Enhanced Feasible-Path Unicast Reverse Path Forwarding
draft-ietf-opsec-urpf-improvements-04

Document Type Active Internet-Draft (opsec WG)
Last updated 2019-09-03 (latest revision 2019-08-30)
Replaces draft-sriram-opsec-urpf-improvements
Stream IETF
Intended RFC status Best Current Practice
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Stream WG state Submitted to IESG for Publication
Document shepherd Sandra Murphy
Shepherd write-up Show (last changed 2019-07-11)
IESG IESG state RFC Ed Queue
Consensus Boilerplate Yes
Telechat date
Responsible AD Warren Kumari
Send notices to Sandra Murphy <sandy@tislabs.com>
IANA IANA review state Version Changed - Review Needed
IANA action state No IANA Actions
RFC Editor RFC Editor state EDIT
OPSEC Working Group                                            K. Sriram
Internet-Draft                                             D. Montgomery
BCP: 84 (if approved)                                           USA NIST
Updates: 3704 (if approved)                                      J. Haas
Intended status: Best Current Practice            Juniper Networks, Inc.
Expires: March 2, 2020                                   August 30, 2019

         Enhanced Feasible-Path Unicast Reverse Path Forwarding
                 draft-ietf-opsec-urpf-improvements-04

Abstract

   This document identifies a need for and proposes improvement of the
   unicast Reverse Path Forwarding (uRPF) techniques (see RFC 3704) for
   detection and mitigation of source address spoofing (see BCP 38).
   The strict uRPF is inflexible about directionality, the loose uRPF is
   oblivious to directionality, and the current feasible-path uRPF
   attempts to strike a balance between the two (see RFC 3704).
   However, as shown in this document, the existing feasible-path uRPF
   still has shortcomings.  This document describes enhanced feasible-
   path uRPF (EFP-uRPF) techniques, which are more flexible (in a
   meaningful way) about directionality than the feasible-path uRPF (RFC
   3704).  The proposed EFP-uRPF methods aim to significantly reduce
   false positives regarding invalid detection in source address
   validation (SAV).  Hence they can potentially alleviate ISPs'
   concerns about the possibility of disrupting service for their
   customers, and encourage greater deployment of uRPF techniques.  This
   document updates RFC 3704.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   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
   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 March 2, 2020.

Sriram, et al.            Expires March 2, 2020                 [Page 1]
Internet-Draft              Enhanced FP-uRPF                 August 2019

Copyright Notice

   Copyright (c) 2019 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Review of Existing Source Address Validation Techniques . . .   4
     2.1.  SAV using Access Control List . . . . . . . . . . . . . .   4
     2.2.  SAV using Strict Unicast Reverse Path Forwarding  . . . .   5
     2.3.  SAV using Feasible-Path Unicast Reverse Path Forwarding .   6
     2.4.  SAV using Loose Unicast Reverse Path Forwarding . . . . .   7
     2.5.  SAV using VRF Table . . . . . . . . . . . . . . . . . . .   8
   3.  SAV using Enhanced Feasible-Path uRPF . . . . . . . . . . . .   8
     3.1.  Description of the Method . . . . . . . . . . . . . . . .   8
       3.1.1.  Algorithm A: Enhanced Feasible-Path uRPF  . . . . . .  10
     3.2.  Operational Recommendations . . . . . . . . . . . . . . .  10
     3.3.  A Challenging Scenario  . . . . . . . . . . . . . . . . .  11
     3.4.  Algorithm B: Enhanced Feasible-Path uRPF with Additional
           Flexibility Across Customer Cone  . . . . . . . . . . . .  12
     3.5.  Augmenting RPF Lists with ROA and IRR Data  . . . . . . .  12
     3.6.  Implementation and Operations Considerations  . . . . . .  13
       3.6.1.  Impact on FIB Memory Size Requirement . . . . . . . .  13
       3.6.2.  Coping with BGP's Transient Behavior  . . . . . . . .  14
     3.7.  Summary of Recommendations  . . . . . . . . . . . . . . .  15
       3.7.1.  Applicability of the enhanced feasible-path uRPF
               (EFP-uRPF) method with Algorithm A  . . . . . . . . .  15
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
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