...metadata hub" we can reduce the problem from n-square to a linear problem the same way as with the n-square physicalconnections. But what does a "metadata hub" look like? This time it is not a physical component, but a Canonical Domain...
http://www.eaipatterns.com/ramblings/03_hubandspoke.html
...devices to achieve a virtual leased line across the IP network. At the host, where there are likely to be many physicalconnections from different sites terminating, further economies are available by using multiple port SyncSwitches to multiplex...
http://www.wanware.com/tsgdocs/ss_paper.pdf