ND SatCom SKYWAN IDU 1070, Руководство пользователя

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2010-10-26 Network Design and Engineering Guide 23
General Carrier Design
Essential SkyWAN
®
Satellite Link Layer Features
2.3 Essential SkyWAN
®
Satellite Link Layer Features
The following section discusses the essential properties of a satellite link in a Sky WAN
®
net-
work. A proper understanding of the properties and features is essential for a successful net-
work design.
2.3.1 SkyWAN
®
Network Topologies
Figure 2-4 Network Topologies
Sky WAN
®
networks support any kind of satellite network topology. The simple topologies pre-
sented in the picture above have the following characteristics:
-
Fully Meshed : Each station has a direct satellite link to each other station. These stations
are commonly referred to as “peer stations”.
- Star : Star terminals have only a satellite link to a common hub station.
Besides these simple topologies, Sky WAN
®
networks can also have hybrid topologies. In a hy-
brid topology a part of the network may be fully meshed while some stations may only have star
connectivity. Or a multi-star topology may be configured where the star terminals have connec-
tivity to multiple hub stations.
The optimal choice of topologies depends on the required network connectivity. A network
where data and voice connections can go from any to any station are optimally served by a
meshed topology, where latency and bandwidth consumption on the satellite link is minimal.
Star topologies require double satellite hops between terminal stations. That means double de-
lay and double bandwidth necessary for any of these connections. If, however, no or only a
small amount of communication is necessary between terminal stations, operating them in a
star mode might reduce the requirements on the outdoor units. Reducing e.g. transmit power
and antenna size would lead to a reduction of station hardware costs. Even in this case, a multi-
star topology might have an advantage, especially if redundancy is required in a network.