SOFTWARE DEFINED NETWORK AND NETWORK FUNCTIONS VIRTUALIZATION

SOFTWARE DEFINED NETWORK AND NETWORK FUNCTIONS VIRTUALIZATION An Inevitable Evolution for Communication Networks VIKRAM NAIR Director, Technology

VINOD KUMAR GUPTA Senior Technical Leader, Technology

SOFTWARE DEFINED NETWORK AND NETWORK FUNCTIONS VIRTUALIZATION An inevitable evolution for communication networks

Introduction

This paper starts with describing SDN and NFV technologies and

Traditional communications network equipment was built over

adoption and challenges impinging the adoption of the technology.

proprietary software platforms tied onto proprietary hardware

The paper then captures the applicability of SDN and NFV

that evolved slowly, being in a walled garden. This approach

technology for mobile networks, for example, the segments or

forced service providers to deal with issues such as longer time-

sub-systems where SDN and NFV can be introduced by service

to-market and end of life equipment.

providers. It also provides a few use cases that can be realized

Decoupling underlying hardware from software, through standardized interfaces, and deploying software solution over COTS (Commercial off the shelf) hardware has been a successful shift witnessed in past years. This enables operators in buying hardware and software platform from a variety of different vendors

their relationship. Then it discusses the accelerators driving

through the technology introduction and the benefits that such solutions can yield. The paper also highlights key considerations for rolling out SDN and NFV technology. Finally, the paper summarizes the essentials requirements for testing SDN and NFV technology for successful deployment.

with no inter-dependence of hardware and software on each other. For example a soft-switch (that is used for VoIP call setup) is a software implementation decoupled from media gateway

Trends and Insights

used to switch voice traffic. As the standardization of this solution

SDN and NFV will bring fundamental shift in CSP’s approach to

is at infancy, today’s communications network industry has yet

build network infrastructure. The network transformation is

to fully embrace this hardware and software decoupling in the

expected to happen in a phased manner, which will not only help

coming years.

mature the technology introduction methods and processes

Software defined networks (SDN) and network function

but also de-risk disruption of network services.

virtualization (NFV) is a new development that builds on a premise

Today, networks are built in silos wherein independent infrastructure

to decouple hardware and software solutions, and further host

is deployed for mobile, fixed, and enterprise markets with minimal

software functions over a virtualized platform to achieve cost

or no infrastructure reuse or sharing. Realizing the benefits from

efficiencies with limitless flexibility for network configuration

virtualization, Communications Service Providers (CSPs) are

and operation.

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Now

Next 2-3 Years

Next 5+ Years

“SDN is a new approach to networking in which network control is decoupled from the data forwarding function and is directly programmable. The result is an extremely dynamic, manageable, cost-effective, and adaptable architecture that gives administrators

Network Silos

Component Virtualization

Network Virtualization

Network virtualization - expected roadmap

stepping up the efforts to analyze the impact of virtualization on networks and O/BSS. It is expected that initial targets for virtualization will be the software components with minimal or no dependency on underlying hardware. In the next 2-3 year it is expected that first step towards virtualization will find its place in the networks wherein selective

unprecedented programmability, automation, and control, through abstraction of the underlying infrastructure. Implementing SDN via an open standard enables extraordinary agility while reducing service deployment and operational costs, and frees network administrators to integrate best-of-breed technology as it is developed – Open Networking Foundation [1]” Decoupled control and data planes help you build a centralized control plane that manages large number of data plane equipment, which is spread across network.

independent network components will get virtualized. For instance,

The control plane comprises SDN controller that interfaces with

in LTE networks, network components that are software only

data plane switches and enforce packet treatment rules on data

implementation with no specific hardware dependencies such as

plane switches. Standardization attempt are underway in defining

MME, IMS, PCRF, HSS will be the first target. OSS transformation

control protocol (OpenFlow) between SDN controller and switches.

will happen simultaneously to manage virtual assets. This phased transformation will require OSS to support both legacy as well as virtual assets with an external management system to manage the virtualization platform infrastructure.

SDN primarily targets layer 2 and layer 3 infrastructure components. The SDN controller, in addition, exposes north bound interface using which many additional services can be built or extended through service chaining and orchestration. Examples

In the next five years, it is expected that majority of network

of such services are discussed in detailed in subsequent section

components will get virtualized enabling CSPs to sell Network as

on use cases.

a Service (NaaS). Additional network components which earlier were not targeted for virtualization because of their dependency on hardware platforms will see de-coupling of such components

The following diagram shows the high level network architecture for Software defined networks.

into control & data plane functions, with control plan functions being pushed onto virtualization platforms. For instance, in LTE

Orchestration Layer

networks, such network components will be deep packet SDN Services

inspection (DPI), serving gateway (SGW) and packet data network gateway (PGW). This phase will have OSS transformation to not only manage the virtual assets but also the virtualization platform

Service Chaining

Resilience

infrastructure in a holistic manner.

What are SDN and NFV

Traffic Management

SDN Controller

SOFTWARE DEFINED NETWORKS (SDN) In traditional networking paradigm, a data packet arriving at conventional equipment (switch / router) is treated with a set of

Open Flow

rules. These rules decide how the inbound data packet are treated

vSwitch

and marked such as forward, duplicate, drop, (de-) tunnel, network address translation (NAT) or quality of service (QoS). Such equipment is not only expensive but also is a challenge to manage

Switch

as the equipment are distributed across the network and may require synchronization of configuration.

Switch

Switch

Architectural Diagram for SDN

Software Defined Network and Network Functions Virtualization - An Inevitable Evolution for Communication Networks

Switch

2

The decoupling will also result into CAPEX optimization by virtue

HSS

of commoditized de-coupled data plane equipment. For instance, by introducing SDN into networks, CAPEX requirements for

MME

PCRF

SGW

PGW

backhaul networks globally will reduce by more than $4 billion by 2017 as per a recent research report [3]. Early benefits of SDN will be greater internal efficiency, reduced

UE

eNodeB

operations costs and higher reliability of the network due to

Internet

greater automation and less room for human error. Ultimate goal is that end customers will be able to interface

LTE Network Architectural Diagram

their service provider’s network and integrate services on an automated, software-controlled basis.

For instance Mobility Management Entity (MME) network element NETWORK FUNCTION VIRTUALIZATION (NFV) Virtualization started with having discrete applications hosted on cloud platform. Driven by the benefits realized through cloud hosting such as scalability, resilience, reduced OPEX, usage of the virtualization technology for communication networks is a logical evolution.

falls under the category of network elements that implement control plane protocol and procedures for managing end-to-end data service. Other network elements that will fall under same category are HSS and PCRF implementing control plane protocol and procedures for subscription and policy control respectively. Such network elements can be moved onto centralized cloud platform as shown in the diagram below.

Cloud appeals because of its potential to lower down risks, costs, and time-to-market, while increasing agility and flexibility to experiment with new offerings. Top-line and bottom-line benefits play into decisions regarding adoption of cloud. MME

“Network Functions Virtualization aims to transform the way that

HSS PCRF

network operators architect networks by evolving standard IT virtualization technology to consolidate many network equipment types onto industry standard high volume servers, switches and storage, which could be located in datacenters, network nodes and in the end user premises. It involves the implementation of

SGW UE

PGW

eNodeB

network functions in software that can run on a range of industry

Internet

standard server hardware, and that can be moved to, or instantiated in, various locations in the network as required, without the need for installation of new equipment – ETSI [2].”

Proposed LTE Network Architectural Diagram with NFV (some NEs)

Early implementations of NFV would target moving those applications on cloud infrastructure that is hardware independent. OSS, BSS and certain VAS applications are example of such applications that are part of mobile networks.

The concept can be further extended for other category of network elements that implement control plane protocol and procedures along with traffic handling i.e. Serving Gateway (SGW)

Subsequent to that, attempt will be to decouple the control and

and Packet Data Network Gateway (PGW). These categories of

data plane implementations of other infrastructure elements

nodes can be split into two entities the control plane and data

to enable migration of control plane software onto cloud and

plane functions. The result will be SGW-Ctrl and SGW-Data for

deploy commoditized data plane equipment in network.

SGW node and PGW-Ctrl and PGW-Data for PGW node. The split will enable moving the control plane functions i.e. SGW-Ctrl and

Consider as an example a LTE network as shown in a high level

PGW-Ctrl onto centralized cloud platform and data plane nodes

network architecture diagram below. Each network element

i.e. SGW-Data and PGW-Data network switch be deployed during

excluding the eNodeB radio node is typically deployed on a

network rollouts to meet traffic handling requirements.

separate hardware unit in data centers. Out of these network elements some are software implementation of control plane protocol and procedures and others require additional specialized hardware function for traffic handling.

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The pyramid above represents the standard OSI reference model [5], which is also a generic representation of any network MME SGW-Ctrl PGW-Ctrl

PCRF HSS

component. SDN and NFV combined will target virtualization of layer 4 till layer 7 and also layer 3 partially. From standardization perspective, ONF [1] is focusing on splitting layer 3 into control plane and data plane wherein layer 3 control plane can be deployed in a virtualized environment. ETSI [2] on the other hand

UE

eNodeB

SGW Data

OpenFlow Switch

PGW Data

is focusing on virtualization of layer 4 till layer 7. What this means is that NFV functions (actually telecom function apps) can sit on top of SDN and leverage (use SDN as a service)

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cost effective SDN routing/switching/transport and enable unprecedented efficiencies in terms of resource utilization,

Proposed LTE Network Architectural Diagram with NFV and SDN

Though, this split is not defined completely as part of specifications, however this is another example of implementing NFV. Additional virtualization use cases would also emerge for Radio side such as Cloud RAN which are discussed under subsequent sections. Additional network element (Open Flow Switch) shown in the diagram above is introduced as part of section on SDN.

configuration, customer interface/support. The venn diagram below shows that SDN and NFV are mutually exclusive technologies but maximum benefits of SDN and NFV can be achieved when these are coupled together with open innovative apps on the top. Use cases and accelerators describe benefits in detail, which are covered in subsequent sections. Creates network abstractions to enable faster innovation

Creates competitive supply of innovative applications by third parties

SDN and NFV Relation SDN and NFV emerged as independent concepts and are self-sufficient for the purpose they were built for. The two technologies are complementary to each other and do not compete against each other. Combined implementation of SDN

Open Innovation

Software-Defined Network

and NFV will maximize the benefits that are mentioned in subsequent sections. The scope of virtualization can be understood with the following diagram.

Virtualization Scope

Layer 7 Layer 6 Layer 5

App Layer

Layer 3 Layer 2 Layer 1

Reduces capex, opex, space and power consumption

Presentation Layer Session Layer

Layer 4

Netowork Functions Virtualization

Venn diagram – interaction of SDN, NFV, Open Innovation

Transport Layer Network Layer Data Link Layer Physical Layer

To summarize, role of SDN and NFV when combined in an implementation can be understood as - decoupling control plane and data plane is what SDN recommends and moving the decoupled control plane (or the entire network equipment software functionality wherever possible) to a virtualized platform is what NFV recommends.

Scope of Virtualization

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Accelerators Driving Adoptions

IMPROVED TIME-TO-MARKET

Numerous benefits across CAPEX & OPEX reduction ease of

network. Most of the solutions will be hardware independent

operation, flexibility and scalability is what will and is driving

and would use the same infrastructure, thus saving testing and

adoption of SDN & NFV technology. Few such benefits that can

integration time. Some of the services would become available

be realized through the technology adoption are:-

by simply adding an app at controller software in a virtualized

Time to market will be drastically reduced in a SDN/NFV enabled

environment. CAPEX AND OPEX REDUCTION Service providers will be able to reduce their CAPEX and OPEX

EASE OF OPERATIONS

spend through SDN and NFV technology adoption. While CAPEX

Key benefit in operations will be homogeneity of the network

benefits will be realized by virtue of control plane functionality

and efficient management and flow control of mobile IPs.

consolidation on cloud and commoditization of data switches,

Centralization and less number of equipment will ease out

the OPEX benefits will be realized by virtue of reduction in power

configuration management, implementation, and also reduces

usage, space requirements and number of operational staff

risk of miss-configuration. There would be no need to login to

required for operation and maintenance

individual equipment for configuration, hence will save time

Service providers can further reduce customer onboarding and

and resources.

support spend by deploying commoditized data switch equipment

Virtualization will give a readymade platform for migration of

at enterprise customer premises as opposed to fully functional

network elements and services to cloud. Scalability and multi-

switch, and manage those switch through control plane in service

tenancy capabilities on virtualized platforms will enable easy

provider’s cloud environment. Thus reducing customer on-boarding

rollouts, upgrades and operations.

and support spend. “It is estimated that a CSP can have up to 50% direct CAPEX

OPENNESS

saving by adopting SDN in backhaul [3]. Some vendors are

SDN will provide an excellent platform for app development work,

claiming 90% saving in CAPEX when purpose built hardware is

which will help in building advanced networks. Dependency

replaced with high performance server and routers [6].”

from OEM to come up with innovative solution will be reduced that provides openness to the technology. Readymade apps from

The ability to host multi-version for applications and multi-tenancy

freelancers and domain experts will reduce cost and time for

will further drive down costs for service providers.

carriers.

NEW REVENUE STREAMS

TECHNOLOGY MANAGEMENT

Mainstream adoption of SDN and NFV technology will not only

Managing multiple technologies, domains, vendors, skills processes

help drive down costs but also help create new revenue streams

and policies are always complicated and challenging. SDN and

that to an extent will compensate for declining ARPUs.

NFV will bring a common platform for technologies, vendors,

Dynamic programmability of network control elements coupled with open standard interfaces will enable rapid introduction

and skills required to manage. Some of the direct benefits from technology management perspective are:

of new revenue generating, value added services in network

>

Improved automation

environment.

>

Common policy management and enforcement

>

Increased availability, reliability, scalability, multi tenancy

For instance, a service that allows an enterprise subscriber to

and security

purchase additional bandwidth through an on-line portal. Such request from a subscriber gets orchestrated in a manner that

>

Easy deployment and up-gradation of new technology, features

the policies to grant additional bandwidth towards subscriber

>

Common skills set for resources to manage network

CPE/device get provisioned automatically at the network layer and at edge router. This dynamic programing of the network will reduce time to provision the policies in the network, if done manually from operations standpoint, resulting into quick upsell of existing data services.

Adoption Challenges SDN and NFV technology is evolving not only from technology standardization standpoint but also in terms of broad set of use

Example of such services/use cases is discussed in subsequent

cases that it can address to realize the benefits claimed.

sections.

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However, there are challenges to be addressed before SDN and

TESTING AND DEBUGGING

NFV technology get into mainstream adoption. Subsequent

In a virtualized environment, network elements would be present

section mentions such challenges.

in distributed fashion i.e. network elements providing same service can be placed at different physical location. So there is a need for specialized testing tools, which can collect data, analyze

STANDARDIZATION As the technology is in its nascent stage standardization of SDN controller APIs is not compete yet. For successful adoption of SDN and NFV technologies there is a need to have standardized APIs for traffic flow management, interconnect policies, and authentication and authorization with other network elements on priority. For instance, in the case of policy management, PCRF and SDN controller integration is required. While PCRF is a service/ application level policy enforcement entity also used in LTE network, SDN controller is a L2/L3 level policy enforcement entity for data network. Integration of these two entities is depicted in the diagram below.

PCEF

to ensure that traffic is properly routed. Dynamic behavior of traffic flow according to configuration and network load would add complications for testing. A rigorous testing is needed keeping in mind APIs, and multiple vendors for general purpose server and user experience.

SECURITY As SDN / NFV are not matured technologies there are many associated security challenges. For instance, service provider would target 3rd party application providers to tap new business opportunities, which risks networks against security threats. To mitigate such security threats, a high level of security in terms of authentication and authorization is required for 3rd party

PCRF Gx

and report exact faults points. In a virtualized network it is difficult

applications that use network assets. Moreover, all controls would

Gx

PCEF

?

SDN Controller

be concentrated at SDN controller and any intrusion at SDN controllers could impact the whole network.

MAINTENANCE Operators have already invested heavily in existing network

OpenFlow

infrastructure. Legacy infrastructure will co-exist for years to come. The migration to SDN/NFV will be gradual with specific nodes and functions being introduced as legacy equipment

Switch

become depreciated or obsolete and based on SDN/NFV available feature set, resilience (carrier grade) and other operational

Interface between SDN controller and PCRF

As shown in the diagram above, interface between PCRF and

attributes. Centralized control plane at SDN controller makes availability of controller an important aspect.

PCEF (policy control enforcement function), labeled Gx, has

Due to the above facts, fault Management (hardware / software

been standardized by 3GPP. However, there is not much focus

failure) is going to be a big challenge, as it would not be easy to

on standardization of APIs between SDN controller and PCRF,

troubleshoot a problem in virtualized network with simple tools.

which implies no coordination between policy decisions across network elements.

PERFORMANCE

This is a big challenge for successful deployment of SDN / NFV

Telecom networks are designed with the consideration to have

and application development community.

minimum latency in the network to provide high throughput and low connection time. Maintaining a low latency is a main challenge.

IMPLEMENTATION Migration would be a real challenge and needs a proper planning in terms of selecting network islands and prioritizing their upgrade keeping in mind minimum interruption to services, co-existence with legacy networks, rollback plans and QoS maintenance.

SDN and NFV will add more complications as single controller has to communicate with multiple nodes and maintaining its huge database will impact the performance. Controller-to-controller interface is not yet standardized which otherwise improve performance by load sharing.

Special considerations are required for integration of SDN controllers as the technology is evolving and security aspects are not mature enough.

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SDN/NFV Applicability for Mobile Networks

demand, service providers would need more hardware, space

SDN and NFV can be implemented in various segments and

management requirements. Refer to section “Network Function

sub-systems of mobile networks using industry standard COTS hardware. Refer to the diagram SDN and NFV applicability in Mobile Networks below for few examples of segments/subsystems, which are elaborated subsequently.

and resources. EPC virtualization is an approach that service providers can leverage to optimally address the capacity and Virtualization” above for details. Implementation of EPC virtualization is possible in many ways. For instance, one virtualized logical node can have multiple virtual machines (VMs) working as different network elements as shown in the following diagrams.

EPC VIRTUALIZATION With the advent of technologies like LTE and LTE-A, data traffic is increasing exponentially on timescale and this demand is expected to explode in the future. To meet the increasing

MME

MME

Server

MME

OPTION 1: Several VMs of same software component can be installed on same virtualized infrastructure. No need for dedicated HW.

Since each VM works in isolation and is independent of other VMs, they don’t impact on performance of one another. These VMs can be configured dynamically (links, network topology etc.) as per required capacity and traffic pattern. EPC virtualization will help operators reduce CAPEX and OPEX and also enable dynamic optimization for rapidly changing needs. Other advantages are stated in the section “Accelerators Driving Adoption”.

Security Functions

Mobile Backhaul

Provisioning

Server Load Balancer

O/BSS

Network Function Virtualization

Software Defined Networks

WAN Accelerator

Cloud RAN

EPC Virtualization CPE Virtualization

SDN & NFV applicability in Mobile Networks

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The above architecture will optimize the requirement for baseband

MME

SGW-Ctrl

PGW-Ctrl

Server

OPTION 2: Several VMs can have different software components running on virtualized infrastructure.

processing capacity as it gets shared across radio heads. “Base Station hotel” has been around for some time with centralized baseband processing and remote radio heads fed with fiber (up to 10-15km) but NFV provides opportunity to run

EPC Virtualization

baseband on inexpensive hardware.

CLOUD RAN An operator’s CAPEX, OPEX expenditure on RAN is much more as compared to core. Cloud RAN will have several benefits right

CPE VIRTUALIZATION

from direct cost reduction (less civil structures, less hardware,

Customer premise equipment (CPE) comprises two logical

less energy consumption) to enhanced capacity and dynamic

functions – service control function and data switch function.

and uniform utilization of resources.

CPE virtualization will enable service provider to host CPE service

Today, cloud RAN architecture is evolving. Possible architecture would have a pole mounted radio head connected through fiber

function within its own cloud environment and deploy standard L2/L3 switch at customer premises.

and RF signals transferred to baseband processers located in

The CPE Virtualization diagram shows architecture where CPE

cloud. An illustrative diagram is shown below.

switch is replaced by a server which is running virtualized router and service code. The previous approach will not only save hardware cost and transportation cost of signaling, but also operational cost as the

Fiber UE

CPE service logic will reside in service provider cloud environment,

PHY MAC O&M

RRH

which can be easily managed from remote location. This implies an efficient way to deploy, upgrade and configure CPEs.

Baseband Processors

UE

RRH Cloud RAN

Orchestration

SP NGN

SP GW

IP Edge

Centralized DC CPE Services L2/L3 CPE router with services functions running in SP Datacenter

Internet

CPE Virtualization

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MOBILE BACKHAUL

This approach will enable implementation of many use cases as

Mobile backhaul comprises a complex mesh and chained

described in subsequent section.

topologies designed for network resilience, traffic carrying capacity while delivering desired QoS. Introduction of SDN in mobile backhaul will enable managing backhaul capacity through optimal resource utilization and dynamic traffic management. In addition, it will also allow for co-existence of multiple technologies

Service providers can benefit from implementing SDN and NFV in many other areas such as O/BSS, security functions (Firewalls, IDS/IPS, SSL, VPNs etc), server load balancers, WAN acceleration and provisioning systems.

on the same mobile backhaul infrastructure. An illustrative diagram is shown below, wherein, a SDN controller, optionally running on a virtualized platform, makes decision on

Use Cases

traffic forwarding and pushes the forwarding rules onto the

As discussed in previous section, SDN & NFV can be introduced

switches deployed.

in many segments/sub-systems of mobile networks. This section presents few end-to-end use cases that can be realized by introducing SDN & NFV.

SDN Controller

DYNAMIC BANDWIDTH MANAGEMENT There is an increasing demand for bandwidth hungry services MME UE

such as HD video on demand, online gaming, cloud based apps etc. To deliver these services with desired QoE there is a need

eNodeB

for better bandwidth management. SGW

By virtue of SDN, subscriber will be able to define his/her bandwidth need, allocate and make changes in required bandwidth dynamically. Bandwidth management can also be orchestrated

UE

by application or end user without involvement of service provider

eNodeB

personal. A framework for dynamic bandwidth management is shown below in this section. UE

Small Cell Mobile Backhaul

Bandwidth Management Application Network Monitoring (OF)

Bandwidth Management

Orchestration Logic SDN Controller OpenFlow API

FTP Server

Online Gaming Servers

Higher bandwidth allocation for network latency sensitive application

Online Gaming Client

FTP Client

Dynamic Bandwidth Management

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As shown in the diagram, the end-to-end traffic between online

The architecture enables implementation of many dynamic

gaming servers and online gaming clients (shown by a solid green

provisioning uses cases eliminating the need to pre-define VLANs,

arc) is shaped to meet service QoS requirement. In a real world

interconnection of VMs and configuration parameters.

scenario such request for dynamic bandwidth allocation for a gaming service will either be ordered by the end user through a self-care portal or by the game provider. The bandwidth management application will orchestrate policies for network wide deployment and pass it to SDN controller which in turn will push required configuration in network switches.

DEEP PACKET INSPECTION Deep packet inspection (DPI) has been used since a long time to identify and act on packet streams in the networks. The DPI solutions today has evolved into software based implementations that brings much better analytics for inspecting application

This auto provisioning will require no intervention from service

level (layer 4+) traffic. The software DPI solutions are easy to

operations teams. This business model wherein the service

manage, upgrade with new traffic signatures and are easy to

provider ties up with OTT players or directly sells on demand

deploy in the networks compared to traditional methods.

bandwidth services to end users will open up new revenue streams for a service provider to cope up with declining ARPU.

DPI software solution, optionally deployed onto virtualized platform, can be utilized for scenarios such as offloading certain traffic streams to other technologies, for example Wi-Fi.

WAN INTERCONNECT As an extension to dynamic bandwidth management use case, WAN interconnect will allow subscribers to design their enterprise level policies for shortest paths through the service provider network as per bandwidth requirement which have less latency or congestion and fewer hops across their networks. This assures network-wide load balancing beyond node-level load balancing, and reduces OPEX for service providers.

APPLICATION AWARE ROUTING Content delivery networks typically comprise a large distributed set of content hosting and content delivery servers that are deployed across multiple data centers. Application aware routing (AAR) service can be used by service providers to route service requests to content servers that can best serve the request. The following diagram shows an architectural implementation of AAR service. The centralized request server, hosted on a

DYNAMIC PROVISIONING Traditional network implementations require configuration of pre-defined VLANs, interconnections etc. without providing flexibility for dynamic provisioning. Introducing SDN, which implies a centralized SDN controller, optionally deployed on virtualized platforms, can be used to configure network switches as per the orchestration function that runs on a remote application server.

virtualized platform, is the first hop for all the service requests from the subscribers. The centralized request router redirects service request to the content server that can best serve the request. The centralized request router acts as an application level (layer 4+) load balancer redirecting requests based on subscriber geographical location, availability of content in the content server, service availability, and content server load.

Centralized Request Router

Caching or Streaming Servers 2 Caching or Streaming Servers

3 4

Caching or Streaming Servers 1 Online user

L7 Monitoring Probes Control Messages Data Flow

Architectural implementation of AAR

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Route Optimization

Configuration

Analytics and Reporting

Network Monitoring

Bandwidth Management

Request Routing

SDN Controller

Caching or Streaming Servers Caching or Streaming Servers

1 2

Caching or Streaming Servers L7 Monitoring Probes Control Messages Data Flow Online user

Provisioning of Flows

AAR implementation with SDN

AAR implementation can be extended further with increased

overheads due to fewer touch points to provision and operate

application awareness, which can be built into the network by

as compared to a traditional network.

developing SDN controller applications that keep track of application-level characteristics and use that intelligence to provision flow into the network switches.

VIRTUALIZATION OF CONTENT DELIVERY NETWORK As an extension to application aware routing (AAR), content delivery servers along with the content can also be hosted on virtualized platforms. Such improvements in network will simplify removal or changing location of content delivery components. Virtualization creates an isolation layer across virtual machines,

Key Considerations While the benefits of adopting SDN & NFV are multi-fold, which is evident from both the applicability of technology across mobile networks and also from the use cases discussed in earlier sections. However, there are few important factors that need to be considered in order to successfully implement the SDN and NFV technologies.

which will enable hosting of multiple instances of content delivery

In SDN architecture, the routing rules will be pushed by SDN

from multiple content providers on same virtualized platform,

controller onto the network switches. Since the network switches

which will optimize management and maintenance cost..

will not inspect the packet flows, there would be need for additional DPI and security solutions.

SERVICE CHAINING

Interoperability across network equipment supporting OpenFlow

As an extension to application aware routing (AAR), service

and also with IT systems would require verification as OpenFlow

providers can further launch composite services by service

implementations are evolving.

chaining the service requests across multiple application servers in a pre-defined order. An example of service chaining is when

Service level policies (which acts on layer 4+ of the traffic) in mobile

a subscriber request for HD video service, this will first trigger

networks is decided by PCRF (policy and charging rules function),

dynamic bandwidth management service to allocate desired

whereas policies for SDN networks (which acts on layer 2/3

bandwidth to the subscriber for service consumption. Upon

traffic) is decided by SDN Controller. These two entities, namely

successful grant of bandwidth, the request is routed to HD video

PCRF and SDN controller, are yet to work in tandem, which

content delivery server to start HD video streaming.

means that service level policies at PCRF shall be linked with L2/L3 traffic policies at SDN controller.

VIRTUALIZED AGGREGATION NETWORK

Network security might require network and process audit and

Service providers can benefit by centralizing the control for

redesign for access privileges, firewalls. For example, a scenario

aggregation network. The centralized control will manage the

would be to detect and block applications generating unwanted

switches that are deployed in networks. This reduces operational

traffic.

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OSS and BSS would require enhancements to support SDN & NFV deployments. OSS transformation would be the key challenge

Testing SDN and NFV Technology

that needs a detailed strategy and planning for architectural

With advent of new technologies like SDN and NFV, the test

impacts and functional impacts.

methodologies also require change which spans across know-

OSS need to support virtualized infrastructure and orchestrate virtualized network elements and virtual platform infrastructure. Additional support to legacy network is needed during transition. Following are some of the subsystems and processes for OSS functional domains (service assurance and service fulfillment) that get impacted.

how of the technology, and specialized testing and diagnostic tools to troubleshoot problems in this complex network environment. Options of putting test tools and test infrastructure on cloud is a natural evolution for test setup leading to resource optimization. Subsequent section gives high level guidelines on scenarios that should be tested for successfully introducing SDN & NFV technologies in the network.

SERVICE ASSURANCE > Impacted subsystems - Fault and alarm management systems, performance and threshold management systems, configuration systems, security systems, service quality

OPENFLOW TEST SCENARIOS (FOR SDN) > Control Channel functional testing to verify signaling protocol e.g. connection setup, failure, and interruption of a control

management systems, health monitoring systems, SLA management systems, reporting systems > Impacted Processes - Network and device configuration process, performance management process, capacity management process

SERVICE FULFILLMENT >

channel. > Conformance testing of protocol messages including negative scenarios. > Spanning tree protocol testing to test port state and its configuration message >

requirements for adding, editing, deleting and removing a

Impacted subsystems - Resource and service provisioning systems, network planning and design systems, activation systems, workforce management, network inventory modeling and management systems, capacity management systems, network discovery systems, reconciliation systems,

Flow administration and management testing to verify the flow along with flow table.

>

Counter value verification per flow, per port, per queue and per table.

>

Data plane testing to verify supported actions by a switch.

GIS systems, reporting systems >

Impacted processes - Inventory reservation and allocation process, Network element discovery process, reconciliation process, Service address change process, order modification

TEST RECOMMENDATIONS BASED ON ETSI REQUIREMENTS FOR NFV >

Interoperability and Integration testing shall verify that

processes, CPE management, IP address management,

the NFV framework is capable to re-host, optimize, and

network and virtual infrastructure capacity management

load integrate Virtualized network functions (VNF) in a

process, service activation process

standardized multivendor environment.

South bound interface for SDN implementation is defined, which

>

is independent of HW used and framework shall be capable

is OpenFlow. However, the north bound interface is yet to be defined. Service providers should consider defining this interface so that it is future proof.

to collect performance related information. >

party entities) and provide authentication, authorization,

extensions and could impact successful interoperability

data encryption, data confidentiality and data integrity. >

Scalability testing shall verify that the NFV framework is capable of scaling VNFs (scale up and scale down) and moving

on how the service is monitored. There will be a shift from

its components from one computing resource to another.

measuring hardware downtime to service downtime. Therefore, resilience shall be built in the service software running on

Security testing shall verify that the NFV framework protects network from E2E vulnerabilities (new HW, interfaces, third

Early implementations from OEMs might have proprietary

NFV will not only bring change in how service is delivered but also

Performance testing shall verify that the NFV framework

>

Resiliency testing shall verify that Network functions are

virtualized platform to instantly start up a new virtual machine

capable to recover after failure and the NFV framework is

on capacity overrun or an instance crash.

able to classify Network functions according to resiliency and facilitate resiliency scheme in both control plane and

NFV would also mean many virtual machines in multiple locations. Service operations should be planned for upgrade, patching, failure recovery across each virtual machine.

user plane. >

O&M testing shall verify that the NFV framework is capable to provide mechanism for automated O&M (creation, scaling and healing of VNFs based on pre-defined criteria)

Software Defined Network and Network Functions Virtualization - An Inevitable Evolution for Communication Networks

12

>

Service continuity testing shall verify that the NFV framework is able to restore services (recover VMs, provide alternative

>

solution) as per SLAs.

Aricent has helped service providers and equipment manufacturer

Co existence and transition testing shall verify that the NFV

across the world with its thought leadership, technology

framework co-exists with legacy network and supports

know-how, and expertise in integration, validation, rollout and

transition phase (interwork with O/BSS, ensure security of

maintenance of new cutting edge technologies.

VNF instances during transition) >

How Aricent Can Help?

Aricent’s expertise spans across SDN and NFV technologies,

Service assurance testing shall verify that Network functions

including OpenFlow, SDN applications and Northbound APIs.

are remotely accessible, monitored, and can perform diagnosis.

Aricent has proven record for successfully delivering end to end solutions, delivering telecom testing services (end-to-end testing,

3GPP COMPLIANCE TESTING

performance testing, functional testing and test automation),

For EPC virtualization scenario as described in sections above,

managed lab services and OSS transformation to support

protocols and messages flow across the network will be impacted

virtualized networks having multi-vendor, multi- technology and

because of the architectural changes. Therefore compliance to

multi-release environment.

3GPP specs is a must to facilitate multi-vendor eco-system. > Exhaustive conformance testing is highly recommended for all virtualized telecom equipment. > KPI, Load, Capacity testing should be performed to raise

Fore-sighting the need for constantly evolving communication networks, Aricent has developed reusable test assets (test strategy, test plans, test cases, and processes) to reduce timeto-market for service providers.

overall QoE. > A new protocol that would get defined between control plane and user plane of S-GW and P-GW, would require thorough testing.

Conclusion NFV and SDN will change the fundamental approach of how networks will be built in future. Focus will shift from building

NETWORK TESTING

networks in silos to component virtualization and then to

There would be significant changes in the network, when SDN /

network virtualization.

NFV are pervasively deployed. It is extremely essential to test all existing network services and to check there is no harm to the

Though lack of standardization and other issues around security,

network in terms of Quality, User Experience with introduction

performance of virtualized appliances / applications currently

of new services. Testing recommended for networks is:

impinge mainstream adoption of SDN and NFV, but, it is a matter

> Integration testing to assure smooth roll-outs. > End-to-end testing of all the services in real or near real network having multi-vendor / multi technology environment. > Field trial to assure overall performance of new technology. > SDN controller security testing. > No Harm to the network testing will assure that all legacy services are working fine and not impacted with

of time, when the specification forums will standardize the technology aspects, some of which are already being addressed in respective forums. The use cases and applicability of NFV and SDN as discussed in this paper will not only bring down CAPEX and OPEX in medium to long term, but also improve time-to-market for new services, simplify network operations and management.

introduction of SDN/NFV

VIKRAM NAIR

VINOD KUMAR GUPTA

is Director Technology at Aricent

is Senior Technical Leader at

responsible for E2E Testing, VAS

Aricent responsible for E2E

& M2M practice.

Testing pre-sales.

[email protected]

[email protected]

Software Defined Network and Network Functions Virtualization - An Inevitable Evolution for Communication Networks

13

REFERENCES (1) Open Networking Foundation https://www.opennetworking.org) (2) Network Functions Virtualization. An Introduction, Benefits, Enablers, Challenges & Call for Action (http://portal.etsi.org/NFV/NFV_White_Paper.pdf) (3) SDN: Bridging the Mobile Backhaul Funding Gap (http://www.tellabs.com/solutions/mobilebackhaul/tlab_bridging_backhaul_funding_gap.pdf) (4) White Paper by Aricent: Application Aware Routing in SDN (http://info2.aricent.com/hs-fs/hub/280086/file-210287459-pdf/Whitepapers/ Aricent_Whitepaper_-_Application_Aware_Routing_in_SDN.pdf) (5) OSI model (http://en.wikipedia.org/wiki/OSI_model) (6) http://www.nfvzone.com/topics/nfv/articles/353495-brocade-discusses-nfv-based-router.htm (7) ETSI GS NFV 004 v1.1.1Network function virtualization (NFV), virtualization requirements (http://www.etsi.org/deliver/etsi_gs/ NFV/001_099/004/01.01.01_60/gs_NFV004v010101p.pdf)

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