The reason for the absence of IPv5 is that it never existed, despite confusion on the part of some people, seemingly fueled by internet videos claiming to explain its disappearance.
The so-called ‘stream protocol’ was actually proposed to support voice communication via the internet, and it was this that was intended to be IPv5.
This protocol was not adopted, and voice communication via IP is now standardised under SIP; as such, the proposal was reincarnated to include support for video, but it also failed to attract support.
The number ‘five’ relates to the version number of the network protocol, and though IPv6 did eventually materialise, there is no tangible connection between it and the stream protocol proposal.
Overall, the video claiming to explain the disappearance of IPv5 is something of a red herring, as it gives the impression of answering a question that never needed asking.
