Site Multihoming by IPv6 Intermediation (shim6)

NOTE: This charter is a snapshot of the . It may now be out-of-date.

Last Modified: 2010-01-05


Kurt Lindqvist <>
Geoff Huston <>

Internet Area Director(s):

Ralph Droms <>
Jari Arkko <>

Internet Area Advisor:

Jari Arkko <>

Technical Advisor(s):

Thomas Narten <>

Mailing Lists:

General Discussion:
To Subscribe:

Description of Working Group:

Earlier efforts in this working group completed the Shim6 protocol
specification, documented in RFCs 5533 through 5535. This protocol is
a layer 3 shim for providing locator agility with failover
capabilities for IPv6 nodes. Hosts that employ Shim6 use multiple IPv6
address prefixes and setup state with peer hosts. This state can later
be used to failover to a different set of locators, should the
original locators stop working.

The Shim6 approach has a number of advantages, such as enabling small
sites to be multihomed without requiring a provider independent IPv6
address prefix for the site. But the approach has also been
criticized, e.g., for the operational impacts that the use of multiple
prefixes causes. At this time there is no clear view on how well Shim6
works in practice. Implementation and deployment in select networks is
needed to determine its true characteristics.

The Shim6 working group is chartered to track the implementation and
testing or deployment efforts. The group is also expected to shepherd
to completion a few remaining informational documents that complement
the existing protocol specifications.

The specific work items of the group are:

o Write an implementation and/or deployment experience report.

o Specify socket API extensions. This API enables interactions between
applications and the Shim6 layer for advanced locator management,
and access to information about failure detection and path
exploration. It also enables some applications to turn Shim6 off.

o Complete the work on the applicability draft. This draft explains
in detail in which types of networks Shim6 is applicable, and
what its advantages and disadvantages are. The draft will also
explain how firewalls are impacted by the use of Shim6. Finally,
the draft will also explain how Shim6 can be used in situations
where native IPv6 connectivity is not available, such as using
Shim6 over 6to4.

The group will also work in co-operation with the 6MAN working group
as they continue their efforts in improving IPv6 address selection

The group shall not work on extensions to the Shim6 protocol itself at
this time. However, new work items can be added through rechartering
as others get completed.

Goals and Milestones:

Done  First draft of architectural document
Done  First draft of protocol document
Done  First draft on cryptographic locators, if required
Done  First draft on multi-homing triggers description
Done  First draft on applicability statement document
Done  WG last-call on protocol document
Done  WG last-call on cryptographic locators, if required
Done  WG last-call on multihoming triggers description
Done  Submit document on cryptographic locators to the IESG, if required
Done  Submit protocol document to the IESG
Done  Submit draft on multihoming triggers description to the IESG
Sep 2009  Next revision of the API document
Nov 2009  First WG draft on an implementation report
Jan 2010  Submit API document to IESG for publication as Informational RFC
Jan 2010  Next revision of the applicability document
Dec 2010  Submit implementation report to IESG for publication as Informational RFC
Dec 2010  Submit applicability document to IESG for publication as Informational RFC
Dec 2010  Close or re-charter


  • draft-ietf-shim6-applicability-05.txt
  • draft-ietf-shim6-multihome-shim-api-13.txt

    Request For Comments:

    RFC5533 PS Shim6: Level 3 Multihoming Shim Protocol for IPv6
    RFC5534 PS Failure Detection and Locator Pair Exploration Protocol for IPv6 Multihoming
    RFC5535 PS Hash-Based Addresses (HBA)