Internet DRAFT - draft-ceccarelli-teas-actn-framework
draft-ceccarelli-teas-actn-framework
TEAS Working Group Daniele Ceccarelli (Ed)
Internet Draft Ericsson
Intended status: Informational Young Lee (Ed)
Expires: November 2016 Huawei
April 14, 2016
Framework for Abstraction and Control of Traffic Engineered Networks
draft-ceccarelli-teas-actn-framework-02
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Abstract
Traffic Engineered networks have a variety of mechanisms to
facilitate the
separation of the data plane and control plane. They also have a
range of management and provisioning protocols to configure and
activate network resources. These mechanisms represent key
technologies for enabling flexible and dynamic networking.
Abstraction of network resources is a technique that can be applied
to a single network domain or across multiple domains to create a
single virtualized network that is under the control of a network
operator or the customer of the operator that actually owns
the network resources.
This draft provides a framework for Abstraction and Control of
Traffic Engineered Networks (ACTN).
Table of Contents
1. Introduction................................................. 3
1.1. Terminology............................................. 5
2. Business Model of ACTN....................................... 7
2.1. Customers............................................... 7
2.2. Service Providers....................................... 9
2.3. Network Providers...................................... 11
3. ACTN architecture........................................... 11
3.1. Customer Network Controller............................ 14
3.2. Multi Domain Service Coordinator....................... 15
3.3. Physical Network Controller............................ 16
3.4. ACTN interfaces........................................ 17
4. VN creation process......................................... 19
5. Access Points and Virtual Network Access Points............. 20
5.1. Dual homing scenario................................... 22
6. End point selection & mobility.............................. 23
6.1. End point selection & mobility......................... 23
6.2. Preplanned end point migration......................... 24
6.3. On the fly end point migration......................... 25
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7. Security.................................................... 25
8. References.................................................. 25
8.1. Informative References................................. 25
9. Contributors................................................ 28
Authors' Addresses............................................. 28
1. Introduction
Traffic Engineered 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.
The term Traffic Engineered Network in this draft refers to any
connection-oriented network that has the ability of dynamic
provisioning, abstracting and orchestrating network resource to the
network's clients. Some examples of networks that are in scope of
this definition are optical networks, MPLS Transport Profile (MPLS-
TP), MPLS Traffic Engineering (MPLS-TE), and other emerging
technologies with connection-oriented behavior.
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 compared with
distributed network control. For TE-based transport network control,
PCE is 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: Detach the network and service
control from underlying technology and help customer express
the network as desired by business needs.
. Coordination of resources across multiple domains and multiple
layers to provide end-to-end services regardless of whether the
domains use SDN or not.
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As networks evolve, the need to provide resource 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 Traffic Engineered 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 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 abstracted network
topology. Such a view may be specific to a specific service, the set
of consumed resources or to a particular customer. Customer
controller of the virtual network is envisioned to support a
plethora of 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 framework described in this draft is named Abstraction and
Control of Traffic Engineered Network (ACTN) and facilitates:
- Abstraction of the underlying network resources to higher-layer
applications and customers [TE-INFO].
- Virtualization of particular underlying resources, whose
selection criterion is the allocation of those resources to a
particular customer, application or service. [ONF-ARCH]
- 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-domain networks into a single
virtualized network;
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- Possibility of providing a customer with virtualized network or
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 presentation of the networks as a virtualized topology to
the customers via open and programmable interfaces. This allows
for the recursion of controllers in a customer-provider
relationship.
1.1. Terminology
The following terms are used in this document. Some of them are
newly defined, some others reference existing definition:
- Node: A node is a topological entity describing the "opaque"
forwarding aspect of the topological component which represents
the opportunity to enable forwarding between points at the edge
of the node. It provides the context for instructing the
formation, adjustment and removal of the forwarding. A node, in
a VN network, can be represented by single physical entity or
by a group of nodes moving from physical to virtual network.
- Link: A link is a topological entity describing the effective
adjacency between two or more forwarding entities, such as two
or more nodes. In its basic form (i.e., point-to-point Link) it
associates an edge point of a node with an equivalent edge
point on another node. Links in virtual network is in fact
connectivity, realized by bandwidth engineering between any two
nodes meeting certain criteria, for example, redundancy,
protection, latency, not tied to any technology specific
characteristics like timeslots or wavelengths. The link can be
dynamic, realized by a service in underlay, or static.
- PNC domain: A PNC domain includes all the resources under the
control of a single PNC. It can be composed by different
routing domains, administrative domains and different layers.
The interconnection between PNC domains can be a link or a
node.
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border
------- link -------
( )---------( )
- - - -
( PNC )+---+( PNC )
( Domain X ) ( Domain Y )
( )+---+( )
- - border- -
( ) node ( )
------- -------
Figure 1 : PNC domain borders
- Virtual Network: A Virtual Network (VN) is a customer view of the
transport network. It is composed by a set of physical
resources sliced in the provider network and presented to the
customer as a set of abstract resources i.e. virtual nodes and
virtual links. Depending on the agreement between customer and
provider a VN can be just represented by:
o How the end points can be connected with given SLA
attributes(e.g., re satisfying the customer's objectives)
o A pre-configured set of physical resources
o Or as outcome of a dynamic request from customer.
In the first case the VN can be seen at customer level as an
e2e connectivity that can be formed by recursive aggregation of
lower layers tunnels within the provider domain.
When the VN is pre-configured, it is provided after a static
negotiation between customer and provider while in the third
case VN can be dynamically created, deleted, or modified in
response to requests from the customer. This implies dynamic
changes of network resources reserved for the customer.
In the second and third case , once that customer has obtained
his VN, can act upon the virtual network resources to perform
connection management (set-up/release/modify connections).
- Abstract Topology: Every lower controller in the provider
network, when is representing its network topology to an higher
layer, it may want to hide details of the actual network
topology. In such case, an abstract topology may be used for
this purpose. Abstract topology enhances scalability for the
MDSC to operate multi-domain networks
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- Access link: A link between a customer node and a provider
node.
- Inter domain link: A link between domains managed by different
PNCs. The MDSC is in charge of managing inter-domain links.
- Border node: A node whose interfaces belong to different
domains. It may be managed by different PNCs or by the MDSC.
- Access Point (AP): An access point is defined on an access
link. It is used to keep confidentiality between the customer
and the provider. It is an identifier shared between the
customer and the provider, used to map the end points of the
border node in the provider NW. The AP can be used by the
customer when requesting connectivity service to the provider.
A number of parameters, e.g. available bandwidth, need to be
associated to the AP to qualify it.
- VN Access Point (VNAP): A VNAP is defined within an AP as part
of a given VN and is used to identify the portion of the AP,
and hence of the access link) dedicated to a given VN.
2. Business Model of ACTN
The Virtual Private Network (VPN) [RFC4026] and Overlay Network (ON)
models [RFC4208] are built on the premise that one single network
provider provides all virtual private or overlay networks to its
customers. These models are simple to operate but have 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
- 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
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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 service offering is not enough and
it is desirable to provide each of them with a customized virtual
network service.
Advanced customers may own dedicated virtual resources, or share
resources. They may also have the ability to modify their service
parameters within the scope of their virtualized environments.
As customers are geographically spread over multiple network
provider domains, they have to interface multiple providers and may
have to support multiple virtual network services with different
underlying objectives set by the network providers. To enable these
customers to support flexible and dynamic applications they need to
control their allocated virtual network resources in a dynamic
fashion, and that means that they need an abstracted view of the
topology that spans all of the network providers.
ACTN's primary focus is Advanced Customers.
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
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+------------------------------------------------------------+ ---
| | ^
| 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 2 : Service 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
need to keep multiple independent network providers as its end-users
span geographically across multiple network provider domains as
shown in Figure 2 where Service Provider A uses resources from
Network Provider A and Network Provider B to offer a virtualized
network to its customer.
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Customer X -----------------------------------X
Service Provider A X -----------------------------------X
Network Provider B X-----------------X
Network Provider A X------------------X
Figure 3 : A service Provider as Customer of Two Network Providers.
The ACTN network model is predicated upon this three tier model and
is summarized in Figure 3:
+----------------------+
| 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 4 : Three tier model.
There can be multiple types of service providers.
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. Data Center providers: can be viewed as a service provider type
as they own and operate data center resources to various WAN
customers, 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.
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
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-
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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 virtual services that are coordinated under ACTN can be split
into two categories:
. 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 in NFV (e.g. cloud) providers and
require connectivity between a customer site and the NFV
provider site (e.g. a data center). These VNF services may
include a security function like firewall, a traffic optimizer,
the provisioning of storage or computation capacity. In these
cases the customer does not care whether the service is
implemented in a given data center or another. This allows the
network provider divert customer requests where most suitable.
This is also known as "end points mobility" case. (See Section
4.2.3)
The types of controller defined are shown in Figure 4 below and are
the following:
. CNC - Customer Network Controller
. MDSC - Multi Domain Service Coordinator
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. PNC - Physical Network Controller
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VPN customer NW Mobile Customer ISP NW service Customer
| | |
+-------+ +-------+ +-------+
| CNC-A | | CNC-B | | CNC-C |
+-------+ +-------+ +-------+
\ | /
----------- |CMI I/F --------------
\ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
------------- |MPI I/F -------------
/ | \
+-------+ +-------+ +-------+
| PNC | | PNC | | PNC |
+-------+ +-------+ +-------+
| GMPLS / | / \
| trigger / | / \
-------- ---- +-----+ +-----+ \
( ) ( ) | PNC | | PCE | \
- - ( Phys ) +-----+ +-----+ -----
( GMPLS ) (Netw) | / ( )
( Physical ) ---- | / ( Phys. )
( Network ) ----- ----- ( Net )
- - ( ) ( ) -----
( ) ( Phys. ) ( Phys )
-------- ( Net ) ( Net )
----- -----
Figure 5 : 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 applications, 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.
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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 MDSC (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 MDSC 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. The key
point of the MDSC and the whole ACTN framework is detaching the
network and service control from underlying technology and help
customer express the network as desired by business needs. The MDSC
envelopes the instantiation of right technology and network control
to meet business criteria. In essence it controls and manages the
primitives to achieve functionalities as desired by CNC
A hierarchy of MDSCs can be foreseen for scalability and
administrative choices.
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+-------+ +-------+ +-------+
| CNC-A | | CNC-B | | CNC-C |
+-------+ +-------+ +-------+
\ | /
---------- | ----------
\ | /
+-----------------------+
| MDSC |
+-----------------------+
/ | \
---------- | -----------
/ | \
+----------+ +----------+ +--------+
| MDSC | | MDSC | | MDSC |
+----------+ +----------+ +--------+
| / | / \
| / | / \
+-----+ +-----+ +-----+ +-----+ +-----+
| PNC | | PNC | | PNC | | PNC | | PNC |
+-----+ +-----+ +-----+ +-----+ +-----+
Figure 6 : Controller recursiveness
A key requirement for allowing recursion of MDSCs is that a single
interface needs to be defined both for the north and the south
bounds.
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
parent MDSC and N child MDSC or 1 MDSC and N PNCs). In addition to
that it could be possible to have also a M:1 relationship between
MDSC and PNC to allow for network resource partitioning/sharing
among different customers not necessarily connected to the same MDSC
(e.g. different service providers).
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]
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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
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.
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) below:
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.--------------
------------- |
| 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 7 : 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-MDSC 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.
The interfaces within the ACTN scope are B and C.
4. VN creation process
The provider can present to the customer different level of network
abstraction, spanning from one extreme (say "black") where nothing
is shown, just the APs, to the other extreme (say "white") where a
slice of the network is shown to the customer. There are shades of
gray in between where a number of abstract links and nodes can be
shown.
The VN creation is composed by two phases: Negotiation and
Implementation.
Negotiation: In the case of grey/white topology abstraction, there
is an a priori phase in which the customer agrees with the provider
on the type of topology to be shown, e.q. 10 virtual links and 5
virtual nodes with a given interconnectivity. This is something that
is assumed to be preconfigured by the operator off-line, what is
online is the capability of modifying/deleting something (e.g. a
virtual link). In the case of "black" abstraction this negotiation
phase does not happen, in the sense that the customer can only see
the APs of the network.
Implementation: In the case of black topology abstraction, the
customers can ask for connectivity with given constraints/SLA
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between the APs and LSPs/tunnels are 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.
5. Access Points and Virtual Network Access Points
In order not to share unwanted topological information between the
customer domain and provider domain, a new entity is defined and
associated to an access link, the Access Point (AP). See the
definition of AP in Section 1.1.
A customer node will use APs as the end points for the request of
VNs.
A number of parameters need to be associated to the APs. Such
parameters need to include at least: the maximum reservable
bandwidth on the link, the available bandwidth and the link
characteristics (e.g. switching capability, type of mapping).
Editor note: it is not appropriate to define link characteristics
like bandwidth against a point (AP). A solution needs to be found.
-------------
( )
- -
+---+ X ( ) Z +---+
|CE1|---+----( )---+---|CE2|
+---+ | ( ) | +---+
AP1 - - AP2
( )
-------------
Figure 8 : APs definition customer view
Let's take as example a scenario in which CE1 is 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 can be summarized as
follows:
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+-----+----------+-------------+----------+
|AP id| MaxResBw | AvailableBw | CE,port |
+-----+----------+-------------+----------+
| AP1 | 10Gb | 10Gb |CE1,portX |
+-----+----------+-------------+----------+
| AP2 | 40Gb | 40Gb |CE2,portZ |
+-----+----------+-------------+----------+
Table 1: AP - customer view
On the other side what the provider sees is:
------- -------
( ) ( )
- - - -
W (+---+ ) ( +---+) Y
-+---( |PE1| Dom.X )----( Dom.Y |PE2| )---+-
| (+---+ ) ( +---+) |
AP1 - - - - AP2
( ) ( )
------- -------
Figure 9 : Provider view of the AP
Which in the example above ends up in a summarization as follows:
+-----+----------+-------------+----------+
|AP id| MaxResBw | AvailableBw | PE,port |
+-----+----------+-------------+----------+
| AP1 | 10Gb | 10Gb |PE1,portW |
+-----+----------+-------------+----------+
| AP2 | 40Gb | 40Gb |PE2,portY |
+-----+----------+-------------+----------+
Table 2: AP - provider view
The second entity that needs to be defined is a structure within the
AP that is linked to a VN and that is used to allow for different VN
to be provided starting from the same AP. It also allows reserving
the bandwidth for the VN on the access link. Such entity is called
Virtual Network Access Point. For each virtual network is defined on
an AP, a different VNAP is created.
In the simple scenario depicted above we suppose to create two
virtual networks. The first one has with VN identifier 9 between AP1
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and AP2 with and bandwidth of 1Gbps, while the second one with VN id
5, again between AP1 and AP2 and bandwidth 2Gbps.
The customer view would evolve as follows:
+---------+----------+-------------+----------+
|AP/VNAPid| MaxResBw | AvailableBw | PE,port |
+---------+----------+-------------+----------+
|AP1 | 10Gbps | 7Gbps |PE1,portW |
| -VNAP1.9| 1Gbps | N.A. | |
| -VNAP1.5| 2Gbps | N.A | |
+---------+----------+-------------+----------+
|AP2 | 40Gb | 37Gb |PE2,portY |
| -VNAP2.9| 1Gbps | N.A. | |
| -VNAP2.5| 2Gbps | N.A | |
+---------+----------+-------------+----------+
Table 3: AP and VNAP - provider view after VN creation
5.1. Dual homing scenario
Often there is a dual homing relationship between a CE and a pair of
PE. This case needs to be supported also by the definition of VN, AP
and VNAP. Suppose to have CE1 connected to two different PE in the
operator domain via AP1 and AP2 and the customer needing 5Gbps of
bandwidth between CE1 and CE2.
AP1 -------------- AP3
-------(PE1) (PE3) -------
W / - - \X
+---+ / ( ) \ +---+
|CE1| ( ) |CE2|
+---+ \ ( ) / +---+
Y \ - - /Z
-------(PE2) (PE4) -------
AP2 -------------- AP4
Figure 10 : Dual homing scenario
In this case the customer will request for a VN between AP1, AP2 and
AP3 specifying a dual homing relationship between AP1 and AP2. As a
consequence no traffic will be flowing between AP1 and AP2. The dual
homing relationship would then be mapped against the VNAPs (since
other independent VNs might have AP1 and AP2 as end points).
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The customer view would be as follows:
+---------+----------+-------------+----------+-----------+
|AP/VNAPid| MaxResBw | AvailableBw | CE,port |Dual Homing|
+---------+----------+-------------+----------+-----------+
|AP1 | 10Gbps | 5Gbps |CE1,portW | |
| -VNAP1.9| 5Gbps | N.A. | | VNAP2.9 |
+---------+----------+-------------+----------+-----------+
|AP2 | 40Gbps | 35Gbps |CE1,portY | |
| -VNAP2.9| 5Gbps | N.A. | | VNAP1.9 |
+---------+----------+-------------+----------+-----------+
|AP3 | 40Gbps | 35Gbps |CE2,portZ | |
| -VNAP3.9| 5Gbps | N.A. | | NONE |
+---------+----------+-------------+----------+-----------+
Table 4: Dual homing - customer view after VN creation
6. End point selection & mobility
Virtual networks could be used as the infrastructure to connect a
number of sites of a customer among them or to provide connectivity
between customer sites and virtualized network functions (VNF) like
for example virtualized firewall, vBNG, storage, computational
functions.
6.1. End point selection & mobility
A VNF could be deployed in different places (e.g. data centers A, B
or C in figure below) but the VNF provider (=ACTN customer) doesn't
know which is the best site where to install the VNF from a network
point of view (e.g. latency). For example it is possible to compute
the path minimizing the delay between AP1 and AP2, but the customer
doesn't know a priori if the path with minimum delay is towards A, B
or C.
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------- -------
( ) ( )
- - - -
+---+ ( ) ( ) +----+
|CE1|---+----( Domain X )----( Domain Y )---+---|DC-A|
+---+ | ( ) ( ) | +----+
AP1 - - - - AP2
( ) ( )
---+--- ---+---
AP3 | AP4 |
+----+ +----+
|DC-B| |DC-C|
+----+ +----+
Figure 11 : End point selection
In this case the VNF provider (=ACTN customer) should be allowed to
ask for a VN between AP1 and a set of end points. The list of end
points is provided by the VNF provider. When the end point is
identified the connectivity can be instantiated and a notification
can be sent to the VNF provider for the instantiation of the VNF.
6.2. Preplanned end point migration
A premium SLA for VNF service provisioning consists on the offering
of a protected VNF instantiated on two or more sites and with a hot
stand-by protection mechanism. In this case the VN should be
provided so to switch from one end point to another upon a trigger
from the VNF provider or an automatic failure detection mechanism.
An example is provided in figure below where the request from the
VNF provider is for connectivity with given constraint and
resiliency between CE1 and a VNF with primary installation in DC-A
and a protection in DC-C.
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------- -------
( ) ( )
- - __ - -
+---+ ( ) ( ) +----+
|CE1|---+----( Domain X )----( Domain Y )---+---|DC-A|
+---+ | ( ) ( ) | +----+
AP1 - - - - AP2 |
( ) ( ) |
---+--- ---+--- |
AP3 | AP4 | HOT STANDBY
+----+ |
|DC-C|<-------------
+----+
Figure 12 : Preplanned endpoint migration
6.3. On the fly end point migration
The one the fly end point migration concept is very similar to the
end point selection one. The idea is to give the provider not only
the list of sites where the VNF can be installed, but also a
mechanism to notify changes in the network that have impacts on the
SLA. After an handshake with the customer controller/applications,
the bandwidth in network would be moved accordingly with the moving
of the VNFs.
7. Security
TBD
8. References
8.1. Informative References
[PCE] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", IETF RFC
4655, August 2006.
[RFC4026] L. Andersson, T. Madsen, "Provider Provisioned Virtual
Private Network (VPN) Terminology", RFC 4026, March 2005.
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[RFC4208] G. Swallow, J. Drake, H.Ishimatsu, Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS) User-
Network Interface (UNI): Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Support for the Overlay
Model", RFC 4208, October 2005.
[PCE-S] Crabbe, E, et. al., "PCEP extension for stateful
PCE",draft-ietf-pce-stateful-pce, work in progress.
[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.
[TE-INFO] A. Farrel, Editor, "Problem Statement and Architecture for
Information Exchange Between Interconnected Traffic
Engineered Networks", draft-ietf-teas-interconnected-te-
info-exchange, work in progress.
[ABNO] King, D., and Farrel, A., "A PCE-based Architecture for
Application-based Network Operations", draft-farrkingel-
pce-abno-architecture, work in progress.
[ACTN-Info] Y. Lee, S. Belotti, D. Dhody, "Information Model for
Abstraction and Control of Transport Networks", draft-
leebelotti-teas-actn-info, work in progress.
[Cheng] W. Cheng, et. al., "ACTN Use-cases for Packet Transport
Networks in Mobile Backhaul Networks", draft-cheng-actn-
ptn-requirements, work in progress.
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[Dhody] D. Dhody, et. al., "Packet Optical Integration (POI) Use
Cases for Abstraction and Control of Transport Networks
(ACTN)", draft-dhody-actn-poi-use-case, work in progress.
[Fang] L. Fang, "ACTN Use Case for Multi-domain Data Center
Interconnect", draft-fang-actn-multidomain-dci, work in
progress.
[Klee] K. Lee, H. Lee, R. Vilata, V. Lopez, "ACTN Use-case for On-
demand E2E Connectivity Services in Multiple Vendor Domain
Transport Networks", draft-klee-actn-connectivity-multi-
vendor-domains, work in progress.
[Kumaki] K. Kumaki, T. Miyasaka, "ACTN : Use case for Multi Tenant
VNO ", draft-kumaki-actn-multitenant-vno, work in
progress.
[Lopez] D. Lopez (Ed), "ACTN Use-case for Virtual Network Operation
for Multiple Domains in a Single Operator Network", draft-
lopez-actn-vno-multidomains, work in progress.
[Shin] J. Shin, R. Hwang, J. Lee, "ACTN Use-case for Mobile Virtual
Network Operation for Multiple Domains in a Single
Operator Network", draft-shin-actn-mvno-multi-domain, work
in progress.
[Xu] Y. Xu, et. al., "Use Cases and Requirements of Dynamic Service
Control based on Performance Monitoring in ACTN
Architecture", draft-xu-actn-perf-dynamic-service-control,
work in progress.
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9. Contributors
Authors' Addresses
Daniele Ceccarelli (Editor)
Ericsson
Torshamnsgatan,48
Stockholm, Sweden
Email: daniele.ceccarelli@ericsson.com
Young Lee (Editor)
Huawei Technologies
5340 Legacy Drive
Plano, TX 75023, USA
Phone: (469)277-5838
Email: leeyoung@huawei.com
Luyuan Fang
Email: luyuanf@gmail.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
Dhruv Dhoddy
Huawei Technologies
dhruv.ietf@gmail.com
Gert Grammel
Juniper Networks
ggrammel@juniper.net
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