Official mailing list for the IETF working group on the Datagram Congestion Control Protocol

Gorry Fairhurst | 2 Mar 2011 21:37

draft-ietf-dccp-udpencap - revised guidance on IANA-assigned port usage


Dan Wing and I have been discussing his comments and I think we now have 
text for most of the transport-related points.  In discussing the use of 
ports, the following revised text was suggested.

OLD:

3.8.  Usage of the UDP port by DCCP-UDP

A DCCP-UDP server (that is, an initially passive endpoint that wishes
to receive DCCP-Request packets [RFC4340] over DCCP-UDP) listens for
connections on one or more UDP ports.  UDP port number XXX IANA PORT
XXX has been reserved as the default listening UDP port for DCCP-UDP
connections.  Some NAT/NAPT topologies may require using a non-
default listening port.

A DCCP-UDP client provides UDP source and destination ports as well as 
DCCP source and destination ports at connection initiation time....

---

NEW:

A DCCP-UDP server (that is, an initially passive endpoint that wishes to 
receive DCCP-Request packets [RFC4340] over DCCP-UDP) listens for 
connections on one or more UDP ports. UDP port number XXX IANA PORT XXX 
has been reserved as the default listening UDP port for a DCCP-UDP 
server.  Some NAT/NAPT topologies may require using a non-default 
listening port.

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Eddie Kohler | 2 Mar 2011 23:13

Re: draft-ietf-dccp-udpencap - revised guidance on IANA-assigned port usage

Hi Gorry, I think the intention is for this:

On 03/02/2011 12:37 PM, Gorry Fairhurst wrote:
> NEW:
>
> A DCCP-UDP server (that is, an initially passive endpoint that wishes to
> receive DCCP-Request packets [RFC4340] over DCCP-UDP) listens for connections
> on one or more UDP ports. UDP port number XXX IANA PORT XXX has been reserved
> as the default listening UDP port for a DCCP-UDP server. Some NAT/NAPT
> topologies may require using a non-default listening port.
>
> The purpose of this IANA-assigned port is for the operating system or a
> framework to receive and process DCCP-UDP datagrams for delivery to the DCCP
> module. Because of this, the IANA-assigned port SHOULD NOT be used as a
> Destination UDP Port by a DCCP-UDP server

Change this last sentence (which is just wrong, servers don't choose 
destination ports) to "Because of this, non-framework DCCP-UDP applications 
SHOULD NOT reserve the IANA-assigned UDP port for listening."  Delete the rest 
of the paragraph I think.

> listening for incoming DCCP-UDP
> packets, and SHOULD NOT be used by as a Source UDP Port by a client
> application sending DCCP-UDP packets.
>
> A DCCP-UDP client provides UDP source and destination ports as well as DCCP
> source and destination ports at connection initiation time....
>
> ----
>

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