Anycast VIPs and Direct Server Return were a couple key parts of VDN "secret sauce" in early to mid-2000s.<p>Cool to see this engine out in open source.<p>To build a VPN edge you also need cooperative tiered caches with some very counterintuitive cache admission and eviction algorithms, unicast front end with p2p (for vod) or multicast (for live) back end, multi-datacenter event aggregation and correlation, cookieless/db-less sessions, and a few other goodies, some of which you can now even find as Nginx plugins.<p>Assembling what you need is much easier now with HLS, DASH, etc., than it was in the MMS/RTSP/RTMP days.<p>As of last couple years, you could almost assemble a viable global VDN with off the shelf open source parts. If the open compute project keeps up its good work, the physical kit gets affordable too.