More from the series of “grawity is hopelessly obsessed with networks”, and because this journal is looking a bit sad & empty at the moment, here's what I've been into recently.
A while ago (two years ago) I signed up on the dn42 network to play around with routing and BGP for a bit. It's a large overlay network that simulates the Internet – in the sense that participants set up their own “autonomous systems”, create WHOIS entries, and set up BGP peerings; although the nodes are connected using just about anything except physical links (IPsec, GRE, IPsec/GRE, OpenVPN, Wireguard, L2TP)... There also are seriously flaky links to parts of freifunk and ChaosVPN.
The second network is Internet – after switching IPv6 tunnels many times, I have obtained an AS number and an IPv6 prefix of my own. (Technically it's still a provider-aggregated prefix but that doesn't stop me from announcing it, primarily via Tunnelbroker and NetAssist.) So now I'm building my own IPv6 tunnels with GRE, OSPF, ZeroTier, and wet string.
(Actually the first time I joined dn42 was three years ago – it seems I have a habit of picking something up, forgetting it after a month or two, and a year later picking it up again for reals. Which, incidentally, is also what happened with the LISP beta network.)
Finally I'm experimenting with LISP – “Locator/Identifier Separation Protocol”, it's a relatively new protocol and one of the proposals brought to IETF for improving the scalability of the global routing table. (It turns out that allowing every nerd to announce their own /48 over shitty ADSL doesn't work all that well.) The current LISP Beta Network is similar in purpose to e.g. the 6BONE network; it's built by several big-name companies, but anyone is allowed to join and obtain a range of EIDs for themselves.
(Interestingly, the IPv4 EIDs provided by LISPnet belong to “Usenix/UUNET Technology Inc.” according to ARIN WHOIS lookup – which is not trivial to perform, as IANA's WHOIS server thinks the addresses belong to APNIC, and APNIC thinks you should ask IANA. The IPv6 EIDs, meanwhile, are just an ordinary Cisco netblock.)
I bought another 30-year-old book about computer networks. This one is called The Matrix: Computer Networks and Conferencing Systems Worldwide – released in 1989 by Digital Equipment Corporation, and yes, the first page out of ~700 refers to a “The Matrix, a worldwide metanetwork”. What more could you want from life. Oh yeah, a soundtrack.