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Whole generations of applications have
been developed around various computing models, each with its own requirements
for network support. In the good old days of host computing, applications
required minimal bandwidth and were relatively time sensitive, and traffic flows
were deterministic between dumb terminals and the mainframe. Capacity planning
involved designing efficient topologies, scaling switches, and sizing trunk
lines. These were relatively straightforward problems, since the application
environment was stable and user requirements were well understood.
As networks evolved toward
interconnected LANs supporting the client/server model, planning became more
difficult. Client/server applications were much more bandwidth intensive and
extremely time-sensitive. Traffic flows were distributed across the entire
network, although they were relatively deterministic. Network managers faced the
more complex challenge of defining a hierarchy and ensuring that traffic flowed
across it, but deterministic traffic flows aided in the development of
applications that successfully addressed business needs.
The intranet model is the latest step
in the evolution of enterprise networks to a peer-to-peer computing paradigm.
The advent of the corporate intranet is replacing traditional client/server
applications with new concepts of information sharing and Web navigation.
Emerging intranet applications are both bandwidth-intensive and time-sensitive,
often requiring support for voice, video, and data multimedia applications
across a common infrastructure. These applications can be deployed by individual
workgroups in an unstructured manner without centralized planning. This results
in peer-to-peer flows that are much
less deterministic than traditional client/server applications while consuming
unpredictable amounts of bandwidth.
The corporate intranet model places new
demands on the networking infrastructure:
Intranets provide their user
community with access 24 hours a day, 7 days a week.Intranets require immediate
connectivity to any local or remote site in the world.Intranet users expect instant
access to information without restriction.
The term intranet is broadly used to
describe the application of Internet technologies within a private corporate
computing environment. Intranets take advantage of the large family of open
standards protocols and multi-platform support (desktops to mainframes) that
have emerged from the Internet to more effectively share information across the
enterprise. The goal is to seamlessly link the organization’s workforce and
information to make employees more productive and information more widely
available.
Intranet deployment requires an
existing network that supports the TCP/IP protocol suite and related Internet
applications. TCP/IP provides the fundamental set of communication protocols
that permit basic connectivity between networks and individual desktop systems.
Internet applications (e-mail, Web browsing, file transfer, terminal emulation,
etc.) provide the tools and services that allow workers to share information
across one or more LANs, a WAN, or the Internet. These applications
significantly increase demand for bandwidth.
Intranet Applications Increase Bandwidth Demands
Of all the Internet applications, the
Web browser has been the greatest driver of corporate intranet development. They
have been called the Swiss army knife interface to information because they are
platform independent and provide users with transparent access to FTP, Gopher,
Telnet, Network News, e-mail, online content search, and interactive database
queries. The tremendous popularity of Web browsers lies in their potential to
act as the universal client interface for any client/server application.
Emergence of TCP/IP
Over the years, efforts to simplify and
consolidate network operations has reduced the number of different protocols
running across enterprise networks, with TCP/IP emerging as the clear winner.
Looking back, there are a number of reasons for the inevitable emergence of
TCP/IP as the winner of the multi-protocol sweepstakes:
TCP/IP has a solid track record
based on years of operational experience on the Internet.TCP/IP was originally designed to
provide efficient communication across both LANs and WANs; over the years,
it has demonstrated its ability to scale to global proportions.TCP/IP provides universal
information exchange between all types of end systems PCs, Macintosh
computers, Unix platforms, supercomputers (Crays, NECs), mainframes (IBM,
Tandem, etc.), minicomputers (HP3000, AS/400), etc.TCP/IP has developed a robust set
of network management tools & #151; Simple Network Management Protocol (SNMP),
Remote Monitoring (RMON), RMON2 & #151; and network management platform
support from leading vendors.TCP/IP has an active development
community (the Internet Engineering Task Force or IETF) to continually
enhance and extend existing tools, develop new tools, and extend the
protocol suite.Internet applications run over
TCP/IP, not IPX, AppleTalk, DECnet, OSI, or VINES. To deploy native Internet
applications on desktops, the network must be running TCP/IP.
Explosion of Corporate Intranets
The public Internet is based on TCP/IP
technology that has been evolving for the past 30 years into a remarkable tool.
Until recently, the riches of the Internet were not readily available to novice
computer users due to the lack of a user interface. It was the development of
easy-to-use, point-and-click Web browsers like NCSA Mosaic, Netscape Navigator,
and Microsoft Internet Explorer that fueled the recent growth of the Internet
and the World Wide Web.
Web browsers were first adopted by
organizations to support inter-enterprise communications across the Internet.
Typically, an enterprise developed an Internet presence and deployed a Web
server to provide sales, marketing, and support information to external users.
As time passed, organizations realized the financial and strategic benefits of
using Web technology to provide information to internal users; the corporate
intranet. Many believe that the next evolutionary step will be the development
of secure extended intranets where Web technology is used to reach key external
customers and suppliers and to support all business transactions electronically.
According to Forrester Research, 22
percent of the Fortune 1000 companies currently use Web servers for internal
applications, and another 40 percent are seriously considering their deployment
in the near future. Zona Research predicts that by the year 2000 there will be
nearly 3.3 million private intranet servers, as opposed to 650,000 for the
public Internet. There are many forces driving organizations to migrate their
internal information management systems to the intranet model:
Intranets flatten the information
delivery system within an organization, delivering content on demand. They
foster the rapid exchange of information required to support reduced product
life cycles, increased cost pressures, demand for customer service, and
rapidly changing markets.The information on Web servers has
the potential to be the latest and most accurate. Information can be
cross-linked to provide point-and- click access to any other document within
the organization or around the world.Intranets are based on open
standards. This plays an important role in overcoming problems with
incompatible computing environments (UNIX, MacOS, DOS, Windows 3.1, Windows
95, Windows NT, OS/2, VMS, etc.) that previously prevented universal access
to information.Desktop browsers can be modified to
function as the client interface for almost any client/server application.
Since they are intuitive and extremely easy to use, browsers do not require
a large investment in training.Intranets provide a high level of
security. Many organizations do not have a direct connection to the global
Internet, and if they are do, they can protect their intranet using an
Internet firewall system. Java-enabled browsers support strong memory
protection, encryption and signatures, and run-time verification.
Internet Firewall System
The prevailing desktop-centric model of
computing is implemented by the deployment of heterogeneous fat clients. A fat
client is a desktop system that is loaded with a complex operating system, local
configuration files, a number of popular desktop
applications, and a variety of incompatible client applications for each network
services. In contrast, the network-centric model of computing motivated by the
corporate intranet is based on the deployment of thin clients with Java and/or
ActiveX-enabled browsers.
By deploying thin clients, network
managers can greatly reduce the complexity and administrative expense of running
their networks. Sun Microsystems estimates that the annual cost of operating
Java-based clients will be less than $2,500/desktop, compared to a $10,000 to
$15,000/desktop range for today’s fat clients.
Thin Client Implementing a Java Webtop
Internet applications provide better
performance within a corporate intranet than they do across the Internet. Most
individual systems are connected to the Internet at data rates from 28.8/33.6
Kbps to the emerging 56 Kbps dial rates. Corporate users may have access at
rates ranging from 128 Kbps (ISDN BRI) up to T1/E1 Mbps, but this may still seem
relatively slow since the bandwidth is shared by many other workstations. In
contrast, corporate intranets generally provide each desktop with access to
local Web servers at data rates of 10/100 Mbps.
Intranets are based on inexpensive
technology that is widely deployed in many private networks. If the enterprise
has TCP/IP on its network, it can easily install Web servers and browsers. This
allows organizations to slowly migrate to the intranet model without discarding
a single computing platform or application.
Challenges for Network Managers
In many enterprises, the deployment of
internal Web servers is a grassroots operation. The proliferation of HyperText
Markup Language (HTML) editors has eased the burden of content creation, and Web
servers are springing up all over organizations, in many cases without the
knowledge or cooperation of the local network administrator or the traditional
IS department. Network administrators who have been accustomed to carefully
planning for traffic flows and bandwidth requirements associated with the
rollout of a network operating system upgrade or a new client/server application
are facing new challenges with the rapid migration to the intranet model:
Internal Web sites with large
graphic or multimedia content will make increasing bandwidth demands on the
corporate infrastructure. The total volume of network traffic will grow as
the content from bandwidth-intensive pages is transmitted across the
organization’s infrastructure.The rollout of new applications
based on Java and/or ActiveX applets can result in additional bandwidth and
performance challenges. In the current client/server model, specialized
client software is preinstalled on the user’s hard drive for each server
that needs to be accessed. In the intranet model, applets are downloaded
from the Web server to the client as they are needed. Although this greatly
reduces LAN administrative costs, it can cause network congestion and slow
response times.Intranet traffic flows will be
impossible to predict and constantly changing. Since the goal of the
intranet is to enable free exchange of information, network managers will
not be able to predict in advance where the traffic bottlenecks will appear.
In contrast to the traditional client/server model, in which large pipes can
be provisioned to provide adequate bandwidth at the core of the network,
user-developed Web servers are typically located on shared media at the edge
of the network. The infrastructure at the periphery may not have sufficient
capacity to support access from clients located across the enterprise. In
addition, narrow WAN communication pipes may experience increased traffic
volumes. Intranets can result in severe network congestion and performance
problems at random locations across the enterprise network infrastructure.All of these changes will have a
negative impact on the performance of existing client/server and legacy
applications. These applications must now fight for basic bandwidth in a
network environment in which there are increasing traffic volumes and
unpredictable/unstable loads.
Supporting Intranet Applications
In an Intranet environment, it is
imperative that network managers deploy RMON and RMON2 probes to gather baseline
information about traffic flows and application trends. RMON and proactive
monitoring are the keys to optimizing existing LAN and WAN resources, uncovering
bottlenecks before they appear, establishing policies regarding the use of
applications on the enterprise intranet, and making wise decisions about
capacity planning and future growth.
After potentially disruptive trends are
discovered via RMON/RMON2, network managers have several options meeting the
challenges to efficient network operation. They can provide additional LAN
bandwidth and improve performance by deploying layer 2 switches at the network
edge. They can provide increased traffic control and packet throughput by
deploying intelligent switches with Fast IP at the network core. Finally, they
can use bandwidth-grooming features to overcome bottlenecks resulting from
increased bandwidth demands on narrow WAN links.
Chuck Semeria, Courtesy: 3Com
For all further information, email at Sayan_Ghosh@3Com.com