Subject: Re: [core] #389 (coap-tcp-tls): Version negotiation

From: "core issue tracker" <[email-masked]>
Date: Tue, 05 Apr 2016 02:42:27 -0000

#389: Version negotiation

Comment (by [email-masked]):

 Clarification from Klaus:
 http://www.ietf.org/mail-archive/web/core/current/msg06947.html

 In CoAP, we have the Uri-Host Option [1] which can be included in CoAP
 requests to indicate the FQDN of the server. In CoAP over UDP a client can
 target a different virtual server with each request.

 In CoAP over WebSockets, the virtual server is specified during the
 WebSocket handshake in the Host header field. The Uri-Host Option is
 therefore not needed. A client wishing to talk to multiple virtual servers
 running on the same IP address has to open one WebSocket
 connection to each virtual server. (Please correct me if I'm wrong.)

 In CoAP over TLS we have the SNI extension, so I would expect that CoAP
 over TLS behaves like CoAP over WebSockets: no Uri-Host Option in
 requests, one connection to each virtual server.

 The question is what CoAP over TCP should do. One option is to include a
 Uri-Host option in each request, like CoAP over UDP. Then only one
 connection would be needed for all virtual servers running on the same IP
 address. Another option is to add a minimal handshake-like message to CoAP
 over TCP.

 I have no particular preference, but I think it's important that CoAP over
 TCP, TLS and WebSockets are consistent and no protocol behaves wildly
 different from the others.

 [1] https://tools.ietf.org/html/rfc7252#section-5.10.1

-- 
-------------------------+-------------------------------------------------
 Reporter:               |       Owner:  draft-ietf-core-coap-tcp-
  [email-masked]         |  [email-masked]
     Type:  protocol     |      Status:  new
  defect                 |   Milestone:
 Priority:  minor        |     Version:
Component:  coap-tcp-    |  Resolution:
  tls                    |
 Severity:  Active WG    |
  Document               |
 Keywords:               |
-------------------------+-------------------------------------------------

Ticket URL: <https://trac.tools.ietf.org/wg/core/trac/ticket/389#comment:1>
core <https://tools.ietf.org/core/>