Dedicated or Shared VSAT ?

If you are utilizing 100% of your broadband connection then you can skip this article. If not you could save a $.

If you are utilizing 100% of your broadband connection then you can skip this article. If not you could save a $.

Are you Dedicated ?

In a dedicated service satellite bandwidth is assigned to a single user (ship) as if you would buy your own part of the satellite. The primary advantage is that the architecture allows the complete direct and synchronous connectivity between the two remote points on Earth and you have all the capacity at all times.

or do you share ?

Satellite Internet Service Providers can also offer shared bandwidth which is designed to make more efficient use of existing physical resources, The rationale behind this is that users are not going to use their data connection at 100% all the time and by sharing the bandwidth they also share in the cost of the connection.

The term "Contention Ratio", also known as Sharing Ratio or Oversubscription Ratio, is the maximum amount of subscribers which can be connected to a service at the same time.  The fundamental reason for sharing is to conserve expensive bandwidth and utilize it to its maximum potential. Bandwidth that is unused and idle, is wasted. 

The intermittent, bursty nature of Internet traffic virtually guarantees that all users are not going to require maximum bandwidth at the same time and the service provider is able to save money by optimizing the use of the available bandwidth. 

Oversubscription vs. Contention Ratio

Oversubscription takes place in traditional terrestrial Internet access services where ISPs "play the odds" using traffic engineering techniques so that they can provide services to large numbers of customers using shared rather than dedicated bandwidth

Satellite Internet Service Providers usually have a disclosed contention ratio and will charge you a certain price for that shared part of the bandwidth.  They are not "playing the odds" and you are informed of the speeds you will get and which contention ratio is applied.   You can then easily calculate what will be the maximum and minimum speed you will receive.

If your Satellite service provider is not open about their contention ratio we suggest to either investigate or consider moving to another one.

Best of both worlds

Sometimes it is difficult to choose between dedicated and shared.  You require the capacity but also need the flexibility.  Even though it might seem a double expense there are situations where both solutions can coexist at a cost similar to a single dedicated connection.  

Unfortunately you can only have one service (shared or dedicated) per antenna so you would need two antennas, but where operations would need a dedicated capacity (1024/1024 kbps the crew might be better off with a shared connection of 4096/512/5 than a dedicated equivalent of 512/128 kbps.

Let us help you select the best solution for your ship

How much do I need

In another article we will discuss how to calculate the actual speed you need to do things like email, video, Skype, VoIP, VPN, ...