Is A Fractional T1 The Better Choice For Your Business
is a fractional t1 the better choice for your business
The number of companies offering DS3 service has exploded.
more on how to choose a data center
A final reason for the reduction in DS3 pricing is the fact that equipement costs and the cost of supplying the bandwidth have decreased. With more competition in the marketplace service providers have to reduce their DS3 prices to attract customers and keep them from going to competitors.
There's a nice little
The Basics Of How Sip Session Initiation Protocol Drives Your Voip System Design And Function
Gigabit Ethernet Applications-is It A Fit For Your Organization TCP/IP,Application Acceleration Technology and the Last Mile Bottleneck
"Everyone wants applications, backups and file downloads to go faster. Network managers are constantly under pressure to make response time at remote sites more like that at headquarters. The traditional answer is to 'throw bandwidth at the problem,' a solution that doesn't always help and can cost a lot of money.
"The truth is that throwing bandwidth at the problem only works when the link utilization is high, and in most cases that is not the case. Applications can be slow for reasons other than lack of bandwidth. These reasons include:
- TCP protocol throttles throughput.
- - Application protocols, such as Microsoft's MAPI used by Exchange Server and CIFS used by its file system, are limited in throughput and slow the application down.
- - There is just too much being sent, the units of work keep growing larger and the amount of bandwidth needed to make a difference is too large to be practical. This is especially true as applications move to HTTP or use larger and larger files such as Word, CAD/CAM or Excel.
- - The size of e-mail attachments.
- - There is too much 'junk' or unimportant traffic taking up the bandwidth, starving the important traffic.
"The answer is found in the devices called Application Accelerators. Application acceleration addresses non-bandwidth congestion problems caused by TCP and application-layer protocols, significantly reduces the size of the data being sent along with the number of packets it takes to complete a transaction, and takes other actions to speed up the entire process.
Application accelerators can also monitor the traffic to let you understand what is happening and help with security. Thus application accelerators are an important tool in solving remote response-time problems."
Now let us understand what TCP is
TCP is a transport technology that is commonly used for the electronic movement of data between servers and other devices. Many storage vendors are beginning to use the TCP transport for replicating data between storage devices. However they are finding out that TCP as a transport has some basic limitations that cause many applications to perform poorly, especially over distance. TCP/IP performs sufficiently over short-distance LAN environments; however it was not well designed for transmission over Wide Area Networks (WANs). This article explores the challenges of TCP performance over the WAN and ways to mitigate these performance challenges with new data center appliances.
TCP Challenges
Window Size Limitations
Window size is the amount of data that is allowed to be outstanding (in the air) at any given point-in-time by the transport software. The available window size on a given bandwidth pipe is the rate of the bandwidth times the round-trip delay or latency. Using a cross-country OC-3 link (approximately 60ms based on a total 6000-mile roundtrip) creates an available data window of 155 Mbps X 60ms = 1,163 Kbytes. A DS3 satellite connection (540ms roundtrip) creates an available data window of 45 Mbps X 540ms = 3,038 Kbytes.
When this is contrasted with standard and even enhanced versions of TCP, there is a very large gap between the available window and the window utilized. Most standard TCP implementations are limited to 65-Kbyte windows. There are a few enhanced TCP versions capable of using up to 512 Kbytes or larger windows. Either case means an incredibly large amount of "dead air" and very inefficient bandwidth utilization resulting in poor performance for applications that are typically mission-critical.
Slow Start by Design
TCP data transfers start slowly and ramp-up to their maximum transfer rate, resulting in poor performance for short sessions. Slow start is used to avoid congestion due to assumptions that large numbers of sessions will be competing for the bandwidth.
Inefficient Error Recovery.During error recovery, TCP causes the entire stream from any lost portion to be retransmitted in its entirety. High-bit-error rates or packet-loss scenarios will cause large amounts of bandwidth to be wasted in resending data that has already been successfully received, all with the long latency time of the path. Each retransmission is additionally subjected to the performance penalty issues of slow start, which was explained above.
Packet Loss is Disruptive
Packet loss describes an error condition in which data packets appear to be transmitted correctly at one end of a connection, but never arrive at the other end. This is mainly due to:
* Poor network conditions causing damage to packets in transit.
* The packet was deliberately dropped by a router and/or switch because of WAN congestion.Packet loss can be disruptive to applications that must move data within windows of time. With more data that must be moved on a regular basis and the fact that backup windows are not growing to meet the data demands, packet loss can have a negative impact on meeting service-level agreements and production for many organizations.
Session Free-For-All is Not Free
Each TCP session is throttled and contends for network resources independently, which can cause over-subscription of resources relative to each individual session.
The net result of these issues is very poor bandwidth utilization. The typical bandwidth utilization for large data transfers over long-haul networks is usually less than 30%, and more often less than 10%. As fast as bandwidth costs are dropping, they are still not free.
How to Mitigate TCP/IP Performance Issues
Consider Using an IP Application Accelerator (Appliance)
Many new data center appliances are being used to optimize data delivery for IP applications. Some appliances mitigate performance issues by simply caching the data and/or compressing the data prior to transfer. Others have the ability to mitigate several TCP issues because of the superior architecture.
Whatever technology is used, it is important the appliances have the ability to mitigate latency issues, compress the data and shield the application from network disruptions. It is also important that these new data center appliances are transparent to operations and provide the same transparency to the IP application.
Transport Protocol Conversion
Some data center appliances provide alternative transport delivery mechanisms between appliances. In doing so, they re-ceive 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. It is important to 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 UDP socket calls as an efficient, low overhead, data streaming protocol to read and write from the network.
Compression Engine
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 TCP/IP Performance improvements centers on the issues 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 .01% to .5% in optical WANs to .01 to 1% in copper-based TDM networks. Either way, the loss of up to 1 or more packets in every 100 causes the TCP transport to retransmit packets, slow down the transmission of packets from a given source, and re-enter 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% 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 didn't make it, not the whole frame. This allows for the use of a better transport protocol that won't 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 from source to destination. This is completely transparent to the process running a given server application.
An Application.
A typical Constraint that can drive the Application Acceleration Market.
Bandwidth Costs have reduced due to the Competition between ISP'S. The Cost of Bandwidth will decrease by the day .The demand for more bandwidth is multiplying, as the health of the Economy is well and growing at high rates in countries like China,India and Brazil. All major verticals are expanding, Industry as a whole is doing well and is modernizing its facilities to remain Competitive and Coming up to best standards.
Although Bandwidth costs are coming down on the whole but due to the last mile bottlenecks the cost of upgrading Networks is very high. Although new Pop's are coming up but there is a huge gap between the supply and demand. Industry has to make do with their current bandwidths because of huge funds required for upgrading the last mile links.
Currently the last mile links are on radio or fiber, and upgrading them even to double their capacity involves a lot of Capital Investment. To upgrade a 2 Mb link to 4 Mb link ,the one time up- gradation cost is around US0,000.
This is one scenario in wich developing countries can derive benifit from Application Accelerators.By re-engineering the present networks and adding application accelerators, demand for higher bandwidth is being met very economically and efficiently.Countries facing Bandwidth bottlenecks will get respite for some time from these Appliances and meanwhich to completely mitigate bottlenecks put in place high speed last miles.
Summary and Conclusion
Business continuity realities, regulations and requirements mean organizations must implement some form of storage-to-storage replication application. Most will turn to TCP/IP WANs and will be disappointed with either the performance or the bandwidth costs. Implementing a TCP/IP performance enhancing proxy in other terms ''Application Accelerators''will eliminate that disappointment.
About the Author
Vijay Kaul is a Technology man doing Global Best Practices Awards assessment and recommendations, Business Analytics, Consulting and Project Management for the Information & Communication Technology Practice of a U.S. M.N.C. Vijay's greatest asset is his domain knowledge of both Telecom & I.T. domains and his understanding of the Markets.Vijay has a past experience of about 14 years and tracks the World Wide I.C.T. Markets
Like most telecommunications services DS3 prices (commonly known as T3) have been falling for the last few years.
Once again, the buyer is in control and can shop until he or she finds the price that is right for them. Perfect resource for every business considering deploying VoIP technology is some form or other. what he said. com">http://BroadBand-Nation.
With more competition in the marketplace service providers have to reduce their DS3 prices to attract customers and keep them from going to competitors. The number of companies offering DS3 service has exploded. This is due to several factors. com where you're always welcome to to drop in and catch up on the latest BroadBand news, tips, and ramblings for the masses.
Bandwidth Requirements For Medical Imaging Systems
is a fractional t1 the better choice for your business
The only factor that seems likely to inhibit prices from falling much further is the "last mile" or the connection from the users premise to the service providers' POP (Point of Presence).
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This is due to several factors. For now, enjoy those affordable DS3's and good luck finding a price. htm" target=_blank>VoIP training center courtesy of VoIP News anyone interested in VoIP should visit. com">http://BroadBand-Nation. This is due to several factors.
