Transparent Interconnection of Lots of Links (trill)

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 It may now be out-of-date.

Last Modified: 2009-05-07


Erik Nordmark <>
Donald Eastlake 3rd <>

Internet Area Director(s):

Ralph Droms <>
Jari Arkko <>

Internet Area Advisor:

Ralph Droms <>

Mailing Lists:

General Discussion:
To Subscribe:

Description of Working Group:

The TRILL WG will design a solution for shortest-path frame routing in
multi-hop IEEE 802.1-compliant Ethernet networks with arbitrary
topologies, using an existing link-state routing protocol technology.

This work will initially be based on draft-perlman-rbridge-03.txt.

The design should have the following properties:

- Minimal or no configuration required
- Load-splitting among multiple paths
- Routing loop mitigation (possibly through a TTL field)
- Support of multiple points of attachment
- Support for broadcast and multicast
- No significant service delay after attachment
- No less secure than existing bridged solutions

Any changes introduced to the Ethernet service model should be
analyzed and clearly documented. To ensure compatibility with IEEE
VLANs and the Ethernet service model, the WG will request an IEEE
liaison relationship with IEEE 802.1, and IEEE 802.1 will be asked to
review the architecture document and specification(s) before they are
submitted to the IESG.

It is not an explicit requirement that the solution should be able to
run on existing IP routers or IEEE 802 switches as a software upgrade.
However, the working group should take deployment considerations into
account, to ensure that the solution can interwork with bridges in a
flexible manner (e.g., to allow incremental deployment into LANs that
currently use 802.1D bridges).

The TRILL working will work with the L2VPN WG to develop interworking
between TRILL and 802.1D bridges at the edge, such that a bridged
sub-cloud could be attached to TRILL devices in more than one place
for redundancy.

The solution must not interfere with the end-to-end transparency of
the Internet architecture or with end-to-end congestion control and
QOS mechanisms.

The WG will work on the following items:

(1) Develop a problem statement and architecture document that
describes the high-level TRILL architecture, discusses the
scalability of that architecture, describes the threat model
and security impacts of the TRILL solution, and describes the
expected impacts (if any) of the TRILL solution on the Ethernet
service model.

(2) Define the requirements for a TRILL-capable routing protocol, and
select one or more existing routing protocols that could meet
those requirements.

(3) Work with the appropriate Routing area working group to extend an
existing routing protocol to meet the TRILL working group

Note: The TRILL working group is not chartered to develop a new
routing protocol or to make substantial modifications to an
existing routing protocol. If, during the requirements definition
and selection phase, the TRILL working group discovers that no
existing routing protocol will meet their needs, we will need to
re-assess the TRILL WG charter to determine how/if this work
should proceed.

(4) Produce a (set of) TRILL specification(s) for standards track
publication that define(s) what information must be carried in an
encapsulation header for data packets. Although this work will
initially be undertaken only for 802.1-compliant links, it
may later be expanded to non-802.1 links, so the design should be
link-layer agnostic to whatever extent possible.

The TRILL working group is chartered to undertake all of the above
tasks and may begin work on more than one of these tasks in parallel.
However, the problem statement and architecture document should be
completed before the details of the base protocol are finalized, while
there is still time to consider changes to the architecture without
major impacts on established specifications.

Goals and Milestones:

Done  Accept base protocol specification as a WG document
Done  Accept problem statement and applicability as a WG work item
Done  Start work with routing area WG(s) to undertake TRILL extensions
Done  Accept architecture document as a WG work item
Done  Accept routing protocol requirements as a WG work item
Done  Choose routing protocol(s) that can meet the requirements
Done  Submit problem statement and applicability to IESG for Informational RFC
May 2009  Submit base protocol specification to IEEE/IETF expert review
Jun 2009  Base protocol specification submitted to the IESG for publication as a Proposed Standard RFC
Aug 2009  First draft showing what is needed for MIB
Jul 2010  Re-charter or shut down the WG


  • draft-ietf-trill-rbridge-protocol-13.txt

    Request For Comments:

    RFC5556 I Transparent Interconnection of Lots of Links (TRILL): Problem and Applicability Statement