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 9.2. Informative References - [I-D.ietf-rtgwg-lfa-manageability] - Litkowski, S., Decraene, B., Filsfils, C., Raza, K., and - M. Horneffer, "Operational management of Loop Free - Alternates", draft-ietf-rtgwg-lfa-manageability-11 (work - in progress), June 2015. - [RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D. McPherson, "OSPF Stub Router Advertisement", RFC 3137, DOI 10.17487/RFC3137, June 2001, . [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, . @@ -650,20 +644,25 @@ [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, DOI 10.17487/RFC5308, October 2008, . [RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and R. Aggarwal, "Support of Address Families in OSPFv3", RFC 5838, DOI 10.17487/RFC5838, April 2010, . + [RFC7916] Litkowski, S., Ed., Decraene, B., Filsfils, C., Raza, K., + Horneffer, M., and P. Sarkar, "Operational Management of + Loop-Free Alternates", RFC 7916, DOI 10.17487/RFC7916, + July 2016, . + Authors' Addresses Pushpasis Sarkar (editor) Individual Email: pushpasis.ietf@gmail.com Shraddha Hegde Juniper Networks, Inc. Electra, Exora Business Park Bangalore, KA 560103 @@ -673,32 +672,31 @@ Chris Bowers Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, CA 94089 US Email: cbowers@juniper.net Uma Chunduri (editor) - Ericsson Inc. - 300 Holger Way, - San Jose, California 95134 + Huawei Technologies + 2330 Central Expressway + Santa Clara, CA 95050 USA - Phone: 408 750-5678 - Email: uma.chunduri@ericsson.com + Email: uma.chunduri@huawei.com Jeff Tantsura Individual Email: jefftant.ietf@gmail.com Bruno Decraene Orange Email: bruno.decraene@orange.com Hannes Gredler - Unaffiliated + RtBrick, Inc. - Email: hannes@gredler.at + Email: hannes@rtbrick.com