I-D ACTION:draft-yang-forces-model-00.txt

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	Title		: ForCES Forwarding Element Functional Model
	Author(s)	: L. Yang et al.
	Filename	: draft-yang-forces-model-00.txt
	Pages		: 12
	Date		: 24-Jun-02
	
This document defines a functional model for ForCES forwarding 
elements (FEs).  This model is used to describe the state of ForCES 
forwarding elements within the context of the ForCES protocol, so 
that ForCES control elements (CEs) can control the FEs accordingly. 
The model is to specify what logical function instances are present 
in the FEs and in what order these functions are performed. The
forwarding element model defined herein is intended to satisfy the 
requirements specified in the ForCES requirements draft [FORCES-
REQ].  Using this model, predefined or vendor specific logical 
functions can be expressed and configured. However, the definition 
of these components are not described and defined in this document. 
Definitions 
A set of terminology associated with the ForCES requirements is 
defined in [FORCES-REQ] and is not copied here. The following list 
of terminology is relevant to the FE model defined in this document. 
Datapath -- A conceptual path taken by packets within the forwarding 
plane, inside an FE. There might exist more than one datapath within 
an FE. 
Forwarding Element (FE) Block -- An abstraction of the basic packet 
processing functions in the datapath. It is the building block of FE 
functionality. This concept abstracts away implementation details 
from the parameters of interest for configuration, control and 
management by CE. The general rule of thumb on the granularity of FE 
blocks is that FE blocks should be coarse grained, stateful and 
focus on a particular domain. For example, RFC1812 compliant IPv4 
forwarder, classifiers, meters, etc..  
Forwarding Element (FE) Stage -- Representation of a FE block 
instance in a FE's datapath. As a packet flows through an FE along a 
datapath, it flows through one or multiple distinct stages, with 
each stage implementing an instance of a certain logical function. 
There may be one or more combination of such instances  in a FE's 
datapath.  Using NAT as

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