draft-ietf-teas-actn-framework-04.txt   draft-ietf-teas-actn-framework-05.txt 
TEAS Working Group Daniele Ceccarelli (Ed) TEAS Working Group Daniele Ceccarelli (Ed)
Internet Draft Ericsson Internet Draft Ericsson
Intended status: Informational Young Lee (Ed) Intended status: Informational Young Lee (Ed)
Expires: August 2017 Huawei Expires: August 2017 Huawei
February 16, 2017 May 5, 2017
Framework for Abstraction and Control of Traffic Engineered Networks Framework for Abstraction and Control of Traffic Engineered Networks
draft-ietf-teas-actn-framework-04 draft-ietf-teas-actn-framework-05
Abstract Abstract
Traffic Engineered networks have a variety of mechanisms to Traffic Engineered networks have a variety of mechanisms to
facilitate the separation of the data plane and control plane. They facilitate the separation of the data plane and control plane. They
also have a range of management and provisioning protocols to also have a range of management and provisioning protocols to
configure and activate network resources. These mechanisms configure and activate network resources. These mechanisms
represent key technologies for enabling flexible and dynamic represent key technologies for enabling flexible and dynamic
networking. networking.
skipping to change at page 2, line 4 skipping to change at page 1, line 45
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This Internet-Draft will expire on August 16, 2017. This Internet-Draft will expire on August 5, 2017.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................3
1.1. Terminology...............................................6 1.1. Terminology...............................................5
2. Business Model of ACTN.........................................9 2. Business Model of ACTN.........................................9
2.1. Customers.................................................9 2.1. Customers.................................................9
2.2. Service Providers........................................10 2.2. Service Providers........................................10
2.3. Network Providers........................................11 2.3. Network Providers........................................12
3. ACTN Architecture.............................................12 3. Virtual Network Service.......................................12
3.1. Customer Network Controller..............................14 4. ACTN Base Architecture........................................13
3.2. Multi Domain Service Coordinator.........................15 4.1. Customer Network Controller..............................15
3.3. Physical Network Controller..............................16 4.2. Multi Domain Service Coordinator.........................16
3.4. ACTN Interfaces..........................................17 4.3. Physical Network Controller..............................17
4. VN Creation Process...........................................20 4.4. ACTN Interfaces..........................................17
4.1. VN Creation Example......................................20 5. Advanced ACTN architectures...................................18
5. Access Points and Virtual Network Access Points...............22 5.1. MDSC Hierarchy for scalability...........................18
5.1. Dual homing scenario.....................................25 5.2. Functional Split of MDSC Functions in Orchestrators......19
6. End Point Selection Based On Network Status...................26 6. Topology Abstraction Method...................................21
6.1. Pre-Planned End Point Migration..........................27 6.1. No abstraction (native/white topology)...................22
6.2. On the Fly End Point Migration...........................28 6.2. One Virtual Node (black topology)........................23
6.3. Abstraction of TE tunnels for all pairs of border nodes
7. Manageability Considerations..................................28 (grey topology)...............................................24
7.1. Policy...................................................29 6.3.1. Grey topology type A: border nodes with a TE links
7.2. Policy applied to the Customer Network Controller........29 between them in a full mesh fashion........................25
7.3. Policy applied to the Multi Domain Service Coordinator...30 6.3.2. Grey topology Type B................................25
7.4. Policy applied to the Physical Network Controller........30 6.4. Topology Abstraction Granularity Level example...........25
8. Security Considerations.......................................31 7. Access Points and Virtual Network Access Points...............27
8.1. Interface between the Customer Network Controller and Multi 7.1. Dual homing scenario.....................................29
Domain Service Coordinator (MDSC), CNC-MDSC Interface (CMI)...32 8. Advanced ACTN Application: Multi-Destination Service..........30
8.2. Interface between the Multi Domain Service Coordinator and 8.1. Pre-Planned End Point Migration..........................31
Physical Network Controller (PNC), MDSC-PNC Interface (MPI)...32 8.2. On the Fly End Point Migration...........................32
9. References....................................................33 9. Advanced Topic................................................32
9.1. Informative References...................................33 10. Manageability Considerations.................................32
10. Contributors.................................................34 10.1. Policy..................................................33
Authors' Addresses...............................................35 10.2. Policy applied to the Customer Network Controller.......34
10.3. Policy applied to the Multi Domain Service Coordinator..34
10.4. Policy applied to the Physical Network Controller.......34
11. Security Considerations......................................35
11.1. Interface between the Customer Network Controller and Multi
Domain Service Coordinator (MDSC), CNC-MDSC Interface (CMI)...36
11.2. Interface between the Multi Domain Service Coordinator and
Physical Network Controller (PNC), MDSC-PNC Interface (MPI)...36
12. References...................................................37
12.1. Informative References..................................37
13. Contributors.................................................38
Authors' Addresses...............................................39
APPENDIX A - Example of MDSC and PNC functions integrated in
Service/Network Orchestrator.....................................40
APPENDIX B - Example of IP + Optical network with L3VPN service..40
APPENDIX C - Example of ODU service connectivity................41
1. Introduction 1. Introduction
Traffic Engineered networks have a variety of mechanisms to Traffic Engineered networks have a variety of mechanisms to
facilitate separation of data plane and control plane including facilitate separation of data plane and control plane including
distributed signaling for path setup and protection, centralized distributed signaling for path setup and protection, centralized
path computation for planning and traffic engineering, and a range path computation for planning and traffic engineering, and a range
of management and provisioning protocols to configure and activate of management and provisioning protocols to configure and activate
network resources. These mechanisms represent key technologies for network resources. These mechanisms represent key technologies for
enabling flexible and dynamic networking. enabling flexible and dynamic networking.
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these features Abstraction and Control of Traffic Engineered these features Abstraction and Control of Traffic Engineered
Networks (ACTN). Networks (ACTN).
Particular attention needs to be paid to the multi-domain case, ACTN Particular attention needs to be paid to the multi-domain case, ACTN
can facilitate virtual network operation via the creation of a can facilitate virtual network operation via the creation of a
single virtualized network or a seamless service. This supports single virtualized network or a seamless service. This supports
operators in viewing and controlling different domains (at any operators in viewing and controlling different domains (at any
dimension: applied technology, administrative zones, or vendor- dimension: applied technology, administrative zones, or vendor-
specific technology islands) as a single virtualized network. specific technology islands) as a single virtualized network.
Network virtualization refers to allowing the customers of network
operators (see Section 2.1) to utilize a certain amount of network
resources as if they own them and thus control their allocated
resources with higher layer or application processes that enables
the resources to be used in the most optimal way. More flexible,
dynamic customer control capabilities are added to the traditional
VPN along with a customer-specific virtual network view. Customers
control a view of virtual network resources, specifically allocated
to each one of them. This view is called an virtual network
topology. Such a view may be specific to a service, the set of
consumed resources, or to a particular customer.
Network abstraction refers to presenting a customer with a view of
the operator's network in such a way that the links and nodes in
that view constitute an aggregation or abstraction of the real
resources in the operator's network in a way that is independent of
the underlying network technologies, capabilities, and topology.
The customer operates an abstract network as if it was their own
network, but the operational commands are mapped onto the underlying
network through domains coordination.
The customer controller for a virtual or abstract network is
envisioned to support many distinct applications. This means that
there may be a further level of virtualization that provides a view
of resources in the customer's virtual network for use by an
individual application.
The ACTN framework described in this document facilitates: The ACTN framework described in this document facilitates:
. Abstraction of the underlying network resources to higher-layer . Abstraction of the underlying network resources to higher-layer
applications and customers [RFC7926]. applications and customers [RFC7926].
. Virtualization of particular underlying resources, whose . Virtualization of particular underlying resources, whose
selection criterion is the allocation of those resources to a selection criterion is the allocation of those resources to a
particular customer, application or service [ONF-ARCH]. particular customer, application or service [ONF-ARCH].
. Slicing of infrastructure to meet specific customers' service . Network slicing of infrastructure to meet specific customers'
requirements. service requirements.
. Creation of a virtualized environment allowing operators to . Creation of a virtualized environment allowing operators to
view and control multi-domain networks as a single virtualized view and control multi-domain networks as a single virtualized
network. network.
. The possibility of providing a customer with a virtualized . The presentation to customers of networks as a virtual network
network. via open and programmable interfaces.
. A virtualization/mapping network function that adapts the
customer's requests for control of the virtual resources that
have been allocated to the customer to control commands applied
to the underlying network resources. Such a function performs
the necessary mapping, translation, isolation and
security/policy enforcement, etc.
. The presentation to customers of networks as a virtualized
topology via open and programmable interfaces. This allows for
the recursion of controllers in a customer-provider
relationship.
1.1. Terminology 1.1. Terminology
The following terms are used in this document. Some of them are The following terms are used in this document. Some of them are
newly defined, some others reference existing definition: newly defined, some others reference existing definition:
. Network Slicing: Network slicing is a collection of resources
that are used to establish logically dedicated virtual networks
over TE networks. It allows a network provider to provide
dedicated virtual networks for application/customer over a
common network infrastructure. The logically dedicated
resources are a part of the larger common network
infrastructures that are shared among various network slice
instances which are the end-to-end realization of network
slicing, consisting of the combination of physically or
logically dedicated resources.
. Node: A node is a vertex on the graph representation of a TE . Node: A node is a vertex on the graph representation of a TE
topology. In a physical network a node corresponds to a network topology. In a physical network topology, a node corresponds to
element (NE). In a sliced network, a node is some subset of the a physical network element (NE). In an abstract network
capabilities of a physical network element. In an abstract topology, a node (sometimes called an abstract node) is a
network, a node (sometimes called an abstract node) is a representation as a single vertex of one or more physical NEs
representation as a single vertex in the topology of the and their connecting physical connections. The concept of a
abstract network of one or more nodes and their connecting node represents the ability to connect from any access to the
links from the physical network. The concept of a node node (a link end) to any other access to that node, although
represents the ability to connect from any access to the node
(a link end) to any other access to that node, although
"limited cross-connect capabilities" may also be defined to "limited cross-connect capabilities" may also be defined to
restrict this functionality. Just as network slicing and restrict this functionality. Just as network slicing and
network abstraction may be applied recursively, so a node in a network abstraction may be applied recursively, so a node in a
topology may be created by applying slicing or abstraction on topology may be created by applying slicing or abstraction on
the nodes in the underlying topology. the nodes in the underlying topology.
. Link: A link is an edge on the graph representation of a TE . Link: A link is an edge on the graph representation of a TE
topology. Two nodes connected by a link are said to be topology. Two nodes connected by a link are said to be
"adjacent" in the TE topology. In a physical network, a link "adjacent" in the TE topology. In a physical network topology,
corresponds to a physical connection. In a sliced topology, a a link corresponds to a physical connection. In an abstract
link is some subset of the capabilities of a physical network topology, a link (sometimes called an abstract link) is
connection. In an abstract network, a link (sometimes called an a representation of the potential to connect a pair of points
abstract link) is a representation as an edge in the topology with certain TE parameters (see RFC 7926 for details). Network
of the abstract network of one or more links and the nodes they slicing/virtualization and network abstraction may be applied
connect from the physical network. Abstract links may be recursively, so a link in a topology may be created by applying
realized by Label Switched Paths (LSPs) across the physical slicing and/or abstraction on the links in the underlying
network that may be pre-established or could be only topology.
potentially achievable. Just as network slicing and network
abstraction may be applied recursively, so a link in a topology
may be created by applying slicing or abstraction on the links
in the underlying topology. While most links are point-to-
point, connecting just two nodes, the concept of a multi-access
link exists where more than two nodes are collectively adjacent
and data sent on the link by one node will be equally delivered
to all other nodes connected by the link.
. PNC: A Physical Network Controller is a domain controller that . CNC: A Customer Network Controller is responsible for
is responsible for controlling devices or NEs under its direct communicating customer's virtual network service requirements
control. This can be an SDN controller, a Network Management to network provider. It has knowledge of the end-point
System (NMS), an Element Management System (EMS), an active PCE associated with virtual network service, service policy, and
or any other mean to dynamically control a set of nodes and other QoS information related to the service it is responsible
that is implementing an NBI compliant with ACTN specification. for instantiating.
. PNC: A Physical Network Controller is responsible for
controlling devices or NEs under its direct control. The PNC
functions can be implemented as part of an SDN domain
controller, a Network Management System (NMS), an Element
Management System (EMS), an active PCE-based controller or any
other means to dynamically control a set of nodes and that is
implementing an NBI compliant with ACTN specification.
. PNC domain: A PNC domain includes all the resources under the . PNC domain: A PNC domain includes all the resources under the
control of a single PNC. It can be composed of different control of a single PNC. It can be composed of different
routing domains and administrative domains, and the resources routing domains and administrative domains, and the resources
may come from different layers. The interconnection between PNC may come from different layers. The interconnection between PNC
domains can be a link or a node. domains can be a link or a node.
_______ Border Link _______ _______ Border Link _______
_( )================( )_ _( )================( )_
_( )_ _( )_ _( )_ _( )_
( ) ---- ( ) ( ) ---- ( )
( PNC )| |( PNC ) ( PNC )| |( PNC )
( Domain X )| |( Domain Y ) ( Domain X )| |( Domain Y )
( )| |( ) ( )| |( )
(_ _) ---- (_ _) (_ _) ---- (_ _)
(_ _) Border (_ _) (_ _) Border (_ _)
(_______) Node (_______) (_______) Node (_______)
Figure 1: PNC Domain Borders Figure 1: PNC Domain Borders
. MDSC: A multi-domain Service Coordinator is a functional block
that implements all four ACTN main functions, i.e., multi
domain coordination, virtualization/abstraction, customer
mapping/translation, and virtual service coordination. The
first two functions of the MDSC, namely, multi domain
coordination and virtualization/abstraction are referred to as
network-related functions while the last two functions, namely,
customer mapping/translation and virtual service coordination
are referred to as service-related functions. See details on
these functions in Section 4.2. In some implementation, PNC and
MDSC functions can be co-located and implemented in the same
box.
. A Virtual Network (VN) is a customer view of the TE . A Virtual Network (VN) is a customer view of the TE
network. It is presented by the provider as a set of physical network. Depending on the agreement between client and
and/or abstracted resources. Depending on the agreement between provider various VN operations and VN views are possible as
client and provider various VN operations and VN views are follows:
possible as follows:
o VN Creation - VN could be pre-configured and created via o VN Creation - VN could be pre-configured and created via
offline negotiation between customer and provider. In offline negotiation between customer and provider. In
other cases, the VN could also be created dynamically other cases, the VN could also be created dynamically
based on a request from the customer with given SLA based on a request from the customer with given SLA
attributes which satisfy the customer's objectives. attributes which satisfy the customer's objectives.
o Dynamic Operations - The VN could be further modified or o Dynamic Operations - The VN could be further modified or
deleted based on a customer request to request. The deleted based on a customer request. The customer can
customer can further act upon the virtual network further act upon the virtual network resources to perform
resources to perform end-to-end tunnel management (set- end-to-end tunnel management (set-up/release/modify).
up/release/modify). These changes will result in
subsequent LSP management at the operator's level.
o VN View: These changes will result in subsequent LSP management at
the operator's level.
o VN Type:
a. The VN can be seen as set of end-to-end tunnels from a a. The VN can be seen as set of end-to-end tunnels from a
customer point of view, where each tunnel is referred customer point of view, where each tunnel is referred
as a VN member. Each VN member can then be formed by as a VN member. Each VN member can then be formed by
recursive slicing or abstraction of paths in recursive slicing or abstraction of paths in
underlying networks. Such end-to-end tunnels may underlying networks. Such end-to-end tunnels may
comprise of customer end points, access links, intra- comprise of customer end points, access links, intra-
domain paths, and inter-domain links. In this view VN domain paths, and inter-domain links. In this view, VN
is thus a set of VN members. is thus a set of VN members (which is referred to as
Type 1 VN)
b. The VN can also be seen as a topology comprising of b. The VN can also be seen as a topology comprising of
physical, sliced, and abstract nodes and links. The physical, sliced, and abstract nodes and links. This
nodes in this case include physical customer end VN is referred to as Type 2 VN. The nodes in this case
points, border nodes, and internal nodes as well as include physical customer end points, border nodes,
abstracted nodes. Similarly the links include physical and internal nodes as well as abstracted nodes.
access links, inter-domain links, and intra-domain Similarly the links include physical access links,
links as well as abstract links. The abstract nodes inter-domain links, and intra-domain links as well as
and links in this view can be pre-negotiated or abstract links. With VN type 2, it is still possible
created dynamically. to view VN member-level.
. Virtual Network Service (VNS) is requested by the customer and
negotiated with the provider. There are three types of VNS
defined in this document. Type 1 VNS refers to VNS in which
customer is allowed to create and operate a Type 1 VN. Type 2a
and 2b VNS refers to the VNS in which customer is allowed to
create and operates a Type 2 VN. With Type 2a VNS, once the VN
is statically created at service configuration time, the
customer is not allowed to change the topology (i.e., adding or
deleting abstract nodes/links). Type 2b VNS is the same as Type
2a VNS except that the customer is allowed to change topology
dynamically from the initial topology created at service
configuration time. See Section 3 for details.
. Abstraction. This process is defined in [RFC7926]. . Abstraction. This process is defined in [RFC7926].
. Abstract Link: The term "abstract link" is defined in . Abstract Link: The term "abstract link" is defined in
[RFC7926]. [RFC7926].
. Abstract Topology: The topology of abstract nodes and abstract . Abstract Topology: The topology of abstract nodes and abstract
links presented through the process of abstraction by a lower links presented through the process of abstraction by a lower
layer network for use by a higher layer network. layer network for use by a higher layer network.
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underlying objectives set by the network providers. To enable these underlying objectives set by the network providers. To enable these
customers to support flexible and dynamic applications they need to customers to support flexible and dynamic applications they need to
control their allocated virtual network resources in a dynamic control their allocated virtual network resources in a dynamic
fashion, and that means that they need a view of the topology that fashion, and that means that they need a view of the topology that
spans all of the network providers. Customers of a given service spans all of the network providers. Customers of a given service
provider can in turn offer a service to other customers in a provider can in turn offer a service to other customers in a
recursive way. recursive way.
2.2. Service Providers 2.2. Service Providers
Service providers are the providers of virtual network services to Service providers are the providers of virtual network services (see
their customers. Service providers may or may not own physical Section 3 for details) to their customers. Service providers may or
network resources (i.e, may or may not be network providers as may not own physical network resources (i.e, may or may not be
described in Section 2.3). When a service provider is the same as network providers as described in Section 2.3). When a service
the network provider, this is similar to existing VPN models applied provider is the same as the network provider, this is similar to
to a single provider. This approach works well when the customer existing VPN models applied to a single provider. This approach
maintains a single interface with a single provider. When customer works well when the customer maintains a single interface with a
spans multiple independent network provider domains, then it becomes single provider. When customer spans multiple independent network
hard to facilitate the creation of end-to-end virtual network provider domains, then it becomes hard to facilitate the creation of
services with this model. end-to-end virtual network services with this model.
A more interesting case arises when network providers only provide A more interesting case arises when network providers only provide
infrastructure, while distinct service providers interface to the infrastructure, while distinct service providers interface to the
customers. In this case, service providers are, themselves customers customers. In this case, service providers are, themselves customers
of the network infrastructure providers. One service provider may of the network infrastructure providers. One service provider may
need to keep multiple independent network providers as its end-users need to keep multiple independent network providers as its end-users
span geographically across multiple network provider domains. span geographically across multiple network provider domains.
The ACTN network model is predicated upon this three tier model and The ACTN network model is predicated upon this three tier model and
is summarized in Figure 2: is summarized in Figure 2:
+----------------------+ +----------------------+
| customer | | customer |
+----------------------+ +----------------------+
| |
| /\ Service/Customer specific VNS || | /\ VNS
| || Abstract Topology Request || | || Reply
| || \/ | ||
+----------------------+ E2E abstract +----------------------+
| Service Provider | topology creation | Service Provider |
+----------------------+ +----------------------+
/ | \ / | \
/ | \ Network Topology / | \
/ | \ (raw or abstract) / | \
/ | \ / | \
+------------------+ +------------------+ +------------------+ +------------------+ +------------------+ +------------------+
|Network Provider 1| |Network Provider 2| |Network Provider 3| |Network Provider 1| |Network Provider 2| |Network Provider 3|
+------------------+ +------------------+ +------------------+ +------------------+ +------------------+ +------------------+
Figure 2: Three tier model. Figure 2: Three tier model.
There can be multiple service providers to which a customer may There can be multiple service providers to which a customer may
interface. interface.
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infrastructure. infrastructure.
2.3. Network Providers 2.3. Network Providers
Network Providers are the infrastructure providers that own the Network Providers are the infrastructure providers that own the
physical network resources and provide network resources to their physical network resources and provide network resources to their
customers. The layered model described in this architecture customers. The layered model described in this architecture
separates the concerns of network providers and customers, with separates the concerns of network providers and customers, with
service providers acting as aggregators of customer requests. service providers acting as aggregators of customer requests.
3. ACTN Architecture 3. Virtual Network Service
Virtual Network Service (VNS) is requested by the customer and
negotiated with the provider. There are three types of VNS defined
in this document.
Type 1 VNS refers to VNS in which customer is allowed to create and
operate a Type 1 VN. Type 1 VN is a VN that comprises a set of end-
to-end tunnels from a customer point of view, where each tunnel is
referred as a VN member. With Type 1 VNS, the network operator does
not need to provide additional abstract VN topology associated with
the Type 1 VN.
Type 2a VNS refer to VNS in which customer is allowed to create and
operates a Type 2 VN, but not allowed to change topology once it is
configured at service configuration time. Type 2 VN is an abstract
VN topology that may comprise of virtual/abstract nodes and links.
The nodes in this case may include physical customer end points,
border nodes, and internal nodes as well as abstracted nodes.
Similarly, the links may include physical access links, inter-domain
links, and intra-domain links as well as abstract links.
Type 2b VNS refers to VNS in which customer is allowed to create and
operate a Type 2 VN and the customer is allowed to dynamically
change abstract VN topology from the initially configured abstract
VN topology at service configuration time.
From an implementation standpoint, Type 2a VNS and Type 2b VNS
differentiation might be fulfilled via local policy.
In all types of VNS, customer can specify a set of service related
parameters such as connectivity type, VN traffic matrix (e.g.,
bandwidth, latency, diversity, etc.), VN survivability, VN service
policy and other characteristics.
4. ACTN Base Architecture
This section provides a high-level model of ACTN showing the This section provides a high-level model of ACTN showing the
interfaces and the flow of control between components. interfaces and the flow of control between components.
The ACTN architecture is aligned with the ONF SDN architecture [ONF- The ACTN architecture is aligned with the ONF SDN architecture [ONF-
ARCH] and presents a 3-tiers reference model. It allows for ARCH] and presents a 3-tiers reference model. It allows for
hierarchy and recursiveness not only of SDN controllers but also of hierarchy and recursiveness not only of SDN controllers but also of
traditionally controlled domains that use a control plane. It traditionally controlled domains that use a control plane. It
defines three types of controllers depending on the functionalities defines three types of controllers depending on the functionalities
they implement. The main functionalities that are identified are: they implement. The main functionalities that are identified are:
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Domain sequence path calculation/determination is also a part Domain sequence path calculation/determination is also a part
of this function. of this function.
. Virtualization/Abstraction function: This function provides an . Virtualization/Abstraction function: This function provides an
abstracted view of the underlying network resources for use by abstracted view of the underlying network resources for use by
the customer - a customer may be the client or a higher level the customer - a customer may be the client or a higher level
controller entity. This function includes network path controller entity. This function includes network path
computation based on customer service connectivity request computation based on customer service connectivity request
constraints, path computation based on the global network-wide constraints, path computation based on the global network-wide
abstracted topology, and the creation of an abstracted view of abstracted topology, and the creation of an abstracted view of
network slices allocated to each customer. These operations network resources allocated to each customer. These operations
depend on customer-specific network objective functions and depend on customer-specific network objective functions and
customer traffic profiles. customer traffic profiles.
. Customer mapping/translation function: This function is to map . Customer mapping/translation function: This function is to map
customer requests/commands into network provisioning requests customer requests/commands into network provisioning requests
that can be sent to the Physical Network Controller (PNC) that can be sent to the Physical Network Controller (PNC)
according to business policies provisioned statically or according to business policies provisioned statically or
dynamically at the OSS/NMS. Specifically, it provides mapping and dynamically at the OSS/NMS. Specifically, it provides mapping and
translation of a customer's service request into a set of translation of a customer's service request into a set of
parameters that are specific to a network type and technology parameters that are specific to a network type and technology
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customer service-related information into virtual network customer service-related information into virtual network
service operations in order to seamlessly operate virtual service operations in order to seamlessly operate virtual
networks while meeting a customer's service requirements. In networks while meeting a customer's service requirements. In
the context of ACTN, service/virtual service coordination the context of ACTN, service/virtual service coordination
includes a number of service orchestration functions such as includes a number of service orchestration functions such as
multi-destination load balancing, guarantees of service multi-destination load balancing, guarantees of service
quality, bandwidth and throughput. It also includes quality, bandwidth and throughput. It also includes
notifications for service fault and performance degradation and notifications for service fault and performance degradation and
so forth. so forth.
Figure 3 depicts the base ACTN architecture with three controller
types and the corresponding interfaces between these controllers.
The types of controller defined in the ACTN architecture are shown The types of controller defined in the ACTN architecture are shown
in Figure 3 below and are as follows: in Figure 3 below and are as follows:
. CNC - Customer Network Controller . CNC - Customer Network Controller
. MDSC - Multi Domain Service Coordinator . MDSC - Multi Domain Service Coordinator
. PNC - Physical Network Controller . PNC - Physical Network Controller
Figure 3 also shows the following interfaces: Figure 3 also shows the following interfaces:
. CMI - CNC-MDSC Interface . CMI - CNC-MDSC Interface
. MPI - MDSC-PNC Interface . MPI - MDSC-PNC Interface
. SBI - South Bound Interface
+--------------+ +---------------+ +--------------+
| CNC-A | | CNC-B | | CNC-C |
|(DC provider) | | (ISP) | | (MVNO) |
+--------------+ +---------------+ +--------------+
\ | /
Business \ | /
Boundary =======\========================|=========================/=======
Between \ | CMI /
Customer & ----------- | --------------
Network Provider \ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
------------ |MPI ----------------
/ | \
+-------+ +-------+ +-------+
| PNC | | PNC | | PNC |
+-------+ +-------+ +-------+
| GMPLS / | / \
| trigger / |SBI / \
-------- ----- | / \
( ) ( ) | / \
- - ( Phys. ) | / -----
( GMPLS ) ( Net ) | / ( )
( Physical ) ---- | / ( Phys. )
( Network ) ----- ----- ( Net )
- - ( ) ( ) -----
( ) ( Phys. ) ( Phys. )
-------- ( Net ) ( Net )
----- -----
VPN customer NW Mobile Customer ISP NW service Customer Figure 3: ACTN Base Architecture
| | |
+-------+ +-------+ +-------+
| CNC-A | | CNC-B | | CNC-C |
+-------+ +-------+ +-------+
\ | /
----------- |CMI I/F --------------
\ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
------------- |MPI I/F -------------
/ | \
+-------+ +-------+ +-------+
| PNC | | PNC | | PNC |
+-------+ +-------+ +-------+
| GMPLS / | / \
| trigger / | / \
-------- ---- | / \
( ) ( ) | / \
- - ( Phys ) | / -----
( GMPLS ) (Netw) | / ( )
( Physical ) ---- | / ( Phys. )
( Network ) ----- ----- ( Net )
- - ( ) ( ) -----
( ) ( Phys. ) ( Phys )
-------- ( Net ) ( Net )
----- -----
Figure 3: ACTN Control Hierarchy
3.1. Customer Network Controller 4.1. Customer Network Controller
A Virtual Network Service is instantiated by the Customer Network A Virtual Network Service is instantiated by the Customer Network
Controller via the CNC-MDSC Interface (CMI). As the Customer Network Controller via the CNC-MDSC Interface (CMI). As the Customer Network
Controller directly interfaces to the applications, it understands Controller directly interfaces to the applications, it understands
multiple application requirements and their service needs. It is multiple application requirements and their service needs. It is
assumed that the Customer Network Controller and the MDSC have a assumed that the Customer Network Controller and the MDSC have a
common knowledge of the end-point interfaces based on their business common knowledge of the end-point interfaces based on their business
negotiations prior to service instantiation. End-point interfaces negotiations prior to service instantiation. End-point interfaces
refer to customer-network physical interfaces that connect customer refer to customer-network physical interfaces that connect customer
premise equipment to network provider equipment. premise equipment to network provider equipment.
3.2. Multi Domain Service Coordinator 4.2. Multi Domain Service Coordinator
The Multi Domain Service Coordinator (MDSC) sits between the CNC The Multi Domain Service Coordinator (MDSC) sits between the CNC
that issues connectivity requests and the Physical Network that issues connectivity requests and the Physical Network
Controllers (PNCs) that manage the physical network resources. The Controllers (PNCs) that manage the physical network resources. The
MDSC can be collocated with the PNC, especially in those cases where MDSC can be collocated with the PNC.
the service provider and the network provider are the same entity.
The internal system architecture and building blocks of the MDSC are The internal system architecture and building blocks of the MDSC are
out of the scope of ACTN. Some examples can be found in the out of the scope of ACTN. Some examples can be found in the
Application Based Network Operations (ABNO) architecture [RFC7491] Application Based Network Operations (ABNO) architecture [RFC7491]
and the ONF SDN architecture [ONF-ARCH]. and the ONF SDN architecture [ONF-ARCH].
The MDSC is the only building block of the architecture that can The MDSC is the only building block of the architecture that can
implement all four ACTN main functions, i.e., multi domain implement all four ACTN main functions, i.e., multi domain
coordination, virtualization/abstraction, customer coordination, virtualization/abstraction, customer
mapping/translation, and virtual service coordination. The first two mapping/translation, and virtual service coordination. The first two
functions of the MDSC, namely, multi domain coordination and functions of the MDSC, namely, multi domain coordination and
virtualization/abstraction are referred to as network virtualization/abstraction are referred to as network-related
control/coordination functions while the last two functions, namely, functions while the last two functions, namely, customer
customer mapping/translation and virtual service coordination are mapping/translation and virtual service coordination are referred to
referred to as service control/coordination functions. as service-related functions.
The key point of the MDSC (and of the whole ACTN framework) is The key point of the MDSC (and of the whole ACTN framework) is
detaching the network and service control from underlying technology detaching the network and service control from underlying technology
to help the customer express the network as desired by business to help the customer express the network as desired by business
needs. The MDSC envelopes the instantiation of the right technology needs. The MDSC envelopes the instantiation of the right technology
and network control to meet business criteria. In essence it and network control to meet business criteria. In essence it
controls and manages the primitives to achieve functionalities as controls and manages the primitives to achieve functionalities as
desired by the CNC. desired by the CNC.
A hierarchy of MDSCs can be foreseen for scalability and
administrative choices. In this case another interface needs to be
defined, the MMI (MDSC-MDSC interface) as shown in Figure 4.
+-------+ +-------+ +-------+
| CNC-A | | CNC-B | | CNC-C |
+-------+ +-------+ +-------+
\ | /
---------- |-CMI I/F -----------
\ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
---------- |-MMI I/F -----------
/ | \
+----------+ +----------+ +--------+
| MDSC | | MDSC | | MDSC |
+----------+ +----------+ +--------+
| / |-MPI I/F / \
| / | / \
+-----+ +-----+ +-----+ +-----+ +-----+
| PNC | | PNC | | PNC | | PNC | | PNC |
+-----+ +-----+ +-----+ +-----+ +-----+
Figure 4: Controller recursiveness
In order to allow for multi-domain coordination a 1:N relationship In order to allow for multi-domain coordination a 1:N relationship
must be allowed between MDSCs and between MDSCs and PNCs (i.e. 1 must be allowed between MDSCs and between MDSCs and PNCs (i.e. 1
parent MDSC and N child MDSC or 1 MDSC and N PNCs). parent MDSC and N child MDSC or 1 MDSC and N PNCs).
In the case where there is a hierarchy of MDSCs, the interface above
the top MDSC (i.e., CMI) and the interface below the bottom MDSCs
(i.e., SBI) remain the same. The recursion of MDSCs in the middle
layers within this hierarchy of MDSCs may take place via the MMI.
Please see Section 4 for details of the ACTN interfaces.
In addition to that, it could also be possible to have an M:1 In addition to that, it could also be possible to have an M:1
relationship between MDSCs and PNC to allow for network resource relationship between MDSCs and PNC to allow for network resource
partitioning/sharing among different customers not necessarily partitioning/sharing among different customers not necessarily
connected to the same MDSC (e.g., different service providers). connected to the same MDSC (e.g., different service providers).
3.3. Physical Network Controller 4.3. Physical Network Controller
The Physical Network Controller (PNC) oversees configuring the The Physical Network Controller (PNC) oversees configuring the
network elements, monitoring the topology (physical or virtual) of network elements, monitoring the topology (physical or virtual) of
the network, and passing information about the topology (either raw the network, and passing information about the topology (either raw
or abstracted) to the MDSC. or abstracted) to the MDSC.
The internal architecture of the PNC, its building blocks, and the The internal architecture of the PNC, its building blocks, and the
way it controls its domain are out of the scope of ACTN. Some way it controls its domain are out of the scope of ACTN. Some
examples can be found in the Application Based Network Operations examples can be found in the Application Based Network Operations
(ABNO) architecture [RFC7491] and the ONF SDN architecture [ONF- (ABNO) architecture [RFC7491] and the ONF SDN architecture [ONF-
ARCH] ARCH]
The PNC, in addition to being in charge of controlling the physical The PNC, in addition to being in charge of controlling the physical
network, is able to implement two of the four main ACTN main network, is able to implement two of the four main ACTN main
functions: multi domain coordination and virtualization/abstraction functions: multi domain coordination and virtualization/abstraction
function. function.
Note that from an implementation point of view it is possible to
integrate one or more MDSC functions and one or more PNC functions
within the same controller.
3.4. ACTN Interfaces 4.4. ACTN Interfaces
To allow virtualization and multi domain coordination, the network
has to provide open, programmable interfaces, through which customer
applications can create, replace and modify virtual network
resources and services in an interactive, flexible and dynamic
fashion while having no impact on other customers. Direct customer
control of transport network elements and virtualized services is
not perceived as a viable proposition for transport network
providers due to security and policy concerns among other reasons.
In addition, as discussed in Section 3.3, the network control plane
for transport networks has been separated from the data plane and as
such it is not viable for the customer to directly interface with
transport network elements.
Figure 5 depicts a high-level control and interface architecture for
ACTN. A number of key ACTN interfaces exist for deployment and
operation of ACTN-based networks. These are highlighted in Figure 5
(ACTN Interfaces).
.--------------
------------- |
| Application |--
-------------
^
| I/F A --------
v ( )
-------------- - -
| Customer | ( Customer )
| Network |--------->( Network )
| Controller | ( )
-------------- - -
^ ( )
| I/F B --------
v
--------------
| MultiDomain |
| Service |
| Coordinator| --------
-------------- ( )
^ - -
| I/F C ( Physical )
v ( Network )
--------------- ( ) --------
| |<----> - - ( )
-------------- | ( ) - -
| Physical |-- -------- ( Physical )
| Network |<---------------------->( Network )
| Controller | I/F D ( )
-------------- - -
( )
--------
Figure 5: ACTN Interfaces
The interfaces and functions are described below:
. Interface A: A north-bound interface (NBI) that communicates The network has to provide open, programmable interfaces, through
the service request or application demand. A request includes which customer applications can create, replace and modify virtual
specific service properties, including service type, topology, network resources and services in an interactive, flexible and
bandwidth, and constraint information. dynamic fashion while having no impact on other customers. Direct
customer control of transport network elements and virtualized
services is not perceived as a viable proposition for transport
network providers due to security and policy concerns among other
reasons. In addition, the network control plane for transport
networks has been separated from the data plane and as such it is
not viable for the customer to directly interface with transport
network elements.
. Interface B: The CNC-MDSC Interface (CMI) is an interface . CMI Interface: The CNC-MDSC Interface (CMI) is an interface
between a CNC and an MDSC. It is used to request the creation between a CNC and an MDSC. As depicted in Figure 3, the CMI is
of network resources, topology or services for the a business boundary between customer and network provider. It
applications. Note that all service related information is used to request virtual network services required for the
conveyed via Interface A (i.e., specific service properties, applications. Note that all service related information such as
including service type, topology, bandwidth, and constraint specific service properties, including virtual network service
information) needs to be transparently carried over this type, topology, bandwidth, and constraint information are
interface. The MDSC may also report potential network topology conveyed over this interface. Most of the information over this
availability if queried for current capability from the CNC. interface is technology agnostic; however, there are some
The CMI is the interface with the highest level of abstraction, cases, e.g., access link configuration, where it should be
where the Virtual Networks are modelled and presented to the
customer/CNC. Most of the information over this interface is
technology agnostic, even if in some cases it should be
possible to explicitly request for a VN to be created at a possible to explicitly request for a VN to be created at a
given layer in the network (e.g. ODU VN or MPLS VN). given layer in the network (e.g. ODU VN or MPLS VN).
. Interface C: The MDSC-PNC Interface (MPI) is an interface . MPI Interface: The MDSC-PNC Interface (MPI) is an interface
between an MDSC and a PNC. It communicates the creation between an MDSC and a PNC. It communicates the creation
requests for new connectivity or for bandwidth changes in the requests for new connectivity or for bandwidth changes in the
physical network. In multi-domain environments, the MDSC needs physical network. In multi-domain environments, the MDSC needs
to establish multiple MPIs, one for each PNC, as there is one to establish multiple MPIs, one for each PNC, as there is one
PNC responsible for control of each domain. The MPI could have PNC responsible for control of each domain. The MPI could have
different degrees of abstraction and present an abstracted different degrees of abstraction and present an abstracted
topology hiding technology specific aspects of the network or topology hiding technology specific aspects of the network or
convey technology specific parameters to allow for path convey technology specific parameters to allow for path
computation at the MDSC level. Please refer to CCAMP Transport computation at the MDSC level. Please refer to CCAMP Transport
NBI work for the latter case [Transport NBI]. NBI work for the latter case [Transport NBI].
. Interface D: The provisioning interface for creating forwarding . SBI Interface: This interface is out of the scope of ACTN. It
state in the physical network, requested via the Physical is shown in Figure 3 for reference reason only.
Network Controller.
The interfaces within the ACTN scope are B and C while interfaces A
and D are out of the scope of ACTN and are only shown in Figure 5 to
give a complete context of ACTN.
As previously stated in Section 3.2 there might be a third interface
in ACTN scope, the MMI. The MMI is a special case of the MPI and
behaves similarly to an MPI to support general functions performed
by the MDSCs such as abstraction function and provisioning function.
From an abstraction point of view, the top level MDSC which
interfaces the CNC operates on a higher level of abstraction (i.e.,
less granular level) than the lower level MSDCs. As such, the MMI
carries more abstract TE information than the MPI.
Please note that for all the three interfaces, when technology Please note that for all the three interfaces, when technology
specific information needs to be included, this info will be add-ons specific information needs to be included, this info will be add-ons
on top of the general abstract topology. As far as general topology on top of the general abstract topology. As far as general topology
abstraction standpoint, all interfaces are still recursive in abstraction standpoint, all interfaces are still recursive in
nature. nature.
4. VN Creation Process 5. Advanced ACTN architectures
The provider can present different level of network abstraction to This section describes advanced forms of ACTN architectures as
the customer, spanning from one extreme (say "black") where nothing possible implementation choices.
except the Access Points (APs) is shown to the other extreme (say
"white") where an actual network topology is shown to the customer.
There are shades of "gray" in between where a number of abstract
links and nodes can be shown.
VN creation is composed of two phases: Negotiation and 5.1. MDSC Hierarchy for scalability
Implementation.
Negotiation: In the case of gray/white topology abstraction, there A hierarchy of MDSCs can be foreseen for many reasons, among which
is an initial phase in which the customer agrees with the provider are scalability, administrative choices or putting together
on the type of topology to be shown (e.g., 10 virtual links and 5 different layers and technologies in the network. In the case where
virtual nodes) with a given interconnectivity. This is something there is a hierarchy of MDSCs, we introduce the higher-level MDSC
that is assumed to be preconfigured by the operator off-line. What (MDSC-H) the lower-level MDSC (MDSC-L) and the interface between
is on-line is the capability to modify/delete something (e.g., a them is basically of a recursive nature of the MPI. An
virtual link). In the case of "black" abstraction this negotiation implementation choice could foresee the usage of an MDSC-L for all
phase does not happen because there is nothing to negotiate: the the PNCs related to a given network layer or technology (e.g.
customer can only see the APs of the network. IP/MPLS) a different MDSC-L for the PNCs related to another
layer/technology (e.g. OTN/WDM) and an MDSC-H to coordinate them.
Implementation: In the case of black topology abstraction, the Figure 4 shows this case.
customers can ask for connectivity with given constraints/SLA
between the APs and LSPs/tunnels created by the provider to satisfy
the request. What the customer sees is only that his CEs are
connected with a given SLA. In the case of grey/white topology the
customer creates his own LSPs accordingly to the topology that was
presented to him.
4.1. VN Creation Example +--------+
| CNC |
+--------+
|
|
+----------+
--------| MDSC-H |--------
| +----------+ |
| |
+---------+ +---------+
| MDSC-L | | MDSC-L |
+---------+ +---------+
This section illustrates how a VN creation process is conducted over Figure 4: MDSC Hierarchy
a hierarchy of MDSCs via MMIs and MPIs, which is shown in Figure 6.
+-----+ Note that both the MDSC-H and the MDSC-L in general cases implement
| CNC | CNC wants to create a VN all four functions of the MDSC discussed in Section 3.2.
+-----+ between CE A and CE B
5.2. Functional Split of MDSC Functions in Orchestrators
Another implementation choice could foresee the separation of MDSC
functions into two groups (i.e., one group for service-related
functions and another group for network-related functions) which
will result in a service orchestrator for providing service-related
functions of MDSC and other non-ACTN functions and a network
orchestrator for providing network-related functions of MDSC and
other non-ACTN functions. Figure 5 shows this case and it also
depicts the mapping between ACTN architecture and the YANG service
model architecture described in [Service-YANG]. This mapping is
helpful for the readers who are not familiar with some TEAS specific
terminology used in this document. A number of key ACTN interfaces
exist for deployment and operation of ACTN-based networks. These are
highlighted in Figure 5 (ACTN Interfaces).
+------------------------------+
| Customer |
| +-----+ +----------+ |
| | CNC | |Other fns.| |
| +-----+ +----------+ |
+------------------------------+
| Customer Service Model
|
+-----------------------------------------------+
********|********************** Service Orchestrator |
* MDSC | +------+ +------+ * +-----------+ |
* | | MDSC | | MDSC | * | Other fns.| |
* | | F1 | | F2 | * | (non-ACTN)| |
* | +------+ +------+ * +-----------+ |
* +---------------------*-------------------------+
* * | Service Delivery Model
* * |
* +---------------------*-------------------------+
* | * Network Orchestrator |
* | +------+ +------+ * +-----------+ |
* | | MDSC | | MDSC | * | Other fns.| |
* | | F3 | | F4 | * | (non-ACTN)| |
* | +------+ +------+ * +-----------+ |
********|********************** |
+-----------------------------------------------+
| Network Configuration Model
|
+-------------------------------------------+
| Domain Controller |
| +------+ +-----------+ |
| | PNC | | Other fns.| |
| +------+ | (non-ACTN)| |
| +-----------+ |
+-------------------------------------------+
| Device Configuration Model
|
--------
| Device |
--------
Figure 5: ACTN Architecture in the context of YANG Service Models
In Figure 5, MDSC F1 and F2 correspond to customer
mapping/translation, and virtual service coordination, respectively,
which are the MDSC service-related functions as defined in Section
4. MDSC F3 and F4 correspond to multi domain coordination,
virtualization/abstraction, respectively, which are the MDSC
network-related functions as defined in Section 4. In some
implementation, MDSC F1 and F2 can be implemented as part of a
Service Orchestrator which may support other non-ACTN functions.
Likewise, the MDSC F3 and F4 can be implemented as part of a Network
Orchestrator which may support other non-ACTN MDSC functions.
Also note that the PNC is not same as domain controller. Domain
controller in general has a larger set of functions than that of
PNC. The main functions of PNC are explained in Section 3.3.
Likewise, Customer has a larger set of functions than that of the
CNC.
Customer service model describes a service as offer or delivered to
a customer by a network operator as defined in [Service-YANG]. The
CMI is a subset of a customer service model to support VNS. This
model encompasses other non-TE/non-ACTN models to control non-ACTN
services (e.g., L3SM).
Service delivery model is used by a network operator to define and
configure how a service is provided by the network as defined in
[Service-YANG]. This model is similar to the MPI model as the
network-related functions of the MDSC, i.e., F3 and F4, provide an
abstract topology view of the E2E network to the service-related
functions of the MDSC, i.e., F1 and F2, which translate customer's
request at the CMI into the network configuration at the MPI.
Network configuration model is used by a network orchestrator to
provide network-level configuration model to a controller as defined
in [Service-YANG]. The MPI is a subset of network configuration
model to support TE configuration. This model encompasses the MPI
model plus other non-TE/non-ACTN models to control non-ACTN
functions of the domain controller (e.g., L3VPN).
Device configuration model is used by a controller to configure
physical network elements.
6. Topology Abstraction Method
This section discusses topology abstraction types and their context
in ACTN architecture. Topology abstraction is useful in ACTN
architecture as a way to scale multi-domain network operation. As
the MDSC needs to coordinate with the PNCs in multi-domain networks
for determining a feasible domain sequence and provisioning the end-
to-end tunnel based on the determined domain sequence, topology
abstraction provides an efficient network scaling mechanism. Note
that this is the abstraction performed by the PNC to the MDSC or by
the MDSC-L to the MDSC-H, and that this is different from the VN
Type 2 topology (that is created and negotiated between the CNC and
the MDSC as part of the VNS). The purpose of topology abstraction
discussed in this section is for an efficient internal network
operation based on abstraction principle.
Refer to [ACTN-Abstraction] for detailed discussions on factors that
affect topology abstraction, how to build topology abstraction,
various considerations and which method to pick based on abstraction
types and the nature of underlying transport technology (e.g., MPLS,
OTN, WSON, etc.).
6.1. No abstraction (native/white topology)
This is a case where the PNC provides the actual network topology to
the MDSC without any hiding or filtering of information as shown in
Figure 6. In this case, the MDSC has the full knowledge of the
underlying network topology and as such there is no need for the
MDSC to send a path computation request to the PNC. The computation
burden will fall on the MDSC to find an optimal end-to-end path and
optimal per domain paths.
+--+ +--+ +--+ +--+
+-+ +-----+ +-----+ +-----+ +-+
++-+ ++-+ +-++ +-++
| | | |
| | | |
| | | |
| | | |
++-+ ++-+ +-++ +-++
+-+ +-----+ +-----+ +-----+ +-+
+--+ +--+ +--+ +--+
Figure 6a: The native/white topology
6.2. One Virtual Node (black topology)
The entire domain network is abstracted as a single virtual node
(see the definition of virtual node in [RFC7926]) with the
access/egress links without disclosing any node internal
connectivity information.
Figure 6b depicts a native topology with the corresponding black
topology with one virtual node and inter-domain links. In this case,
the MDSC has to make path computation requests to the PNCs before it
can determine an end-to-end path. If there are a large number of
inter-connected domains, this abstraction method may impose a heavy
coordination load at the MDSC level in order to find an optimal end-
to-end path.
The black topology would not give the MDSC any critical network
resource information other than the border nodes/links information
and as such it is likely to have a need for complementary
communications between the MDSC and the PNCs (e.g., Path computation
Request/Reply).
+--+ +--+ +--+ +--+
+-+ +-----+ +-----+ +-----+ +-+
++-+ ++-+ +-++ +-++
| | | |
| | | |
| | | |
| | | |
++-+ ++-+ +-++ +-++
+-+ +-----+ +-----+ +-----+ +-+
+--+ +--+ +--+ +--+
+--------+
+--+ +--+
| |
| |
| |
| |
| |
| |
+--+ +--+
+--------+
Figure 6b: The native topology and the corresponding black topology
with one virtual node and inter-domain links
6.3. Abstraction of TE tunnels for all pairs of border nodes (grey
topology)
This abstraction level, referred to a grey topology is between black
topology and white topology from a granularity point of view. As
shown in Figures 7a and 7b, we may further differentiate from a
perspective of how to abstract internal TE resources between the
pairs of border nodes:
. Grey topology type A: border nodes with a TE links between them
in a full mesh fashion (See Figure 7a)
. Grey topology type B: border nodes with some internal
abstracted nodes and abstracted links (See Figure 7b)
+--+ +--+ +--+ +--+
+-+ +-----+ +-----+ +-----+ +-+
++-+ ++-+ +-++ +-++
| | | |
| | | |
| | | |
| | | |
++-+ ++-+ +-++ +-++
+-+ +-----+ +-----+ +-----+ +-+
+--+ +--+ +--+ +--+
+--+ +--+
+-+ +----+ +-+
++-+ +-++
| \ / |
| \/ |
| /\ |
| / \ |
++-+ +-++
+-+ +----+ +-+
+--+ +--+
Figure 7a: The native topology and the corresponding grey topology
type A with TE links between border nodes
+--+ +--+ +--+
+-+ +-----+ +-----+ +-+
++-+ ++-+ +-++
| |
| |
| |
| |
++-+ ++-+ +-++
+-+ +-----+ +-----+ +-+
+--+ +--+ +--+
Figure 7b: The grey topology type B with abstract nodes/links
between border nodes
6.3.1. Grey topology type A: border nodes with a TE links
between them in a full mesh fashion
For each pair of ingress and egress nodes (i.e., border nodes
to/from the domain), TE link metric is provided with TE attributes
such as max bandwidth available, link delay, etc. This abstraction
depends on the underlying TE networks.
Note that this grey topology can also be represented as a single
abstract node with the connectivity matrix defined in [TE-Topology],
abstracting the internal connectivity information. The only thing
might be different is some additional information about the end
points of the links of the border nodes (i.e., links outward
customer-facing) as they cannot be included in the connectivity
matrix's termination points.
6.3.2. Grey topology Type B
The grey abstraction type B would allow the MDSC to have more
information about the internals of the domain networks by the PNCs
so that the MDSC can flexibly determine optimal paths. The MDSC may
configure some of the internal virtual nodes (e.g., cross-connect)
to redirect its traffic as it sees changes from the domain networks.
6.4. Topology Abstraction Granularity Level example
This section illustrates how topology abstraction operates in
different level of granularity over a hierarchy of MDSCs which is
shown in Figure 8 below.
+-----+
| CNC | CNC wants to create a VN
+-----+ between CE A and CE B
| |
| |
+-----------------------+ +-----------------------+
| MDSC 1 | | MDSC-H |
+-----------------------+ +-----------------------+
/ \ / \
/ \ / \
+--------+ +--------+ +--------+ +--------+
| MDSC 2 | | MDSC 3 | | MDSC-L1| | MDSC-L2|
+--------+ +--------+ +--------+ +--------+
/ \ / \ / \ / \
/ \ / \ / \ / \
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
CE A o----|PNC 1| |PNC 2| |PNC 3| |PNC 4|----o CE B CE A o----|PNC 1| |PNC 2| |PNC 3| |PNC 4|----o CE B
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
Topology Seen at MDSC 1 Topology operated by MDSC-H
--o-o--o-o- --o=o=o=o--
Topology Seen at MDSC 2 Topology Seen at MDSC 3 Topology operated by MDSC-L1 Topology operated by MDSC-L2
_ _ _ _ _ _ _ _
( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
--(o---o)==(o---o)== ==(o---o)==(o---o)-- --(o---o)==(o---o)== ==(o---o)==(o---o)--
( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
(_) (_) (_) (_) (_) (_) (_) (_)
Actual Topology Actual Topology
___ ___ ___ ___ ___ ___ ___ ___
( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
( o ) ( o ) ( o--o) ( o ) ( o ) ( o ) ( o--o) ( o )
( / \ ) ( |\ ) ( | | ) ( / \ ) ( / \ ) ( |\ ) ( | | ) ( / \ )
----(o-o---o-o)==(o-o-o-o-o)==(o--o--o-o)==(o-o-o-o-o)---- ----(o-o---o-o)==(o-o-o-o-o)==(o--o--o-o)==(o-o-o-o-o)----
( \ / ) ( | |/ ) ( | | ) ( \ / ) ( \ / ) ( | |/ ) ( | | ) ( \ / )
( o ) (o-o ) ( o--o) ( o ) ( o ) (o-o ) ( o--o) ( o )
(___) (___) (___) (___) (___) (___) (___) (___)
Domain 1 Domain 2 Domain 3 Domain 4 Domain 1 Domain 2 Domain 3 Domain 4
Where o is a node and -- is a link and === a border link Where o is a node and -- is a link and === a border link
Figure 6: Illustration of topology abstraction granularity levels in Figure 8: Illustration of topology abstraction granularity levels
the MDSC Hierarchy In the example depicted in Figure 8, there are four domains under
In the example depicted in Figure 6, there are four domains under
control of the respective PNCs, namely, PNC 1, PNC 2, PNC3 and PNC4. control of the respective PNCs, namely, PNC 1, PNC 2, PNC3 and PNC4.
Assume that MDSC 2 is controlling PNC 1 and PNC 2 while MDSC 3 is Assume that MDSC L-1 is controlling PNC 1 and PNC 2 while MDSC L-2
controlling PNC 3 and PNC 4. Let us assume that each of the PNCs is controlling PNC 3 and PNC 4. Let us assume that each of the PNCs
provides a grey topology abstraction in which to present only border provides a grey topology abstraction in which to present only border
nodes and border links. The abstract topology MDSC 2 would operate nodes and links within and outside the domain. The abstract topology
is shown on the left side of MDSC 2 in Figure 6. It is basically a MDSC-L1 would operate is basically a combination of the two
combination of the two topologies the PNCs (PNC 1 and PNC 2) topologies the PNCs (PNC 1 and PNC 2) provide. Likewise, the
provide. Likewise, the abstract topology MDSC 3 would operate is abstract topology MDSC-L2 would operate is shown in Figure 8. Both
shown on the right side of MDSC 3 in Figure 6. Both MDSC 2 and MDSC MDSC-L1 and MDSC-L2 provide a black topology abstraction in which
3 provide a grey topology abstraction in which each PNC domain is each PNC domain is presented as one virtual node to its top level
presented as one virtual node to its top level MDSC 1. Then the MDSC MDSC-H. Then the MDSC-H combines these two topologies updated by
1 combines these two topologies updated by MDSC 2 and MDSC 3 to MDSC-L1 and MDSC-L2 to create the abstraction topology to which it
create the abstraction topology to which it operates. MDSC 1 sees operates. MDSC-H sees the whole four domain networks as four virtual
the whole four domain networks as four virtual nodes connected via nodes connected via virtual links. This illustrates the point
virtual links. This illustrates the point discussed in Section 3.4: discussed in Section 5.1: The top level MDSC may operate on a higher
The top level MDSC operates on a higher level of abstraction (i.e., level of abstraction (i.e., less granular level) than the lower
less granular level) than the lower level MSDCs. As such, the MMI level MSDCs.
carries more abstract TE information than the MPI.
In the process of creating a VN, the same principle applies. Let us
assume that a customer wants to create a virtual network that
connects its CE A and CE B which is depicted in Figure 6. Upon
receipt of this request generated by the CNC, MDSC 1, based on its
abstract topology at hand, determines that CE A is connected a
virtual node in domain 1 and CE B is connected to a virtual node in
domain 4 and. MDSC 1 further determines that domain 2 and domain 3
are interconnected to domain 1 and 4 respectively. MDSC 1 then
partitions the original VN request from the CNC into two separate VN
requests and make a VN creation request, respectively to MDSC 2 and
MDSC 3. MDSC 1 for instance make a VN request to MDSC 2 to connect
two virtual nodes. When MDSC 2 receives this VN request from MDSC 1,
it further partitions into two separate requests respectively to PNC
1 and PNC 2. This illustration shows that VN creation request
process recursively takes place over MMI and MPI.
5. Access Points and Virtual Network Access Points 7. Access Points and Virtual Network Access Points
In order not to share unwanted topological information between the In order not to share unwanted topological information between the
customer domain and provider domain, a new entity is defined which customer domain and provider domain, a new entity is defined which
is referred to as the Access Point (AP). See the definition of AP in is referred to as the Access Point (AP). See the definition of AP in
Section 1.1. Section 1.1.
A customer node will use APs as the end points for the request of A customer node will use APs as the end points for the request of
VNs as shown in Figure 7. VNS as shown in Figure 9.
------------- -------------
( ) ( )
- - - -
+---+ X ( ) Z +---+ +---+ X ( ) Z +---+
|CE1|---+----( )---+---|CE2| |CE1|---+----( )---+---|CE2|
+---+ | ( ) | +---+ +---+ | ( ) | +---+
AP1 - - AP2 AP1 - - AP2
( ) ( )
------------- -------------
Figure 7: APs definition customer view Figure 9: APs definition customer view
Let's take as an example a scenario shown in Figure 7. CE1 is Let's take as an example a scenario shown in Figure 7. CE1 is
connected to the network via a 10Gb link and CE2 via a 40Gb link. connected to the network via a 10Gb link and CE2 via a 40Gb link.
Before the creation of any VN between AP1 and AP2 the customer view Before the creation of any VN between AP1 and AP2 the customer view
can be summarized as shown in Table 1: can be summarized as shown in Table 1:
+----------+------------------------+ +----------+------------------------+
|End Point | Access Link Bandwidth | |End Point | Access Link Bandwidth |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
|AP id| CE,port | MaxResBw | AvailableBw | |AP id| CE,port | MaxResBw | AvailableBw |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
| AP1 |CE1,portX | 10Gb | 10Gb | | AP1 |CE1,portX | 10Gb | 10Gb |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
| AP2 |CE2,portZ | 40Gb | 40Gb | | AP2 |CE2,portZ | 40Gb | 40Gb |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
Table 1: AP - customer view Table 1: AP - customer view
On the other hand, what the provider sees is shown in Figure 8. On the other hand, what the provider sees is shown in Figure 10.
------- ------- ------- -------
( ) ( ) ( ) ( )
- - - - - - - -
W (+---+ ) ( +---+) Y W (+---+ ) ( +---+) Y
-+---( |PE1| Dom.X )----( Dom.Y |PE2| )---+- -+---( |PE1| Dom.X )----( Dom.Y |PE2| )---+-
| (+---+ ) ( +---+) | | (+---+ ) ( +---+) |
AP1 - - - - AP2 AP1 - - - - AP2
( ) ( ) ( ) ( )
------- ------- ------- -------
Figure 8: Provider view of the AP Figure 10: Provider view of the AP
Which results in a summarization as shown in Table 2. Which results in a summarization as shown in Table 2.
+----------+------------------------+ +----------+------------------------+
|End Point | Access Link Bandwidth | |End Point | Access Link Bandwidth |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
|AP id| PE,port | MaxResBw | AvailableBw | |AP id| PE,port | MaxResBw | AvailableBw |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
| AP1 |PE1,portW | 10Gb | 10Gb | | AP1 |PE1,portW | 10Gb | 10Gb |
+-----+----------+----------+-------------+ +-----+----------+----------+-------------+
skipping to change at page 25, line 19 skipping to change at page 29, line 29
+---------+----------+----------+-------------+ +---------+----------+----------+-------------+
|AP1 |PE1,portW | 10Gbps | 7Gbps | |AP1 |PE1,portW | 10Gbps | 7Gbps |
| -VNAP1.9| | 1Gbps | N.A. | | -VNAP1.9| | 1Gbps | N.A. |
| -VNAP1.5| | 2Gbps | N.A | | -VNAP1.5| | 2Gbps | N.A |
+---------+----------+----------+-------------+ +---------+----------+----------+-------------+
|AP2 |PE2,portY | 40Gbps | 37Gbps | |AP2 |PE2,portY | 40Gbps | 37Gbps |
| -VNAP2.9| | 1Gbps | N.A. | | -VNAP2.9| | 1Gbps | N.A. |
| -VNAP2.5| | 2Gbps | N.A | | -VNAP2.5| | 2Gbps | N.A |
+---------+----------+----------+-------------+ +---------+----------+----------+-------------+
Table 3: AP and VNAP - provider view after VN creation Table 3: AP and VNAP - provider view after VNS creation
5.1. Dual homing scenario 7.1. Dual homing scenario
Often there is a dual homing relationship between a CE and a pair of Often there is a dual homing relationship between a CE and a pair of
PEs. This case needs to be supported by the definition of VN, APs PEs. This case needs to be supported by the definition of VN, APs
and VNAPs. Suppose CE1 connected to two different PEs in the and VNAPs. Suppose CE1 connected to two different PEs in the
operator domain via AP1 and AP2 and that the customer needs 5Gbps of operator domain via AP1 and AP2 and that the customer needs 5Gbps of
bandwidth between CE1 and CE2. This is shown in Figure 9. bandwidth between CE1 and CE2. This is shown in Figure 11.
____________ ____________
AP1 ( ) AP3 AP1 ( ) AP3
-------(PE1) (PE3)------- -------(PE1) (PE3)-------
W / ( ) \X W / ( ) \X
+---+/ ( ) \+---+ +---+/ ( ) \+---+
|CE1| ( ) |CE2| |CE1| ( ) |CE2|
+---+\ ( ) /+---+ +---+\ ( ) /+---+
Y \ ( ) /Z Y \ ( ) /Z
-------(PE2) (PE4)------- -------(PE2) (PE4)-------
AP2 (____________) AP2 (____________)
Figure 9: Dual homing scenario Figure 11: Dual homing scenario
In this case, the customer will request for a VN between AP1, AP2 In this case, the customer will request for a VN between AP1, AP2
and AP3 specifying a dual homing relationship between AP1 and AP2. and AP3 specifying a dual homing relationship between AP1 and AP2.
As a consequence no traffic will flow between AP1 and AP2. The dual As a consequence no traffic will flow between AP1 and AP2. The dual
homing relationship would then be mapped against the VNAPs (since homing relationship would then be mapped against the VNAPs (since
other independent VNs might have AP1 and AP2 as end points). other independent VNs might have AP1 and AP2 as end points).
The customer view would be shown in Table 4. The customer view would be shown in Table 4.
+----------+------------------------+ +----------+------------------------+
skipping to change at page 26, line 22 skipping to change at page 30, line 32
+---------+----------+----------+-------------+-----------+ +---------+----------+----------+-------------+-----------+
|AP2 |CE1,portY | 40Gbps | 35Gbps | | |AP2 |CE1,portY | 40Gbps | 35Gbps | |
| -VNAP2.9| | 5Gbps | N.A. | VNAP1.9 | | -VNAP2.9| | 5Gbps | N.A. | VNAP1.9 |
+---------+----------+----------+-------------+-----------+ +---------+----------+----------+-------------+-----------+
|AP3 |CE2,portX | 40Gbps | 35Gbps | | |AP3 |CE2,portX | 40Gbps | 35Gbps | |
| -VNAP3.9| | 5Gbps | N.A. | NONE | | -VNAP3.9| | 5Gbps | N.A. | NONE |
+---------+----------+----------+-------------+-----------+ +---------+----------+----------+-------------+-----------+
Table 4: Dual homing - customer view after VN creation Table 4: Dual homing - customer view after VN creation
6. End Point Selection Based On Network Status 8. Advanced ACTN Application: Multi-Destination Service
A further advanced application of ACTN is in the case of Data Center A further advanced application of ACTN is in the case of Data Center
selection, where the customer requires the Data Center selection to selection, where the customer requires the Data Center selection to
be based on the network status; this is referred to as Multi- be based on the network status; this is referred to as Multi-
Destination in [ACTN-REQ]. In terms of ACTN, a CNC could request a Destination in [ACTN-REQ]. In terms of ACTN, a CNC could request a
connectivity service (virtual network) between a set of source Aps connectivity service (virtual network) between a set of source Aps
and destination APs and leave it up to the network (MDSC) to decide and destination APs and leave it up to the network (MDSC) to decide
which source and destination access points to be used to set up the which source and destination access points to be used to set up the
connectivity service (virtual network). The candidate list of source connectivity service (virtual network). The candidate list of source
and destination APs is decided by a CNC (or an entity outside of and destination APs is decided by a CNC (or an entity outside of
ACTN) based on certain factors which are outside the scope of ACTN. ACTN) based on certain factors which are outside the scope of ACTN.
Based on the AP selection as determined and returned by the network Based on the AP selection as determined and returned by the network
(MDSC), the CNC (or an entity outside of ACTN) should further take (MDSC), the CNC (or an entity outside of ACTN) should further take
care of any subsequent actions such as orchestration or service care of any subsequent actions such as orchestration or service
setup requirements. These further actions are outside the scope of setup requirements. These further actions are outside the scope of
ACTN. ACTN.
Consider a case as shown in Figure 10, where three data centers are Consider a case as shown in Figure 12, where three data centers are
available, but the customer requires the data center selection to be available, but the customer requires the data center selection to be
based on the network status and the connectivity service setup based on the network status and the connectivity service setup
between the AP1 (CE1) and one of the destination APs (AP2 (DC-A), between the AP1 (CE1) and one of the destination APs (AP2 (DC-A),
AP3 (DC-B), and AP4 (DC-C)). The MDSC (in coordination with PNCs) AP3 (DC-B), and AP4 (DC-C)). The MDSC (in coordination with PNCs)
would select the best destination AP based on the constraints, would select the best destination AP based on the constraints,
optimization criteria, policies, etc., and setup the connectivity optimization criteria, policies, etc., and setup the connectivity
service (virtual network). service (virtual network).
------- ------- ------- -------
( ) ( ) ( ) ( )
skipping to change at page 27, line 21 skipping to change at page 31, line 31
|CE1|---+----( Domain X )----( Domain Y )---+---|DC-A| |CE1|---+----( Domain X )----( Domain Y )---+---|DC-A|
+---+ | ( ) ( ) | +----+ +---+ | ( ) ( ) | +----+
AP1 - - - - AP2 AP1 - - - - AP2
( ) ( ) ( ) ( )
---+--- ---+--- ---+--- ---+---
AP3 | AP4 | AP3 | AP4 |
+----+ +----+ +----+ +----+
|DC-B| |DC-C| |DC-B| |DC-C|
+----+ +----+ +----+ +----+
Figure 10: End point selection based on network status Figure 12: End point selection based on network status
6.1. Pre-Planned End Point Migration 8.1. Pre-Planned End Point Migration
Further in case of Data Center selection, customer could request for Further in case of Data Center selection, customer could request for
a backup DC to be selected, such that in case of failure, another DC a backup DC to be selected, such that in case of failure, another DC
site could provide hot stand-by protection. As shown in Figure 10 site could provide hot stand-by protection. As shown in Figure 13
DC-C is selected as a backup for DC-A. Thus, the VN should be setup DC-C is selected as a backup for DC-A. Thus, the VN should be setup
by the MDSC to include primary connectivity between AP1 (CE1) and by the MDSC to include primary connectivity between AP1 (CE1) and
AP2 (DC-A) as well as protection connectivity between AP1 (CE1) and AP2 (DC-A) as well as protection connectivity between AP1 (CE1) and
AP4 (DC-C). AP4 (DC-C).
------- ------- ------- -------
( ) ( ) ( ) ( )
- - __ - - - - __ - -
+---+ ( ) ( ) +----+ +---+ ( ) ( ) +----+
|CE1|---+----( Domain X )----( Domain Y )---+---|DC-A| |CE1|---+----( Domain X )----( Domain Y )---+---|DC-A|
+---+ | ( ) ( ) | +----+ +---+ | ( ) ( ) | +----+
AP1 - - - - AP2 | AP1 - - - - AP2 |
( ) ( ) | ( ) ( ) |
---+--- ---+--- | ---+--- ---+--- |
AP3 | AP4 | HOT STANDBY AP3 | AP4 | HOT STANDBY
+----+ | +----+ +----+ |
|DC-C|<------------- |DC-D| |DC-C|<-------------
+----+ +----+ +----+
Figure 10: Pre-planned end point migration Figure 13: Pre-planned end point migration
6.2. On the Fly End Point Migration 8.2. On the Fly End Point Migration
Compared to pre-planned end point migration, on the fly end point Compared to pre-planned end point migration, on the fly end point
selection is dynamic in that the migration is not pre-planned but selection is dynamic in that the migration is not pre-planned but
decided based on network condition. Under this scenario, the MDSC decided based on network condition. Under this scenario, the MDSC
would monitor the network (based on the VN SLA) and notify the CNC would monitor the network (based on the VN SLA) and notify the CNC
in case where some other destination AP would be a better choice in case where some other destination AP would be a better choice
based on the network parameters. The CNC should instruct the MDSC based on the network parameters. The CNC should instruct the MDSC
when it is suitable to update the VN with the new AP if it is when it is suitable to update the VN with the new AP if it is
required. required.
7. Manageability Considerations 9. Advanced Topic
This section describes how ACTN architecture supports some
deployment scenarios. See Appendix A for details on MDSC and PNC
functions integrated in Service/Network Orchestrator and Appendix B
for IP + Optical with L3VPN service.
10. Manageability Considerations
The objective of ACTN is to manage traffic engineered resources, and The objective of ACTN is to manage traffic engineered resources, and
provide a set of mechanism to allow clients to request virtual provide a set of mechanism to allow clients to request virtual
connectivity across server network resources. ACTN will support connectivity across server network resources. ACTN will support
multiple clients each with its own view of and control of the server multiple clients each with its own view of and control of the server
network, the network operator will need to partition (or "slice") network, the network operator will need to partition (or "slice")
their network resources, and manage them resources accordingly. their network resources, and manage them resources accordingly.
The ACTN platform will, itself, need to support the request, The ACTN platform will, itself, need to support the request,
response, and reservations of client and network layer connectivity. response, and reservations of client and network layer connectivity.
It will also need to provide performance monitoring and control of It will also need to provide performance monitoring and control of
traffic engineered resources. The management requirements may be traffic engineered resources. The management requirements may be
categorized as follows: categorized as follows:
. Management of external ACTN protocols . Management of external ACTN protocols
. Management of internal ACTN protocols . Management of internal ACTN protocols
. Management and monitoring of ACTN components . Management and monitoring of ACTN components
. Configuration of policy to be applied across the ACTN system . Configuration of policy to be applied across the ACTN system
7.1. Policy 10.1. Policy
It is expected that a policy will be an important aspect of ACTN It is expected that a policy will be an important aspect of ACTN
control and management. Typically, policies are used via the control and management. Typically, policies are used via the
components and interfaces, during deployment of the service, to components and interfaces, during deployment of the service, to
ensure that the service is compliant with agreed policy factors ensure that the service is compliant with agreed policy factors
(often described in Service Level Agreements - SLAs), these include, (often described in Service Level Agreements - SLAs), these include,
but are not limited to: connectivity, bandwidth, geographical but are not limited to: connectivity, bandwidth, geographical
transit, technology selection, security, resilience, and economic transit, technology selection, security, resilience, and economic
cost. cost.
skipping to change at page 29, line 43 skipping to change at page 34, line 7
This objective of this section is to discuss the applicability of This objective of this section is to discuss the applicability of
ACTN policy: requirements, components, interfaces, and examples. ACTN policy: requirements, components, interfaces, and examples.
This section provides an analysis and does not mandate a specific This section provides an analysis and does not mandate a specific
method for enforcing policy, or the type of policy agent that would method for enforcing policy, or the type of policy agent that would
be responsible for propagating policies across the ACTN components. be responsible for propagating policies across the ACTN components.
It does highlight examples of how policy may be applied in the It does highlight examples of how policy may be applied in the
context of ACTN, but it is expected further discussion in an context of ACTN, but it is expected further discussion in an
applicability or solution specific document, will be required. applicability or solution specific document, will be required.
7.2. Policy applied to the Customer Network Controller 10.2. Policy applied to the Customer Network Controller
A virtual network service for a customer application will be A virtual network service for a customer application will be
requested from the CNC. It will reflect the application requirements requested from the CNC. It will reflect the application requirements
and specific service policy needs, including bandwidth, traffic type and specific service policy needs, including bandwidth, traffic type
and survivability. Furthermore, application access and type of and survivability. Furthermore, application access and type of
virtual network service requested by the CNC, will be need adhere to virtual network service requested by the CNC, will be need adhere to
specific access control policies. specific access control policies.
7.3. Policy applied to the Multi Domain Service Coordinator 10.3. Policy applied to the Multi Domain Service Coordinator
A key objective of the MDSC is to help the customer express the A key objective of the MDSC is to help the customer express the
application connectivity request via its CNC as set of desired application connectivity request via its CNC as set of desired
business needs, therefore policy will play an important role. business needs, therefore policy will play an important role.
Once authorised, the virtual network service will be instantiated Once authorised, the virtual network service will be instantiated
via the CNC-MDSC Interface (CMI), it will reflect the customer via the CNC-MDSC Interface (CMI), it will reflect the customer
application and connectivity requirements, and specific service application and connectivity requirements, and specific service
transport needs. The CNC and the MDSC components will have agreed transport needs. The CNC and the MDSC components will have agreed
connectivity end-points, use of these end-points should be defined connectivity end-points, use of these end-points should be defined
as a policy expression when setting up or augmenting virtual network as a policy expression when setting up or augmenting virtual network
services. Ensuring that permissible end-points are defined for CNCs services. Ensuring that permissible end-points are defined for CNCs
and applications will require the MDSC to maintain a registry of and applications will require the MDSC to maintain a registry of
permissible connection points for CNCs and application types. permissible connection points for CNCs and application types.
It may also be necessary for the MDSC to resolve policy conflicts, It may also be necessary for the MDSC to resolve policy conflicts,
or at least flag any issues to administrator of the MDSC itself. or at least flag any issues to administrator of the MDSC itself.
Conflicts may occur when virtual network service optimisation Conflicts may occur when virtual network service optimization
criterion are in competition. For example, to meet objectives for criterion are in competition. For example, to meet objectives for
service reachability a request may require an interconnection point service reachability a request may require an interconnection point
between multiple physical networks; however, this might break a between multiple physical networks; however, this might break a
confidentially policy requirement of specific type of end-to-end confidentially policy requirement of specific type of end-to-end
service. This type of situation may be resolved using hard and soft service. This type of situation may be resolved using hard and soft
policy constraints. policy constraints.
7.4. Policy applied to the Physical Network Controller 10.4. Policy applied to the Physical Network Controller
The PNC is responsible for configuring the network elements, The PNC is responsible for configuring the network elements,
monitoring physical network resources, and exposing connectivity monitoring physical network resources, and exposing connectivity
(direct or abstracted) to the MDSC. It is therefore expected that (direct or abstracted) to the MDSC. It is therefore expected that
policy will dictate what connectivity information will be exported policy will dictate what connectivity information will be exported
between the PNC, via the MDSC-PNC Interface (MPI), and MDSC. between the PNC, via the MDSC-PNC Interface (MPI), and MDSC.
Policy interactions may arise when a PNC determines that it cannot Policy interactions may arise when a PNC determines that it cannot
compute a requested path from the MDSC, or notices that (per a compute a requested path from the MDSC, or notices that (per a
locally configured policy) the network is low on resources (for locally configured policy) the network is low on resources (for
example, the capacity on key links become exhausted). In either example, the capacity on key links become exhausted). In either
case, the PNC will be required to notify the MDSC, which may (again case, the PNC will be required to notify the MDSC, which may (again
per policy) act to construct a virtual network service across per policy) act to construct a virtual network service across
another physical network topology. another physical network topology.
Furthermore, additional forms of policy-based resource management Furthermore, additional forms of policy-based resource management
will be required to provide virtual network service performance, will be required to provide virtual network service performance,
security and resilience guarantees. This will likely be implemented security and resilience guarantees. This will likely be implemented
via a local policy agent and subsequent protocol methods. via a local policy agent and subsequent protocol methods.
8. Security Considerations 11. Security Considerations
The ACTN framework described in this document defines key components The ACTN framework described in this document defines key components
and interfaces for managed traffic engineered networks. Securing the and interfaces for managed traffic engineered networks. Securing the
request and control of resources, confidentially of the information, request and control of resources, confidentially of the information,
and availability of function, should all be critical security and availability of function, should all be critical security
considerations when deploying and operating ACTN platforms. considerations when deploying and operating ACTN platforms.
Several distributed ACTN functional components are required, and as Several distributed ACTN functional components are required, and as
a rule implementations should consider encrypting data that flow a rule implementations should consider encrypting data that flow
between components, especially when they are implemented at remote between components, especially when they are implemented at remote
skipping to change at page 32, line 5 skipping to change at page 36, line 9
communication between different ACTN components. communication between different ACTN components.
The conclusion is that all protocols used to realize the ACTN The conclusion is that all protocols used to realize the ACTN
framework should have rich security features, and customer, framework should have rich security features, and customer,
application and network data should be stored in encrypted data application and network data should be stored in encrypted data
stores. Additional security risks may still exist. Therefore, stores. Additional security risks may still exist. Therefore,
discussion and applicability of specific security functions and discussion and applicability of specific security functions and
protocols will be better described in documents that are use case protocols will be better described in documents that are use case
and environment specific. and environment specific.
8.1. Interface between the Customer Network Controller and Multi Domain 11.1. Interface between the Customer Network Controller and Multi
Service Coordinator (MDSC), CNC-MDSC Interface (CMI) Domain Service Coordinator (MDSC), CNC-MDSC Interface (CMI)
The role of the MDSC is to detach the network and service control The role of the MDSC is to detach the network and service control
from underlying technology to help the customer express the network from underlying technology to help the customer express the network
as desired by business needs. It should be noted that data stored by as desired by business needs. It should be noted that data stored by
the MDSC will reveal details of the virtual network services, and the MDSC will reveal details of the virtual network services, and
which CNC and application is consuming the resource. The data stored which CNC and application is consuming the resource. The data stored
must therefore be considered as a candidate for encryption. must therefore be considered as a candidate for encryption.
CNC Access rights to an MDSC must be managed. MDSC resources must be CNC Access rights to an MDSC must be managed. MDSC resources must be
properly allocated, and methods to prevent policy conflicts, properly allocated, and methods to prevent policy conflicts,
resource wastage and denial of service attacks on the MDSC by rogue resource wastage and denial of service attacks on the MDSC by rogue
CNCs, should also be considered. CNCs, should also be considered.
A CNC-MDSC protocol interface will likely be an external protocol A CNC-MDSC protocol interface will likely be an external protocol
interface. Again, suitable authentication and authorization of each interface. Again, suitable authentication and authorization of each
CNC connecting to the MDSC will be required, especially, as these CNC connecting to the MDSC will be required, especially, as these
are likely to be implemented by different organisations and on are likely to be implemented by different organizations and on
separate functional nodes. Use of the AAA-based mechanisms would separate functional nodes. Use of the AAA-based mechanisms would
also provide role-based authorization methods, so that only also provide role-based authorization methods, so that only
authorized CNC's may access the different functions of the MDSC. authorized CNC's may access the different functions of the MDSC.
8.2. Interface between the Multi Domain Service Coordinator and 11.2. Interface between the Multi Domain Service Coordinator and
Physical Network Controller (PNC), MDSC-PNC Interface (MPI) Physical Network Controller (PNC), MDSC-PNC Interface (MPI)
The function of the Physical Network Controller (PNC) is to The function of the Physical Network Controller (PNC) is to
configure network elements, provide performance and monitoring configure network elements, provide performance and monitoring
functions of the physical elements, and export physical topology functions of the physical elements, and export physical topology
(full, partial, or abstracted) to the MDSC. (full, partial, or abstracted) to the MDSC.
Where the MDSC must interact with multiple (distributed) PNCs, a Where the MDSC must interact with multiple (distributed) PNCs, a
PKI-based mechanism is suggested, such as building a TLS or HTTPS PKI-based mechanism is suggested, such as building a TLS or HTTPS
connection between the MDSC and PNCs, to ensure trust between the connection between the MDSC and PNCs, to ensure trust between the
physical network layer control components and the MDSC. physical network layer control components and the MDSC.
Which MDSC the PNC exports topology information to, and the level of Which MDSC the PNC exports topology information to, and the level of
detail (full or abstracted) should also be authenticated and detail (full or abstracted) should also be authenticated and
specific access restrictions and topology views, should be specific access restrictions and topology views, should be
configurable and/or policy-based. configurable and/or policy-based.
9. References 12. References
9.1. Informative References 12.1. Informative References
[RFC2702] Awduche, D., et. al., "Requirements for Traffic [RFC2702] Awduche, D., et. al., "Requirements for Traffic
Engineering Over MPLS", RFC 2702, September 1999. Engineering Over MPLS", RFC 2702, September 1999.
[RFC4026] L. Andersson, T. Madsen, "Provider Provisioned Virtual [RFC4026] L. Andersson, T. Madsen, "Provider Provisioned Virtual
Private Network (VPN) Terminology", RFC 4026, March 2005. Private Network (VPN) Terminology", RFC 4026, March 2005.
[RFC4208] G. Swallow, J. Drake, H.Ishimatsu, Y. Rekhter, [RFC4208] G. Swallow, J. Drake, H.Ishimatsu, Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS) User- "Generalized Multiprotocol Label Switching (GMPLS) User-
Network Interface (UNI): Resource ReserVation Protocol- Network Interface (UNI): Resource ReserVation Protocol-
skipping to change at page 34, line 5 skipping to change at page 38, line 5
1.1, ONF TR-521, June 2016. 1.1, ONF TR-521, June 2016.
[RFC7491] King, D., and Farrel, A., "A PCE-based Architecture for [RFC7491] King, D., and Farrel, A., "A PCE-based Architecture for
Application-based Network Operations", RFC 7491, March Application-based Network Operations", RFC 7491, March
2015. 2015.
[Transport NBI] Busi, I., et al., "Transport North Bound Interface [Transport NBI] Busi, I., et al., "Transport North Bound Interface
Use Cases", draft-tnbidt-ccamp-transport-nbi-use-cases, Use Cases", draft-tnbidt-ccamp-transport-nbi-use-cases,
work in progress. work in progress.
10. Contributors [ACTN-Abstraction] Y. Lee, et al., "Abstraction and Control of TE
Networks (ACTN) Abstraction Methods", draft-lee-teas-actn-
abstraction, work in progress.
13. Contributors
Adrian Farrel Adrian Farrel
Old Dog Consulting Old Dog Consulting
Email: adrian@olddog.co.uk Email: adrian@olddog.co.uk
Italo Busi Italo Busi
Huawei Huawei
Email: Italo.Busi@huawei.com Email: Italo.Busi@huawei.com
Khuzema Pithewan Khuzema Pithewan
skipping to change at page 35, line 39 skipping to change at page 39, line 39
Sergio Belotti Sergio Belotti
Alcatel Lucent Alcatel Lucent
Via Trento, 30 Via Trento, 30
Vimercate, Italy Vimercate, Italy
Email: sergio.belotti@nokia.com Email: sergio.belotti@nokia.com
Daniel King Daniel King
Lancaster University Lancaster University
Email: d.king@lancaster.ac.uk Email: d.king@lancaster.ac.uk
Dhruv Dhoddy Dhruv Dhody
Huawei Technologies Huawei Technologies
dhruv.ietf@gmail.com Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Gert Grammel Gert Grammel
Juniper Networks Juniper Networks
ggrammel@juniper.net Email: ggrammel@juniper.net
APPENDIX A - Example of MDSC and PNC functions integrated in
Service/Network Orchestrator
This section provides an example of a possible deployment scenario,
in which Service/Network Orchestrator can include a number of
functionalities, among which, in the example below, PNC
functionalities for domain 2 and MDSC functionalities to coordinate
the PNC1 functionalities (hosted in a separate domain controller)
and PNC2 functionalities (co-hosted in the network orchestrator).
Customer
+-------------------------------+
| +-----+ |
| | CNC | |
| +-----+ |
+-------|-----------------------+
|-CMI
Service/Network |
Orchestrator |
+-------|------------------------+
| +------+ MPI +------+ |
| | MDSC |----|--> | PNC2 | |
| +------+ +------+ |
+-------|------------------|-----+
|-MPI |
Domain Controller | |
+-------|-----+ |
| +-----+ | |
| |PNC1 | | |
| +-----+ | |
+-------|-----+ |
v v
------- -------
( ) ( )
- - - -
( ) ( )
( Domain 1 )----( Domain 2 )
( ) ( )
- - - -
( ) ( )
------- -------
APPENDIX B - Example of IP + Optical network with L3VPN service
This section provides a more complex deployment scenario in which
ACTN hierarchy is deployed to control a multi-layer network via an
IP/MPLS PNC and an Optical PNC. The scenario is further enhanced by
the introduction of an upper layer service configuration (e.g.
L3VPN). The provisioning of the L3VPN service is outside ACTN scope
but it is worth showing how the two parts are integrated for the end
to end service fulfilment. An example of service configuration
function in the Service/Network Orchestrator is discussed in [I-
D.dhjain-bess-bgp-l3vpn-yang].
Customer
+-------------------------------+
| +-----+ |
| | CNC | |
| +-----+ |
+-------|--------+--------------+
|-CMI | Customer Service Model
| | (non-ACTN interface)
Service/Network | |
Orchestrator | |
+-------|--------|--------------------------+
| | +-------------------------+ |
| | |Service Mapping Function | |
| | +-------------------------+ |
| | | | |
| +------+ | +---------------+ |
| | MDSC |--- |Service Config.| |
| +------+ +---------------+ |
+------|------------------|-----------------+
MPI-| +------------+ (non-ACTN Interf.)
| /
+-----------/------------+
IP/MPLS | / |
Domain | / | Optical Domain
Controller | / | Controller
+--------|-------/----+ +---|--------------+
| +-----+ +-----+ | | +-----+ |
| |PNC1 | |Serv.| | | |PNC2 | |
| +-----+ +-----+ | | +-----+ |
+---------------------+ +------------------+
| |
v |
+---------------------------------+ |
/ IP/MPLS Network \ |
+-------------------------------------+ |
V
+--------------------------------------+
/ Optical Network \
+------------------------------------------+
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