The IT industry is going through a revolution. With
increased focus of businesses on the application benefits that an Enterprise Network could
deliver rather than the technological superiority of the components of the network itself,
the network is perceived today as a Critical Success Factor for achieving business
differentiation and a sustainable competitive advantage in the market.
Traveling back in time to analyze the
traffic patterns flowing through the network, we find that 80 percent of the traffic was
on the workgroup side with locally attached file/application serv-ers, shared printing
resources, and electronic messaging. The rest of the traffic flew over the backbone for
electronic messaging between workgroups and for enterprise applications.
Based on these trends, the networking
industry provided switching and routing components which could handle this traffic
effectively. However, there has been a paradigm shift in the application deployment over
the past one year wherein there has been a complete reversal of traffic patterns on the
A future-proof network of an enterprise
today has 80 percent traffic flowing over the backbone for emerging applications like
Internet access, intranet communications, peer-to-peer applications, shared resources, and
electronic messaging becoming a complete enterprise application. Peer-to-peer
collaborative applications and increased server-to-server communications are pushing the
traditional backbones to limits.
And with more and more companies talking
about desktop-to-desktop video, voice, and other means of interactive communications,
there is an increased intranet web server traffic. To manage this, the network manager has
to provide for lower latency and significantly increased bandwidth requirements as well as
plan for more peer-to-peer data, voice, and video traffic.
Let us take a closer look at how networks
have evolved in India and thereby understand the intended and actual roles that a
traditional switch and router play in the Indian environment. The networking industry in
India started in 1984. At that time there was just one flat long segment carrying Ethernet
envelopes on shared paths. As the users grew in number, the flat network had more
collisions and thereby more delays.
The easiest thing to do then was to break
the network into smaller segments and use a bridge. This bridge operates in Data Link
layer and not on the network layer. Due to this, bridges were simple to deploy for
creating segments based on traffic patterns and not on protocols. However, in a
multi-protocol scenario, the limitations of the bridge were quite apparent and a tighter
control at protocol level could not be established.
Due to these limitations, in 1988, the
bridges gave way to routers, a new class of network devices which could detect an
envelope, read network address (Layer 3), look for best path, and send the envelope along
that path. Being protocol savvy, router had to process each and every packet that it
received, look for the address and send the packet through the best path, which meant that
the processing throughput of network was slowed down considerably.
The Ethernet hub functions as a
concentrator and allows multiple users to share the available bandwidth. When the shared
bandwidth of the hub was being stretched, there was a need for a faster device and the
Ethernet switch came into the market. The switch provided dedicated paths to each of the
nodes connected to it and optimized the bandwidth available for better performance.
The switch and the router perform two
exclusive functions in a network. The router is used as a communication device between
segments of the network while the switch was used to optimize the bandwidth available
within each segment itself.
Today, Layer 2 switching is widespread in
the Indian market. There are a number of reasons to this exponential growth of switches in
a network. A switch, by way of its architecture, has a faster throughput than traditional
routers and thereby a lower latency than routers. It is an easily installable and
manageable device (near plug-and-play) compared to the complex installation and support of
routers. However, the most important feature is the extremely low cost per port of a
switch compared to the same of a router. This has resulted in MIS managers resorting to
switches more often for expanding networks, hence leading to the traditional Indian
enterprise network to be a flat one.
However, as we deploy increasingly more
switches, we should be conscious of that a switch is a Layer 2 device and is nothing but a
multi-port bridge. Though switches are cost-effective, what they could end up doing over a
period of time is flatten out the network. This would bring in the traditional bridging
problems into the network including broadcast storms, limited loop detection, and limited
To understand this issue more, let us take
a closer look at how networks grow over a period of time. A typical network contains two
parts-the core of the network and the edge of the network. The core normally is the
backbone through which entire traffic of the network flows. It often contains the gateway
through which a network communicates with other networks in the external world. The edge
consists of the different physical or logical segments of the network in an enterprise.
The classical model of building networks
can also be classified into two categories-the tactical approach and the strategic
approach. The tactical approach involves a reactive network infrastructure deployment
where the network manager evolves the network with more emphasis on the edge of the
network. He typically installs LAN switches and hubs on the edge of the network to provide
more ports for his increasing number of users.
The common argument favoring this approach
is that the investment in a network is not done upfront and as the technology prices drop
on the switching side, the entire cost of procuring the active components of a network is
fairly low over a period of time. However, this approach can be classified as a short-term
approach where the core of a network is often neglected. The unplanned growth of the edge
devices normally brings the weak backbone under tremendous pressure which could also lead
to a total collapse of the backbone.
And more often than not, the performance
and hence productivity of a network is drastically crippled due to its weak core which is
not able to handle the increasing backbone bandwidth requirements that emerging
applications demand. The strategic approach is a radically different one and is often very
difficult to implement. The network manager does a thorough evaluation and planning of his
network over a reasonably long period of time-e.g. five years. He then plans his core
carefully in such a way that the backbone can take care of all emerging applications the
company might deploy to increase user”s productivity. This would normally involve
optimization and planning of the switching to routing components ratio. Such a manager
normally appreciates the mutually different functions that switching and routing perform.
Once the robust core is put into place in his network, the manger expands the edge of the
network as the need arises.
The philosophy that a strategic approach
preaches is ”switch when you can, route when you must”. The strategic deployment would
normally involve a more robust and newer technology like Switched Routing and would not be
a one-time low cost. However, what is evaluated is the Total Cost of Ownership and not
just the purchasing cost.
In strategic approach, the various emerging
technologies need to be closely considered. The traditional router possesses Layer 3
intelligence which is normally required for robust networks. However, the traditional
router is not the ideal solution for the backbone, since the overall performance of the
backbone is slowed down due to the fact that the router has to process each and every
packet flowing through the backbone.
Which is why emerging Layer 3 standards
like MPOA (Multi Protocol Over ATM) are becoming increasingly popular. MPOA combines the
two essential functions involved in a network namely Switching and Routing. What MPOA
addresses is the requirement of faster performance on Layer 3 by using routing only when
needed and using Layer 2 switching technology used for frame forwarding after the
destination address is identified.
The MPOA model distributes routing among
the edge devices and attached hosts with MPOA clients, which forward packets, and MPOA
servers, which supply routing information. The MPOA client will look at the destination
network layer address of the packet, and resolve this to the correct address based on the
information received from the MPOA server or use information from its cache, if the
information is already downloaded.
The MPOA client will then establish a
direct virtual channel connection to the appropriate destination (due to the capabilities
of ATM) for the subsequent packets to flow through. This breaks the routing out of the
box, thereby overcoming the limitations of traditional routing. It gives a massive
performance advantage, simplifies management and control, and enables new applications
like corporate intranets and voice/multimedia communications.
The commoditization of Ethernet switches in
the market has been a bottleneck since it curbs the strategic planning of the network. A
network manager is tempted to go the tactical way due to the low costs involved in
installing LAN switches to stop the bleeding of the network itself. The price war in the
Ethernet Switch market and the confusion created by vendors about the capabilities of
Ethernet switching has made the Indian MIS manager overlook the Layer 3 traffic on his
network. This is a problem which will materialize slowly over a period of time and will
slowly hamper the performance of the network with the new applications that are needed
The onus is on the vendors to correctly
position the capabilities and drawbacks of the LAN switches and to present the newer
technologies to the Indian customer. Unless a strategic approach to building networks is
adopted by the Indian companies and til the vendors move out of the role of just selling
switches in the market to meet their revenues and start educating the customer on the
emerging new technologies, the Indian network is not going to be able to stand the assault
of the challenges posed by the twenty-first century.
Marketing Manager, Newbridge Networks.