Application Acceleration Technology
Many corporations require combined voice, video and Internet access with a
two-way Internet bandwidth of at least 100 Mbps. This is a forward-looking
composite requirement that recognizes that a typical corporation with 250+
employees will be watching videos, talking on the telephone, and accessing the
Internet all at the same time.
About 300 million people in the world are telecommuting to work today.
Better, faster, and cheaper communication infrastructure would mean a phenomenal
increase in productivity and a better quality of life.
Knowing the impact of Internet on mankind and despite hundreds of terabyte
Internet bandwidth capacity across the world, what is stopping us from using
bandwidth to its full extent? Why are we still talking of speed in terms of
kilobits when hundreds of terabyte Internet capacities have already been laid
The fiber glut
There exists a vast international bandwidth capacity across all continents
and countries connecting their various cities and towns and terminating at
various places that are called Point of Presence (PoP). More than a billion
Internet users exist throughout the world. The challenge consists of connecting
these users to the nearest POP. The connectivity between various client sites
and POPs, called the last mile connectivity, is the bottleneck.
Internet Service Providers (ISPs) built the long haul and backbone networks
spending billions over the past five years. ISPs spent to this extent to
increase the broadband capacity by 250 times in long haul; yet, the capacity in
the metro area increased only 16 fold. Over this period, the last mile access
has remained the same, with the result that data moves very slowly in the last
mile. Upgrading to higher bandwidths is either not possible or the cost is
extremely prohibitive. The growth of Internet seems to have reached a dead end,
with possible adverse effects on the quality and quantity of the Internet
bandwidth that is available for the growing needs of enterprises and
consumers.Compounding this is the technical limitations of Transmission Control
Protocol / Internet Protocol (TCP/IP).
The Internet works on a protocol called the TCP/IP. TCP/IP performs well over
short-distance Local Area Network (LAN) environments but poorly over Wide Area
Networks (WANs) because it was not designed for it.
TCP as a transport layer has several limitations that cause many applications
to perform poorly, especially over distance. These
include: window size limitations for transmission of data, slow start of data
transmission, inefficient error recovery mechanisms, packet loss, and disruption
of transmission of data. The net result of issues is poor bandwidth utilization.
The typical bandwidth utilization for large data transfers over long-haul
networks is usually less than 30 percent, and more often less than 10 percent.
Even if a chance of upgrading the last miles even at very high costs exists, the
effective increase would be only 10 percent of the upgraded bandwidth. Hence,
upgrading networks is a very expensive proposition.
A new technology called the 'Application Acceleration' has emerged, which
accelerates the Internet applications over WANs using the same Internet
infrastructure, circumventing to some extent the problems caused due to lack of
Application accelerators, as the name suggests, are appliances that
accelerate applications by reengineering the way data, video, and voice is
sent/transmitted over networks. Application acceleration addresses non-bandwidth
congestion problems caused by TCP and application-layer protocols, thereby,
significantly reducing the size of the data being sent along with the number of
packets it takes to complete a transaction, and performs other actions to speed
up the entire process.
Application accelerators can also monitor the traffic and help with security.
Some appliances mitigate performance issues by simply caching the data and/or
compressing the data before transfer. Others have the ability to mitigate
several TCP issues because of their superior architecture.
These appliances have the ability to mitigate latency issues, compress the
data, and shield the application from network disruptions. Further, these new
appliances are transparent to operations and provide the same transparency to
the IP application as TCP/IP application accelerators have the following
features using Layer 4-7 Switching.
Transport protocol conversion
Some data center appliances provide alternative transport delivery mechanisms
between appliances. In doing so, they receive the optimized buffers from the
local application and deliver them to the destination appliance for subsequent
delivery to the remote application process. Alternative transport technologies
are responsible for maintaining acknowledgements of data buffers and resending
buffers when required.
They maintain a flow control mechanism on each connection in order to
optimize the performance of each connection to match the available bandwidth and
network capacity. Some appliances provide a complete transport mechanism for
managing data delivery and use User Datagram Protocol (UDP) socket calls as an
efficient, low overhead, data streaming protocol to read and write from the
A compression engine as part of the data center appliance compresses the
aggregated packets that are in the highly efficient IP accelerator appliance
buffers. This provides an even greater level of compression efficiency, since a
large block of data is compressed at once rather than multiple small packets
being compressed individually. Allowing compression to occur in the
LAN-connected appliance frees up significant CPU cycles on the server where the
application is resident.
Overcoming packet loss
The largest challenge in the TCP/IP performance improvements centers is the
issue of packet loss. Packet loss is caused by network errors or changes better
known as network exceptions. Most networks have some packet loss, usually in the
0.01 percent to 0.5 percent in optical WANs to 0.01 percent to 1 percent in
copper-based Time Division Multiplexing (TDM) networks. Either way, the loss of
up to one or more packets in every 100 packets causes the TCP transport to
retransmit packets, slows down the transmission of packets from a given source,
and re-enters slow-start mode each time a packet is lost. This error recovery
process causes the effective throughput of a WAN to drop to as low as 10 percent
of whatever the available bandwidth is between two sites.
IP application accelerators optimize blocks of data traversing the WAN by
maintaining acknowledgements of the data buffers and only sending the buffers
that did not make it, and not the whole frame. This allows for the use of a
better transport protocol that will not retract data or move into a slow start
mode. Using a more efficient transport protocol has lower overhead and streams
the data on reads and writes cycles from source to destination. This is
completely transparent to the process running a given server application.
Web documents retrieved may be stored (cached) for a time so that they can be
conveniently accessed if further requests are made for them. There is no need
for the entire data to move cross the network and only updating requests are
sent across, thereby optimizing network bandwidth.
Server load Balancing
Server load balancers distribute processing and communications activity
evenly across a computer network so that no single device is overwhelmed. Load
balancing is especially important for networks where it is difficult to predict
the number of requests that will be issued to a server. Busy Web sites/Web sites
with a heavy traffic typically employ two or more Web servers in a
Secure sockets layer (SSL) is a popular method for encrypting data that is
transferred over the Internet. SSL acceleration is a method of offloading the
processor-intensive public key encryption algorithms involved in SSL
transactions to a hardware accelerator. Typically, this is a separate card in an
appliance that contains a co-processor able to handle most of the SSL
Despite the fact that it uses faster symmetric encryption for
confidentiality, SSL still causes a performance slowdown. That is because there
is more to SSL than the data encryption. The "handshake" process, whereby the
server (and sometimes the
client) is authenticated, uses digital certificates based on asymmetric or
public key encryption technology. Public key encryption is very secure, but also
very processor-intensive and thus has a significant
negative impact on performance. The method used to address the SSL
performance problem is the hardware accelerator. By using an intelligent card
that plugs into a PCI slot or SCSI port to do the SSL processing, it relieves
the load on the Web server's main processor.
Connection multiplexing works by taking advantage of a feature in HTTP/1.1
that allows for multiple HTTP requests to be made over the same TCP connection.
So instead of passing each HTTP connection from the client to the server in a
one-to-one manner, the appliance combines many separate HTTP requests from
clients into relatively few HTTP connections to the server. This keeps the
connections to the server open across multiple requests, thus eliminating the
high turnover that is typically encountered in high volume Web sites. The
ultimate result is that there is higher performance out of the same servers
without any changes or improvements to the server infrastructure.
A cluster is a group of application servers that transparently run
applications as if it were a single entity. Clusters can comprise redundant and
fail over-capable machines: A typical cluster in a network integrates Layer 4-7
Load Balancers, Gateway Routers, which exist at the end of a network on each
side, and various switches in a network, which integrates the application and
Web Servers with the whole Network. Firewalls are used in filtering port level
access to all network resources and data storage devices (which can use any
media such as Tape drives, Magneto- Optical drives or Simple hard drives). A
cluster manages the writing of data on main storage devices as well as the
redundant ones and manages switchover to redundant storage media in case of a
failure of primary data storage devices.
Network security (Firewalls)
Network security protects the networks and their services from unauthorized
modification, destruction, or disclosure, and provides assurance that the
network performs its critical functions correctly and that there are no harmful
side effects. It also includes providing for data integrity. Gateway that limits
access between networks in accordance with local security policy is called
Firewalls and can be implemented in Layer 4-7 Switching.
Firewalls are used to prevent unauthorized Internet users from accessing
private networks. All messages entering or leaving the intranet pass through the
firewall, which examines each message and blocks those that do not meet the
specified security criteria.A firewall is usually considered a first line of
defense in protecting private information.
Bandwidth management, QoS, monitoring and reporting
Bandwidth management appliances allocate bandwidth to mission-critical
applications, slow down non-critical applications, and stop bandwidth abuse in
order to efficiently deliver networked applications to the branch office. The
primary goal of Quality of Service (QoS) is to provide priority including
dedicated bandwidth, controlled jitter, and atency (required by some real-time
and interactive traffic) to applications traveling on the network.
End-to-end performance monitoring and reporting provides the WAN visibility
required to analyze the traffic; Layer 7 QoS allocates bandwidth according to
rules and policies. Traffic is automatically categorized into application
Easy to understand shaping policies such as "real-time" or "block" govern the
flow of traffic. Packet fragmentation assures that large data packets do not
violate VoIP/video latency budgets, while packet aggregation ensures higher WAN
capacity and stabilizes jitter. This guarantees that delay-sensitive traffic
such as VoIP can be allocated a minimum amount of bandwidth to ensure optimal
voice quality even when WAN links are congested or oversubscribed.
The net result of these features is that very high data transfer speeds, some
times as much as 10X, are achieved. This technology has come as a boon to the
Internet-starved industry achievement of higher bandwidth speeds and means that
organizations can now look forward to explosive growth in their Internet
The demand for Internet bandwidth is bound to increase by the day. The
application acceleration technology is expected to give the much-needed respite
to ISPs and the Government to better plan and implement the last miles on the
best possible media and resolve the last mile bottlenecks forever.
About the author: Vijay Kaul is a Technology man doing Business Analytics, Consulting and
Project Management for the Information & Communication Technology Practice of a
U.S. M.N.C. as an Industry Analyst .Vijay's greatest asset is his domain
knowledge of both Telecom & I.T. domains and his understanding of the Markets in
the Asia-Pacific. Vijay has a past experience of about 14 years and tracks the
Asia-Pacific I.C.T. Market