< draft-penno-sfc-yang-12.txt   draft-penno-sfc-yang-13.txt >
SFC Netmod R. Penno SFC Netmod R. Penno
Internet-Draft P. Quinn Internet-Draft P. Quinn
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: September 3, 2015 D. Zhou Expires: September 3, 2015 D. Zhou
J. Li J. Li
Intel Corporation Intel Corporation
March 02, 2015 March 02, 2015
Yang Data Model for Service Function Chaining Yang Data Model for Service Function Chaining
draft-penno-sfc-yang-12 draft-penno-sfc-yang-13
Abstract Abstract
This document defines a YANG data model that can be used to configure This document defines a YANG data model that can be used to configure
and manage Service Function Chains. and manage Service Function Chains.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
skipping to change at page 3, line 32 skipping to change at page 3, line 32
and manage Service Function Chains and manage Service Function Chains
2. Definitions and Acronyms 2. Definitions and Acronyms
The reader should be familiar with the terms contained in The reader should be familiar with the terms contained in
[I-D.ietf-sfc-architecture], [I-D.ietf-sfc-problem-statement] [I-D.ietf-sfc-architecture], [I-D.ietf-sfc-problem-statement]
,[I-D.ietf-sfc-architecture] and [I-D.quinn-vxlan-gpe] ,[I-D.ietf-sfc-architecture] and [I-D.quinn-vxlan-gpe]
3. Understanding SFC Yang Models 3. Understanding SFC Yang Models
There are three main models in SFC: service-function(SF) and service- There are two main models in SFC: service-function (SF) and service-
function-forwarder (SFF). Most other models are used or derived from function-forwarder (SFF). Most other models are used or derived from
those models. SF describes a service function like firewall, napt44, those models. SF describes a service function like firewall, napt44,
dpi, http-proxy, etc. SFF describes a forwarding element that moves dpi, http-proxy, etc. SFF describes a forwarding element that moves
packets along a service path. A SFF to function only needs to be packets along a service path. A SFF to function only needs to be
able to associate a Service Path ID and SI to a next hop data plane able to associate a Service Path ID and SI to a next hop data plane
locator. locator.
The service-locator model provides a centralized place to register The service-locator model provides a centralized place to register
transport and endpoints used with SFFs and SFs. This allows reuse transport and endpoints used with SFFs and SFs. This allows reuse
across a large number of other models since in networking usually across a large number of other models since in networking usually
data plane locators are widely used. Some examples of transport data plane locators are widely used. Some examples of transport
types are GRE, VXLAN-GPE and the data plane locator are IP:port, types are GRE, VXLAN-GPE and the data plane locator are IP:port,
VLAN-ID and MPLS Label. This model is imported by SFF, SF and VLAN-ID and MPLS Label. This model is imported by SFF, SF and
Rendered Service Path (RSP) models. Rendered Service Path (RSP) models.
Service Function Type model serves as a registry for SF types. The Service Function Type model serves as a registry for SF types. The
model can be easily extended by anyone looking to define their own model can be easily extended by anyone looking to define their own
service type. This model is imported by SF and SFC. Since a SFC is service type. This model is imported by SF and Service Function
an abstract order of service function types, having a registry of Chain (SFC). Since a SFC is an abstract order of service function
types is important. Furthermore, instantiating a SFP and RSP from a types, having a registry of types is important. Furthermore, when we
SFC we need to choose the actual SFs that will be traversed by the instantiate a SFP and RSP from a SFC we need to choose the actual SFs
packets and this requires us to know the types associated with a that will be traversed by the packets and this requires us to know
Service Function. the type associated with a Service Function.
A service function path is an intermediate step between SFC and RSP. A service function path (SFP) is an intermediate step between SFC and
It allows the user to provide input or constraints into the RSP. It allows the user to provide input or constraints into the
construction of a RSP. This input ranges from nothing to specifying construction of a RSP. This input ranges from nothing to specifying
the entire path. During RSP construction, the controller examines the entire path. During RSP construction, the controller examines
the SFP and 'fill in the blanks'. the SFP and 'fill in the blanks'.
One of the most important configuration aspects of a SF is the data One of the most important configuration aspects of a SF is the data
plane locators. A SF data plane locators indicates how the SF can be plane locators. A SF's data plane locators indicates how the SF can
reached. A SF can have multiple data plane locators of different be reached. A SF can have multiple data plane locators of different
types as specified in the service locator model. transport and types as specified in the service locator model.
A SFF has also can have multiple data plane locators that indicated A SFF has also can have multiple data plane locators that indicate
how it can be reached. It is very important when constructing a RSP how it can be reached. It is very important when constructing a RSP
to pick SFFs that have data plane locators of the same transport and to pick SFFs that have data plane locators of the same transport and
type so that the path works. A SFF has an additional very important type so that the path works. A SFF has an additional very important
configuration container, the service function dictionary. The configuration container, the service function dictionary. The
service function dictionary stores the SFF's view of the Service service function dictionary stores the SFF's view of the Service
Functions. It contains all SFs and their data plane locators. Functions. It contains all SFs and their data plane locators.
Therefore the Service Function data plane locators and the SFF Therefore the Service Function data plane locators and the SFF
service function dictionary constitute two pieces of a puzzle. If service function dictionary constitute two pieces of a puzzle. If
they fit, it means they can be used in a path, otherwise they can they fit, it means they can be used in a path, otherwise they can
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