Source Address Validation Improvement (SAVI) Solution for DHCP
RFC 7513

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Internet Engineering Task Force (IETF)                             J. Bi
Request for Comments: 7513                                         J. Wu
Category: Standards Track                                         G. Yao
ISSN: 2070-1721                                           Tsinghua Univ.
                                                                F. Baker
                                                                   Cisco
                                                                May 2015

     Source Address Validation Improvement (SAVI) Solution for DHCP

Abstract

   This document specifies the procedure for creating a binding between
   a DHCPv4/DHCPv6-assigned IP address and a binding anchor on a Source
   Address Validation Improvement (SAVI) device.  The bindings set up by
   this procedure are used to filter packets with forged source IP
   addresses.  This mechanism complements BCP 38 (RFC 2827) ingress
   filtering, providing finer-grained source IP address validation.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7513.

Copyright Notice

   Copyright (c) 2015 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
   described in the Simplified BSD License.

Bi, et al.                   Standards Track                    [Page 1]
RFC 7513                        SAVI DHCP                       May 2015

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Deployment Scenario and Configuration . . . . . . . . . . . .   8
     4.1.  Elements and Scenario . . . . . . . . . . . . . . . . . .   8
     4.2.  SAVI Binding Type Attributes  . . . . . . . . . . . . . .  10
       4.2.1.  Trust Attribute . . . . . . . . . . . . . . . . . . .  10
       4.2.2.  DHCP-Trust Attribute  . . . . . . . . . . . . . . . .  11
       4.2.3.  DHCP-Snooping Attribute . . . . . . . . . . . . . . .  11
       4.2.4.  Data-Snooping Attribute . . . . . . . . . . . . . . .  11
       4.2.5.  Validating Attribute  . . . . . . . . . . . . . . . .  12
       4.2.6.  Table of Mutual Exclusions  . . . . . . . . . . . . .  13
     4.3.  Perimeter . . . . . . . . . . . . . . . . . . . . . . . .  13
       4.3.1.  SAVI-DHCP Perimeter Overview  . . . . . . . . . . . .  13
       4.3.2.  SAVI-DHCP Perimeter Configuration Guideline . . . . .  14
       4.3.3.  On the Placement of the DHCP Server and Relay . . . .  15
       4.3.4.  An Alternative Deployment . . . . . . . . . . . . . .  15
       4.3.5.  Considerations regarding Binding Anchors  . . . . . .  16
     4.4.  Other Device Configuration  . . . . . . . . . . . . . . .  17
   5.  Binding State Table (BST) . . . . . . . . . . . . . . . . . .  17
   6.  DHCP Snooping Process . . . . . . . . . . . . . . . . . . . .  18
     6.1.  Rationale . . . . . . . . . . . . . . . . . . . . . . . .  18
     6.2.  Binding States Description  . . . . . . . . . . . . . . .  19
     6.3.  Events  . . . . . . . . . . . . . . . . . . . . . . . . .  19
       6.3.1.  Timer Expiration Event  . . . . . . . . . . . . . . .  19
       6.3.2.  Control Message Arriving Events . . . . . . . . . . .  19
     6.4.  The State Machine of DHCP Snooping Process  . . . . . . .  21
       6.4.1.  Initial State: NO_BIND  . . . . . . . . . . . . . . .  21
       6.4.2.  Initial State: INIT_BIND  . . . . . . . . . . . . . .  24
       6.4.3.  Initial State: BOUND  . . . . . . . . . . . . . . . .  27
       6.4.4.  Table of State Machine  . . . . . . . . . . . . . . .  30
   7.  Data Snooping Process . . . . . . . . . . . . . . . . . . . .  31
     7.1.  Scenario  . . . . . . . . . . . . . . . . . . . . . . . .  31
     7.2.  Rationale . . . . . . . . . . . . . . . . . . . . . . . .  32
     7.3.  Additional Binding States Description . . . . . . . . . .  33