02-06-2012, 11:26 AM
ADDING –INTELLIGENCE-TO-INTERNET
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INTRODUCTION
Satellites have been used for years to provide communication network links. Historically, the use of satellites in the Internet can be divided into two generations.
In the first generation, satellites were simply used to provide commodity links between countries. Internet Protocol (IP) routers were attached to the link endpoints to use the links as single-hop alternatives to multiple terrestrial hops. Two characteristics marked these first-generation systems: they had limited bandwidth, and they had large latencies that were due to the propagation delay to the high orbit position of a geosynchronous satellite.
In the second generation of systems now appearing, intelligence is added at the satellite link endpoints to overcome these characteristics. This intelligence is used as the basis for a system for providing Internet access engineered using a collection or fleet of satellites, rather than operating single satellite channels in isolation. Examples of intelligent control of a fleet include monitoring which documents are delivered over the system to make decisions adaptively on how to schedule satellite time; dynamically creating multicast groups based on monitored data to conserve satellite bandwidth; caching documents at all satellite channel endpoints; and anticipating user demands to hide latency.
Several key questions arise in the design of a satellite-based system:
• Can international Internet access using a geosynchronous satellite be competitive with today's terrestrial networks?
• What elements constitute an "intelligent control" for a satellite-based Internet link?
• What are the design issues that are critical to the efficient use of satellite channels?
1.1 HISTORY
As technology continued to improve, the Internet continued to grow, and the number of satellites in orbit continued to increase, researchers began working on ways to transmit data across wireless communication relays--like packet radio and satellite repeaters.
1973 : These efforts came to fruition in 1973, when researchers successfully linked two European computers to an American network by way of satellite communication services. As the technology grew and matured, more and more data found its way across satellite connections.
1996 : The first consumer satellite Internet service went into service. Marketed as Internet services for remote users and those who could otherwise not access networks without expensive long distance charges, DirecPC (which later became HughesNet) set the precedent for satellite Internet services of today.
1998 : Intel has invested in satellite Internet businesses and announced to produce a new kind of modem that could bring mass-marketed high-speed Internet access to every home and business.
2000 : America Online Inc., the world's biggest online service, and Hughes Electronics Corp. tested a high-speed satellite Internet service in 16 cities.
2002 : StarBand Communications Inc. and Hughes offer Internet connections through a satellite network.
2005 : WildBlue's brought its satellite Internet service to rural areas around the United States with high-speed alternative to dialup.
2008 : Internet firm Google and Europe's biggest bank HSBC have thrown their weight behind a plan to provide cheap, high-speed Web access via satellite to millions in Africa and other emerging markets.
2009 : Hughes high-speed satellite internet service is available at US military bases in Afghanistan, Iraq and Kuwait, with local installation and logistics support provided by partner companies in the region.
2. TECHNOLOGY AND CURRENT TRENDS
In order for seamless and efficient communication, satellite data networks have to employ special techniques to deal with the increased distances the packets of data have to travel. Although these packets travel at the speed of light (i.e.186000 miles per second), this still adds extra milliseconds of latency in the network. Latency is not directly related to speed. However, latency can cause performance degradation over satellite links if not handled properly. VSAT Systems deals with latency through the use of the most advanced TCP/IP acceleration technology available.
2.1 TECHNOLOGICAL TRENDS
Off all forms of communication, satellite communication is probably the most complex.
In order for seamless and efficient communication, satellite data networks have to employ special techniques to deal with the increased distances the packets of data have to travel. Although these packets travel at the speed of light (i.e.186000 miles per second), this still adds extra milliseconds of latency in the network. Latency is not directly related to speed. However, latency can cause performance degradation over satellite links if not handled properly. VSAT Systems deals with latency through the use of the most advanced TCP/IP acceleration technology available.
TCP/IP is the "language" of the Internet. TCP functions by sending packets of data, and then waits for acknowledgments of receipt. These acknowledgments signal the sender to transmit more data. When acknowledgments return slowly, TCP slows the speed at which data is sent. This is done to prevent network overloading as TCP assumes it is already congested.
TCP works by starting a TCP/IP session slowly. Speed builds as the networks' capacity to carry traffic is verified by the rate at which acknowledgements are received. In Internet terminology, this effect is known as "slow-start".
TCP was designed for terrestrial networks where packets of data travel shorter distances and not all the way to the geostationary orbit. Larger distances mean greater latency (600 ms or more for satellite links). Thus causes TCP to expect an acknowledgement before the round trip to the remote site is completed. As TCP was originally designed for low-latency terrestrial networks, it does not understand that a satellite is involved. The resulting network operates as if the satellite latency was caused by congestion. If uncorrected, this effect causes all packets over a satellite network to be sent at the slow-start rate.
2.2 CURRENT TRENDS
Advanced Satellite Internet Modems
The systems indoor unit (IDU) is a single-box broadband satellite Internet modem. The IDU is equipped with onboard TCP optimization and QoS (Quality of Service) capabilities, router and DNS.
The unit is centrally managed from Network Operations Center (NOC) which frees the users from periodic software and firmware updates. In fact, the IDU can also be managed remotely from our NOC for configuration changes, real-time monitoring and historical reporting.
Satellite Internet service is also available with a software load that can allow it to operate in site-to-site mode as opposed to its normal site-to-Internet mode. With this capability, two sites can be directly connected to each other over a single broadband satellite "hop".
Secure communications - 3DES Encryption
Satellite Internet provides data transmission through the space link. This medium is extremely secure compared to the typical terrestrial broadband connection. Basic encryption through the space segment is standard for every customer. For applications requiring end-to-end encryption, optional 3DES encryption across the satellite Internet space link is the most secure available, allowing the remote site(s) to connect to the hub over a secure 3DES VPN(Virtual Private Network) satellite link.
Enforced Quality of Service (QoS)
Satellite solutions enable our customers to have complete control over the networks they operate by using network-based QoS prioritization. QoS can be based on protocol type, source port number, destination port number, source IP address or destination IP address. This feature also provides class based queuing, which assigns a percentage of bandwidth to each class. The rate limiting allocates only the bandwidth that is needed to be used in the network to maximize resources for all end users.