Broadband Satellite Internet:
Protocols & ApplicationsSkycasters service is a TCP/IP service. The term "TCP/IP" refers to the layered combination of TCP and IP protocols, on which many higher-level application protocols (like HTTP, FTP, SMTP) have been built. Skycasters service supports TCP/IP applications with hardware acceleration performed on its Satellite Gateway units and on equipment at the customers remote site. Acceleration is more thoroughly described elsewhere on this site, but essentially it is a product of hardware in the network that allows TCP/IP to function without regard to the latency in the connection. Acceleration makes multi-megabit speeds possible over satellite. Protocols other than TCP/IP are not in any way blocked, however they cannot be accelerated. As stated, Internet applications like email and web browsing perform very well over satellite, delivering high speed service similar to DSL or Cable. There are some known issues with certain applications which are expanded upon below. The service is asymmetrical, meaning that around 80% of the bandwidth is allocated towards download traffic with the balance allocated for uploads. For this reason, VSAT does not support applications that require a high-speed upload such as web or application hosting at the remote site or 2-way video conferencing. The satellite remote sites should not be expected to host any applications, especially web servers. Access from the outside to remote site computers is limited.
Applications that are affected by high latency may have problems. Satellite latency in the range of 700ms to 900ms or more are typical. Known latency-affected applications include interactive gaming, VoIP, and most non-TCP/IP applications: UDP is a protocol that cannot be accelerated because it is not a connection-based protocol. NetBIOS is a LAN technology that cannot be accelerated, and was not designed to function in a WAN environment however it is sometimes used in this manner. NetBIOS will function slowly over satellite. Drive-mapping is not supported. RDP (Citrix) and RCP (Exchange) can also be slow over a satellite connection.
If a customer needs to use shared folders, web folders can be used by creating a directory using an application such as Microsoft Internet Information Server (free, and included in Windows 2000 and NT), Apache or other web front-end. Shared folders and drive mapping will perform slowly over any satellite connection unless setup in this manner. Microsoft Internet Information Server (IIS) or equivalent also needs to be set up with SQL server for optimum performance. Any application that is compatible with IIS will perform better when set up in this fashion. Skycasters recommends that hosted applications be configured with an IIS or other web front end. Generally, any application that requires client software loaded at the remote site can have problems with satellite connections unless adjustments are made at both the client and server end. These types of applications need to be evaluated individually by checking with the manufacturer to determine the effects of latency on the particular application. Depending on the underlying application, Citrix can be affected by latency, and will perform more slowly over satellite. Some customers will have better results with Citrix than others, based on the configuration and application involved. A Citrix engineer should be consulted prior to its use over satellite to determine how a particular customer-specific application will perform. Standard IPSec VPN clients like Cisco, Nortel, Checkpoint etc. will have severe performance issues although they can be used in a single-user environment for occasional use. Skycasters does offer 2 VPN solutions that function well over satellite. Terminal emulators must have local-echo enabled at the remote site in order to perform properly. Direct dish-to-dish connections will have 2x the latency, and may have difficulty communicating directly with each other, although it is possible to successfully use the system in this manner. | 
