WAN Optimization for Enterprise Applications by soft.as.heart


									                                                                                                                                           White Paper

WAN Optimization for Enterprise
Enterprises are increasingly looking for wide-area connectivity solutions      Operations that span two or more locations within the same metro area

that address issues they are, or will soon be, encountering. Trends that       increasingly require high speed network connections where 10/100

are poised to drive the demand for bandwidth-intensive solutions               LAN speeds are simply not sufficient. Even single location enterprises

include Business Continuance (BC)/Disaster Recovery (DR) compliance            are looking to WAN connectivity to support the BC solution they

requirements, and increasingly, the emergence of web services and              require in support of replication of data over long distances.

software oriented architectures in multi-location enterprises.
                                                                               The issue in many cases becomes ensuring that the dollars being

Costs for Wide Area Network (WAN) solutions can be significant. While          spent on wide-area networking services and solutions are efficiently

consumers and small businesses may have a wide range of services to            used both now and in the future as demands grow. Optimizing the

choose from to get basic internet access, these emerging enterprise            balance between the applications that can be supported, the

applications place much more stringent requirements on the wide                resulting performance, and the overall solution cost is a daunting task

area. Applications may demand high security, high bandwidths, low              because often times the impacts on the computing infrastructure of

latencies, or low packet loss ratios. Furthermore, when mass market            WAN performance metrics like latency, Quality of Service (QoS) and

solutions from the major software vendors begin to leverage fast               capacity are unknown and unquantifiable. Additionally, while the most

networks for essential and basic operation, the need for 'heavy lifting'       common networking protocol in both enterprises and service

WAN solutions becomes real for a wider range of enterprises.                   providers is usually IP, in many cases the common sense approach of

                                                                                                                 marrying the two technologies to

                                                                                                                 deliver WAN solutions may not be

                                                                                                                 the most optimal approach.

                                             Service Provider                                                    As shown in Figure 1, a number of
                                               IP Network
                                                                                                                 applications in use today are easily

                                                                                                                 adapted to operation over WANs.
    Enterprise Domain                    Service Provider Domain                    Enterprise Domain
                                                                                                                 Email, web browsing, and file

                                                                                                                 sharing all lend themselves to
                                       Shared WAN
                                      packet network                                                             reliable operation, even in lossy, low-
                                                                                                                 throughput, high-latency environ-
            Web                                                                               Web
                                                                                                                 ments, due to the use of TCP.
           Email                                                                              Email
                                                                                                                 IP routers are very well suited to
     File Sharing                                                                             File Sharing       providing    the   ‘WAN        gateway‘
           VOIP                             10/100 VLAN or VPN                                VOIP               function, since their task is to

                    Bandwidth                                                                                    adapt IP to IP, and provide the
                     rich LAN
                                                                                                                 necessary capabilities.

                                      Figure 1: Typical initial MAN solution
                                                                                                             WAN Optimization for Enterprise Applications

Compression technologies bring strong
                                                                                                                                    XML - enormous BW implications
benefits in these environ-ments, whether                             Application growth             QoS
                                                                                                                                      BC/DR - mission critical data

                                                                      New apps BC/DR              Impacts
delivered as a function of the router, or by a
                                                             Web                                                                                                 Web
standalone unit, by reducing recurring WAN                  Email                                                                                                Email
                                                      File Sharing                                                                                               File Sharing
charges or increasing effective bandwidth.

This solution is arguably the most affordable               VOIP                                                                                                 VOIP
                                                             XML                                                                                                 XML
                                                           BC/DR                                    10/100 VLAN or VPN                                           BC/DR
for an initial solution, but as illustrated in                                                       Limited Throughput
Figure 2, several problems arise as demands                                                                               But WAN links experience
                                                                The LAN can handle
                                                                bandwidth demands                                         increased loss and latency
for new applications, performance and                                                                                         as demands grow,
                                                                                                                            exceeding capabilities
capacity increase:

» As bandwidth usage increases, the likelihood                  Lease a faster                   How to deal with                  Plan for today or plan
                                                                 VLN/VLAN?                      storage protocols?                    for tomorrow?
  of packet loss on the WAN increases
  dramatically. This affects the network in two
  ways—applications using TCP slow down considerably, and the                                  Figure 2: Demands impact network performance and cost
  'effective usage' of the WAN decreases. TCP reacts to packet loss by
  slowing down its transmit rate, and retransmitting packets, which takes
  time to complete, and uses additional WAN bandwidth. This problem is
  greatly exacerbated by distance.                                                   T H E T R A N S I T I O N F R O M L E A S E D T O P R I VAT E N E T W O R K

» Contention between applications for access to the WAN occurs in an                 One of the most important elements in optimizing your wide area
  ad hoc manner, and there is little to no control over what application             network is understanding if and when you should consider migration
  gets what bandwidth and when.                                                      from a leased WAN services network, to a private network. The long

» Some applications and equipment do not rely on Ethernet and IP as                  term business case for such a move involves the comparison between
  their communication protocol. Storage equipment (disk arrays, tape                 the Total Cost of Ownership (TCO) of leasing versus owning, and the
  drives, Storage Area Network (SAN) switches) use protocols like                    costs have to include all aspects of both, as shown in Figure 3. In it's
  SCSI, Fibre Channel, ESCON® and FICON™ to move storage data
                                                                                     simplest form, the economics many times boil down to comparison of
  from device to device. These protocols are typically very sensitive to
                                                                                     the yearly cost of leased services, compared to the yearly cost of leased
  packet loss, and were not designed to tolerate it. As a result,
                                                                                     fiber between sites, and an amortized capital expense for WAN
  additional technology must be used to merge these traffic sources
  into the IP infrastructure. This approach can be problematic and                   equipment.

  often comes at severe performance restrictions.
                                                                                     These costs are highly variable, and often depend on geography. For
» Over time, recurring wide-area service charges add up, and at some                 example, unused fiber cable in some metro areas may be plentiful and
  point it becomes valid to look at longer term approaches to                        low cost, while in other areas leased telecoms services may be
  bandwidth planning. For example, it may become affordable to lease
                                                                                     economical, or vice-versa.
  optical cable fiber between locations, and build a private WAN.
  When is the right time to consider such an investment?                             One thing is for certain, the evolution of enterprise applications is

» The emergence of SOX regulations is pushing enterprises to examine their
                                                                                     driving the network towards higher and higher bandwidth

  BC/DR solutions. XML applications are poised to distribute applications            requirements, and WAN requirements will follow suit. This trend will
  across servers, relying upon high network bandwidths to operate in a               exacerbate the recurring cost issues with leased solutions, and shift the
  trouble-free manner. These fundamental changes in bandwidth demands                economic point where leasing may no longer be cost-effective.
  force a new consideration in how to architect the right solution.

                                                                                                                                                     WAN Optimization for Enterprise Applications

                                                                                                                                                                    expect to run. Typically, when
                                      b urst
                                              able                                            Cumulative $$    WAN expenditures
                                  b/s                                                                                                                               stringent applications are in use,
                    able    50
                                 M                                                                                                                es
                urst                                                                                                                         ervic
            /s b                                                                                                                         ed s
     10                                   P                                                                                         Leas
                                                                                                              Leased fiber
                                                                                                                                                                    higher quality services pay off by
                                                                       Initial costs are higher to
                                                                       lease dark fiber…
                                                                                                                                                                    delivering much elevated perfor-
                                                                                                                                    … but the long term benefits
          Lease a faster VPN/VLAN?                                                                                   When?            may be worth it
          • does it meet my cost targets?                                                                                                                           mance in comparison to shared
          • does it meet my quality needs?
          • can it support the applications?
                                                                                                                                                 Time...            data and IP services. An example

                                                                                                                                                                    could be shared 10/100 VLAN
                                                            ck                                                                 How do I deal with the
                                                                                                                                 variety of protocols               service between two sites, where
                                          Tap                               Fib                                                          AND
                                             e   on                             re
                                                                                   C                                         the time-of-day bandwidth
                                                                                       nn                                             demands?
                                                                                                                                                                    the target applications running
                                              ffi   ce LAN                                                                                                          were LAN extension (file sharing,
                                     Ethernet for video                                                                                                             email)     and     synchronous       disk
                                                                                                                     To the other site
                                                     ions                                                                                                           mirroring for BC/DR. While the
                                 X ML A

                                                                 s                                     WAN gateway                                                  bandwidth may be affordable, the
                                                                                                                                                                    resulting performance on the disk

                                                                                                                                                                    mirroring application will be very
                           Figure 3: Optimization considerations                                                       low due to the effect of packet loss, latency, which slow the

                                                                                                                       synchronous nature of the disk mirroring. The end result is a functional

                                                                                                                       LAN but an under-utilized, poor performing BC/DR solution.

The lowest cost services for WAN are typically shared services, where                                                  T H E VA L U E O F M U LT I - P R O T O C O L A D A P T I V E S O L U T I O N S

data is delivered across the WAN using a shared IP. This is different                                                  When the networking requirements within the enterprise are primarily
than traditional telecoms services, where private, isolated leased lines                                               serviced by low-bandwidth Ethernet and IP, it may be practical to seek

or 'circuits' are created using SONET technology. When is one better                                                   out Ethernet and IP solutions from service providers to meet WAN

than the other? The most important performance characteristic that                                                     needs. However, storage-based applications like disk mirroring and

determines the usefulness of one or the other is packet loss. Packet                                                   remote tape typically employ different protocols, like Fibre Channel,

loss (especially when combined with the long network transit times                                                     ESCON and FICON. These optical protocols, and the storage

associated with WANs) has a very detrimental effect on TCP-IP based                                                    applications that use them, are designed primarily for dedicated

                                                                                                                       connection-oriented networks, and do not operate efficiently over IP-
applications. When packet loss occurs, applications are forced to
                                                                                                                       based connectivity. So, while technologies exist for running “Storage
resend large volumes of data in response to a single packet failure,
                                                                                                                       over IP”, in many cases the IP network itself cannot deliver the
causing application slowdowns and network congestion.
                                                                                                                       underlying quality that storage systems require to perform at expected
Applications that were designed with packet loss in mind tend to be                                                    levels.
able to tolerate this disturbance. However, emerging applications, due
                                                                                                                       An alternative to consider is to look for WAN services that support
to their high bandwidth consumption and low-latency/low-loss
                                                                                                                       storage protocols directly. These services provide the enterprise a
requirements, generally do not perform to expectations in a lossy
                                                                                                                       fundamental advantage for storage applications: storage traffic is not
                                                                                                                       forced over the IP infrastructure; it can ride alongside other enterprise

One must understand the conditions under which using a shared WAN                                                      data traffic, independently and unaffected by congestion and loss

service will be inappropriate for the applications their end users will                                                inherent in an IP environment. These multi-protocol solutions typically

                                                                                                                       WAN Optimization for Enterprise Applications

allow both burstable service types and deterministic service types, so                        SU8MMARY

the user may make better use of the available WAN resource.                                   Emerging applications are driving new network performance
Furthermore, compression technology may bring benefits in that data                           requirements on enterprise and government networks. There are
has an average compressibility of 2-3x, meaning that any WAN                                  several approaches that attempt to deal with these network
bandwidth may be doubled or tripled in its usefulness via this                                performance challenges—including optimizing IP or leveraging IP
technology.                                                                                   level compression on existing IP data services. Over time though,

                                                                                              private networks, which provide all required bandwidth, will enable
D E A L I N G W I T H T I M E - O F - D AY B A N D W I D T H S H A R I N G B E T W E E N
                                                                                              emerging IT apps to have the network performance they require and
                                                                                              this will be more cost effective in the long term.
Lastly, as bandwidth demands increase, rarely are the bandwidth
                                                                                              Enterprises may leverage WDM or SONET technologies and can
requirements static. Rather, they vary throughout the business cycle;
                                                                                              enable multiple network protocols to run at high speeds with high
daily, weekly and yearly. Yet, service provider WAN services tend to
                                                                                              levels of performance. They need to be flexible, cost effective, and
have static SLAs. One important consideration then is—how can one
                                                                                              adapt to changing IT requirements—Ciena terms this ‘Adaptive
manage which applications gain access to 'scarce WAN resources'? It
makes little sense to allow LAN traffic to overwhelm the WAN links

while critical traffic like disk mirroring is struggling to maintain its pace,                Ciena provides industry leading flexible, intelligent network
in competition for bandwidth between sites. Technologies exist that                           platforms and expertise to help you address these challenges. These
allow users to directly gain control of their networks to address this                        platforms are available through world's leading carriers and
issue by leveraging strong traffic management processes and                                   integrators for managed private network solutions. They can be
management tools. These tools provide visibility into how WAN                                 managed by the enterprise or by the service provider/integrator.
bandwidth is assigned to different applications in the IT infrastructure,                     Ciena can assist you in forming adaptive WANs to meet your
and they enable provisioning as needed to fit IT application                                  IT challenges.

Of primary importance in maintaining a BC strategy is to ensure that

when an urgent situation arises, the highest priority traffic be given

the priority it needs to WAN resources to establish a complete

remote data set, or facilitate the fastest recovery possible. The ability

to dynamically provision bandwidth to support rapidly changing

business requirements is therefore of paramount importance.

                                About Ciena: Ciena Corporation, the network specialist, supplies application-focused network systems, software and services to customers
                                worldwide. The company leverages core competencies in optical networking, data networking and broadband access to solve its customers’
                                most critical networking challenges so they can best exploit the applications that are driving their businesses forward.
                                For more information about Ciena, please call 1-800-207-3714 (US) or 1-410-865-8671 (outside US), or visit www.ciena.com

                                Ciena may from time to time make changes to the products or specifications contained herein without notice. ESCON and FICON are trademarks
                                or registered trademarks of International Business Machines Corporation. © 2005 Ciena Corporation. All rights reserved. WP024 5.2005

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