draft-ietf-idr-bgp-bestpath-selection-criteria-11.txt   draft-ietf-idr-bgp-bestpath-selection-criteria-12.txt 
IDR Working Group Rajiv Asati IDR Working Group Rajiv Asati
Internet-Draft Cisco Systems Internet Draft Cisco Systems
Updates: 4271 (if approved)
Intended status: Standards Track Intended status: Standards Track
Expires: December 3, 2019 Expires: December 5, 2019
June 3, 2019 June 5, 2019
BGP Bestpath Selection Criteria Enhancement BGP Bestpath Selection Criteria Enhancement
draft-ietf-idr-bgp-bestpath-selection-criteria-11.txt draft-ietf-idr-bgp-bestpath-selection-criteria-12.txt
Abstract Abstract
BGP specification prescribes 'BGP next-hop reachability' as one BGP specification (RFC4271) prescribes 'BGP next-hop reachability'
of the key 'Route Resolvability Condition' that must be satisfied as one of the key 'Route Resolvability Condition' that must be
before the BGP bestpath candidate selection. This condition, satisfied before the BGP bestpath candidate selection. This
however, may not be sufficient (as explained in the Appendix condition, however, may not be sufficient (as explained in the
section) and would desire further granularity. Appendix section) and would desire further granularity.
This document defines enhances the "Route Resolvability Condition" This document defines enhances the "Route Resolvability Condition"
to facilitate the next-hop to be resolved in the chosen data plane. to facilitate the next-hop to be resolved in the chosen data plane.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 3, 2019. This Internet-Draft will expire on December 5, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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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document must include Simplified BSD License text as described in document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License. warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction...................................................2
2. Specification Language.........................................3 2. Specification Language.........................................3
3. Route Resolvability Condition - Modification...................3 3. Route Resolvability Condition - Modification...................3
4. Conclusions....................................................4 4. Conclusions....................................................4
5. Security Considerations........................................4 5. Security Considerations........................................5
6. IANA Considerations............................................5 6. IANA Considerations............................................5
7. Acknowledgments................................................5 7. Acknowledgments................................................5
8. Appendix.......................................................5 8. Appendix.......................................................5
9. References.....................................................7 9. References.....................................................8
Author's Addresses................................................8 Author's Addresses................................................9
1. Introduction 1. Introduction
As per BGP specification [RFC4271], when a router receives a BGP As per BGP specification [RFC4271], when a router receives a BGP
path, BGP must qualify it as the valid candidate prior to the BGP path, BGP must qualify it as the valid candidate prior to the BGP
bestpath selection using the 'Route Resolvability Condition' bestpath selection using the 'Route Resolvability Condition'
(section#9.1.2.1 of RFC4271]. After the path gets qualified as the (section#9.1.2.1 of RFC4271]. After the path gets qualified as the
bestpath candidate, it becomes eligible to be the bestpath, and may bestpath candidate, it becomes eligible to be the bestpath, and may
get advertised out to the neigbhor(s), if it became the bestpath. get advertised out to the neigbhor(s), if it became the bestpath.
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and/or availability in a particular data plane. and/or availability in a particular data plane.
It is not expected that the proposed amendments would negatively It is not expected that the proposed amendments would negatively
impact BGP convergence, barring any implementation specifics. impact BGP convergence, barring any implementation specifics.
The intention of this document is to help operators to build BGP The intention of this document is to help operators to build BGP
networks that can avoid self-blackholing. networks that can avoid self-blackholing.
5. Security Considerations 5. Security Considerations
This draft doesn't impose any additional security constraints. While this draft doesn't impose any additional security constraints,
it can help with mitigating one particular type of routing attack in
which a BGP speaker could receive routes with an arbitrary next-hop.
If the next-hop is not reachable, then those routes/paths would not
get selected.
6. IANA Considerations 6. IANA Considerations
None. None.
7. Acknowledgments 7. Acknowledgments
Yakov Rekhter provided critical suggestions and feedback to improve Yakov Rekhter provided critical suggestions and feedback to improve
this document. Thanks to John Scudder and Chandrashekhar Appanna for this document. Thanks to John Scudder and Chandrashekhar Appanna for
contributing to the discussions that formed the basis of this contributing to the discussions that formed the basis of this
document. Thanks to Ilya Varlashkin and Michael Benjamin, who made document. Thanks to Ilya Varlashkin and Michael Benjamin, who made
the case to revive this document and provided useful feedback. Also the case to revive this document and provided useful feedback. Also
thanks to Keyur Patel for his feedback. thanks to Robert Raszuk and Keyur Patel for constructive feedback.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
8. Appendix 8. Appendix
8.1. Problem Applicability 8.1. Problem Applicability
In IP networks using BGP, a router would continue to attract traffic In IP networks using BGP, a router would continue to attract traffic
by advertising the BGP prefix reachability to neighbor(s) as long as by advertising the BGP prefix reachability to neighbor(s) as long as
the router had a route to the next-hop in its routing table, but the router had a route to the next-hop in its routing table, but
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