Sky X Technology
#1

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Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
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#2
INTRODUCTION

Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.

The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC's, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers.

Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.


The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC's.


PERFORMANCE OF TCP OVER SATELLITE

Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. However data networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks.

Communication over geosynchronous satellites, orbiting at an altitude of 22,300 miles has round trip times of approximately 540 m/s, an order of magnitude larger than terrestrial networks. The journey through the atmosphere can also introduce bit errors into the data stream. These factors, combined with backchannel bandwidth typically much smaller than that available on the forward channel, reduce the effectiveness of TCP which is optimized for short hops over low-loss cables or fiber.Eventhough the TCP is very effective in the local network connected by using cables or optical fibers by using its many features such as LPV6, LPsec and other leading-edge functionality. Also it will work with real time operating systems.TCP is designed for efficiency and high performance ,and optimized for maximum throughput and the highest transaction speeds in local networks.

But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links. Thus the advantages achieved by TCP in LAN's are no longer effective in the satellite link. So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the satellite link

The simple, heuristic data acknowledgment scheme used by TCP does not adapt well to long latency or highly asymmetric bandwidth conditions. To provide reliable data transmission, the TCP receiver constantly sends acknowledgments back to the sender. The sender does not assume that any data is lost or corrupted until a multiple of the round-trip time has passed without receiving an acknowledgment. This algorithm does not respond well over satellite networks where the round-trip time is long and error rates can be high. Further, this constant stream of acknowledgments wastes precious back channel bandwidth and if the back channel is small, the return of the acknowledgments to the sender can become the system bottleneck. The acknowledgements and error messages will always dominate the data transfer and the rate of flow reduces very much.

Congestion Avoidance

In order to avoid the possibility of congestive network meltdown, TCP usually assumes that all data loss is caused by congestion and responds to this by reducing the transmission rate. However, over satellite links, TCP misinterprets the long round-trip time and bit errors as congestion and responds inappropriately. Similarly, the TCP Slow Start algorithm, which over the terrestrial infrastructure prevents new connections from flooding an already congested network, forces an excessively long ramp-up period for each new connection over satellite. While these congestion avoidance mechanisms are vital in routed environments, they are ill-suited to single-path satellite links.

So the congestion avoidance mechanisms used by TCP is also not suited for the satellite page link since it reduces the data flow through the network and thus reduces the overall rate of data transfer.

SKY X SYSTEM

Sky X Technology Overcomes TCP Performance Limitations

Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users. The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions

The Sky X gateway works by intercepting the TCP connection from the client and converting the data to the Xpress Transport Protocol (XTP) for transmission over the satellite. The Sky X gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the server. This architecture offers vastly improved performance while remaining entirely transparent to the end user and fully compactable with the internet infrastructure. No changes are required to the client or server and all applications continue to function without modification. This architecture is also referred to as TCP Performance Enhancing Proxy (TCP-PEP) and is compactable with IETF RFC 3135.

Sky X Technology

The Sky X gateway splits the single TCP connection into three separate components. A TCP connection on the remote side between the client and Sky X gateway, an XTP connection involving Sky X protocol over the satellite between the two Sky X gateways and a TCP connection between the opposite Sky X gateway and server.

XTP is a reliable, transport-layer protocol specifically designed to operate efficiently over high-speed networks and offers a level of performance not possible with TCP on long latency, high loss satellite links. XTP is an open standard developed by the XTP Forum, a non-profit organization composed of networking protocol researchers, implementers, and user organizations.
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By splitting the end-to-end TCP connection, the segment over the satellite can take advantage of the performance of XTP. TCP congestion avoidance mechanisms remain in place over the terrestrial connections to protect the stability of the routed network. The two Sky X gateways pass control data between each other, allowing the Sky X gateway on the opposite side of the satellite to appear to be the original source or destination device. This architecture maintains full TCP reliability and end-to-end flow control.

Sky X Technology
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Web Pre-Fetch functionality further enhances the performance of HTTP transfers over the satellite page link by pro-actively retrieving the many embedded objects on a Web page along with the requested HTML page. The Sky X system delivers the Web objects to the Sky X gateway on the client side of the satellite page link where they can be served locally when requested by the browser, avoiding the satellite delay
The Sky X gateway XR10, XH45, and XH155 are available as ready-to-install hardware solutions which can be added to any satellite network. The Sky X Client software installs directly on the PCs of end-users and works in conjunction with a Sky X Server SS10 or SS45 hardware unit located at the network hub. Mentat also licenses the Sky X gateway technology in software source code form for integration with satellite modems, VSATs, routers, caching systems, or any other satellite connectivity equipment. The Sky X gateway can also be used in multilink configurations where a single Sky X gateway hub unit enhances the performance of multiple separate outbound links from a single uplink facility.

The Sky X Client / Server product operates similarly to the Sky X gateway except the Sky X Client software is installed directly onto the client PC. Connections from applications running on the PC are intercepted and sent over the satellite using Sky X protocol. At the network hub, a Sky X Server establishes a TCP connection with the destination server.

Sky X Client/Server

The Sky X Client / Server increases the throughput and efficiency of network access over satellites by transparently replacing TCP with the Xpress Transport Protocol (XTP) for the satellite segment of the connection. Combined with data compression and Web-specific enhancements, the Sky X system provides maximum performance under the long latency, high loss, and asymmetric bandwidth conditions typical of satellite communications.

The sky X client/server system enhances the performance of the internet and private network access over satellite links. The sky X client software installed on the PC™s of the end user, works in conjunction with a sky X server hardware unit located at the network hub. Through the use of a unique connection splitting and protocol “translation system, the sky X client/server system overcomes the deficiencies of TCP/IP in satellite “based networks while remaining entirely transparent to end-user applications. The sky X client is ideal for use with any satellite receiver card or set “top box

Sky X Client / Sky X Server Operation

The Sky X Client / Server increases the throughput and efficiency of network access over satellites by transparently replacing TCP with the Xpress Transport Protocol (XTP) for the satellite segment of the connection. Combined with data compression and Web-specific enhancements, the Sky X system provides maximum performance under the long latency, high loss, and asymmetric bandwidth conditions typical of satellite communications.

The Sky X Client, installed on Microsoft Windows-based computers, transparently intercepts TCP connections from applications running on the PC and transmits the data over the satellite page link using XTP. The Sky X Server, installed at the hub of the satellite network, establishes a new TCP connection for communication with any device on the local network or over the Internet. Through this unique, patented architecture, the Sky X Client / Server system requires no proxy settings while providing performance enhancement for all TCP applications.

The Sky X Server is available in two models namely the SS10 and SS45. The SS10 provides Sky X enhancement for links of up to 10 Mbps while the SS45 provides Sky X enhancement for links of up to 45 Mbps.

Sky X Multicast Fan-Out

Computer networking traditionally relies on unicast data transfers which establish point-to-point connections between devices. In situations where the same data is transferred to multiple users, the server must send a copy of the file to each recipient independently. This process is both time consuming and wastes much of the bandwidth resources.

In contrast, multicast technology makes it possible for multiple recipients to receive a single data stream. This can be an especially powerful tool for satellite networks or similar architectures where the multicast transfer can take advantage of an underlying page link layer broadcast media. Unfortunately, the only multicast capability built into the Internet Protocol is a UDP-based, unreliable, best-effort service that is only appropriate for real-time streaming applications such as event broadcasting. Because UDP-based IP multicast does not include any mechanisms for detection and retransmission of lost or corrupted data and does not resequence any packets that arrive out of order, IP multicast is not suitable for file downloads and other data transfer applications. Sky X Multicast Fan-Out offers a simple and convenient solution for reliable multicast over wide area networks. By taking advantage of reliable multicast functionality built directly into XTP, the open-standard transport-layer protocol used by the Sky X Gateway to transfer data over the WAN link, the Sky X Gateway provides fast, efficient, fully reliable multicast file transfers. Any data that is lost or corrupted is retransmitted, providing transfer reliability and rendering special FEC software unnecessary
The Sky X multicast fanout, an integral component of the Sky X gateway, transparently converts TCP unicast connections into reliable multicast transfers. Through the use of common TCP based applications such as FTP, the Sky X gateway can deliver a file to every remote location across a wide area network with only a single multicast transfer. Sky X multicast fanout is built on the industry leading Sky X gateway IP over satellite performance enhancement system. Because the Sky X multicast fanout process is transparent to the end devices , any machine can originate or receive the multicast transfer regardless of operating system and without requiring the installation of any specialized multicast software.

By combining this reliable multicast transmission technology with a transparent fanout functionality which allows any TCP connection to be converted into a multicast transfer, the Sky X gateway marries the power of multicasting with the convenience of using FTP or any other TCP-based application. In addition to the multicast benefits themselves, the Sky X gateway includes on-the-fly data compression which further increases transfer speeds for compressible data by up to 5 times. Sky X multicast fanout functionality is ideal for file transfers, cache replication, video file distribution, content delivery networks, database replication, and any other distribution of data or files to multiple users over a satellite page link or other wide area network.

Sky X Performance

The performance benefits of the sky X gateway depend on many factors including the bandwidth, delay, asymmetry and bit error rate of the link, the number of simultaneous connections, the compressibility of the data and the behavior of the application itself. Below are data for two typical applications across a range of conditions

File Transfers

The following file transfer tests illustrate the benefits of Sky X performance enhancement for different windows sizes, page link band-widths, round-trip times, and bit error rates. Users should expect similar results for any large, single-connection data transfer. Each graph shows Sky X enhancement for three cases: no compression, highly compressible text, and Corpus benchmark compressibility.

Window Size and Link Speed vs. Throughput
Without performance enhancement, a default window size of 8 KB limits TCP throughput to less than 100 Kbps over satellite. As the graph on the left illustrates, even on server operating systems using a 32 KB window, TCP is only able to reach a through-put of 440 Kbps. Sky X gateway overcomes this limitation, taking full advantage of the available bandwidth regardless of the window size of the client or server. For compressible data, Sky X can provide throughput rates far greater than the page link bandwidth.

Sky X Technology

Round-Trip Delay vs. Throughput

The Sky X gateway system removes the dependency of TCP on the round-trip time of the link. The figure below shows the measured throughput on an error-free, 10 Mbps link. These results illustrate that TCP throughput drops rapidly as the round-trip time increases. In contrast, Sky X is able to maintain full usage of the page link regardless of the round-trip time. For compressible text, Sky X consistently delivers throughput rates greater than the actual bandwidth.

Sky X Technology

Bit Error Rate vs. Throughput
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The Sky X system overcomes the high sensitivity of TCP to the bit error rate of the link. The graph given below shows the throughput as a function of the bit error rate for a 10 Mbps satellite page link using a 1 MB TCP window. Even at low error rates, TCP is able to deliver only 1.5 Mbps, while at an error rate of 1×10-5, TCP™s throughput drops to less than 0.03 Mbps. Sky X fully saturates the page link at low error rates and even at an error rate of 1×10-5, achieves 5.1 Mbps without compression and up to 15.8 Mbps for compressible data
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courtesy
http://smartlogixtechnicalarticles/sky-x-technology/
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#3
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Submitted by
M. Srikanth
06B91A0551
CSE “ IV (1)1. Topic Identification:
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks
is restricted to only a fraction of available bandwidth. We can overcome these restrictions by using the Sky X protocol.
2. Scope:
Networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks. The Sky-X technology can be used to overcome these drawbacks.
The Sky-X family consists of the Sky-X Gateway, Sky-X Client/Server and the Sky-X OEM product. The Sky-X solution is entirely
transparent to end users, works with all TCP applications and does not require any modifications to end client and servers.
3. Mechanism:
The Sky-X Gateway and Sky-X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long
latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky-X system to a
satellite network allows users to take full advantage of the available bandwidth. The Sky-X Gateway transparently enhances
the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky-X
Client and the Sky-X Server enhance the performance of data transmissions over satellites directly to end user PC's, thereby
increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. Sky-X products are the leading
implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP), or
satellite spoofer. The Sky-X gateways are available as ready to install hardware solutions which can be added to any
satellite network.
Sky-X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data
compression, and Web pre-fetching, while remaining entirely transparent to end users. The Sky-X gateway works by
transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the
hop over the satellite page link which the protocol is optimized for satellite conditions.
The Sky-X gateway works by intercepting the TCP connection from the client and converting the data to the Xpress Transport
Protocol (XTP) for transmission over the satellite. The Sky-X gateway on the opposite side of the satellite page link translates
the data back to TCP for communication with the server. This architecture offers vastly improved performance while remaining
entirely transparent to the end user and fully compactable with the internet infrastructure. No changes are required to the
client or server and all applications continue to function without modification. This architecture is also referred to as TCP
Performance Enhancing Proxy (TCP-PEP)
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#4
send me power point presentation of sky x technology
send me sky x technology fuull ppt
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#5
send me power point presentation of sky x technology pl
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#6
[attachment=3358]


WELCOME TO SEMINAR

ON SKY X-TECHNOLOGY

: submitted By:
Priti.s.k


AGENDA:

Introduction
Why sky X- Technology?
Working Details
Application
Merits
Demerits
Conclusion
Bibliography


Introduction :

Satellites are an attractive option for

carrying Internet and other IP traffic

to many locations across the globe where

terrestrial options are limited .

The Sky X technology replaces TCP over

satellite page link with a protocol optimized

for the high loss and bandwidth

conditions of the typical satellite

communication.

Adding the Sky X system to a satellite

network allows users to take full

advantage of the available bandwidth





The Sky X technology transparently

enhances the performance of all users on

a satellite network .

The Sky X increases web performance

by 3 times or more and file transfer

speeds by 10 to 100 times.

The Sky X solution is entirely

transparent to end users, works with all

TCP applications and does not require

any modifications to end client and

servers.
Why sky X-Technology???
Satellites are ideal for providing

internet and private network access over

long distance and to remote locations.

However the internet protocols are not

optimized for satellite conditions and

consequently the throughput over the

satellite networks is restricted to only

a fraction of available bandwidth.

Thus We need sky x technology to over

come these restrictions and to access

maximum bandwidth.
WORKING :

Sky X Technology Overcome TCP


Performance Limitations.

Even though the TCP is very effective in

the local network connected by using

cables or optical fibers by using its

many features

But the satellite conditions adversely

interact with a number of elements of

the TCP architecture, including it s

window sizing, congestion avoidance

algorithms, and data acknowledgment

mechanisms, which contribute to severely

constrict the data throughput that can

be achieved over satellite links.






Thus the advantages achieved by TCP in

LAN's are no longer effective in the

satellite link.

So it is desirable to design a separate

protocol for communication through the

satellite to eliminate the disadvantages

of using TCP over the sat


Sky X products increase the

performance of IP over satellite through

a combination of protocol connection-

splitting, data compression.





The Sky X gateway works by transparently

replacing TCP connections from the

client and converting the data to Xpress

Transport protocol (XTP) for the hop

over the satellite page link .

The Sky X system delivers the Web

objects to the Sky X gateway on the

client side of the satellite page link where

they can be served locally when

requested by the browser, avoiding the

satellite delay.

The sky X client/server system enhances

the performance of the internet and

private network access over satellite

links
XTP Protocol :


Xpress Transport Protocol (XTP) is a

transport layer protocol for high-speed

networks promoted by the XTP Forum

developed to replace TCP.

XTP provides protocol options for error

control, flow control, and multicast

mode.

Instead of separate protocols for each

type of communication, XTP controls

packet exchange patterns to produce

different models.

Characteristics of XTP :

1> Error control
2> flow Control
3>Byte ordering
4>Prioritization Issues
5>Multicast mode
6>Selective Retransmission
7>Multi-packet handshaking
Multi-Packet Handshaking :

The scenario above depicts how XTP can

reliably set up a connection between two

user processes, transmit data, and close

the connection with a minimum of three

packets .

In this scenario, the source initially

transmits packet (A) . At the

destination the header is examined and

it is determined that the source wishes

to establish a connection

The packet's data are then queued for

transfer to the waiting destination user

process .

After successfully transferring the

received data to the host, the

destination complies by sending control

packet (B) .

This packet acknowledges the receipt of

the data, and indicates that the

destination is also ready t o close the

connection.

On receiving packet (B), the sender

emits control packet ©, and closes its

side of the connection ” thus completing

the three way handshake.
Sky x-Gateway :

The Sky X gateway works by intercepting

the TCP connection from the client and

converting the data to the XTP for

transmission over the satellite.

The Sky X gateway on the opposite side

of the satellite page link translates the

data back to TCP for communication with

the server.

This architecture offers vastly improved

performance while remaining entirely

transparent to the end user and fully

compactable with the internet

infrastructure.

No changes are required to the client

or server and all applications continue

to function without modification.







The SkyX Gateway XR10 is well suited to


networks with high latency, high bit

error and asymmetric links.

Designed as an remote device, it

performs best at maximum bandwidth with

a single, very large FTP”and supports an

industry-best number of simultaneous

sessions and connection turnover rate.

Application :

Used for Satellite communication.

Used for accessing web in fastest speed.

Used For data transfer, File Transfer

efficiently.



Merits :

1> Increases web performance 3 times

faster.

2> Does not require any modifications to

end client and servers.
3>Sky X Gateway provides fast,

efficient, fully reliable multicast file

transfers.
Future enhancement :
A product called XipLink which is under

developing will replace the Sky X.

It is very much the same as the Sky X

with extra capabilities.

It optimize all TCP/IP traffic,

basically the page link itself.

Conclusion :
Thus Sky -x technology is best suited

for for satellite communication using

XTP protocol and Sky x gateway.

The Sky X system of a satellite network

allows users to take full advantage of

the available bandwidth

It gives all features required for

successful data Transmission.




Bibliography :

The Xpress Transfer Protocol (XTP) ” A

Paper by Robert M. Sanders and Alfred C.

Weaver, University of Virginia

weaver@virginia .edu.

Research and Development of High-End

Computer Networks at GSFC . by J.

Patrick Gary. Earth and Space Data

Computing Division.

Wikipedia


Any Questions???

Thank you!!!
Reply
#7
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SKY X TECHONOLOGY
Contents
INTRODUCTION

The internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth.
The Sky X systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication.
Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth.
The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PCâ„¢s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times.


Sky X System

Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users.
The Sky X works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions.


Gateway Operations..

The Sky X gateway works by intercepting the TCP connection from the client and converting the data to the Xpress Transport Protocol (XTP) for transmission over the satellite.
The Sky X gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the server.
This architecture offers vastly improved performance while remaining entirely transparent to the end user.
The Sky X gateway splits the single TCP connection into three separate components.
A TCP connection on the remote side between the client and Sky X gateway, an XTP connection involving Sky X protocol over the satellite between the two Sky X gateways and a TCP connection between the opposite Sky X gateway and server.

XTP

XTP is a reliable, transport-layer protocol specifically designed to operate efficiently over high-speed networks and offers a level of performance not possible with TCP on long latency, high loss satellite links.


Working

The two Sky X gateways pass control data between each other, allowing the Sky X gateway on the opposite side of the satellite to appear to be the original source or destination device. This architecture maintains full TCP reliability and end-to-end flow control.


Client-server operations

The Sky X Client / Server increases the throughput and efficiency of network access over satellites by transparently replacing TCP with the Xpress Transport Protocol (XTP) for the satellite segment of the connection.
The sky X client/server system enhances the performance of the internet and private network access over satellite links.
The sky X client software installed on the PCâ„¢s of the end user, works in conjunction with a sky X server hardware unit located at the network hub.



Operations of client-server¦

The Sky X Client, installed on Microsoft Windows-based computers, transparently intercepts TCP connections from applications running on the PC and transmits the data over the satellite page link using XTP.
The Sky X Server, installed at the hub of the satellite network, establishes a new TCP connection for communication with any device on the local network or over the Internet.
The Sky X Server is available in two models namely the SS10 and SS45. The SS10 provides Sky X enhancement for links of up to 10 Mbps while the SS45 provides Sky X enhancement for links of up to 45 Mbps.


Sky X Multicast Fan out

Computer networking traditionally relies on unicast data transfers which establish point-to-point connections between devices.
In situations where the same data is transferred to multiple users, the server must send a copy of the file to each recipient independently. This process is both time consuming and wastes much of the bandwidth resources.
In contrast, multicast technology makes it possible for multiple recipients to receive a single data stream.
The Sky X multicast fanout, an integral component of the Sky X gateway, transparently converts TCP unicast connections into reliable multicast transfers.
Through the use of common TCP based applications such as FTP, the Sky X gateway can deliver a file to every remote location across a wide area network with only a single multicast transfer.
By combining this reliable multicast transmission technology with a transparent fanout functionality which allows any TCP connection to be converted into a multicast transfer.
Sky X multicast fanout functionality is ideal for file transfers, cache replication, video file distribution, content delivery networks, database replication, and any other distribution of data or files to multiple users over a satellite page link or other wide area network.


Performance

Without performance enhancement, a default window size of 8 KB limits TCP throughput to less than 100 Kbps over satellite. As the graph on the left illustrates, even on server operating systems using a 32 KB window, TCP is only able to reach a through-put of 440 Kbps.
Sky X gateway overcomes this limitation, taking full advantage of the available bandwidth regardless of the window size of the client or server. For compressible data, Sky X can provide throughput rates far greater than the page link bandwidth.




Round-Trip Delay vs. Throughput

The Sky X gateway system removes the dependency of TCP on the round-trip time of the link.
The figure below shows the measured throughput on an error-free, 10 Mbps link. These results illustrate that TCP throughput drops rapidly as the round-trip time increases.
In contrast, Sky X is able to maintain full usage of the page link regardless of the round-trip time. For compressible text, Sky X consistently delivers throughput rates greater than the actual bandwidth.



Bit Error Rate vs. Throughput

The Sky X system overcomes the high sensitivity of TCP to the bit error rate of the link.
The graph given below shows the throughput as a function of the bit error rate for a 10 Mbps satellite page link using a 1 MB TCP window.
Even at low error rates, TCP is able to deliver only 1.5 Mbps.
Sky X fully saturates the page link at low error rates and even at an error rate of 1×10-5, achieves 5.1 Mbps.




Applications

The Sky X gateway combines protocol, application and system level enhancements to provide maximum throughput for satellite networks.
The Sky X Protocol utilizes a highly efficient selective retransmission algorithm for the acknowledgment of data. Because there is only a single path over the satellite with no intermediate routing.
Sky X products include HTTP specific optimizations to further accelerate web downloads.



Packeteer SKY X

Packeteer Introduces New SkyX Accelerators for Improved TCP-Based Application Performance.
New SkyX Accelerators Support Expanded Range of Link Speeds.
The introduction of two new SkyX Accelerator models based on new hardware platforms that provide substantially improved scalability to support future features and functional enhancements.
Packeteer's SkyX Accelerators improve TCP-based application performance including SAP, FTP file transfers, e-mail and Web access.



SKY X accelerator

When TCP protocol design limitations, high latency and lost packets threaten application connection speed, SkyX Accelerator ramps flow, fully utilizes links and keeps data moving along.
Accelerate file trasfers, large and small speed XML.
Optimize application performance over high-latency and satellite links.
Increase page link utilization on fat WAN Links.
Maximize bandwidth utilization and ROI.
Minimize retransmission and recover more quickly from errors.


Conclusion

The sky X gateway is the leading solution for overcoming the limitations of TCP/IP over satellite. ISPâ„¢s, corporations, governments, and military organizations around the world rely on sky X gateway to enhance the performance of their satellite networks.
Testing by independent third parties including INTELSAT and NASA confirms that the sky X Gateway dramatically improves performance for the internet and private access over satellite networks.
The world is reducing to a global village by the use of satellite communication and so the improvement in the rate of information interchange through satellite is a must and thus sky X technology becomes unavoidable.
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#8
[attachment=3884]

PRESENTATION ON
Sky X TECH.

INTRODUCTION

¢ Sky X is a new techology which overcome some restriction in the networks.
Satellites are ideal for providing internet and private network access over long distance and to remote locations.
However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth.
The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers.
The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC's, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times.

Sky X technology

¢ Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users.
¢ The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions
The Sky X gateway works by intercepting the TCP connection from the client and converting the data to the Xpress Transport Protocol (XTP) for transmission over the satellite.
The Sky X gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the server.
This architecture offers vastly improved performance while remaining entirely transparent to the end user and fully compactable with the internet infrastructure.
No changes are required to the client or server and all applications continue to function without modification.
The two Sky X gateways pass control data between each other, allowing the Sky X gateway on the opposite side of the satellite to appear to be the original source or destination device. This architecture maintains full TCP reliability and end-to-end flow control.
The Sky X system delivers the Web objects to the Sky X gateway on the client side of the satellite page link where they can be served locally when requested by the browser, avoiding the satellite delay.
The Sky X gateway XR10, XH45, and XH155 are available as ready-to-install hardware solutions which can be added to any satellite network.
The Sky X Client software installs directly on the PCs of end-users and works in conjunction with a Sky X Server SS10 or SS45 hardware unit located at the network hub.
¢ The Sky X gateway can also be used in multilink configurations where a single Sky X gateway hub unit enhances the performance of multiple separate outbound links from a single uplink facility.
¢ The Sky X Client / Server product operates similarly to the Sky X gateway except the Sky X Client software is installed directly onto the client PC.



Sky X Client/Server

The Sky X Client / Server increases the throughput and efficiency of network access over satellites by transparently replacing TCP with the Xpress Transport Protocol (XTP) for the satellite segment of the connection.
The sky X client/server system enhances the performance of the internet and private network access over satellite links.
The sky X client software installed on the PCâ„¢s of the end user, works in conjunction with a sky X server hardware unit located at the network hub.
The Sky X client/server system overcomes the deficiencies of TCP/IP in satellite “based networks while remaining entirely transparent to end-user applications. The sky X client is ideal for use with any satellite receiver card or set “top box

Sky X Client / Sky X Server Operation

The Sky X Client, installed on Microsoft Windows-based computers, transparently intercepts TCP connections from applications running on the PC and transmits the data over the satellite page link using XTP. The
¢ Sky X Server, installed at the hub of the satellite network, establishes a new TCP connection for communication with any device on the local network or over the Internet.

¢ The Sky X Server is available in two models namely the SS10 and SS45.
¢ The SS10 provides Sky X enhancement for links of up to 10 Mbps while the SS45 provides Sky X enhancement for links of up to 45 Mbps.
The SkyX Gateway intercepts TCP connections from the sender and converts the data to the SkyX Protocol for transmission over the satellite.
The SkyX Gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the receivers.

Advantages
1. Increased Performance:-

The SkyX Gateway increases the throughput rate by 3 times or more for Web traffic and up to 10 to 100 times for file downloads.

2. Reduced FEC Usage:-

The SkyX Gateway offers high levels of performance even at bit error rates that reduce TCP performance to near zero. Improved response to bit errors reduces the effects of rain fade and lowers the level of forward error correction encoding required, thereby gaining additional usable bandwidth from a given link.

Important Features:-
1.Easy Installation:-

The XH45 includes two 10/100baseT Ethernet ports for easy installation into any standard TCP/IP network.

2. High Performance:-

The SkyX Gateway enhances the performance of Internet, intranet, extranet, private network, or any other TCP/IP connections over satellite links.

4.45 Mbps Capacity:-
The XH45 is designed for satellite links of up to 45 Mbps. The XH45 can also be used in combination with multiple XR10 units as the hub configuration.
¢ Data Compression:-
In addition to protocol enhancement to overcome TCP's limitations, depending on data rates and traffic patterns, the SkyX Gateway can offer compression ratios of up to 4:1, extending the value of your satellite bandwidth.

Web-Based Monitoring Console:-

Performance of the XH45 can be monitored through a Web-based console, accessible from any browser.
Reply
#9
I tried to enhance the images using photoshop. The text has been made readable. I've increased the resolution of the images too. Some text remain unreadable as they are very hazy. I'm sure that one who has read the report can figure out what the text maybe.
[attachment=3939]
[attachment=3940]
[attachment=3941]
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click the images to enlarge
Reply
#10
plz send me d demerits and year of introduction of sky x technology
my id is: lekha.tharoor[at]gmail.com
Reply
#11
pls send me the year of introduction of sky x technology...
my gmail id is SreesaEaswar[at]gmail.com
Reply
#12
please give detailed discription about sky x accelerator,xtp.
Reply
#13



Submitted by
Asha Thomas

[attachment=7771]

INTRODUCTION
Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited .

The Sky X technology replaces TCP over satellite page link with a protocol optimized for the high loss and bandwidth conditions of the typical satellite communication.

Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth


The Sky X Technology transparently enhances the performance of all users on a satellite network.

The Sky X increases web performance by 3 times or more and file transfer speeds by 10 to 100 times.

The Sky X solution is entirely transparent to end users , works with all TCP applications and does not require any modifications to end client and servers.

IMPORTANT FEATURES

Easy Installation:- This technology provides easy installation into any standard TCP/IP network.

High Performance:- The Sky X Gateway enhances the performance of Internet,Intranet,Extranet,private network or any other TCP/IP connections over satellite links.

4.45 Mbps Capacity:-The Sky X acclerator XH45 is designed for satellite links upto 45 Mbps.The XH45 can also be used in combination with multiple XR10 units as the hub configuration.


WHY DO WE NEED SKY X TECHNOLOGY ?

The internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth.


Thus,we need Sky X Technology to overcome these restrictions and to access maximum bandwidth.

WORKING:-

The Sky X works by transparently replacing TCP connections from the client and converting the data to Xpress Transport Protocol(XTP) which is the protocol optimized for satellite conditions.

Sky X Gateway works by intercepting the TCP connection from the client and converting the data to the Xpress Transport Protocol(XTP) for transmission over satellite.

The Sky X gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the server.
The 2 Sky X gateways pass control data between each other allowing the Sky X gateway on the opposite side of the satellite to appear to be the orginal source or destination device.



Reply
#14


please provide additional information about SKY- X TECHNOLOGY technical seminar report
Reply
#15
additional information are there in previous pages and the below thread.

http://studentbank.in/report-technical-s...technology
Reply
#16


[attachment=8519]

[attachment=8520]

zAfter successfully transferring the received data to the host, the destination complies by sending control packet (B) .


Introduction :

Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited .

The Sky X technology replaces TCP over satellite page link with a protocol optimized for the high loss and bandwidth conditions of the typical satellite communication.

Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth

The Sky X technology transparently enhances the performance of all users on a satellite network .

The Sky X increases web performance by 3 times or more and file transfer speeds by 10 to 100 times.

The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers.

Why sky X-Technology???


WORKING :


Sky X Technology Overcome TCP Performance Limitations.

Even though the TCP is very effective in the local network connected by using cables or optical fibers by using its many features

But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links.


Thus the advantages achieved by TCP in LAN's are no longer effective in the satellite link.

So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the sat


Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression.


The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link .

The Sky X system delivers the Web objects to the Sky X gateway on the client side of the satellite page link where they can be served locally when requested by the browser, avoiding the satellite delay.

The sky X client/server system enhances the performance of the internet and private network access over satellite links

XTP Protocol :

Xpress Transport Protocol (XTP) is a transport layer protocol for high-speed networks promoted by the XTP Forum developed to replace TCP.

XTP provides protocol options for error control, flow control, and multicast mode.

Instead of separate protocols for each type of communication, XTP controls packet exchange patterns to produce different models.


Characteristics of XTP :

1> Error control
2> flow Control
3>Byte ordering
4>Prioritization Issues
5>Multicast mode
6>Selective Retransmission
7>Multi-packet handshaking

The scenario above depicts how XTP can reliably set up a connection between two user processes, transmit data, and close the connection with a minimum of three packets .

In this scenario, the source initially transmits packet (A) . At the destination the header is examined and it is determined that the source wishes to establish a connection

The packet's data are then queued for transfer to the waiting destination user process .

After successfully transferring the received data to the host, the destination complies by sending control packet (B) .

This packet acknowledges the receipt of the data, and indicates that the destination is also ready t o close the connection.

On receiving packet (B), the sender emits control packet ©, and closes its side of the connection — thus completing the three way handshake.


Sky x-Gateway :
The Sky X gateway works by intercepting the TCP connection from the client and converting the data to the XTP for transmission over the satellite.

The Sky X gateway on the opposite side of the satellite page link translates the data back to TCP for communication with the server.

This architecture offers vastly improved performance while remaining entirely transparent to the end user and fully compactable with the internet infrastructure.

No changes are required to the client or server and all applications continue to function without modification.


Application :
Used for Satellite communication.

Used for accessing web in fastest speed.

Used For data transfer, File Transfer efficiently.



Merits :
1> Increases web performance 3 times faster.

2> Does not require any modifications to end client and servers.
3>Sky X Gateway provides fast, efficient, fully reliable multicast file transfers.

Future enhancement :
A product called XipLink which is under developing will replace the Sky X.

It is very much the same as the Sky X with extra capabilities.

It optimize all TCP/IP traffic, basically the page link itself.

Conclusion :
Thus Sky -x technology is best suited for for satellite communication using XTP protocol and Sky x gateway.

The Sky X system of a satellite network allows users to take full advantage of the available bandwidth

It gives all features required for successful data Transmission.





Reply
#17
plz provide additional info on sky x technology....the references and biblograph...thanks in advance..
Reply
#18
send the document and ppt
Reply
#19
thanku....................
Reply
#20
[attachment=9948]
SKY X TECHNOLOGY
Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or [censored] prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
INTRODUCTION
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC’s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers
Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.
The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC’s.
Reply
#21
PRESENTED By-:
Prakash Upadhyay

[attachment=11226]
INTRODUCTION
• SKY- X Technology
• A Technology that use for remote access of internet through satellite.
• We can over come internet protocols restrictions by using the Sky X protocols.
• Sky X products are the leading implementation of a class of products
• known variously as protocol gateway TCP Performance Enhancing Proxy
• (TCP/PEP) , or satellite spoofer.
• PROTOCOLS
• TYPES OF PROTOCOL
• PROTOCOL SERVICES
• Importance Of Protocol:
• Why SKY-X ...?
• Architecture
• Sky-x Client
Sky-x Client Architecture
• Sky-X Server
• SKY-X Client Server
• CLIENT SERVER
• Sky-X Gateway
• Gateway System
• XTP- Connection
• XTP- Connection
• SKY - X Characteristic
CHARACTERISTIC
 File Transfers
-The following file transfer tests illustrate the benefit of Sky X performance enhancement for different windows sizes, page link band-widths, round-trip times, and bit error rates. Users should expect similar results for any large, single connection data transfer. Each graph shows Sky X enhancement for three cases:
no compression, highly compressible text, and Corpus benchmark compressibility
 Window Size and Link Speed vs Throughput
A default window size of 8 KB limits TCP throughput to less than 100 Kbps over satellite. Even on server operating systems using a 32 KB window, TCP is only able to reach a through-put of 440 Kbps.
• Sky X gateway overcomes this limitation, taking full advantage of the available bandwidth .
• Regardless of the window size of the client or server. For compressible data, Sky X can provide throughput rates far greater than the page link bandwidth.
 Round-Trip Delay vs. Throughput
 The Sky X gateway system removes the dependency of TCP on the round-trip time of the link.
 These results illustrate that TCP throughput drops rapidly as the round-trip time increases.
 In contrast, Sky X is able to maintain full usage of the page link regardless of the round-trip time.
 For compressible text, Sky X consistently delivers throughput rates greater than the actual bandwidth.
 Bit Error Rate vs. Throughput
 The Sky X system overcomes the high sensitivity of TCP to the bit error rate of the link.
 The throughput as a function of the bit error rate for a 10 Mbps satellite page link using a 1 MB TCP window.
 Even at low error rates, TCP is able to deliver only 1.5 Mbps, while at an error rate of 110-5, TCP's throughput drops to less than 0.03 Mbps.
 Sky X fully saturates the page link at low error rates and even at an error rate of 110-5, achieves 5.1 Mbps without compression and up to 15.8 Mbps for compressible data.
 Web Performance
 Unlike file transfers which typically consist of a single, large download, Web traffic is characterized by large numbers of short connections.
 Fast Start feature specically optimizes Web performance by reducing time required to establish new connection.
 The average response time for a mixture of 50 simultaneous web connections using the sky X gateway is between 0.7 and 1.1 seconds depending on the compressibility of the data, compared to 3.0 seconds with TCP.
Future Scope
CONCLUSION

 The sky X gateway is the leading solution for overcoming the limitations of TCP/IP over satellite
 ISP's, corporations, governments, and military organizations around the world rely on sky X gateway to enhance the performance of their satellite networks.
 The world is reducing to a global village by the use of satellite communication and so the improvement in the rate of information interchange through satellite is a must and thus sky X technology becomes unavoidable.
Reply
#22
[attachment=11304]
SKY X TECHNOLOGY
Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or [censored] prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
INTRODUCTION
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC’s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers
Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.
The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC’s.
PERFORMANCE OF TCP OVER SATELLITE
Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. However data networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks
Communication over geosynchronous satellites, orbiting at an altitude of 22,300 miles has round trip times of approximately 540 m/s, an order of magnitude larger than terrestrial networks. The journey through the atmosphere can also introduce bit errors into the data stream. These factors, combined with backchannel bandwidth typically much smaller than that available on the forward channel, reduce the effectiveness of TCP which is optimized for short hops over low-loss cables or fiber.Eventhough the TCP is very effective in the local network connected by using cables or optical fibers by using its many features such as LPV6, LPsec and other leading-edge functionality. Also it will work with real time operating systems.TCP is designed for efficiency and high performance ,and optimized for maximum throughput and the highest transaction speeds in local networks.
But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links. Thus the advantages achieved by TCP in LAN’s are no longer effective in the satellite link. So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the satellite link. The adverse effects of using TCP over satellite page link in its various features are as follows:
Window size
TCP utilizes a sliding window mechanism to limit the amount of data in flight. When the window becomes full, the sender stops transmitting until it receives new acknowledgement. Over satellite networks, where acknowledgements are slow to return, the TCP window size gradually sets a hard limit on the maximum throughput rate. The minimum window size needed to fully utilize an error-free page link known as the “bandwidth-delay product” is 100 KB for a T1 satellite page link and 675 KB for a 10 Mbps link. However many implementations of TCP are limited to maximum window size of 64 KB and most operating systems use a default window size of only 8 KB , imposing a maximum throughput rate over a satellite page link of only 128 Kbps per connection , regardless of the bandwidth available. So the high bandwidth available in the network is no longer effective, thus the data availability in a client is restricted to a small fraction of the available bandwidth. Thus the window sizing mechanism of the TCP limits the rate of flow of data through satellite link.
The simple, heuristic data acknowledgment scheme used by TCP does not adapt well to long latency or highly asymmetric bandwidth conditions. To provide reliable data transmission, the TCP receiver constantly sends acknowledgments back to the sender. The sender does not assume that any data is lost or corrupted until a multiple of the round-trip time has passed without receiving an acknowledgment. This algorithm does not respond well over satellite networks where the round-trip time is long and error rates can be high. Further, this constant stream of acknowledgments wastes precious back channel bandwidth and if the back channel is small, the return of the acknowledgments to the sender can become the system bottleneck. The acknowledgements and error messages will always dominate the data transfer and the rate of flow reduces very much.
Congestion Avoidance
In order to avoid the possibility of congestive network meltdown, TCP usually assumes that all data loss is caused by congestion and responds to this by reducing the transmission rate. However, over satellite links, TCP misinterprets the long round-trip time and bit errors as congestion and responds inappropriately. Similarly, the TCP “Slow Start” algorithm, which over the terrestrial infrastructure prevents new connections from flooding an already congested network, forces an excessively long ramp-up period for each new connection over satellite. While these congestion avoidance mechanisms are vital in routed environments, they are ill-suited to single-path satellite links.
So the congestion avoidance mechanisms used by TCP is also not suited for the satellite page link since it reduces the data flow through the network and thus reduces the overall rate of data transfer.
SKY X SYSTEM
Sky X Technology Overcomes TCP Performance Limitations
Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users. The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions.
Reply
#23
[attachment=11869]
SKY X TECHNOLOGY
Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or [censored] prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
INTRODUCTION
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC’s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers
Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.
The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC’s.
PERFORMANCE OF TCP OVER SATELLITE
Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. However data networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks
Communication over geosynchronous satellites, orbiting at an altitude of 22,300 miles has round trip times of approximately 540 m/s, an order of magnitude larger than terrestrial networks. The journey through the atmosphere can also introduce bit errors into the data stream. These factors, combined with backchannel bandwidth typically much smaller than that available on the forward channel, reduce the effectiveness of TCP which is optimized for short hops over low-loss cables or fiber.Eventhough the TCP is very effective in the local network connected by using cables or optical fibers by using its many features such as LPV6, LPsec and other leading-edge functionality. Also it will work with real time operating systems.TCP is designed for efficiency and high performance ,and optimized for maximum throughput and the highest transaction speeds in local networks.
But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links. Thus the advantages achieved by TCP in LAN’s are no longer effective in the satellite link. So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the satellite link. The adverse effects of using TCP over satellite page link in its various features are as follows:
Window size
TCP utilizes a sliding window mechanism to limit the amount of data in flight. When the window becomes full, the sender stops transmitting until it receives new acknowledgement. Over satellite networks, where acknowledgements are slow to return, the TCP window size gradually sets a hard limit on the maximum throughput rate. The minimum window size needed to fully utilize an error-free page link known as the “bandwidth-delay product” is 100 KB for a T1 satellite page link and 675 KB for a 10 Mbps link. However many implementations of TCP are limited to maximum window size of 64 KB and most operating systems use a default window size of only 8 KB , imposing a maximum throughput rate over a satellite page link of only 128 Kbps per connection , regardless of the bandwidth available. So the high bandwidth available in the network is no longer effective, thus the data availability in a client is restricted to a small fraction of the available bandwidth. Thus the window sizing mechanism of the TCP limits the rate of flow of data through satellite link.
The simple, heuristic data acknowledgment scheme used by TCP does not adapt well to long latency or highly asymmetric bandwidth conditions. To provide reliable data transmission, the TCP receiver constantly sends acknowledgments back to the sender. The sender does not assume that any data is lost or corrupted until a multiple of the round-trip time has passed without receiving an acknowledgment. This algorithm does not respond well over satellite networks where the round-trip time is long and error rates can be high. Further, this constant stream of acknowledgments wastes precious back channel bandwidth and if the back channel is small, the return of the acknowledgments to the sender can become the system bottleneck. The acknowledgements and error messages will always dominate the data transfer and the rate of flow reduces very much.
Congestion Avoidance
In order to avoid the possibility of congestive network meltdown, TCP usually assumes that all data loss is caused by congestion and responds to this by reducing the transmission rate. However, over satellite links, TCP misinterprets the long round-trip time and bit errors as congestion and responds inappropriately. Similarly, the TCP “Slow Start” algorithm, which over the terrestrial infrastructure prevents new connections from flooding an already congested network, forces an excessively long ramp-up period for each new connection over satellite. While these congestion avoidance mechanisms are vital in routed environments, they are ill-suited to single-path satellite links.
So the congestion avoidance mechanisms used by TCP is also not suited for the satellite page link since it reduces the data flow through the network and thus reduces the overall rate of data transfer.
SKY X SYSTEM
Sky X Technology Overcomes TCP Performance Limitations
Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users. The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions.
Reply
#24
[attachment=13698]
[attachment=13699]
[attachment=13700]
[attachment=13701]
[attachment=13702]
SKY X TECHNOLOGY
Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or [censored] prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
INTRODUCTION
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC’s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers
Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.
The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC’s.
PERFORMANCE OF TCP OVER SATELLITE
Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. However data networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks
Communication over geosynchronous satellites, orbiting at an altitude of 22,300 miles has round trip times of approximately 540 m/s, an order of magnitude larger than terrestrial networks. The journey through the atmosphere can also introduce bit errors into the data stream. These factors, combined with backchannel bandwidth typically much smaller than that available on the forward channel, reduce the effectiveness of TCP which is optimized for short hops over low-loss cables or fiber.Eventhough the TCP is very effective in the local network connected by using cables or optical fibers by using its many features such as LPV6, LPsec and other leading-edge functionality. Also it will work with real time operating systems.TCP is designed for efficiency and high performance ,and optimized for maximum throughput and the highest transaction speeds in local networks.
But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links. Thus the advantages achieved by TCP in LAN’s are no longer effective in the satellite link. So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the satellite link. The adverse effects of using TCP over satellite page link in its various features are as follows:
Window size
TCP utilizes a sliding window mechanism to limit the amount of data in flight. When the window becomes full, the sender stops transmitting until it receives new acknowledgement. Over satellite networks, where acknowledgements are slow to return, the TCP window size gradually sets a hard limit on the maximum throughput rate. The minimum window size needed to fully utilize an error-free page link known as the “bandwidth-delay product” is 100 KB for a T1 satellite page link and 675 KB for a 10 Mbps link. However many implementations of TCP are limited to maximum window size of 64 KB and most operating systems use a default window size of only 8 KB , imposing a maximum throughput rate over a satellite page link of only 128 Kbps per connection , regardless of the bandwidth available. So the high bandwidth available in the network is no longer effective, thus the data availability in a client is restricted to a small fraction of the available bandwidth. Thus the window sizing mechanism of the TCP limits the rate of flow of data through satellite link.
The simple, heuristic data acknowledgment scheme used by TCP does not adapt well to long latency or highly asymmetric bandwidth conditions. To provide reliable data transmission, the TCP receiver constantly sends acknowledgments back to the sender. The sender does not assume that any data is lost or corrupted until a multiple of the round-trip time has passed without receiving an acknowledgment. This algorithm does not respond well over satellite networks where the round-trip time is long and error rates can be high. Further, this constant stream of acknowledgments wastes precious back channel bandwidth and if the back channel is small, the return of the acknowledgments to the sender can become the system bottleneck. The acknowledgements and error messages will always dominate the data transfer and the rate of flow reduces very much.
Congestion Avoidance
In order to avoid the possibility of congestive network meltdown, TCP usually assumes that all data loss is caused by congestion and responds to this by reducing the transmission rate. However, over satellite links, TCP misinterprets the long round-trip time and bit errors as congestion and responds inappropriately. Similarly, the TCP “Slow Start” algorithm, which over the terrestrial infrastructure prevents new connections from flooding an already congested network, forces an excessively long ramp-up period for each new connection over satellite. While these congestion avoidance mechanisms are vital in routed environments, they are ill-suited to single-path satellite links.
So the congestion avoidance mechanisms used by TCP is also not suited for the satellite page link since it reduces the data flow through the network and thus reduces the overall rate of data transfer.
SKY X SYSTEM
Sky X Technology Overcomes TCP Performance Limitations
Sky X products increase the performance of IP over satellite through a combination of protocol connection-splitting, data compression, and Web pre-fetching, while remaining entirely transparent to end users. The Sky X gateway works by transparently replacing TCP connections from the client and converting the data to Xpress Transport protocol (XTP) for the hop over the satellite page link which is the protocol optimized for satellite conditions.
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#25
[attachment=14407]
SKY X TECHNOLOGY
Satellites are attractive option for carrying internet and other IP traffic to many locations across the globe where terrestrial options are limited or [censored] prohibitive. But data networking on satellite is faced with overcoming the large latency and high bit error rate typical of satellite communications as well as the asymmetric bandwidth design of most satellite network.Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions. So the throughput over the satellite networks is restricted to only a fraction of available bandwidth.Mentat , the leading supplies of TCP/IP to the computer industry have overcome their limitations with the development of the Sky X product family.The Sky X system replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. The Sky X family consists of Sky X Gateway, Sky X Client/Server and Sky X OEM products.Sky X products increase the performance of IP over satellite by transparency replacing. The Sky X Gateway works by intercepting the TCP connection from client and converting the data to Sky X protocol for transmission over the satellite. The Sky X Client /Server product operates in a similar manner except that the Sky X client software is installed on each end users PC.Connection from applications running on the PC is intercepted and send over the satellite using the Sky X protocol.
INTRODUCTION
Satellites are ideal for providing internet and private network access over long distance and to remote locations. However the internet protocols are not optimized for satellite conditions and consequently the throughput over the satellite networks is restricted to only a fraction of available bandwidth. We can over come these restrictions by using the Sky X protocol.
The Sky X Gateway and Sky X Client/Servers systems replaces TCP over satellite page link with a protocol optimized for the long latency, high loss and asymmetric bandwidth conditions of the typical satellite communication. Adding the Sky X system to a satellite network allows users to take full advantage of the available bandwidth. The Sky X Gateway transparently enhances the performance of all users on a satellite network without any modifications to the end clients and servers. The Sky X Client and the Sky X Server enhance the performance of data transmissions over satellites directly to end user PC’s, thereby increasing Web performance by 3 times or more and file transfer speeds by 10 to 100 times. The Sky X solution is entirely transparent to end users, works with all TCP applications and does not require any modifications to end client and servers
Sky X products are the leading implementation of a class of products known variously as protocol gateway TCP Performance Enhancing Proxy (TCP/PEP) , or satellite spoofer.The Sky X gateways are available as ready to install hardware solutions which can be added to any satellite network.
The Sky X family consists of the Sky X Gateway, Sky x Client/Server and the sky X OEM products. The Sky X Gateway is a hardware solution designed for easy installation into any satellite network and provides performance enhancement for all devices on the network. The Sky X Client/Server provides performance enhancement to individual PC’s.
PERFORMANCE OF TCP OVER SATELLITE
Satellites are an attractive option for carrying Internet and other IP traffic to many locations across the globe where terrestrial options are limited or price prohibitive. However data networking over satellites is faced with overcoming the latency and high bit error rates typical of satellite communications, as well as the asymmetric bandwidth of most satellite networks
Communication over geosynchronous satellites, orbiting at an altitude of 22,300 miles has round trip times of approximately 540 m/s, an order of magnitude larger than terrestrial networks. The journey through the atmosphere can also introduce bit errors into the data stream. These factors, combined with backchannel bandwidth typically much smaller than that available on the forward channel, reduce the effectiveness of TCP which is optimized for short hops over low-loss cables or fiber.Eventhough the TCP is very effective in the local network connected by using cables or optical fibers by using its many features such as LPV6, LPsec and other leading-edge functionality. Also it will work with real time operating systems.TCP is designed for efficiency and high performance ,and optimized for maximum throughput and the highest transaction speeds in local networks.
But the satellite conditions adversely interact with a number of elements of the TCP architecture, including it s window sizing, congestion avoidance algorithms, and data acknowledgment mechanisms, which contribute to severely constrict the data throughput that can be achieved over satellite links. Thus the advantages achieved by TCP in LAN’s are no longer effective in the satellite link. So it is desirable to design a separate protocol for communication through the satellite to eliminate the disadvantages of using TCP over the satellite link. The adverse effects of using TCP over satellite page link in its various features are as follows:
Window size
TCP utilizes a sliding window mechanism to limit the amount of data in flight. When the window becomes full, the sender stops transmitting until it receives new acknowledgement. Over satellite networks, where acknowledgements are slow to return, the TCP window size gradually sets a hard limit on the maximum throughput rate. The minimum window size needed to fully utilize an error-free page link known as the “bandwidth-delay product” is 100 KB for a T1 satellite page link and 675 KB for a 10 Mbps link. However many implementations of TCP are limited to maximum window size of 64 KB and most operating systems use a default window size of only 8 KB , imposing a maximum throughput rate over a satellite page link of only 128 Kbps per connection , regardless of the bandwidth available. So the high bandwidth available in the network is no longer effective, thus the data availability in a client is restricted to a small fraction of the available bandwidth. Thus the window sizing mechanism of the TCP limits the rate of flow of data through satellite link.
The simple, heuristic data acknowledgment scheme used by TCP does not adapt well to long latency or highly asymmetric bandwidth conditions. To provide reliable data transmission, the TCP receiver constantly sends acknowledgments back to the sender. The sender does not assume that any data is lost or corrupted until a multiple of the round-trip time has passed without receiving an acknowledgment. This algorithm does not respond well over satellite networks where the round-trip time is long and error rates can be high. Further, this constant stream of acknowledgments wastes precious back channel bandwidth and if the back channel is small, the return of the acknowledgments to the sender can become the system bottleneck. The acknowledgements and error messages will always dominate the data transfer and the rate of flow reduces very much.
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