Forwarding and Control Element Separation
charter-ietf-forces-03-03

The ForCES working group has created a framework, requirements, a solution
protocol, a logical function block library, and other associated documents in
support of Forwarding and Control Element Separation.

The ForCES working group is now working on a set of additions to the model,
protocol, and libraries based on the experience gained from developing the
standards and from many efforts using this architecture.

The following 5 work items are the chartered tasks of this working group:

o Extensions to Model and Protocol

This work is to address a set of extensions to the base model and protocol
resulting in updates to RFCs 5810 and 5812. This effort will produce 2
standards effort documents (one for the model and another for the protocol).

The model extensions will:
1. Allow complex metadata
2. Allow optional default values for datatypes
3. Allow optional access-type for datatypes inside complex components
4. Define new base type: Bitmap
5. Define new events to monitor states.

The protocol extensions will:
1. Support table range query
2. Support table append
3. Define additional return codes to reduce ambiguity
4. Define data packing rule for bitmap datatype.

o Inter-FE Connectivity

ForCES processing is often spread across multiple Forwarding Elements (FEs).
The original framework identified the interface between FEs as the "Fi"
reference point. Protocol and Logigal Function Block (LFB) mechanisms to
carry metadata across the Fi interface are needed. This effort will produce
a standards track doument defining the protocol on the wire to address this
need, and the LFBs used to represent the Interfaces for sending and receiving
such information. It is expected that this work will draw heavily on existing
protocol and LFB definitions.

o Paralellization

An FE can implement an LFB chain with paralellization, but the currently-
defined mechanism has no means to represent when synchronization is needed,
or to allow the CE to specify where it believes such paralllism is useful.
This work item will produce a single standards track document to improve the
handling of this case.

o Subsidiary Management

Deployment experience has demonstrated usefulness of expressing the
Forwarding Element Model (FEM) using the same semantics as for any other LFB.
This allows it to be controlled by the same Control Element (CE). This work
item assumes the presence of an initially booted FE whose configuration could
then be updated at runtime via an FEM LFB for runtime config purposes (e.g.,
by adding a new CE and its associated IP address). This work item can also be
useful in addressing control of virtual FEs where individual FEM Managers can
be addressed to control the creation, configuration, and resource assignment
of such virtual FEs within a physical FE. This work would result in a
standards track LFB FEM library RFC.

In addition to the specific work items listed above, the working group will
allow discussions of how to use ForCES to model topics of interest to
Network Function Virtualization, I2RS, or OpenFlow may be discussed and
reviewed. It is understood that the primary responsibility for such documents
lives with other working groups, individual contributions, or other standards
bodies.

== Goals and Milestones ==
September 2013 Request for Publication of Standards Track document specifying
model changes
September 2013 Request for Publication of Standards Track document specifying
protocol changes
February 2014 Request for publication of Subsidiary management LFB
March 2014 Request for publication of Inter-FE LFB
March 2014 Request for publication of parallelization LFBs
April 2014 Recharter or shutdown

This working group focuses on the ForCES architecture.

The ForCES architecture constitutes:
* One or more Control Elements (CE) interacting with one or more Forwarding
Elements (FEs) to form a Network Element (NE). Any or all of these entities
could be physical or virtual.
* a data model to define the controlled or configured entity
* a protocol used to communicate between CEs and FEs which is agnostic to the
model used
* one or more xml documents describing the controlled entity using the ForCES
data model. The protocol acts (in the direction of the controller to datapath)
on these definitions to achieve an end goal of control, configuration, packet
redirect and in the reverse direction for responses, packet redirects and
events.

This working group was originally started to address the desire to create a
standardized control-datapath architecture to control off-the shelf hardware
that implements IP forwarding plane capability. This could be commercial chips,
ASICs, FPGAs, Network Processors, or software based forwarding plane devices.

As the work evolved, in order to avoid prejudicing implementation choices an
abstract data model for the forwarding elements and a protocol for manipulating
those forwarding elements was developed and standardized. Implementations and
interoperation were demonstrated.

With the emergence of SDN as an industry focus, there is renewed interest in the
control capabilities and data plane flexibility provided by the ForCES
architecture. Also, with this interest in SDN there has been a realization that
the same abstractions can be used for service manipulation for overall device
control or for configuration of the services.