In your letter dated Mon, 04 Jan 2016 15:53:50 -0500 you wrote: >The draft says in section 2.1: > > o [RFC1078] U, "TCP Port Service Multiplexer (TCPMUX)" should be > deprecated, because: >.... > * There are no known client-side deployments. Just for reference. I use TCPMUX for a private protocol. It is nice for prototyping because it is easier pick a unique string for a protocol than to pick un unused port. (Obviously, when DNS is used, SRV can also be used for this) The second argument is a weird. * It requires all new connections to be received on a single port, which limits the number of connections between two machines." There are many systems that receive essentially all of their traffic over one port. So those system already have this problem. It also is very rare that a single host connects to a remote host more than 16000 times in parallel. So I wonder if this is a practical limitation.