https://www.mediawiki.org/wiki/Requests_for_comment/CentralNotice_Caching_Ov...
Matt Walker, praise be upon him, has just massively revised this RfC. See the update for new details on URL unification, Varnish usage, and estimated usage. It's now ready for another review pass, so have at it. :-)
Sumana Harihareswara Senior Technical Writer Wikimedia Foundation