Network Working Group Daniele Ceccarelli
Internet Draft Ericsson
Intended status: Informational Luyuan Fang
Expires: June 2015 Microsoft
Young Lee
Huawei
Diego Lopez
Telefonica
Sergio Belotti
Alcatel-Lucent
Daniel King
Lancaster University
December 23, 2014
Framework for Abstraction and Control of Transport Networks
draft-ceccarelli-actn-framework-06.txt
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Abstract
This draft provides a framework for abstraction and control of
transport networks.
Table of Contents
1. Introduction...................................................3
2. Business Model of ACTN.........................................5
2.1. Customers.................................................6
2.2. Service Providers.........................................7
2.3. Network Providers.........................................9
3. ACTN architecture..............................................9
3.1. Customer Network Controller..............................12
3.2. Multi Domain Service Coordinator.........................13
3.3. Physical Network Controller..............................13
3.4. ACTN interfaces..........................................14
4. ACTN Applicability............................................16
4.1. ACTN Use cases Summary...................................17
4.2. Work in Scope of ACTN....................................20
4.2.1. Coordination of Multi-destination Service
Requirement/Policy.........................................25
4.2.2. Application Service Policy-aware Network Operation..27
4.2.3. Network Function Virtualization Services............29
4.2.4. Dynamic Service Control Policy Enforcement for
Performance and Fault Management...........................30
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4.2.5. E2E VN Survivability and Multi-Layer (Packet-Optical)
Coordination for Protection/Restoration....................32
5. ACTN interfaces requirements..................................33
5.1. CMI Interface Requirements...............................34
5.2. MPI (MDSC-PNC Interface).................................37
6. References....................................................41
6.1. Informative References...................................41
Appendix A.......................................................42
Contributors' Addresses..........................................42
Authors' Addresses...............................................43
7. Appendix I: Abstracted Topology Illustration..................44
1. Introduction
Transport networks have a variety of mechanisms to facilitate
separation of data plane and control plane including distributed
signaling for path setup and protection, centralized path
computation for planning and traffic engineering, and a range of
management and provisioning protocols to configure and activate
network resources. These mechanisms represent key technologies for
enabling flexible and dynamic networking.
Transport networks in this draft refer to a set of different type of
connection-oriented networks, primarily Connection-Oriented Circuit
Switched (CO-CS) networks and Connection-Oriented Packet Switched
(CO-PS) networks. This implies that at least the following transport
networks are in scope of the discussion of this draft: Layer 1(L1)
and Layer 0 (L0) optical networks (e.g., Optical Transport Network
(OTN), Optical Channel Data Unit (ODU), Optical Channel
(OCh)/Wavelength Switched Optical Network (WSON)), Multi-Protocol
Label Switching - Transport Profile (MPLS-TP), Multi-Protocol Label
Switching - Traffic Engineering (MPLS-TE), as well as other emerging
technologies with connection-oriented behavior. One of the
characteristics of these network types is the ability of dynamic
provisioning and traffic engineering such that resource guarantees
can be provided to their clients.
One of the main drivers for Software Defined Networking (SDN) is a
decoupling of the network control plane from the data plane. This
separation of the control plane from the data plane has been already
achieved with the development of MPLS/GMPLS [GMPLS] and PCE [PCE]
for TE-based transport networks. One of the advantages of SDN is its
logically centralized control regime that allows a global view of
the underlying network under its control. Centralized control in SDN
helps improve network resources utilization from a distributed
network control. For TE-based transport network control, PCE is
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essentially equivalent to a logically centralized control for path
computation function.
Two key aspects that need to be solved by SDN are:
. Network and service abstraction
. End to end coordination of multiple SDN and pre-SDN domains
e.g. NMS, MPLS-TE or GMPLS.
As transport networks evolve, the need to provide network and
service abstraction has emerged as a key requirement for operators;
this implies in effect the virtualization of network resources so
that the network is "sliced" for different tenants shown as a
dedicated portion of the network resources
Particular attention needs to be paid to the multi-domain case,
where Abstraction and Control of Transport Networks (ACTN) can
facilitate virtual network operation via the creation of a single
virtualized network or a seamless service. This supports operators
in viewing and controlling different domains (at any dimension:
applied technology, administrative zones, or vendor-specific
technology islands) as a single virtualized network.
Network virtualization, in general, refers to allowing the customers
to utilize a certain amount of network resources as if they own them
and thus control their allocated resources in a way most optimal
with higher layer or application processes. This empowerment of
customer control facilitates introduction of new services and
applications as the customers are permitted to create, modify, and
delete their virtual network services. 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 abstracted network topology.
Such a view may be specific to the set of consumed services as well
as to a particular customer. As the Customer Network Controller is
envisioned to support a plethora of distinct applications, there
would be another level of virtualization from the customer to
individual applications.
The framework described in this draft is named Abstraction and
Control of Transport Network (ACTN) and facilitates:
- Abstraction of the underlying network resources to higher-layer
applications and users (customers); abstraction for a specific
application or customer is referred to as virtualization in the
ONF SDN architecture. [ONF-ARCH]
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- Slicing infrastructure to connect multiple customers to meet
specific customer's service requirements;
- Creation of a virtualized environment allowing operators to
view and control multi-subnet multi-technology networks into a
single virtualized network;
- Possibility of providing a customer with abstracted network or
abstracted services (totally hiding the network).
- A virtualization/mapping network function that adapts customer
requests to the virtual resources (allocated to them) to the
supporting physical network control and performs the necessary
mapping, translation, isolation and security/policy
enforcement, etc.; This function is often referred to as
orchestration.
- The multi-domain coordination of the underlying transport
domains, presenting it as an abstracted topology to the
customers via open and programmable interfaces. This allows for
the recursion of controllers in a customer-provider
relationship.
The organization of this draft is as follows. Section 2 provides a
discussion for a Business Model, Section 3 ACTN Architecture,
Section 4 ACTN Applicability, and Section 5 ACTN Interface
requirements.
2. Business Model of ACTN
The traditional Virtual Private Network (VPN) and Overlay Network
(ON) models are built on the premise that one single network
provider provides all virtual private or overlay networks to its
customers. This model is simple to operate but has some
disadvantages in accommodating the increasing need for flexible and
dynamic network virtualization capabilities.
The ACTN model is built upon entities that reflect the current
landscape of network virtualization environments. There are three
key entities in the ACTN model [ACTN-PS]:
- Customers
- Service Providers
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- Network Providers
2.1. Customers
Within the ACTN framework, different types of customers may be taken
into account depending on the type of their resource needs, on their
number and type of access. As example, it is possible to group them
into two main categories:
Basic Customer: Basic customers include fixed residential users,
mobile users and small enterprises. Usually the number of basic
customers is high; they require small amounts of resources and are
characterized by steady requests (relatively time invariant). A
typical request for a basic customer is for a bundle of voice
services and internet access. Moreover basic customers do not modify
their services themselves; if a service change is needed, it is
performed by the provider as proxy and they generally have very few
dedicated resources (subscriber drop), with everything else shared
on the basis of some SLA, which is usually best-efforts.
Advanced Customer: Advanced customers typically include enterprises,
governments and utilities. Such customers can ask for both point to
point and multipoint connectivity with high resource demand
significantly varying in time and from customer to customer. This is
one of the reasons why a bundled services offer is not enough but it
is desirable to provide each of them with customized virtual network
services. Advanced customers may own dedicated virtual resources, or
share resources, but shared resources are likely to be governed by
more complex SLA agreements; moreover they may have the ability to
modify their service parameters directly (within the scope of their
virtualized environments. As customers are geographically spread
over multiple network provider domains, the necessary control and
data interfaces to support such customer needs is no longer a single
interface between the customer and one single network provider. With
this premise, customers have to interface multiple providers to get
their end-to-end network connectivity service and the associated
topology information. Customers may have to support multiple virtual
network services with different service objectives and QoS
requirements. For flexible and dynamic applications, customers may
want to control their allocated virtual network resources in a
dynamic fashion. To allow that, customers should be given an
abstracted view of topology on which they can perform the necessary
control decisions and take the corresponding actions. ACTN's primary
focus is Advanced Customers.
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Customers of a given service provider can in turn offer a service to
other customers in a recursive way. An example of recursiveness with
2 service providers is shown below.
- Customer (of service B)
- Customer (of service A) & Service Provider (of service B)
- Service Provider (of service A)
- Network Provider
+------------------------------------------------------------+ ---
| | ^
| Customer (of service B)| .
| +--------------------------------------------------------+ | B
| | | |--- .
| |Customer (of service A) & Service Provider(of service B)| | ^ .
| | +---------------------------------------------------+ | | . .
| | | | | | . .
| | | Service Provider (of service A)| | | A .
| | |+------------------------------------------+ | | | . .
| | || | | | | . .
| | || Network provider| | | | v v
| | |+------------------------------------------+ | | |------
| | +---------------------------------------------------+ | |
| +--------------------------------------------------------+ |
+------------------------------------------------------------+
Figure 1: Network Recursiveness.
2.2. Service Providers
Service providers are the providers of virtual network services to
their customers. Service providers may or may not own physical
network resources. When a service provider is the same as the
network provider, this is similar to traditional VPN models. This
model works well when the customer maintains a single interface with
a single provider. When customer location spans across multiple
independent network provider domains, then it becomes hard to
facilitate the creation of end-to-end virtual network services with
this model.
A more interesting case arises when network providers only provide
infrastructure while service providers directly interface their
customers. In this case, service providers themselves are customers
of the network infrastructure providers. One service provider may
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need to keep multiple independent network providers as its end-users
span geographically across multiple network provider domains.
Customer X -----------------------------------X
Service Provider A X -----------------------------------X
Network Provider B X-----------------X
Network Provider A X------------------X
The ACTN network model is predicated upon this three tier model and
is summarized in figure below:
+----------------------+
| customer |
+----------------------+
|
| /\ Service/Customer specific
| || Abstract Topology
| ||
+----------------------+ E2E abstract
| Service Provider | topology creation
+----------------------+
/ | \
/ | \ Network Topology
/ | \ (raw or abstract)
/ | \
+------------------+ +------------------+ +------------------+
|Network Provider 1| |Network Provider 2| |Network Provider 3|
+------------------+ +------------------+ +------------------+
Figure 2: Three tier model.
There can be multiple types of service providers.
. Data Center providers: can be viewed as a service provider type
as they own and operate data center resources to various WAN
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clients, they can lease physical network resources from network
providers.
. Internet Service Providers (ISP): can be a service provider of
internet services to their customers while leasing physical
network resources from network providers.
. Mobile Virtual Network Operators (MVNO): provide mobile
services to their end-users without owning the physical network
infrastructure.
The network provider space is the one where recursiveness occurs. A
customer-provider relationship between multiple service providers
can be established leading to a hierarchical architecture of
controllers within service provider network.
2.3. Network Providers
Network Providers are the infrastructure providers that own the
physical network resources and provide network resources to their
customers. The layered model proposed by this draft separates the
concerns of network providers and customers, with service providers
acting as aggregators of customer requests.
3. ACTN architecture
This section provides a high-level control and interface model of
ACTN.
The ACTN architecture, while being aligned with the ONF SDN
architecture [ONF-ARCH], is presenting a 3-tiers reference model. It
allows for hierarchy and recursiveness not only of SDN controllers
but also of traditionally controlled domains. It defines three types
of controllers depending on the functionalities they implement. The
main functionalities that are identified are:
. Multi domain coordination function: With the definition of
domain being "everything that is under the control of the same
controller",it is needed to have a control entity that oversees
the specific aspects of the different domains and to build a
single abstracted end-to-end network topology in order to
coordinate end-to-end path computation and path/service
provisioning.
. Virtualization/Abstraction function: To provide an abstracted
view of the underlying network resources towards customer,
being it the client or a higher level controller entity. It
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includes computation of customer resource requests into virtual
network paths based on the global network-wide abstracted
topology and the creation of an abstracted view of network
slices allocated to each customer, according to customer-
specific virtual network objective functions, and to the
customer traffic profile.
. Customer mapping function: In charge of mapping customer VN
setup commands into network provisioning requests to the
Physical Network Controller (PNC) according to business OSS/NMS
provisioned static or dynamic policy. Moreover it provides
mapping and translation of customer virtual network slices into
physical network resources
. Virtual service coordination: Virtual service coordination
function in ACTN incorporates customer service-related
knowledge into the virtual network operations in order to
seamlessly operate virtual networks while meeting customer's
service requirements.
The functionality is covering two types of services:
- Service-aware Connectivity Services: This category includes
all the network service operations used to provide
connectivity between customer end-points while meeting
policies and service related constraints. The data model for
this category would include topology entities such as
virtual nodes, virtual links, adaptation and termination
points and service-related entities such as policies and
service related constraints. (See Section 4.2.2)
- Network Function Virtualization Services: These kinds of
services are usually setup between customers' premises and
service provider premises and are provided mostly by cloud
providers or content delivery providers. The context may
include, but not limited to a security function like
firewall, a traffic optimizer, the provisioning of storage
or computation capacity where the customer does not care
whether the service is implemented in a given data center or
another. These services may be hosted virtually by the
provider or physically part of the network. This allows the
service provider to hide his own resources (both network and
data centers) and divert customer requests where most
suitable. This is also known as "end points mobility" case
and introduces new concepts of traffic and service
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provisioning and resiliency. (e.g. Virtual Machine
mobility)." (See Section 4.2.3)
About the Customer service-related knowledge it includes:
- VN Service Requirements: The end customer would have
specific service requirements for the VN including the
customer endpoints access profile as well as the E2E
customer service objectives. The ACTN framework
architectural "entities" would monitor the E2E service
during the lifetime of VN by focusing on both the
connectivity provided by the network as well as the customer
service objectives. These E2E service requirements go beyond
the VN service requirements and include customer
infrastructure as well.
- Application Service Policy: Apart for network connectivity,
the customer may also require some policies for application
specific features or services. The ACTN framework would take
these application service policies and requirements into
consideration while coordinating the virtual network
operations, which require end customer connectivity for
these advanced services.
While the "types" of controller defined are shown in Figure 3 below
and are the following:
. CNC - Customer Network Controller
. MDSC - Multi Domain Service Coordinator
. PNC - Physical Network Controller
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VPN customer NW Mobile Customer ISP NW service Customer
| | |
+-------+ +-------+ +-------+
| CNC-A | | CNC-B | | CNC-C |
+-------+ +-------+ +-------+
\ | /
---------- | ------------
\ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
--------- | ------------
/ | \
+-------+ +-------+ +-------+
| PNC | | PNC | | PNC |
+-------+ +-------+ +-------+
| GMPLS / | / \
| trigger / | / \
-------- ---- +-----+ +-----+ \
( ) ( ) | PNC | | PCE | \
- - ( Phys ) +-----+ +-----+ -----
( GMPLS ) (Netw) | / ( )
( Physical ) ---- | / ( Phys. )
( Network ) ----- ----- ( Net )
- - ( ) ( ) -----
( ) ( Phys. ) ( Phys )
-------- ( Net ) ( Net )
----- -----
Figure 3: ACTN Control Hierarchy
3.1. Customer Network Controller
A Virtual Network Service is instantiated by the Customer Network
Controller via the CMI (CNC-MDSC Interface). As the Customer Network
Controller directly interfaces the application stratum, it
understands multiple application requirements and their service
needs. It is assumed that the Customer Network Controller and the
MDSC have a common knowledge on the end-point interfaces based on
their business negotiation prior to service instantiation. End-point
interfaces refer to customer-network physical interfaces that
connect customer premise equipment to network provider equipment.
Figure 10 in Appendix shows an example physical network topology
that supports multiple customers. In this example, customer A has
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three end-points A.1, A.2 and A.3. The interfaces between customers
and transport networks are assumed to be 40G OTU links.
In addition to abstract networks, ACTN allows to provide the CNC
with services. Example of services include connectivity between one
of the customer's end points with a given set of resources in a data
center from the service provider.
3.2. Multi Domain Service Coordinator
The MSDC (Multi Domain Service Coordinator) sits between the CNC
(the one issuing connectivity requests) and the PNCs (Physical
Network Controllersr - the ones managing the physical network
resources). The MSDC can be collocated with the PNC, especially in
those cases where the service provider and the network provider are
the same entity.
The internal system architecture and building blocks of the MDSC are
out of the scope of ACTN. Some examples can be found in the
Application Based Network Operations (ABNO) architecture [ABNO] and
the ONF SDN architecture [ONF-ARCH].
The MDSC is the only building block of the architecture that is able
to implement all the four ACTN main functionalities, i.e. multi
domain coordination function, virtualization/abstraction function,
customer mapping function and virtual service coordination.
A hierarchy of MSDCs can be foreseen for scalability and
administrative choices.
3.3. Physical Network Controller
The physical network controller is the one in charge of configuring
the network elements, monitoring the physical topology of the
network and passing it, either raw or abstracted, to the MDSC.
The internal architecture of the PNC, his building blocks and the
way it controls its domain, are out of the scope of ACTN. Some
examples can be found in the Application Based Network Operations
(ABNO) architecture [ABNO] and the ONF SDN architecture [ONF-ARCH]
The PNC, in addition to being in charge of controlling the physical
network, is able to implement two of the four ACTN main
functionalities: multi domain coordination function and
virtualization/abstraction function
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A hierarchy of PNCs can be foreseen for scalability and
administrative choices.
3.4. ACTN interfaces
To allow virtualization and multi domain coordination, the network
has to provide open, programmable interfaces, in 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 the previous section, the network
control plane for transport networks has been separated from data
plane and as such it is not viable for the customer to directly
interface with transport network elements.
While the current network control plane is well suited for control
of physical network resources via dynamic provisioning, path
computation, etc., a multi service domain controller needs to be
built on top of physical network controller to support network
virtualization. On a high-level, virtual network control refers to a
mediation layer that performs several functions:
Figure 4 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 4
(ACTN Interfaces) below:
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.--------------
------------- |
| Application |--
-------------
^
| I/F A --------
v ( )
-------------- - -
| Customer | ( Customer )
| Network |--------->( Network )
| Controller | ( )
-------------- - -
^ ( )
| I/F B --------
v ^ ^
-------------- : :
| MultiDomain | : .
| Service | : .
| Coordinator| -------- . I/F E
-------------- ( ) .
^ - - .
| I/F C ( Physical ) .
v ( Network ) .
--------------- ( ) --------
| |<----> - - ( )
-------------- | ( ) - -
| Physical |-- -------- ( Physical )
| Network |<---------------------->( Network )
| Controller | I/F D ( )
-------------- - -
( )
--------
Figure 4: ACTN Interfaces
The interfaces and functions are described below:
. Interface A: A north-bound interface (NBI) that will
communicate the service request or application demand. A
request will include specific service properties, including:
services, topology, bandwidth and constraint information.
. Interface B: The CNC-MSDC Interface (CMI) is an interface
between a Customer Network Controller and a Multi Service
Domain Controller. It requests the creation of the network
resources, topology or services for the applications. The
Virtual Network Controller may also report potential network
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topology availability if queried for current capability from
the Customer Network Controller.
. Interface C: The MDSC-PNC Interface (MPI) is an interface
between a Multi Domain Service Coordinator and a Physical
Network Controller. It communicates the creation request, if
required, of new connectivity of bandwidth changes in the
physical network, via the PNC. In multi-domain environments,
the MDSC needs to establish multiple MPIs, one for each PNC, as
there are multiple PNCs responsible for its domain control.
. Interface D: The provisioning interface for creating forwarding
state in the physical network, requested via the Physical
Network Controller.
. Interface E: A mapping of physical resources to overlay
resources.
The interfaces within the ACTN scope are B and C.
4. ACTN Applicability
This section provides a high-level applicability of ACTN based on a
number of use-cases listed in the following:
- draft-cheng-actn-ptn-requirements-00 (ACTN Use-cases for Packet
Transport Networks in Mobile Backhaul Networks)
- draft-dhody-actn-poi-use-case-03 (Packet Optical Integration (POI)
Use Cases for Abstraction and Control of Transport Networks
(ACTN))
- draft-fang-actn-multidomain-dci-01 (ACTN Use Case for Multi-domain
Data Center Interconnect)
- draft-klee-actn-connectivity-multi-vendor-domains-03 (ACTN Use-
case for On-demand E2E Connectivity Services in Multiple Vendor
Domain Transport Networks)
- draft-kumaki-actn-multitenant-vno-00 (ACTN : Use case for Multi
Tenant VNO)
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- draft-lopez-actn-vno-multidomains-01 (ACTN Use-case for Virtual
Network Operation for Multiple Domains in a Single Operator
Network)
- draft-shin-actn-mvno-multi-domain-00 (ACTN Use-case for Mobile
Virtual Network Operation for Multiple Domains in a Single
Operator Network)
- draft-xu-actn-perf-dynamic-service-control-02 (Use Cases and
Requirements of Dynamic Service Control based on Performance
Monitoring in ACTN Architecture)
4.1. ACTN Use cases Summary
Listed below is a set of generalized requirements identified by each of
the aforementioned use-cases:
- draft-cheng-actn-ptn-requirements-00
o Faster End-to-End Enterprise Services Provisioning
o Multi-layer coordination in L2/L3 Packet Transport Networks
o Optimizing the network resources utilization (supporting
various performances monitoring matrix, such as traffic flow
statistics, packet delay, delay variation, throughput and
packet-loss rate)
o Virtual Networks Operations for multi-domain Packet Transport
Networks
- draft-dhody-actn-poi-use-case-03
o Packet Optical Integration to support Traffic Planning,
performance Monitoring, automated congestion management and
Automatic Network Adjustments
o Protection and Restoration Synergy in Packet Optical Multi-
layer network.
o Service Awareness and Coordination between Multiple Network
Domains
- draft-fang-actn-multidomain-dci-01
- Multi-domain Data Center Interconnection to support VM Migration,
Global Load Balancing, Disaster Recovery, On-demand Virtual
Connection/Circuit Services
- The interfaces between the Data Center Operation and each
transport network domain SHOULD support standards-based
abstraction with a common information/data model to support the
following:
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. Network Query (Pull Model) from the Data Center
Operation to each transport network domain to collect
potential resource availability (e.g., BW availability,
latency range, etc.) between a few data center
locations.
. Network Path Computation Request from the Data Center
Operation to each transport network domain to estimate
the path availability.
. Network Virtual Connections/Circuits Request from the
Data Center Operation to each transport domain to
establish end-to-end virtual connections/circuits (with
type, concurrency, duration, SLA.QoS parameters,
protection.reroute policy options, policy constraints
such as peering preference, etc.).
. Network Virtual Connections/Circuits Modification
Request
- draft-klee-actn-connectivity-multi-vendor-domains-02
o Two-stage path computation capability in a hierarchical
control architecture (MDSC-PNC) and a hierarchical
composition of integrated network views
o Coordination of signal flow for E2E connections.
o Abstraction of:
. Inter-connection data between domains
. Customer Endpoint data
. The multiple levels/granularities of the abstraction of
network resource (which is subject to policy and service
need).
. Any physical network constraints (such as SRLG, link
distance, etc.) should be reflected in abstraction.
. Domain preference and local policy (such as preferred
peering point(s), preferred route, etc.), Domain network
capability (e.g., support of push/pull model).
- draft-kumaki-actn-multitenant-vno-00
o On-demand Virtual Network Service Creation
o Domain Control Plane/Routing Layer Separation
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o Independent service Operation for Virtual Services from
control of other domains
o Multiple service level support for each VN (e.g., bandwidth
and latency for each VN service).
o VN diversity/survivability should be met in physical network
mapping.
o VN confidentiality and sharing constraint should be supported.
- draft-lopez-actn-vno-multidomains-01
o Creation of a global abstraction of network topology: The VNO
Coordinator assembles each domain level abstraction of
network topology into a global abstraction of the end-to-
endnetwork.
o End-to-end connection lifecycle management
o Invocation of path provisioning request to each domain
(including optimization requests)
o Invocation of path protection/reroute to the affected
domain(s)
o End-to-end network monitoring and fault management. This could
imply potential KPIs and alarm correlation capabilities.
o End-to-end accounting and generation of detailed records for
resource usage
o End-to-end policy enforcement
- draft-shin-actn-mvno-multi-domain-00
o Resource abstraction: operational mechanisms in mobile
backhaul network to give the current network usage
information for dynamic and elastic applications be
provisioned dynamically with QoS guarantee.
o Load balancing or for recovery, the selection of core DC
location from edge constitutes a data center selection
problem.
o Multi-layer routing and optimization, coordination between
these two layers.
- draft-xu-actn-perf-dynamic-service-control-02
o Dynamic Service Control Policy enforcement and Traffic/SLA
Monitoring:
. Customer service performance monitoring strategy,
including the traffic monitoring object (the service
need to be monitored)
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. monitoring parameters (e.g., transmitted and received
bytes per unit time),
. traffic monitoring cycle (e.g., 15 minutes, 24 hours),
. threshold of traffic monitoring (e.g., high and low
threshold), etc.
4.2. Work in Scope of ACTN
This section provides a summary of use-cases in terms of two
categories: (i) service-specific requirements; (ii) network-related
requirements.
Service-specific requirements listed below are uniquely applied to
the work scope of ACTN. Service-specific requirements are related to
virtual service coordination function defined in Section 3. These
requirements are related to customer's VNs in terms of service
policy associated with VNs such as service performance objectives,
VN endpoint location information for certain required service-
specific functions (e.g., security and others), VN survivability
requirement, or dynamic service control policy, etc.
Network-related requirements are related to virtual network
operation function defined in Section 3. These requirements are
related to multi-domain and multi-layer signaling, routing,
protection/restoration and synergy, re-optimization/re-grooming,
etc. These requirements are not inherently unique for the scope of
ACTN but some of these requirements are in scope of ACTN, especially
for coherent/seamless operation aspect of multiple controller
hierarchy.
The following table gives an overview of service-specific
requirements and network-related requirements respectively for each
ACTN use-case and identifies the work in scope of ACTN.
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Use- Service- Network-related ACTN Work
case specific Requirements Scope
Requirements
------- -------------- --------------- --------------
Cheng - E2E service - Multi-layer - Dynamic
provisioning (L2/L2.5) multi-layer
- Performance coordination coordination
monitoring - VNO for multi- based on
- Resource domain transport utilization is
utilization networks in scope of
abstraction ACTN
- YANG for
utilization
abstraction
------- -------------- ---------------- --------------
Dhody - Service - POI - Performance
awareness/ Performance related data
coordination monitoring model may be
between P/O. - Protection/ in scope of
Restoration ACTN
synergy - Customer's
VN
survivability
policy
enforcement
for
protection/
restoration
is unique to
ACTN
------- -------------- ---------------- --------------
Fang - Dynamic VM - On-demand - Multi-
migration virtual circuit destination
(service), request service
Global load - Network Path selection
balancing Connection policy
(utilization request enforcement
efficiency), and its
Disaster related
recovery primitives/inf
- Service- ormation are
aware network unique to
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query ACTN.
- Service - Service-
Policy aware network
Enforcement query and its
data model can
be extended by
ACTN.
------- -------------- ---------------- --------------
Klee - Two stage path - Multi-domain
computation service policy
E2E signaling coordination
coordination to network
primitives is
- Abstraction of in scope of
inter-domain ACTN.
info
- Enforcement of
network policy
(peering, domain
preference)
- Network
capability
exchange
(pull/push,
abstraction
level, etc.)
------- -------------- ---------------- --------------
Kumaki - On-demand VN - All of the
creation service-
- Multi- specific lists
service level in the left
for VN column is
- VN unique to
survivability ACTN.
/diversity/con
fidentiality
------- -------------- ---------------- --------------
Lopez - E2E - E2E connection - Escalation
accounting and management, path of performance
resource usage provisioning and fault
data - E2E network management
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- E2E service monitoring and data to CNC
policy fault management and the policy
enforcement enforcement
for this area
is unique to
ACTN.
------- -------------- ---------------- --------------
Shin - Current - LB for - Multi-layer
network recovery routing and
resource - Multi-layer optimization
abstraction routing and are related to
Endpoint/DC optimization VN's dynamic
dynamic coordination endpoint
selection (for selection
VM migration) policy.
------- -------------- ---------------- --------------
Xu - Dynamic - Traffic - Dynamic
service monitoring service
control policy - SLA monitoring control policy
enforcement enforcement
- Dynamic and its
service control
control primitives are
in scope of
ACTN
- Data model
to support
traffic
monitoring
data is an
extension of
YANG model
ACTN can
extend.
The subsequent sections provide some illustration of the ACTN's unique
work scope identified by the above analysis:
- Coordination of Multi-destination Service Requirement/Policy
(Section 4.2.1)
- Application Service Policy-aware Network Operation (section 4.2.2)
- Network Function Virtualization Services (section 4.2.3)
- Dynamic Service Control Policy Enforcement for Performance/Fault
Management (Section 4.2.4)
- E2E VN Survivability and Multi-Layer (Packet-Optical) Coordination
for Protection/Restoration (Section 4.2.5)
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4.2.1. Coordination of Multi-destination Service Requirement/Policy
+----------------+
| CNC |
| (Global DC |
| Operation |
| Control) |
+--------+-------+
| | Service Requirement/Policy:
| | - Endpoint/DC location info
| | - Endpoint/DC dynamic
| | selection policy
| | (for VM migration, DR, LB)
| v
+---------+--------+
| Multi-domain | Service policy-driven
|Service Controller| dynamic DC selection
+-----+---+---+----+
| | |
| | |
+----------------+ | +----------------+
| | |
+-----+-----+ +-----+------+ +------+-----+
| PNC for | | PNC for | | PNC for |
| Transport | | Transport | | Transport |
| Network A | | Network B | | network C |
+-----------+ +------------+ +------------+
| | |
+---+ ------ ------ ------ +---+
|DC1|--//// \\\\ //// \\\\ //// \\\\---+DC4|
+---+ | | | | | | +---+
| TN A +-----+ TN B +----+ TN C |
/ | | | | |
/ \\\\ //// / \\\\ //// \\\\ ////
+---+ ------ / ------ \ ------ \
|DC2| / \ \+---+
+---+ / \ |DC6|
+---+ \ +---+ +---+
|DC3| \|DC4|
+---+ +---+
DR: Disaster Recovery
LB: Load Balancing
Figure 5: Service Policy-driven Data Center Selection
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Figure 5 shows how VN service policies from the CNC are incorporated
by the MDSC to support multi-destination applications. Multi-
destination applications refer to applications in which the
selection of the destination of a network path for a given source
needs to be decided dynamically to support such applications.
Data Center selection problems arise for VM mobility, disaster
recovery and load balancing cases. VN's service policy plays an
important role for virtual network operation. Service policy can be
static or dynamic. Dynamic service policy for data center selection
may be placed as a result of utilization of data center resources
supporting VNs. The MSDC would then incorporate this information to
meet the service objective of this application.
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4.2.2. Application Service Policy-aware Network Operation
+----------------+
| CNC |
| (Global DC |
| Operation |
| Control) |
+--------+-------+
| | Application Service Policy
| | - VNF requirement (e.g.
| | security function, etc.)
| | - Location profile for each VNF
| v
+---------+--------+
| Multi-domain | Dynamically select the
|Service Controller| network destination to
+-----+---+---+----+ meet VNF requirement.
| | |
| | |
+---------------+ | +----------------+
| | |
+------+-----+ +-----+------+ +------+-----+
| PNC for | | PNC for | | PNC for |
| Transport | | Transport | | Transport |
| Network A | | Network B | | network C |
| | | | | |
+------------+ +------------+ +------------+
| | |
{VNF b} | | | {VNF b,c}
+---+ ------ ------ ------ +---+
|DC1|--//// \\\\ //// \\\\ //// \\\\-|DC4|
+---+ | | | | | |+---+
| TN A +---+ TN B +--+ TN C |
/ | | | | |
/ \\\\ //// / \\\\ //// \\\\ ////
+---+ ------ / ------ \ ------ \
|DC2| / \ \\+---+
+---+ / \ |DC6|
{VNF a} +---+ +---+ +---+
|DC3| |DC4| {VNF a,b,c}
+---+ +---+
{VNF a, b} {VNF a, c}
Figure 6: Application Service Policy-aware Network Operation
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This scenario is similar to the previous case in that the VN service
policy for the application can be met by a set of multiple
destinations that provide the required virtual network functions
(VNF). Virtual network functions can be, for example, security
functions required by the VN application. The VN service policy by
the CNC would indicate the locations of a certain VNF that can be
fulfilled. This policy information is critical in finding the
optimal network path subject to this constraint. As VNFs can be
dynamically moved across different DCs, this policy should be
dynamically enforced from the CNC to the MDSC and the PNCs.
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4.2.3. Network Function Virtualization Services
+----------------+
| CNC |
| (Global DC |
| Operation |
| Control) |
+--------+-------+
| | Service Policy
| | (e.g., firewall, traffic
| | optimizer)
| |
| v
+---------+--------+
| Multi-domain | Select network
|Service Controller| connectivity subject to
+-----+---+---+----+ meeting service policy
| | |
| | |
+---------------+ | +----------------+
| | |
+------+-----+ +-----+------+ +------+-----+
| PNC for | | PNC for | | PNC for |
| Transport | | Transport | | Transport |
| Network A | | Network B | | network C |
| | | | | |
+------------+ +------------+ +------------+
| | |
| | |
+---+ ------ ------ ------ +---+
|DC1|--//// \\\\ //// \\\\ //// \\\\-|DC4|
+---+ | | | | | |+---+
| TN A +---+ TN B +--+ TN C |
/ | | | | |
/ \\\\ //// / \\\\ //// \\\\ ////
+---+ ------ / ------ \ ------ \
|DC2| / \ \\+---+
+---+ / \ |DC6|
+---+ +---+ +---+
|DC3| |DC4|
+---+ +---+
Figure 7: Network Function Virtualization Services
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Network Function Virtualization Services are usually setup between
customers' premises and service provider premises and are provided
mostly by cloud providers or content delivery providers. The context
may include, but not limited to a security function like firewall, a
traffic optimizer, the provisioning of storage or computation
capacity where the customer does not care whether the service is
implemented in a given data center or another.
These services may be hosted virtually by the provider or physically
part of the network. This allows the service provider to hide his
own resources (both network and data centers) and divert customer
requests where most suitable. This is also known as "end points
mobility" case and introduces new concepts of traffic and service
provisioning and resiliency (e.g., Virtual Machine mobility).
4.2.4. Dynamic Service Control Policy Enforcement for Performance and
Fault Management
+------------------------------------------------+
| Customer Network Controller |
+------------------------------------------------+
1.Traffic| /|\4.Traffic | /|\
Monitor& | | Monitor | | 8.Traffic
Optimize | | Result 5.Service | | modify &
Policy | | modify& | | optimize
\|/ | optimize Req.\|/ | result
+------------------------------------------------+
| Mult-domain Service Controller |
+------------------------------------------------+
2. Path | /|\3.Traffic | |
Monitor | | Monitor | |7.Path
Request | | Result 6.Path | | modify &
| | modify& | | optimize
\|/ | optimize Req.\|/ | result
+------------------------------------------------+
| Physical Network Controller |
+------------------------------------------------+
Figure 8: Dynamic Service Control for Performance and Fault
Management
Figure 8 shows the flow of dynamic service control policy
enforcement for performance and fault management initiated by
customer per their VN. The feedback loop and filtering mechanism
tailored for VNs performed by the MDSC differentiates this ACTN
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scope from traditional network management paradigm. VN level dynamic
OAM data model is a building block to support this capability.
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4.2.5. E2E VN Survivability and Multi-Layer (Packet-Optical)
Coordination for Protection/Restoration
+----------------+
| Customer |
| Network |
| Controller |
+--------*-------+
* | E2E VN Survivability Req.
* | - VN Protection/Restoration
* v - 1+1, Restoration, etc.
+------*-----+ - End Point (EP) info.
| |
| MDSC | MDSC enforces VN survivability
| | requirement, determining the
| | optimal combination of Packet/
+------*-----+ Opticalprotection/restoration,
* Optical bypass, etc.
*
*
**********************************************
* * * *
+----*-----+ +----*----+ +----*-----+ +----*----+
|PNC for | |PNC for | |PNC for | |PNC for |
|Access N. | |Packet C.| |Optical C.| |Access N.|
+----*-----+ +----*----+ +----*-----+ +---*-----+
* --*--- * *
* /// \\\ * *
--*--- | Packet | * ----*-
/// \\\ | Core +------+------/// \\\
| Access +----\\ /// * | Access |
| Network | ---+-- * | Network | +---+
|\\\ /// | * \\\ ///---+EP6|
| +---+- | | -----* -+---+ +---+
+-+-+ | | +----/// \\\ | |
|EP1| | +--------------+ Optical | | | +---+
+---+ | | Core +------+ +--+EP5|
+-+-+ \\\ /// +---+
|EP2| ------ |
+---+ | |
+--++ ++--+
|EP3| |EP4|
+---+ +---+
Figure 9: E2E VN Survivability and Multi-layer Coordination for
Protection and Restoration
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Figure 9 shows the need for E2E protection/restoration control
coordination that involves CNC, MDSC and PNCs to meet the VN
survivability requirement. VN survivability requirement and its
policy need to be translated into multi-domain and multi-layer
network protection and restoration scenarios across different
controller types. After an E2E path is setup successfully, the MSDC
has a unique role to enforce policy-based flexible VN survivability
requirement by coordinating all PNC domains.
As seen in Figure 9, multi-layer (i.e., packet/optical) coordination
is a subset of this E2E protection/restoration control operation.
The MDSC has a role to play in determining an optimal
protection/restoration level based on the customer's VN
survivability requirement. For instance, the MDSC needs to interface
the PNC for packet core as well as the PNC for optical core and
enforce protection/restoration policy as part of the E2E
protection/restoration. Neither the PNC for packet core nor the PNC
for optical core is in a position to be aware of the E2E path and
its protection/restoration situation. This role of the MSDC is
unique for this reason. In some cases, the MDSC will have to
determine and enforce optical bypass to find a feasible reroute path
upon packet core network failure which cannot be resolved the packet
core network itself.
To coordinate this operation, the PNCs will need to update its
domain level abstract topology upon resource changes due to a
network failure or other factors. The MSDC will incorporate all
these update to determine if an alternate E2E reroute path is
necessary or not based on the changes reported from the PNCs. It
will need to update the E2E abstract topology and the affected CN's
VN topology in real-time. This refers to dynamic synchronization of
topology from Physical topology to abstract topology to VN topology.
MDSC will also need to perform the path restoration signaling to the
affected PNCs whenever necessary.
5. ACTN interfaces requirements
This section provides ACTN interface requirements for the two
interfaces that are within the ACTN scope.
. CMI: CNC-MDSC Interface (Section 5.1)
. MPI: MDSC-PNC Interface (Section 5.2)
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For each requirement, it also identifies the following categories
where possible:
1. Applicable [App]: Existing components are applicable to ACTN
architecture
2. Extensible [Ext]: Existing components can be extended to ACTN
architecture
3. New [New]: The components are new work to ACTN architecture
5.1. CMI Interface Requirements
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Requirement Notes
------------------------------- ----------------------------
1. Security/Policy Negotiation - Some new element for
(Who are you?) (Between CNC controller-controller
and MDSC) (CNC-MDSC)
- Configured vs. Discovered security/policy
[new] negotiation aspect.
- Trust domain verification - It is not entirely
(External Entity vs. Internal clear if there is
Service Department) [ext] existing work that can
- Push/Pull support (for be extended to support
policy) [ext/new?] all requirements
2. VN Topology Query (Can you - New for some primitives
give me VN?) (From CNC to and IEs (e.g., VN
MDSC) Topology Query, VN
- VN end-points (CE end) [new] Topo. Negotiation, VN
- VN Topology Service-specific end-points)
Multi-Cost Objective Function
[ext] - Extensible for some
o Latency Map IE/Objects from PCEP
o Available B/W Map (e.g., Objective
o Latency Map and function, etc.)
Available B/W Map
together
o Other types
- VN Topology diversity [new]
o Node/Link disjoint from
other VNs
o VN Topology level
diversity (e.g., VN1 and
VN2 must be disjoint)
- VN Topology type [ext]
o Path vector (tunnel)
o Node/Links (graph)
3. VN Topology Query Response - Similar comment to #2.
(From MDSC to CNC: Here's the
VN Topology that can be given
to you if you accept)
- For VN Topology, [ext]
o This is what can be
reserved for you
o This is what is
available beyond what is
given to you (potential)
4. VN Topology Abstraction Model - Applicable (Generic TE
(generic network model) [App] YANG model)
5. VN Topology Abstraction Model - Extensible from generic
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(Service-specific model that TE Abstraction Model
include customer endpoints) (TEAS WG) to include
[Ext] service-related
parameters and end-
point abstraction
6. Basic VN Instantiation - It is not completely
Request/Confirmation clear if existing
(Between CNC and MDSC: I need components can be
VN for my service, please extended or if these
instantiate my VN) require new
- VN instance ID [ext] protocol/primitives/IEs
- VN end-points [ext/new?] .
- VN service requirement [ext] - It appears that there
o Latency only is no existing proper
o B/W guarantee protocol that supports
o Latency and B/W all required
guarantee together primitives/IEs, but
- VN diversity [ext] this is subject to
o Node/Link disjoint from further analysis.
other VNs
- VN level diversity (e.g., VN1
and VN2 must be disjoint)
[ext]
- VN type [ext]
o Path vector (tunnel)
o Node/Links (graph)
- VN instance ID per service
(unique id to identify VNs)
[ext/new?]
- If failed to instantiate the
requested VN, say why [ext]
7. Dynamic/On-demand VN - New: dynamic policy
Instantiation/Modification enforcement seems to be
and Confirmation with new while abstraction
feedback loop (This is to be of service-aware
differentiated from Basic VN abstraction model can
Instantiation) be extended from basic
- Performance/Fault Monitoring TE YANG model.
[ext/new?] - Note: Feedback loop
- Utilization Monitoring requires very frequent
(Frequency of report) [new] updates of abstracted
- Abstraction of Resource topology real-time.
Topology reflecting these - Current management
service-related parameters interface may not be
[ext/new?] appropriate to support
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- Dynamic Policy enforcement this feedback loop and
[new] the real-time
operation.
This is related to Section
4.2.4.
8. VN lifecycle - This is extensible from
management/operation [ext] existing LSP lifecycle
- Create (same as VN management/operation.
instantiate Request)
- Delete
- Modify
- Update (VN level OAM
Monitoring) under policy
agreement
9. Coordination of multi- - This is from Section
destination service 4.2.1 and Requirement 7
requirement/policy to support (above) but there are
dynamic applications such as unique requirements.
VM migration, disaster - New: Primitives that
recovery, load balancing, allow integrated
etc. network operation and
- Service-policy primitives and service operation
its parameters [new] - See also the
corresponding MPI
requirement.
5.2. MPI (MDSC-PNC Interface)
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Requirement Notes
------------------------------ -------------------------------
1. Security/Policy negotiation - Extensible from
(who are you?) PCEP/YANG
- Exchange of key, etc. [ext] - End-point mobility for
- Domain preference + local multi-destination
policy exchange [ext] policy is new element
- Push/Pull support [ext] in primitives and Data
- Preferred peering points Model
[ext]
- Preferred route [ext]
- Reroute policy [ext]
- End-point mobility (for
multi-destination) [new]
2. Topology Query /Response - Pull Model with
(Pull Model from MDSC to PNC: Customer's VN
Please give me your domain requirement can be
topology) extended from existing
- TED Abstraction level components.
negotiation [new] - Abstraction negotiation
- Abstract topology (per primitive seems to be
policy) [ext] new ACTN work.
o Node/Link metrics
o Node/Link Type
(Border/Gateway, etc.)
o All TE metrics (SRLG,
etc.)
o Topology Metrics
(latency, B/W available,
etc.)
3. Topology Update (Push Model - Push/Subscription can
from PNC to MDSC) be extended from
- Under policy agreement, existing components
topology changes to be pushed (YANG)
to MDSC from PNC [ext]
4. VN Path Computation Request - Extensible from PCEP
(From MDSC to PNC: Please
give me a path in your
domain)
- VN Instance ID [ext]
- End-point information [ext]
- CE ends [ext]
- Border points (if applicable)
[ext]
- All other PCE request info
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(PCEP) [ext]
5. VN Path Computation Reply - Extensible from PCEP
(here's the path info per
your request)
- Path level abstraction [ext]
- LSP DB [ext]
- LSP ID ?? [ext]
- VN ID [ext]
6. Coordination of multi-domain - New element on
Centralized Signaling (MSDC centralized signaling
operation) Path Setup operation for MSDC as
Operation well as control-control
- MSDC computes E2E path across primitives (different
multi-domain (based on from NE-NE signaling
abstract topology from each primitives) although
PNC) [new] RSVP-TE can be extended
- MDSC determines the domain to support some
sequence [new/ext?] functions defined here
- MDSC request path signaling if not all.
to each PNC (domain) [ext]
- MDSC finds alternative path
if any of the PNCs cannot
find its domain path [ext]
o PNC will crankback to
MDSC if it cannot find
its domain path
o PNC will confirm to MDSC
if it finds its domain
path
7. Path Restoration Operation - New for MDSC's central
(after an E2E path is setup path restoration
successfully, some domain had primitives and
a failure that cannot be interaction with each
restored by the PNC domain) PNC to coordinate this
- The problem PNC will send real-time operation.
this notification with
changed abstract topology - Related to Section 4.2.5.
(computed after resource
changes due to failure/other
factors) [ext]
- MDSC will find an alternate
E2E path based on the changes
reported from PNC. It will
need to update the E2E
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abstract topology and the
affected CN's VN topology in
real-time (This refers to
dynamic synchronization of
topology from Physical
topology to abstract topology
to VN topology) [new/ext?]
- MDSC will perform the path
restoration signaling to the
affected PNCs.[ext]
8. Coordination of Multi- - Related to Section
destination service 4.2.1.
restoration operation (CNC - New for ACTN in
have, for example, multiple determining the optimal
endpoints where the source destination on the fly
endpoint can send its data to given customer policy
either one of the endpoints) and network condition
- PNC reports domain problem and its related real-
that cannot be resolved at time network operation
MDSC level because of there procedures.
is no network restoration - Other operations are
path to a given destination. extensible from
[ext] existing mechanism.
- Then MDSC has Customers'
profile in which to find the
customer has "multi-
destination" application.
[new]
- Under policy A, MDSC will be
allowed to reroute the
customer traffic to one of
the pre-negotiated
destinations and proceed with
restoration of this
particular customer's
traffic. [ext]
- Under policy B, CNC may
reroute on its VN topology
level and push this to MDSC
and MDSC maps this into its
abstract topology and proceed
with restoration of this
customer's traffic. [new]
- In either case, the MDSC will
proceed its restoration
operation (as explained in
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Req. 6) to the corresponding
PNCs. [ext]
9. MDSC-PNC policy negotiation - This seems to be new to
is also needed as to how ACTN.
restoration is done across
MDSC and PNCs. [new]
10. Generic Abstract Topology - Current Generic TE YANG
Update per changes due to new model applicable.
path setup/connection However, the real-time
failure/degradation/restorati nature of these models
on [ext] with frequent update
and synchronization
check is new for ACTN.
11. Service-specific Abstract - Extensible from generic
Topology Update per changes TE Abstraction Model
due to new path (TEAS WG) to include
setup/connection service-related
failure/degradation/restorati parameters and end-
on [ext] point abstraction
12. Abstraction model of - Extensible from generic
technology-specific topology TE Abstraction Model
element [ext] (TEAS WG) to include
abstraction of
technology-specific
element.
6. References
6.1. Informative References
[PCE] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", IETF RFC
4655, August 2006.
[PCE-S] Crabbe, E, et. al., "PCEP extension for stateful
PCE",draft-ietf-pce-stateful-pce, work in progress.
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[GMPLS] Manning, E., et al., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, October 2004.
[NFV-AF] "Network Functions Virtualization (NFV); Architectural
Framework", ETSI GS NFV 002 v1.1.1, October 2013.
[ACTN-PS] Y. Lee, D. King, M. Boucadair, R. Jing, L. Contreras
Murillo, "Problem Statement for Abstraction and Control of
Transport Networks", draft-leeking-actn-problem-statement,
work in progress.
[ONF] Open Networking Foundation, "OpenFlow Switch Specification
Version 1.4.0 (Wire Protocol 0x05)", October 2013.
[ABNO] King, D., and Farrel, A., "A PCE-based Architecture for
Application-based Network Operations", draft-farrkingel-
pce-abno-architecture, work in progress.
[VNM-OP] Melo, M, et al. "Virtual Network Mapping - An Optimization
Problem", Springer Berlin Heidelberg, January 2012.
Appendix A
Contributors' Addresses
Dhruv Dhoddy
Huawei Technologies
dhruv.ietf@gmail.com
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Authors' Addresses
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm, Sweden
Email: daniele.ceccarelli@ericsson.com
Luyuan Fang
Email: luyuanf@gmail.com
Young Lee
Huawei Technologies
5340 Legacy Drive
Plano, TX 75023, USA
Phone: (469)277-5838
Email: leeyoung@huawei.com
Diego Lopez
Telefonica I+D
Don Ramon de la Cruz, 82
28006 Madrid, Spain
Email: diego@tid.es
Sergio Belotti
Alcatel Lucent
Via Trento, 30
Vimercate, Italy
Email: sergio.belotti@alcatel-lucent.com
Daniel King
Lancaster University
Email: d.king@lancaster.ac.uk
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7. Appendix I: Abstracted Topology Illustration
There are two levels of abstracted topology that needs to be
maintained and supported for ACTN. Customer-specific Abstracted
Topology refers to the abstracted view of network resources
allocated (shared or dedicated) to the customer. The granularity of
this abstraction varies depending on the nature of customer
applications. Figure 11 illustrates this.
Figure 10 shows how three independent customers A, B and C provide
its respective traffic demand matrix to the MDSC. The physical
network topology shown in Figure 6 is the provider's network
topology generated by the PNC topology creation engine such as the
link state database (LSDB) and Traffic Engineering DB (TEDB) based
on control plane discovery function. This topology is internal to
PNC and not available to customers. What is available to them is an
abstracted network topology (a virtual network topology) based on
the negotiated level of abstraction. This is a part of VNS
instantiation between a client control and MDSC.
+------+ +------+ +------+
A.1 ------o o-----------o o----------o o------- A.2
B.1 ------o 1 | | 2 | | 3 |
C.1 ------o o-----------o o----------o o------- B.2
+-o--o-+ +-o--o-+ +-o--o-+
| | | | | |
| | | | | |
| | | | | |
| | +-o--o-+ +-o--o-+
| `-------------o o----------o o------- B.3
| | 4 | | 5 |
`----------------o o----------o o------- C.3
+-o--o-+ +------+
| |
| |
C.2 A.3
Traffic Matrix Traffic Matrix Traffic Matrix
for Customer A for Customer B for Customer C
A.1 A.2 A.3 B.1 B.2 B.3 C.1 C.2 C.3
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------------------- ------------------ -----------------
A.1 - 20G 20G B.1 - 40G 40G C.1 - 20G 20G
A.2 20G - 10G B.2 40G - 20G C.2 20G - 10G
A.3 20G 10G - B.3 40G 20G - C.3 20G 10G -
Figure 10: Physical network topology shared with multiple customers
Figure 11 depicts illustrative examples of different level of
topology abstractions that can be provided by the MDSC topology
abstraction engine based on the physical topology base maintained by
the PNC. The level of topology abstraction is expressed in terms of
the number of virtual nodes (VNs) and virtual links (VLs). For
example, the abstracted topology for customer A shows there are 5
VNEs and 10 VLs. This is by far the most detailed topology
abstraction with a minimal link hiding compared to other abstracted
topologies.
(a) Abstracted Topology for Customer A (5 VNEs and 10 VLs)
+------+ +------+ +------+
A.1 ------o o-----------o o----------o o------- A.2
| 1 | | 2 | | 3 |
| | | | | |
+-o----+ +-o----+ +-o----+
| | |
| | |
| | |
| +-o----+ +-o--o-+
| | | | |
| | 4 | | 5 |
`----------------o o----------o |
+----o-+ +------+
|
|
A.3
(b) Abstracted Topology for Customer B (3 VNEs and 6 VLs)
+------+ +------+
B.1 ------o o-----------------------------o o------ B.2
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| 1 | | 3 |
| | | |
+-o----+ +-o----+
\ |
\ |
\ |
`------------------- |
` +-o----+
\ | o------ B.3
\ | 5 |
`-------o |
+------+
(c) Abstracted Topology for Customer C (1 VNE and 3 VLs)
+-------------------------------------------+
| |
| |
C.1 ------o |
| |
| |
| |
| o--------C.3
| |
+--------------------o----------------------+
|
|
|
|
C.2
Figure 11: Topology Abstraction Examples for Customers
As different customers have different control/application needs,
abstracted topologies for customers B and C, respectively show a
much higher degree of abstraction. The level of abstraction is
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determined by the policy (e.g., the granularity level) placed for
the customer and/or the path computation results by the PCE operated
by the PNC. The more granular the abstraction topology is, the more
control is given to the Customer Network Controller. If the Customer
Network Controller has applications that require more granular
control of virtual network resources, then the abstracted topology
shown for customer A may be the right abstraction level for such
controller. For instance, if the customer is a third-party virtual
service broker/provider, then it would desire much more
sophisticated control of virtual network resources to support
different application needs. On the other hand, if the customer were
only to support simple tunnel services to its applications, then the
abstracted topology shown for customer C (one VNE and three VLs)
would suffice.
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