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Concluded WG Source Address Validation Improvements (savi)

Note: The data for concluded WGs is occasionally incorrect.

WG Name Source Address Validation Improvements
Acronym savi
Area Internet Area (int)
State Concluded
Charter charter-ietf-savi-02 Approved
Document dependencies
Additional resources Issue tracker, Wiki
Personnel Chair Jean-Michel Combes
Area Director Suresh Krishnan
Tech Advisor Jianping Wu
Secretary Jun Bi
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Final Charter for Working Group

While ingress filtering [RFC 2827, BCP 38] provides a way to validate
IP source addresses at an aggregated level, there is not yet a
standardized mechanism for IP source address validation at a finer
granularity. Having a finer granularity would be helpful in a number
of situations, including filtering traffic from customer interfaces
implemented as ports in a layer 3 aware bridge or a router, general
improvements in filtering accuracy in enterprise networks, etc.
Depending on the situation, there may be a requirement for blocking
spoofed packets or merely logging packets that appear to be spoofed.

Partial solutions exist to prevent nodes from spoofing the IP source
address of another node in the same IP link (e.g., the "IP source
guard"), but are proprietary. The purpose of the proposed "Source
Address Validation Improvements" working group is to standardize
mechanisms that prevent nodes attached to the same IP link from
spoofing each other's IP addresses.

The scope of the WG is as follows:

  • The working group considers only solutions implemented on systems
    located on the same IP link as a to-be-verified node. The goal of the
    working group is the LAN environment and solutions running in routers or
    layer 3 aware Ethernet bridges.

  • Both IPv4 and IPv6 need to be covered.

  • The first goal of the working group is on unicast traffic, but
    using the same mechanisms to police multicast traffic is also
    within the scope.

  • All address assignment mechanisms need to be supported, including
    stateless, stateful, and manual configuration; as well as privacy and
    cryptographically generated addresses.

  • Solutions are preferably based on observing user traffic, or on
    observing or using existing signaling protocols. Examples of
    protocols that can be useful to observe/use are ARP, Neighbor
    Discovery, DHCP, and DHCP Prefix Delegation protocols. Observing
    addresses in IP headers can also be useful. The gathered
    information is used to determine what IP source addresses in
    packets are appropriate. Where automatic operation is impossible
    or would lead to sub-optimal validation results, solutions may
    require manual configuration.

  • Interdomain scenarios (across Autonomous Systems) that require
    information from routing protocols like BGP are out of scope.
    Nevertheless, solution may observe routing protocol signaling
    to detect that a device is a router.

  • Tracking other protocols is not within the scope of the WG.

  • No changes to hosts are allowed.

  • The WG is prohibited from creating its own protocols
    or extensions/modifications of current protocols.

These limitations in the scope may be relaxed through later
rechartering. For instance, solutions tailored for PPP links
and specific environments may be added later, or solutions
involving co-operation of the nodes on the link may be
developed once the baseline solutions have been completed.
However, the WG is already chartered to work also on a
solution for Ethernet-based broadband access networks that
are used in DSL environments. This work is a specialization
of the working group's primary LAN-based solution.

In order to reach a result that is widely usable and unlikely to
disturb existing network practices, the working group needs to
take into account

  • nodes that use static addresses,
  • nodes with multiple IP addresses on the same interface,
  • nodes that use multiple link-layer addresses on the same interface,
  • nodes that have multiple interfaces to the same link,
  • attachment of another bridge at a bridge port,
  • presence of routers, NATs, and other similar devices on the same link,
    including their distinction from hosts with multiple interfaces or
    hosts with multiple IP addresses on a single interface,
  • use of SEcure Neighbor Discovery in some networks,
  • nodes that move to another port on the same link, and
  • hosts with anycast addresses.

However, should such wide applicability turn out to be impossible,
the working group will document the limitations of the solutions
in due manner. In particular, it is likely that anycast addressing
and nodes that employ multiple interfaces for load balancing at
link layer are indistinguishable from an actual spoofing attack.
There may also be a difference in the applicability between blocking
and merely logging spoofed packets. In any case, the solutions
may require to be explicitly turned on for each network or interface
where they are applicable.

For background information, the working group will also develop a
threats analysis document that describes what threats the solutions
from the WG protect against. This document also contrasts SAVI
to existing solutions.


Date Milestone Associated documents
Jul 2011 Submit mix scenario solution to IESG for Proposed Standard
Apr 2011 First WG draft on mix scenario solution
Dec 2010 Submit DHCP solution to IESG for Proposed Standard
Dec 2010 Submit SeND solution to IESG for Proposed Standard
Dec 2010 Submit SLAAC solution to IESG for Proposed Standard
Dec 2010 Submit protocol framework to IESG for Informational RFC
Dec 2010 Submit Ethernet-based broadband access network solution to IESG for Proposed Standard
Mar 2010 First WG draft on solution for Ethernet-based broadband access networks
Mar 2010 Submit document on threats to IESG for Informational RFC
Dec 2009 First WG draft on protocol framework
Dec 2009 First WG draft on DHCP solution
Dec 2008 First WG draft on SeND solution
Oct 2008 First WG draft on SLAAC solution
Aug 2008 First WG draft on threats document
Jul 2008 WG approval