Native IP with Acceleration
Article repost from http://www.vsat-systems.com
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 over satellite, some background
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.
TCP/IP Spoofing
VSAT Systems employs TCP/IP acceleration also known as TCP Spoofing. This technique compensates for the space-link transit time using state-of-the-art routers, switches and protocol processors which are fine tuned for satellite applications. This equipment appears to TCP as if it were the remote location, while acting as a relay or forwarder for data packets going to and from the remote satellite location. When the spoofing equipment receives Internet traffic destined for a remote satellite location, it acknowledges receipt of the packet immediately on behalf of the remote site. This mitigates the slow-start effects and data packets begin to follow immediately.In this manner, the latency is "hidden" because the acknowledgments are returned rapidly. As a result, TCP moves out of slow-start mode quickly and builds speed to reach maximum levels.
The VSAT Systems acceleration equipment also watches for real acknowledgements coming back from the remote site and suppresses them. If the acknowledgement is not received from the remote site, the system automatically re-sends the packet from its buffer. Thus, our satellite-connected sites communicate seamlessly with servers on the terrestrial Internet.
Our satellite modems are equipped with Dynamic Tx Power Control
A unique feature of the VSAT Systems modem equipment is the dynamic transmit (Tx) power control technology. This feature automatically adjusts the transmitter power of the VSAT dish in response to a weather condition, particularly during storms. Standard transmitters have pre-set limits for the Tx power and do not possess the capabilities to manage Tx power dynamically. While standard transmitters perform perfectly when the sky is clear, their performance is severely affected on rainy days and during storms. Our systems are well equipped to respond to such weather conditions.Advanced Satellite Internet Modems
The VSAT 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 our Network Operations Center (NOC) which frees you and your customers 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.
VSAT Systems 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 comunications - 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 VSAT Systems customer. For applications requiring end-to-end encryption, optional VSAT Systems 3DES encryption across the satellite Internet space link is the most secure available, allowing the remote site(s) to connect to the VSAT hub over a secure 3DES VPN satellite link.Enforced Quality of Service (QoS)
VSAT Systems 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.At VSAT Systems, we can provide QoS levels that are customized to your unique needs, be it VoIP, video conferencing or streaming video. Most importantly, we can provide Committed Information Rates (CIR) - the ability to dedicate bandwidth as required in order to support voice or other bandwidth critical services.
