I'm pretty sure John is asking about UDP support under bufferevents.
That's nontrivial.
The last time I looked, it appeared that the socket-backed
bufferevent code was almost exactly right for a UDP transition, but
that the underlying evbuffer objects didn't have a lot of sensible
overlap in their API. Internally, evbuffers are optimized for
stream-oriented data, and it's not easy to come up with an elegant way
to make them handle packet-oriented data instead, especially if you
want the packet-oriented data to come with optional addresses (to
support unconnected UDP sockets with sendfrom/recvto), and you want to
avoid excessive copy operations, and you don't want to need one malloc
per packet.