VSAT Network Architecture: Understanding Star and Mesh VSAT Topologies

VSAT (Very Small Aperture Terminal) network architecture is integral to satellite communication, enabling connectivity for various applications in remote locations. This architecture primarily utilizes two topologies viz. Star and Mesh, each designed to meet specific communication needs.

Broadly VSAT network as a whole consists of VSAT terminals distributed across different regions on the Earth and Hub station located at one central place. Communication between Hub station and VSAT terminals is carried out using RF frequencies in different bands (e.g. C band, Ku band) as per applications and regions of use. Refer Ku band versus C band➨.

The figure-1 depicts topologies used in VSAT network architecture. As shown there are only two topologies viz. Star and Mesh. In Star type of VSAT network, all the communications occur through Hub station using multi hop communication. In mesh type of VSAT network, all the communications occur directly between VSATs without the need of any central Hub station. Let us differentiate star and mesh vsat topologies used in satellite architecture.

VSAT Star Topology

In the Star topology, all VSAT terminals communicate through a central hub. The hub acts as an intermediary, receiving signals from each remote VSAT and then retransmitting them to other terminals or the internet. This topology is typically used in scenarios where centralized control and management are necessary, such as corporate networks, banking, and retail industries.
➨The advantages of VSAT Star topology are as follows :
• Centralized control
• Easy to manage and troubleshoot
• Suitable for large networks
➨The disadvantages of star vsat topology are as follows :
• Hub dependency: If the hub fails, the entire network goes down
• Higher latency due to routing through the hub

The star based VSAT network architecture is further classified into Shared Hub and distributed Hub types.
➨In shared Hub network type, One large hub station is used and all the VSATs are divided into sub-networks. Each subnetwork is assigned to particular CUG (Closed User Group). Different CUG is created for all the clients separately. Each CUG will have their own inbound and outbound rf carriers. VSATs in all the CUGs use the same one Hub station.
➨In distributed Hub network type, each network will have its own hub station known as "min-Hub". This mini hub is located near the client's premises. In this network, all the clients will have its own traffic hub dedicated to its own CUG.

VSAT Mesh Topology

In the Mesh topology, VSAT terminals communicate directly with each other via the satellite, without the need for a central hub. This peer-to-peer communication model is ideal for networks where direct communication between remote sites is needed, such as in military, emergency services, or collaborative networks.
➨The advantages of VSAT Mesh topology are as follows :
• Direct communication reduces latency
• More efficient for inter-site communication
• Less dependent on a central hub
➨The disadvantages of mesh vsat topology are as follows :
• More complex to manage
• Higher equipment costs

Comparison Table: Star vs. Mesh Topology

Both topologies offer unique advantages based on the needs of the network, and understanding these differences can help in choosing the right architecture for a particular application.

Conclusion

In summary, VSAT network architecture plays a crucial role in establishing reliable satellite communication, with Star and Mesh topologies offering distinct advantages and challenges. The Star topology provides centralized control and ease of management where as the Mesh topology enhances direct communication between terminals. Evaluating the specific needs of a network can guide the selection of the appropriate topology, ensuring optimal performance and connectivity.

VSAT System Block Diagram

Refer VSAT System operation➨ and VSAT network configurations➨ for more information.

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