What is the type of broadband internet in which the connection is degraded by adding multiple users?

Broadband speed is the rate at which data is transported, measured in megabits per second (Mbps). The higher the broadband speed a service offers, the more data can be transferred per second. Broadband speed applies to both the rate at which that data passes through to your device from the internet or server (‘download’) and the rate at which data passes from your device to the internet or server (‘upload’).

Broadband speed is determined by the network access type (i.e. you may have an internet connection using ADSL, hybrid fibre cable, FTTN, etc), and a range of other factors as outlined below. Because of variations within the retail service provider’s broadband network (including access provided by nbn or another wholesale access provider) you may not always get the same speed all the time.

Broadband services are often marketed according to the access line connection speed, the theoretical speed which should be achieved (or very close to achieved) in ideal circumstances. The speed of your broadband service will not exceed the ‘access line connection speed, and will often be less. This is because consumer-grade broadband services available for sale in Australia are not a dedicated connection between your home and the internet. They are a shared connection offering variable broadband speeds subject to contention by multiple users, the speed experienced by an individual user can be reduced when there is high demand from these other users.

This diagram from nbn provides a background on the various factors that affect broadband speeds delivered over next-generation networks.

This diagram is for illustrative purposes only.  It does not and is not intended to capture all network configurations or all possible elements affecting network performance or speeds.

You can also find further information in our FAQ and Troubleshooting sections.

Computers communicate with each other across a network by sending blocks of information, called packets. When packets get disrupted or lost, it can affect the performance of your internet connection and therefore your browsing or viewing experience.

There are many factors that affect the actual speed you experience. Examples of these include your location in relation to the broadband node, the gateway software being used, whether the site you are trying to access is based in Australia or overseas, your home wiring, your home network set-up (e.g. modem location/quality, Wi-Fi) and internet traffic congestion.

When you download data from a server, the overall broadband speed and performance you experience depends on the overall network path all the way to your device in the home. This includes the host server’s capabilities, particularly if multiple users are trying to download from that server at the same time. These factors are common to all broadband technologies.

Other factors that can influence broadband performance include the capacity of your service provider’s network, the type of technology being used to provide your broadband service, the broader internet infrastructure and content provider networks. The length and or quality of your ADSL or FTTN line may also impact the broadband access connection speed. Speed outcomes can also vary from region to region as service providers continue to develop and upgrade network links on an ongoing basis.

Peak Hours

Busy, or peak hours are the times when slower or more variable speeds are most common, and typically fall between 7.00 pm to10.00pm. Peak hours are the periods when the largest demands are being placed on the internet networks and servers that provide content and services. During the busiest hours, an individual’s upload and download speed tests may vary from the maximum access connection speed down to significantly slower speeds. During the busiest hours, for example, typical off-peak average speed of 10Mbps may slow significantly.

In some cases, congestion may be the key determining factor for speed outcomes during peak hours. Those outcomes may differ widely across different RSPs. Some consumers are very cost conscious and will prefer to pay for a lower-priced, more congested service, even if the average performance is not as strong as that of higher priced offerings.

Technology (Access Type):

All broadband networks will be impacted by constraints relating to shared capacity – that is, multiple consumers sharing access to the infrastructure. Next generation networks – such as the nbn™ network – are typically capable of achieving high data speeds but these networks are also impacted by shared capacity. The access types recommended by your RSP will depend on what is available where you live.

Factors related to access technology which could impact broadband speed include:

• Access connection speed on an ADSL, FTTN, or FTTC service will depend on distance from the exchange or street cabinet to your home. The further away, the slower your connection speed. ADSL, FTTN, and FTTC services may also slow in busy hours (i.e. 7.00 to 10.00 pm) due to congestion.
• HFC and FTTP services can download content at close to the full-service speed in non-busy times, but may experience lower average speed in busy hours due to congestion.
• In some cases an apartment building may be served by two competing FTTB networks. Where this is the case, the customer may experience a lower quality of service due to network interference between the two networks.
  

In-household set up

The number of users accessing the internet within a single household may have a noticeable impact on service performance. This is more likely when that household has a relatively low maximum access speed. For example, ADSL services in premises that are more than 4km from an exchange are likely to have relatively low maximum access speeds (i.e. less than 5Mbps). For such premises, where the access line is the bottleneck, speeds experienced by multiple users uploading, downloading or streaming at the same time will be significantly slower than for a single user.

Speed will also be impacted by the modem you use. If you think your modem may be a factor in not getting the speed you think you should be getting, speak to your RSP or follow the troubleshooting tips available from your modem manufacturer.

There is further information in our FAQs on what to consider for your in-household set up.

End-user experience with high bit-rate activities such as downloading/uploading will be improved by a high-speed service. Streaming high definition video can also require moderately high bit-rates - more so if multiple householders stream simultaneously. However, speeds higher than that required to avoid buffering will not improve the user experience of streaming video.

This section includes some technical information. For an overview of broadband uses and potentially relevant speeds, please see our section on Speed under “Choosing a Broadband Service.”

E-Mail

Does not require much speed or capacity and will typically work the same regardless of broadband speed. If you receive big attachments these may take additional time to download.

Web browsing

Does not require much speed or capacity and the consumer experience is unlikely to benefit from increases in download speeds beyond about 10 Mbps. Upload speed is relatively unimportant, however if the latency, e.g. when visiting a site hosted a long way away or on some satellite broadband connections.

Audio or video streaming

The coded video rate depends on the quality of the content being streamed (e.g. standard definition video or high definition video) and the compression technology (codec) being used by the content provider. Standard definition video typically operates optimally at 3 Mbps, while high definition video typically operates at 6Mbps. Audio content requires much lower speeds, typically 100-300 kilobits per second (i.e. 0.1-0.3 Mbps).

Audio and video streaming employ “buffering” whereby a small amount of content (e.g. from a few seconds to minutes) is downloaded to your device and stored in advance of its playback. This delays the playback of the video by that interval, but means it can tolerate short pauses or decreases in speed without interrupting playback, as long as the download speed exceeds the content streaming rate for most of the time. If the available download rate is below the video rate the buffer gradually empties and when it empties the video stops. Most streaming services can adjust their video speed down to avoid interrupting the video when download speeds reduce, and the user may notice lower picture quality at those times.

The requirements to maintain acceptable streaming video quality are therefore:

• Access line speed which is significantly higher (by 30% to 50%) than the video streaming rate to allow the buffer to refill when depleted.
• An uncongested network path from the video server that can download on average at twice the video streaming rate or faster.
• Low packet loss
• Minimal or no dropouts.

Packet loss can also result in slower downloading that can result in video quality degradation or stops in a similar manner to congestion.

Dropouts that commonly occur on ADSL and FTTN (VDSL2) access lines can cause video to stop if the duration of the dropout exceeds the video buffer size. Long buffers (e.g. Netflix) can tolerate ADSL dropouts of 20 to 40 seconds but not VDSL2 dropouts lasting 2-3 minutes.

Downloading video to hard drive and playing while downloading

This is the same as streaming video (see above), except that instead of using a temporary buffer, a copy of the downloaded video is retained permanently. As with streaming video, the average download speed needs to exceed the bit-rate of the content.

Voice over IP (VoIP)

Only requires a low speed –i.e. greater than 0.1 Mbps is normally acceptable. However, packet loss and latency can have a high impact on VoIP user experience if conversations are delayed. VOIP may suffer during peak hours if the broadband access line to the house is being used for multiple applications / by multiple users at the same time.

Gaming

12Mbps is sufficient for playing most online games. However, packet loss, dropouts and delays can significantly affect user experience.

nbn and other wholesale network operators do not sell directly to consumers. They sell to Retail Service Providers (RSPs), which then manage your connection to the internet, using the nbn™ network and other network infrastructure.

It is important to recognise the wholesale service provides the upper limit of attainable speeds under ideal conditions. For example, nbn offers FTTH/P download access line speed tiers to Retail Service Providers (RSP) at 12 Mbps, 25 Mbps, 50 Mbps and 100 Mbps. These tiers do not describe the speed of a broadband service delivered over nbn access lines. RSPs are free to choose which wholesale services they buy from nbn and how these are offered as retail services to customers.

The speed of any broadband service delivered over nbn access lines is also determined by the amount of Connectivity Virtual Circuit (CVC) capacity purchased by an RSP. For example, a customer on a 25/5 plan with an RSP that doesn’t purchase enough CVC capacity may experience speeds far below the maximum access line speed during busy hours (i.e. 7.00 pm to 10.00 pm), whereas a customer with an RSP that purchases enough capacity may experience speeds closer to the nbn access line speed in busy hours.

However, the actual speed that can be experienced will be determined by the customer’s access technology, plan speed, local conditions e.g. distance from the node or exchange for DSL, external interference for DSL, and in home customer equipment.