All about connection speed: guaranteed, symmetrical, etc.

Guillaume Barre
18 Aug 2020

When it comes to an internet connection, speed is often key. Internet access feeds all the connected services present on the network infrastructure: WiFi, VoIP, CCTV and much more. As for usage increases year after year, the volume of data in transit is constantly growing. The need for bandwidth is therefore becoming increasingly important. What are the elements to take into account when talking about bandwidth? Is a throughput fixed? Are there several types of throughput? Can we have guarantees (SLA) on the flow?

Downstream vs. upstream speed?

The downstream rate is the rate used to receive data on your device from the Internet. The most typical use, i.e. surfing the web, requires mainly downstream speed.

Upload speed, on the other hand, corresponds to the speed devoted to sending data from your device to the Internet. Secondary in the past, it is associated with uses such as sending files and emails, but also more demanding services such as video conferencing.

Until now, Internet use has been based mainly on downloading data. For this reason, most consumer offers are packaged with much higher download speeds than upload speeds.

Now, the discrepancy between download and upload needs is less important. This is especially true in a professional context.

Symmetric vs. asymmetric flow?

Symmetrical throughput is when the upload rate is equal to the download rate. Conversely, the flow is asymmetrical when they are not equal. However, the asymmetry is generally in one direction only: a downstream rate higher than the upstream rate.

As mentioned above, in France, Internet access offers for individuals have always been based on asymmetric speeds, largely favouring downloads. Symmetrical connections are aimed more at the business market, where bandwidth requirements are usually higher.

Videoconferencing has become commonplace internally for remote working and externally for business relationships. The emergence of cloud hosting services means more file transfers over the internet. The transition from analogue to IP for many connected services such as telephony or video surveillance is also contributing to the growth in needs.

The main types of Internet access offering symmetrical speeds are SDSL and dedicated fibre (FTTO).

Guaranteed vs. peak flow?

Did you know? Generally speaking, all internet offers advertise theoretical maximum speeds. This is known as the peak speed. In practice, it is unlikely that you will benefit from the advertised speeds, they will be slightly lower or even much lower depending on the circumstances (sharp drops can be observed at peak times). 

In contrast to standard Internet offers, the speeds of dedicated connections are the same in theory and in practice. This is called a guaranteed speed. This means that internet access offers the maximum speed, whatever the circumstances. Dedicated internet offers are designed for businesses, so that they do not have to deal with the instability of the internet connection speed, especially in the event of critical connectivity needs. Guaranteed throughput is one of the main components of SLAs.

Scalable flow rate?

Internet accesses offer maximum speeds defined upstream. What about the possibility of changing these speeds if bandwidth requirements increase?

Only dedicated offers allow for scalable speeds. It is indeed possible, without changing the Internet access, to have a higher speed within a few days, on request to the operator (with a consequent increase in price).

Example :

My hotel is equipped with FTTO dedicated fibre with 100 Mb/s guaranteed and symmetrical. My guests tell me that the internet connection does not provide an optimal experience at peak times. After diagnosis, it turns out that internet access is undersized compared to the actual need. It is possible to increase the speed to 200 Mb/s in 48 hours (or more depending on the operator).