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A Guide To
Prepared by Zeus Kerravala |
M arch 2014
Network Virtualization
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Introduction: It’s Time for the Network to Evolve
A
gility has become a key initiative for business leaders. Companies need the capability
to respond to competitive pressures fast, and to add new applications and services
as quickly as possible. This is the primary reason that business agility has become a
top initiative for almost every C-level executive and line-of-business manager.
The job of creating an agile business has fallen on the shoulders of today’s CIOs. The only
way to have an agile company is to support the business with agile technology infrastructure.
This is why IT leaders have implemented many technologies at the compute and application
layer, such as server virtualization, cloud computing and application componentization. However, organizations cannot achieve the necessary level of IT agility without the network reach-
ABOUT THE AUTHOR
Zeus Kerravala is the founder and
principal analyst with ZK Research.
Kerravala provides a mix of tactical
advice to help his clients in the current
business climate and long-term strategic advice. He delivers research and
advice to the following constituents:
end-user IT and network managers;
vendors of IT hardware, software and
services; and members of the financial
community looking to invest in the
companies that he covers.
ing a correspondingly higher level of agility.
The network has evolved through the different eras of computing and has become a more
strategic asset with each successive evolutionary step (Exhibit One, see page 3).
The shift to virtual and cloud computing will be the single biggest transition in the history
of computing and will impact IT in the following ways:
• Agile IT will become a reality. Today’s business leaders must be able to rapidly change or
augment corporate strategy. To accomplish this, CIOs need a dynamic, agile IT infrastructure to
support the business. The virtualization of IT resources creates a significantly higher level of IT
agility than legacy compute models.
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A Guide to Network Virtualization
Exhibit One: Computing Through the Ages
Computing Era:
Mainframe
Computing Era:
Internet Computing
Connected Endpoints:
Tens of Thousands
Connected Endpoints:
Millions
Role of Network:
N/A
Role of Network:
Limited Optimization
1960
to
1980
1980
to
1995
1995
to
2010
2010+
Computing Era:
Client/Server
Computing Era:
Virtual/Cloud Computing
Connected Endpoints:
Hundreds of Thousands
Connected Endpoints:
Billions
Role of Network:
Basic Connectivity
Role of Network:
IT Enabler – Strategic Asset
Source: ZK Research, 2014
• IT will adopt a services model. As IT moves from virtual to cloud computing, it will evolve
along the lines of “X-as-a-service.” This will enable organizations to allocate appropriate resources to the applications and services that require them as per business policy. Consequent3
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A Guide to Network Virtualization
ly, businesses can significantly improve resource utilization and maximize investments in infrastructure such as servers and storage.
• IT silos will disappear. The next IT era will require greater coordination and orchestration
of all IT resources—from applications through the network. This will require tighter integration
37%
of network
downtime is caused
by human error
among IT resources and the operations teams, which will ultimately drive organizations away
from traditional IT silos and toward a more unified structure.
While the majority of IT today has evolved, the network has yet to change as virtualization
has become a bigger part of IT strategy. The architecture used to build networks today is fundamentally the same as it was 20 years ago. If the network is going to become an agile, flexible
IT resource, business-centric network virtualization must become a reality.
Section II: The Challenge with Legacy Networks
The current network architecture used to build enterprise networks and data centers is outdated and cannot enable IT agility. The historical value chain in traditional IT assigned applications the highest value and considered the network to be the “plumbing”—having the least
value relative to the rest of the technology stack. Although the network has always been necessary, it ultimately did not play a critical role in the overall performance of the business because
most applications were best-effort.
Now that IT is shifting to a network-centric model, the following limitations will inhibit a
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company’s journey to building an agile business:
• Built on old protocols: Legacy infrastructure uses the archaic Spanning Tree Protocol
(STP) to prevent routing loops and broadcast radiation by disabling ports that are not part of
the “tree.” These disabled ports are made active in the event of a link failure on one of the active
ports. This means that up to half of the ports in a network could be in “passive” mode, leading
to a highly inefficient, underutilized network.
• Static architecture: Network infrastructure is very rigid and optimized for static environments. Network infrastructure provisioning can often have long lead times, and changes often must be made manually on a box-by-box basis. This process can lead to large amounts of
human error. ZK Research studies have shown that the largest amount of network downtime,
37%, is due to human error induced during changes (Exhibit Two, see page 6).
• Not designed for modern compute models: Traditional networks are designed for
best-effort traffic, such as e-mail and Internet browsing. Today’s IT strategies revolve around
trends such as real-time collaboration, virtualization and cloud computing. This places the emphasis on the network evolving away from best-effort solutions and toward a network that
features guaranteed delivery and low latency.
• Protocol overlays: With legacy network technologies, the same protocols and features
need to be implemented at Layer 2 and then again at Layer 3, creating extra complexity due to
the successive overlay of standalone protocols.
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A Guide to Network Virtualization
• High amounts of latency and insufficient resiliency: Legacy networks are architected
with three or more tiers, and traffic is passed through each tier of the network core and then
back through each tier. Each of these hops between network devices adds latency and creates
points of failure that can impede the performance of mission-critical applications.
Exhibit Two: Human Error Is the Largest Cause of Network Downtime
Causes of Network Downtime
6%
3%
Other
Power Outage
9%
Hardware Failure
37%
Human Error
14%
Software Bugs/Error
31%
Telco Outage
Source: ZK Research, 2014
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A Guide to Network Virtualization
For organizations to leverage the network and create a more agile business, the network
must now evolve and itself become a more agile resource.
Section III: The Evolution to Network Virtualization
Network evolution is long overdue. Server virtualization, mobile computing, the cloud and
real-time collaboration have put new demands on the network that legacy designs simply
Network virtualization
can’t meet. This begs the question: If the current network architecture is outdated, what are
creates the ability
the characteristics of an agile network? An agile network needs to be significantly less com-
to rapidly scale the
plex than traditional networks. Additionally, the network being put in place today must be
network up or down
future-proofed to be a foundation for forthcoming initiatives. To meet both of these goals, or-
or to create new
ganizations should look to leverage the power of network virtualization.
networks on demand.
Virtualization is the act of decoupling an infrastructure service from the physical platform
on which that service operates. The IT service that is being utilized is not identified with any
physical asset; rather, services exist entirely in a logical abstraction layer running within virtualization software.
Network virtualization uses network resources and creates multiple logical network segments that run on a single physical network (Exhibit Three, see page 8). The concept of network
virtualization isn’t new. High availability demands have created the need for the dynamic use
of alternative resources. The problem with legacy implementations of network virtualization
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Exhibit Three: Server Virtualization vs. Network Virtualization
Application
Application
Application
Workload
x86 Environment
Virtual
Machine
Virtual
Machine
Workload
Workload
L2, L3, L4-7 Network Services
Virtual
Machine
Decoupled
Virtual
Network
Virtual
Network
Virtual
Network
Server Hypervisor
Network Virtualization Platform
Requirement: x86
Requirement: IP Transport
Physical Compute and Memory
Physical Network
Source: ZK Research, 2014
is that one set of network resources—such as links, switches and routers—remains idle while
waiting for the failure of an active resource. Although this methodology met the challenge of
creating dynamic resources, it was highly inefficient because many network resources remain
idle most of the time.
Network virtualization addresses these issues by abstracting control of the resources and
centralizing it in a common control plane. This control plane enables the dynamic allocation of
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the resources based on demand or business policy. Organizations that deploy network virtualization will realize the following benefits:
• Dynamic network control: Network virtualization offers centralized control over all network resources, with the ability to dynamically provision and reconfigure them. Additionally,
through the use of northbound APIs, the applications and compute resources can communicate directly with virtual network resources and automate provisioning to optimize application
performance and resource utilization.
• Lower cost of hardware: There are many ways network virtualization can reduce the cost
The overall solution
of hardware, such as lowering hardware costs and providing more efficient bandwidth utili-
must simplify many
zation. Additionally, because of centralized control and automation, many of the operational
of the complexities
processes required to manage the network are also greatly reduced, lowering operational ex-
associated with
penses.
legacy networks.
• Rapid scalability: Network virtualization creates the ability to rapidly scale the network
up or down or to create new networks on demand. This becomes increasingly important as
organizations move IT resources to the cloud and shift to an “as-a-service” model.
Section IV: What to Look for in a Solution
Business and IT leaders are striving to create business agility. To accomplish this, CIOs have
turned to a number of emerging technologies to increase overall IT agility. The requirements
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of cloud, bring your own device (BYOD), virtualization and collaboration are putting unprecedented demands on today’s networks. Organizations should adopt network virtualization to
enable the levels of network agility and flexibility necessary to align better with the rest of the
technology stack. This is a new role for the network. Consequently, network decision makers
must shed old-school buying strategies based primarily on brand or vendor incumbency, and
instead evaluate network infrastructure based on its ability to support the needs of the evolving enterprise network.
However, a full understanding of what to look for in a network solution provider may not be
obvious. Enterprises evaluating network virtualization solutions must consider the following:
• Simplicity of the solution: The goal of network virtualization is to simplify the network
architecture and the operational model. This means the overall solution must simplify many of
the complexities associated with legacy networks. For example, the network protocols must be
unified at Layers 2 and 3 to avoid overlay complexity. Additionally, the solution must provide
topology freedom so all services are available whether the virtual network is operating at Layer
2 or 3.
• Extends beyond the data center: Most network virtualization vendors have solutions targeted at the data center only. Network virtualization can bring tremendous value
to points in the network outside the data center including the campus edge, wireless
edge and branch offices. Additionally, the solution should span geographically dispersed
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data centers and make them appear as a single enterprise resource.
• Integrated multi-tenancy: The solution must offer more than just separation of traffic; it
must provide full multi-tenant networking. This will allow organizations to keep departmental
or tenant networks separated but still offer access to some of the shared services. Additionally,
the solution should allow secure zones to be set up across the backbone to isolate different
traffic types or groups of users. This is particularly important for businesses operating in environments with regulatory or compliance obligations.
Any solution deployed
• Improved network uptime: Any solution deployed today must offer sub-second recov-
today must offer
ery of all network services, including complex ones such as IP multicast. This is in stark contrast
sub-second recovery
to STP, which would often take tens of minutes before all services were made fully available.
of all network services,
• Improved scalability: The network must be able to scale beyond the 4,096-VLAN limita-
including complex ones
tion associated with traditional networks. This will provide an excellent foundation for future
such as IP multicast.
applications as well as the upcoming wave of mobile devices.
• Open, standards-based solution: There are many ways for solution providers to meet
the challenge of network evolution. Many vendors choose to use proprietary protocols and
solutions to develop new products. This can sometimes short-cut development time and allow vendors to get products to market early. However, in the long term, it causes vendor lockin and impairs a customer’s ability to choose best-of-breed products in the future. An open,
standards-based solution guarantees interoperability with other best-of-breed products and
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ensures a wide variety of choice. For example, there are a number of candidate replacements
for STP; but to date, only Shortest Path Bridging (SPB) is based on a standard (IEEE 802.1aq specifications). TRILL and other protocols have yet to be fully standardized, and this uncertainty may
lead to interoperability issues in the future.
Section V: Conclusion and Recommendations
The drive toward business agility is transforming IT at an unprecedented rate. Virtualization
has already had a significant impact on the software and server industry, and it will have a sim-
Companies should look
ilar impact on networking because the network plays a critical role in fulfilling on the vision of
to migrate away from
agile IT. The network is the only pervasive resource, and it connects all IT resources to different
three-tier designs
users and devices no matter where they are. To do this, though, the network needs to evolve
to a two-tier or even
and become a virtual resource that has the same level of flexibility and agility as other enter-
single-tier option when
prise IT resources.
feasible.
Network virtualization will put the network in a position to become the key point of
competitive differentiation for organizations as they look to capitalize on the flexibility and cost efficiencies of virtualization. This introduces new requirements for network
design and the choice of solution provider. Customers must move decision criteria away
from things like market share and vendor incumbency, and focus instead on attributes
such as how resilient the network is, to what degree the network simplifies the infra12
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A Guide to Network Virtualization
structure, and how it enables virtualization to be used more broadly. With this in mind,
ZK Research makes the following recommendations for companies looking to implement
network virtualization:
• Simplify the network architecture as much as possible. Companies should look to migrate away from three-tier designs to a two-tier or even single-tier option when feasible. The
less complex the network is, the easier it is to manage and troubleshoot.
• Stick with a standards-based, open solution. Implementing network virtualization requires a large ecosystem of solution providers. A network built on closed, proprietary technologies may not be able to interoperate with all the necessary ecosystem vendors. A standards-based, open solution guarantees the broadest range of choice for customers.
• Deploy a no-compromise network, even if that means moving away from your incumbent vendor. Choosing the incumbent vendor often seems like the easy choice because
of product familiarity: It’s the “safe” option. However, this often forces IT organizations to make
compromises they may regret in the future. The requirements of the network today are signifiInfluence and insight through social media
cantly different from those of the past; simply going down the path of least resistance might
be the wrong choice. Organizations should no longer have to compromise between purchase
© 2014 ZK Research: A Division of Kerravala Consulting
All rights reserved. Reproduction or redistribution
in any form without the express prior permission
of ZK Research is expressly prohibited.
For questions, comments or further information, e-mail
[email protected].
price, resiliency, power efficiency and feature set. Choose the vendor that best supports your
network virtualization initiatives, and do not compromise on any features needed to fulfill on
the vision of agile IT.
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