Indeed, and the ace-coap-est examples use port 61616 mostly. The discovery Link 
Format is quite inefficient when returning results on *different* endpoints. 
Example:

REQ: GET coap://[2001:db8::2:1]/.well-known/core?rt=ace.est
RES: 2.05 Content
  <coaps://hostcanhavealongname.example.com:61616/est>;rt="ace.est"

Although in above case the server could shorten the response payload by 
returning its IP address ( <coaps://[2001:db8::2:1]:61616/est>;rt="ace.est"). 
But still it’s a waste of bytes.
The current example in Section 5 of ace-coap-est is problematic, because 
discovery is on port 5683 and the hosted EST endpoint is on the secure port 
5684. So the following won’t work according to RFC 7252 / RFC 6690:

REQ: GET coap://[2001:db8::2:1]/.well-known/core?rt=ace.est
RES: 2.05 Content
  </est>;rt="ace.est"

Because strictly speaking this tells the client that /est is hosted on port 
5683 (no statement about 5684 hosting!)
I see this as a design flaw in CoAP discovery; we would like to be able to use 
the above short syntax of course.

@Michael:
Since the EST resource is always present on the fixed port 5684 on URI 
/.well-known/est - if a fixed port is needed e.g. for a join proxy, use 5684 
and the well-known URI. No discovery needed.

Esko

From: Peter van der Stok <[email protected]>
Sent: Thursday, September 20, 2018 16:56
To: Michael Richardson <[email protected]>
Cc: Esko Dijk <[email protected]>; Panos Kampanakis (pkampana) 
<[email protected]>; [email protected]
Subject: Re: [Ace] ace-coap-est: unclear definition of /.well-known/est URI



Michael Richardson schreef op 2018-09-20 16:51:


I didn't think that CoAP resource discovery supports port numbers, does it?

It does; at least for the 3rd party registration, but also examples in the RD 
show return of port
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