



SAVNET                                                             D. Li
Internet-Draft                                                     J. Wu
Intended status: Informational                       Tsinghua University
Expires: 7 April 2026                                             L. Qin
                                                                M. Huang
                                                 Zhongguancun Laboratory
                                                                 N. Geng
                                                                  Huawei
                                                          4 October 2025


Source Address Validation in Intra-domain Networks Gap Analysis, Problem
                      Statement, and Requirements
          draft-ietf-savnet-intra-domain-problem-statement-19

Abstract

   This document provides a gap analysis of existing intra-domain source
   address validation mechanisms, describes the fundamental problems,
   and defines the basic requirements for technical improvements.

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 7 April 2026.

Copyright Notice

   Copyright (c) 2025 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 carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components



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   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.  Current Operational Intra-domain SAV Mechanisms . . . . . . .   5
   3.  Gap Analysis  . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Intra-domain SAV for Traffic from Non-BGP Customer Networks
           or Directly Connected Hosts . . . . . . . . . . . . . . .   6
       3.1.1.  Asymmetric Routing  . . . . . . . . . . . . . . . . .   7
       3.1.2.  Hidden Prefix . . . . . . . . . . . . . . . . . . . .   9
     3.2.  Intra-domain SAV for Traffic from External ASes . . . . .   9
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .  10
   5.  Requirements for New SAV Mechanisms . . . . . . . . . . . . .  11
     5.1.  Accurate Validation . . . . . . . . . . . . . . . . . . .  12
     5.2.  Automatic Update  . . . . . . . . . . . . . . . . . . . .  12
     5.3.  Working in Incremental Deployment . . . . . . . . . . . .  12
     5.4.  Fast Convergence  . . . . . . . . . . . . . . . . . . . .  12
     5.5.  Security  . . . . . . . . . . . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Source Address Validation (SAV) defends against source address
   spoofing.  Network operators can enforce SAV at the following levels
   (see [RFC5210]):

   *  Within the access network

   *  Within the domain (i.e., the autonomous system)

   *  Between domains (i.e., autonomous systems)

   Access networks have already deployed SAV mechanisms.  These
   mechanisms typically are deployed on switches and prevent hosts from
   using the source address of another host on the Internet.  Mechanisms
   include:




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   *  Source Address Validation Improvement (SAVI) Solution for DHCP
      [RFC7513]

   *  IP Source Guard (IPSG) based on DHCP snooping [IPSG]

   *  Cable Source-Verify [cable-verify]

   Sadly, access-network SAV mechanisms are not universally deployed.
   Therefore, intra-domain (i.e., intra-AS) SAV or/and inter-domain
   (i.e., inter-AS) SAV are required.

   This document analyzes intra-domain SAV and focuses on deployment at
   external interfaces for verifying incoming traffic.  SAV at internal
   interfaces is considered out of scope.  Within a domain (i.e., an
   autonomous system), an external interfaces may connect to a set of
   hosts, a non-BGP customer network, or an external AS.  As illustrated
   in Figure 1, the goals of intra-domain SAV can be summarized as
   follows:

   *  At external interfaces facing hosts or non-BGP customer networks:
      Prevent them from injecting packets with source addresses they are
      not authorized to use into the domain

   *  At external interfaces facing external ASes: Prevent those ASes
      from injecting packets with internal-use-only source addresses
      into the domain

























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   +---------------------------------------------------+
   |             Other Autonomous Systems              |
   +---------------------------------------------------+
                 |                           |
                 |                           |
                 |                           |
   +-------------|---------------------------|---------+
   |   AS        \/                          \/        |
   |         +---#------+               +----#-----+   |
   |         | Router 3 +---------------+ Router 4 |   |
   |         +----------+               +----------+   |
   |          /        \                     |         |
   |         /          \                    |         |
   |        /            \                   |         |
   | +----------+     +----------+      +----------+   |
   | | Router 1 |     | Router 2 +------+ Router 5 |   |
   | +------*---+     +--*-------+      +----X-----+   |
   |        /\           /\                  /\        |
   |         \           /                   |         |
   |          \         /                    |         |
   |      +----------------+         +---------------+ |
   |      |Non-BGP Customer|         |     Hosts     | |
   |      |   Network      |         |               | |
   |      |     (P1)       |         |     (P2)      | |
   |      +----------------+         +---------------+ |
   |                                                   |
   +---------------------------------------------------+

   - SAV at interface 'X' prevents hosts from sending
     packets with unauthorized source addresses (i.e.,
     addresses outside prefix P2).
   - SAV at interface '*' prevents the non-BGP customer
     network from sending packets with unauthorized
     source addresses (i.e., addresses outside prefix P1).
   - SAV at interface '#' prevents the external AS from
     injecting packets with internal-use-only source
     addresses (e.g., prefixes P1 and P2).

                    Figure 1: Goals of intra-domain SAV

   Building on the last goal of intra-domain SAV, inter-domain SAV
   additionally prevents other ASes from injecting packets with other
   spoofed source addresses into the domain.

   This document provides a gap analysis of the current operational
   intra-domain SAV mechanisms, identifies key problems to solve, and
   proposes basic requirements for solutions.




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1.1.  Terminology

   Non-BGP Customer Network: A stub network connected to one or more
   routers of the AS for Internet connectivity.  It only originates
   traffic and does not participate in BGP routing exchanges with the
   AS.

   SAV Rule: The rule in a router that describes the mapping
   relationship between a source address (prefix) and the valid incoming
   interface(s).  It is used by a router to make SAV decisions.

   Improper Block: The validation results that the packets with
   legitimate source addresses are blocked improperly due to inaccurate
   SAV rules.

   Improper Permit: The validation results that the packets with spoofed
   source addresses are permitted improperly due to inaccurate SAV
   rules.

   SAV-specific Information: The information specialized for SAV rule
   generation.

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Current Operational Intra-domain SAV Mechanisms

   Although BCP 38 [RFC2827] and BCP 84 [RFC3704] specify several
   ingress filtering methods primarily intended for inter-domain SAV,
   some of these methods have also been applied to intra-domain SAV in
   operational practice.  This section describes the mechanisms
   currently used to implement intra-domain SAV.














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   *  Access Control Lists (ACLs) [RFC2827] are SAV filters that check
      the source address of each packet against a set of permitted or
      prohibited prefixes.  When applied on a router interface, packets
      that do not match the ACL entries are blocked.  ACLs can be
      deployed on interfaces facing a non-BGP customer network or a set
      of hosts, permitting only packets with authorized source
      addresses.  They are also commonly used on interfaces facing an
      external AS to block packets with unacceptable source addresses,
      such as internal-use-only prefixes.  Since ACLs are typically
      configured and updated manually, timely updates are essential
      whenever the set of permitted or prohibited prefixes changes.

   *  Strict uRPF [RFC3704] provides an automated SAV filter by
      validating the source address of each packet against the router’s
      local Forwarding Information Base (FIB).  A packet is accepted
      only if (i) the FIB contains a prefix covering the source address,
      and (ii) the FIB entry’s outgoing interface matches the packet’s
      incoming interface.  Otherwise, the packet is discarded.  Strict
      uRPF is commonly used to block spoofed packets originating from a
      directly connected host or non-BGP customer network.

   *  Loose uRPF [RFC3704] also relies on the local FIB for validation,
      but only checks for the presence of a covering prefix.  A packet
      is accepted if the FIB contains a prefix that covers the source
      address, regardless of the incoming interface.  Loose uRPF is
      typically used to block spoofed packets that use non-routable or
      non-global source addresses.

   Enhanced Feasible Path uRPF (EFP-uRPF) [RFC8704] is an advanced SAV
   mechanism specifically designed for inter-domain SAV.  It enforces
   source address validation on router interfaces facing customer ASes
   by leveraging BGP data received from other ASes.  EFP-uRPF is not
   analyzed in this document, as it is outside the scope of intra-domain
   SAV.

3.  Gap Analysis

   This section analyzes the gaps and key challenges of the current
   operational intra-domain SAV mechanisms.

3.1.  Intra-domain SAV for Traffic from Non-BGP Customer Networks or
      Directly Connected Hosts

   To achieve the first goal described in Section 1, an AS operator can
   deploy ACL rules or strict uRPF on the appropriate routers to enforce
   intra-domain SAV for traffic originating from non-BGP customer
   networks or directly connected hosts.




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   For example, an AS operator can configure an ACL on router interfaces
   facing a non-BGP customer network or directly connected hosts,
   specifying the set of prefixes authorized for use as source
   addresses.  The router then blocks any packet whose source address
   falls outside this set.  The main drawback of ACL-based SAV is its
   high operational overhead.  Because ACLs are typically maintained
   manually, operators must update them promptly to reflect changes in
   prefixes or topology.  Failure to do so may result in outdated ACLs
   that inadvertently block legitimate traffic.

   Strict uRPF automatically generates and updates SAV rules, but it may
   drop legitimate packets in scenarios such as asymmetric routing or
   hidden prefixes.  The following subsections describe two specific gap
   scenarios that arise when using strict uRPF for intra-domain SAV.

3.1.1.  Asymmetric Routing

   Asymmetric routing means a packet traverses from a source to a
   destination in one path and takes a different path when it returns to
   the source.  Asymmetric routing can occur within an AS due to routing
   policy, traffic engineering, etc.  For example, a non-BGP customer
   network connected to multiple routers of the AS may need to perform
   load balancing on incoming traffic, thereby resulting in asymmetric
   routing.

   Figure 2 illustrates an example of asymmetric routing.  The non-BGP
   customer network owns prefix 2001:db8::/55 [RFC6890] and connects to
   two routers of the AS, Router 1 and Router 2.  Router 1, Router 2,
   and Router 3 exchange routing information via the intra-domain
   routing protocol.  To achieve load balancing for inbound traffic, the
   non-BGP customer network expects traffic destined for 2001:db8:0::/56
   to enter through Router 1, and traffic destined for
   2001:db8:0:100::/56 to enter through Router 2.  To this end, Router 1
   advertises 2001:db8:0::/56 and Router 2 advertises
   2001:db8:0:100::/56 through the intra-domain routing protocol.
   Figure 2 also shows the corresponding FIB entries of Router 1 and
   Router 2 for the two prefixes.














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    +----------------------------------------------------------+
    |                                                       AS |
    |                      +----------+                        |
    |                      | Router 3 |                        |
    |                      +----------+                        |
    |                       /       \                          |
    |                      /         \                         |
    |                     /           \                        |
    |            +----------+       +----------+               |
    |            | Router 1 |       | Router 2 |               |
    |            +-------#--+       +----------+               |
    |                    /\           /                        |
    |Traffic with         \          / Traffic with            |
    |source IP addresses   \        /  destination IP addresses|
    |of 2001:db8:0:100::/56 \      \/  of 2001:db8:0:100::/56  |
    |                   +----------------+                     |
    |                   |Non-BGP Customer|                     |
    |                   |    Network     |                     |
    |                   |(2001:db8::/55) |                     |
    |                   +----------------+                     |
    |                                                          |
    +----------------------------------------------------------+

    FIB of Router 1                FIB of Router 2
    Dest                Next_hop   Dest                Next_hop
    2001:db8:0::/56     Non-BGP    2001:db8:0:100::/56 Non-BGP
                        Customer                       Customer
                        Nestwork                       Network
    2001:db8:0:100::/56 Router 3   2001:db8:0::/56     Router 3

    The legitimate traffic originated from non-BGP customer network
    with source addresses in 2001:db8:0:100::/56 will be improperly
    blocked by strict uRPF on Router 1.

                 Figure 2: An example of asymmetric routing

   While the non-BGP customer network does not expect traffic destined
   for the prefix 2001:db8:0:100::/56 to arrive via Router 1, it can
   still send traffic with source addresses within 2001:db8:0:100::/56
   to Router 1.  As a result, data packets between the non-BGP customer
   network and Router 1 may follow asymmetric paths.  Arrows in the
   figure indicate the direction of traffic flow.

   If Router 1 enforces strict uRPF by checking the FIB entry for the
   prefix 2001:db8:0:100::/56, the corresponding SAV rule would only
   allow packets with a source address from 2001:db8:0:100::/56 that
   arrive via Router 3.  Consequently, when the non-BGP customer network
   sends packets with a source address in 2001:db8:0:100::/56 to Router



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   1, strict uRPF would incorrectly drop these legitimate packets.
   Similarly, if Router 2 enforces strict uRPF, it would incorrectly
   block legitimate packets from the non-BGP customer network that use
   source addresses within the prefix 2001:db8:0::/56.

3.1.2.  Hidden Prefix

   The intra-domain hidden prefix scenario refers to two situations in
   which a host or non-BGP customer legitimately originates traffic
   using source addresses that are not visible to the intra-domain
   routing protocol:

   *  A host (for example, a cloud server instance operated by a tenant)
      that originates traffic with a source address not allocated by the
      AS operator, for legitimate purposes such as Direct Server Return
      (DSR) deployments.

   *  A non-BGP customer network that originates traffic with a source
      address not advertised to the AS operator, also for valid
      operational reasons.

   For ACL-based SAV, enforcing correct filtering in these scenarios
   requires authoritative information that explicitly specifies which
   source addresses the host or non-BGP customer is authorized to use.
   In practice, such authoritative information is often missing.

   Existing uRPF-based mechanisms (strict uRPF or loose uRPF) also fail
   in hidden prefix scenarios.  They will drop packets from hidden
   prefixes because the source addresses are absent from the router's
   FIB or are received from unexpected interfaces.

3.2.  Intra-domain SAV for Traffic from External ASes

   To achieve the second goal described in Section 1, intra-domain SAV
   is typically deployed on router interfaces facing external ASes to
   block packets carrying internal-use-only source addresses (see
   Figure 3).  ACL-based SAV is commonly used for this purpose.  The AS
   operator can configure ACL rules containing a set of unacceptable
   prefixes (for example, internal-use-only prefixes) to block any
   packet with a source address within these prefixes.  However, the
   operational overhead of maintaining ACL rules can be extremely high,
   particularly when multiple router interfaces require such
   configurations, as illustrated in Figure 3.








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   +---------------------------------------------------+
   |             Other Autonomous Systems              |
   +---------------------------------------------------+
                 | Traffic using internal-   |
                 | use-only source addresses |
                 | (e.g., P1 or P2)          |
   +-------------|---------------------------|---------+
   |   AS        \/                          \/        |
   |         +---#------+               +----#-----+   |
   |         | Router 3 +---------------+ Router 4 |   |
   |         +----------+               +----------+   |
   |          /        \                     |         |
   |         /          \                    |         |
   |        /            \                   |         |
   | +----------+     +----------+      +----------+   |
   | | Router 1 |     | Router 2 +------+ Router 5 |   |
   | +----------+     +----------+      +----------+   |
   |        \             /                  |         |
   |         \           /                   |         |
   |          \         /                    |         |
   |      +----------------+         +---------------+ |
   |      |Non-BGP Customer|         |     Hosts     | |
   |      |   Network      |         |               | |
   |      |     (P1)       |         |     (P2)      | |
   |      +----------------+         +---------------+ |
   |                                                   |
   +---------------------------------------------------+

         Figure 3: Intra-domain SAV for traffic from external ASes

   In addition, loose uRPF can be used in this context to block packets
   from external ASes that carry non-global or non-routed source
   addresses.  However, it may allow spoofed packets using internal-use-
   only source addresses, since internal-use-only prefixes exist in the
   router's local FIB.

4.  Problem Statement

   As discussed above, current operational intra-domain SAV mechanisms
   have significant limitations with respect to automatic updates and
   accurate validation.

   ACL-based SAV relies entirely on manual maintenance, resulting in
   high operational overhead in dynamic networks.  To ensure the
   accuracy of ACL-based SAV, AS operators must manually update ACL
   rules whenever prefixes or topology change; otherwise, packets may be
   improperly blocked or permitted.




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   Strict uRPF can automatically update SAV rules, but it may block
   legitimate traffic in the asymmetric routing or hidden prefix
   scenarios.  As discussed in Section 3.1, strict uRPF may mistakenly
   consider a valid incoming interface as invalid, resulting in
   legitimate packets being dropped (i.e., an improper block problem).

   Loose uRPF is also an automated SAV mechanism, but its rules are
   overly permissive.  As discussed in Section 3.2, any spoofed packet
   with a source address present in the FIB may be accepted by loose
   uRPF (i.e., an improper permit problem).

   In summary, even if an AS operator has a comprehensive view and can
   configure correct ACL rules, manual maintenance imposes high
   operational overhead and may result in improper blocks due to
   operator oversight. uRPF cannot guarantee the accuracy of SAV because
   it relies solely on the router’s local FIB to determine SAV rules,
   which may not correspond to the incoming interfaces of legitimate
   packets.  Consequently, strict uRPF may block legitimate traffic in
   asymmetric routing and hidden prefix scenarios, while loose uRPF has
   limited effectiveness against source address spoofing, as it only
   blocks non-global or non-routed addresses.  For hidden prefix
   scenarios, the key challenge remains how to provide authoritative
   information that allows the host or non-BGP customer to legitimately
   use such source addresses.

   Another consideration is that uRPF-based mechanisms rely on routing
   information to make SAV decisions, assuming that the routing
   information in the local FIB is correct.  If the routing information
   is incorrect, SAV decisions may also be incorrect, potentially
   resulting in improper blocks or permits.  It should be emphasized
   that ensuring the correctness of routing information is the
   responsibility of mechanisms or operational processes outside the
   scope of SAV.  Network operators and SAV mechanisms are encouraged to
   leverage such solutions to validate the routing information used by
   SAV.

5.  Requirements for New SAV Mechanisms

   This section outlines five general requirements for technical
   improvements that should be considered when designing future intra-
   domain SAV architectures and solutions.  These informational
   requirements can not be used to initiate standards-track protocol
   changes.








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5.1.  Accurate Validation

   The new intra-domain SAV mechanism MUST improve the accuracy of
   existing intra-domain SAV mechanisms.  It MUST achieve the goals
   described in Section 1, preventing spoofed traffic from entering the
   domain.  At the same time, it MUST avoid blocking legitimate packets,
   particularly in the presence of prefix changes, asymmetric routes, or
   hidden prefixes.  To overcome the improper block problems, routers
   may need to use additional information (e.g., SAV-specific
   information) beyond the local FIB information to make SAV decisions.
   By integrating such information, routers can account for asymmetric
   routes and hidden prefixes, resulting in more accurate SAV rules.

5.2.  Automatic Update

   The new intra-domain SAV mechanism MUST be capable of automatically
   generating and updating SAV rules on routers, rather than relying
   entirely on manual updates as in ACL-based SAV.  Although some
   initial configuration may be necessary to improve SAV accuracy,
   automation reduces the subsequent operational overhead for the AS
   operator.

5.3.  Working in Incremental Deployment

   The new mechanism MUST support incremental deployment and MUST
   provide incremental benefits under such partial deployment.  In an
   incremental deployment scenario, the mechanism MUST avoid improper
   blocks and MUST clearly specify the extent to which the goals
   described in Section 1 can be partially achieved.

5.4.  Fast Convergence

   The new intra-domain SAV mechanism MUST be able to update SAV rules
   promptly when prefixes, routes, or topology change within an AS.  If
   SAV-specific information is communicated via a protocol, two
   considerations are essential.  First, the mechanism MUST allow
   routers to learn updated SAV-specific information in a timely manner.
   Second, the mechanism MUST NOT transmit excessive SAV-specific
   information, as this could significantly increase the burden on the
   routers’ control planes and potentially degrade the performance of
   existing protocols.

5.5.  Security

   The new intra-domain SAV mechanisms MUST NOT introduce additional
   security vulnerabilities or create confusion in existing intra-domain
   architectures or protocols.  Section 6 details the security scope and
   considerations for the new intra-domain SAV mechanism.



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6.  Security Considerations

   Similar to the security scope of intra-domain routing protocols,
   intra-domain SAV mechanisms can ensure the integrity and
   authentication of protocol messages that convey the required SAV-
   specific information and can help prevent unintentional
   misconfigurations.  It is not necessary for SAV mechanisms to protect
   against compromised or malicious intra-domain routers that attempt to
   poison existing control or management plane protocols.  Such
   compromised or malicious routers could not only affect SAV, but also
   disrupt the entire intra-domain routing domain.  Security mechanisms
   to defend against these attacks are beyond the scope and capability
   of intra-domain SAV.

7.  IANA Considerations

   This document does not request any IANA allocations.

8.  Acknowledgements

   Many thanks to the valuable comments from: Jared Mauch, Joel Halpern,
   Aijun Wang, Michael Richardson, Gert Doering, Libin Liu, Li Chen,
   Tony Przygienda, Yingzhen Qu, James Guichard, Linda Dunbar, Robert
   Sparks, Stephen Farrel, Ron Bonica, etc.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
              May 2000, <https://www.rfc-editor.org/info/rfc2827>.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March
              2004, <https://www.rfc-editor.org/info/rfc3704>.



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   [RFC5210]  Wu, J., Bi, J., Li, X., Ren, G., Xu, K., and M. Williams,
              "A Source Address Validation Architecture (SAVA) Testbed
              and Deployment Experience", RFC 5210,
              DOI 10.17487/RFC5210, June 2008,
              <https://www.rfc-editor.org/info/rfc5210>.

   [RFC8704]  Sriram, K., Montgomery, D., and J. Haas, "Enhanced
              Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
              RFC 8704, DOI 10.17487/RFC8704, February 2020,
              <https://www.rfc-editor.org/info/rfc8704>.

   [RFC7513]  Bi, J., Wu, J., Yao, G., and F. Baker, "Source Address
              Validation Improvement (SAVI) Solution for DHCP",
              RFC 7513, DOI 10.17487/RFC7513, May 2015,
              <https://www.rfc-editor.org/info/rfc7513>.

   [cable-verify]
              "Cable Source-Verify and IP Address Security", January
              2021, <https://www.cisco.com/c/en/us/support/docs/
              broadband-cable/cable-security/20691-source-verify.html>.

   [IPSG]     "Configuring DHCP Features and IP Source Guard", January
              2016, <https://www.cisco.com/c/en/us/td/docs/switches/lan/
              catalyst2960/software/release/12-
              2_53_se/configuration/guide/2960scg/swdhcp82.html>.

   [RFC6890]  Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
              "Special-Purpose IP Address Registries", BCP 153,
              RFC 6890, DOI 10.17487/RFC6890, April 2013,
              <https://www.rfc-editor.org/info/rfc6890>.

Authors' Addresses

   Dan Li
   Tsinghua University
   Beijing
   China
   Email: tolidan@tsinghua.edu.cn


   Jianping Wu
   Tsinghua University
   Beijing
   China
   Email: jianping@cernet.edu.cn






Li, et al.                Expires 7 April 2026                 [Page 14]

Internet-Draft    Intra-domain SAVNET Problem Statement     October 2025


   Lancheng Qin
   Zhongguancun Laboratory
   Beijing
   China
   Email: qinlc@mail.zgclab.edu.cn


   Mingqing Huang
   Zhongguancun Laboratory
   Beijing
   China
   Email: huangmq@mail.zgclab.edu.cn


   Nan Geng
   Huawei
   Beijing
   China
   Email: gengnan@huawei.com
































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