I have an assignment for my university course that requires to review the 2020 report of Measuring Broadband Australia that covers the current state of the connection quiality within Australian NBN broadband network.
In particular in one of the sections the report covers the topic of why most of the users of NBN can usually attain between 90 and 95% of advertised download speed and the authors say:
This reiterates the point raised in previous reports that NBN tier
speeds are not provisioned so that maximum plan speeds are attainable
after accounting for protocol overhead.
The go on to further elaborate in the footnote that:
Protocol overhead include packet headers, which are added to network communications to
ensure that they arrive at the right network
address. Packet headers take up space, which means that the connection has less room for whatever data is being sent.
This gap of 5-10% of the advertised speed appears to be independent of the advertised speed so a person on 50/20 plan loses 2.5-5 Mbps and on 100/40 plan they lose 5-10 Mbps and this seems like an extremely high overhead.
Unfortunately, I couldn’t find any reliable sources on protocol overhead for broadband connections and was wondering if anyone here knows any sources or has any information.
For information, the Australian NBN is a combination of fibre-to-the-curb (FTTC), fibre-to-the-node (FTTN), fibre-to-the-premises (FTTP) and hybrid fibre coaxial (HFC).