57 lines
1.4 KiB
Plaintext
57 lines
1.4 KiB
Plaintext
|
DCCP protocol
|
||
|
|
============
|
||
|
|
|
||
|
|
Last updated: 10 November 2005
|
||
|
|
|
||
|
|
Contents
|
||
|
|
========
|
||
|
|
|
||
|
|
- Introduction
|
||
|
|
- Missing features
|
||
|
|
- Socket options
|
||
|
|
- Notes
|
||
|
|
|
||
|
|
Introduction
|
||
|
|
============
|
||
|
|
|
||
|
|
Datagram Congestion Control Protocol (DCCP) is an unreliable, connection
|
||
|
|
based protocol designed to solve issues present in UDP and TCP particularly
|
||
|
|
for real time and multimedia traffic.
|
||
|
|
|
||
|
|
It has a base protocol and pluggable congestion control IDs (CCIDs).
|
||
|
|
|
||
|
|
It is at draft RFC status and the homepage for DCCP as a protocol is at:
|
||
|
|
http://www.icir.org/kohler/dcp/
|
||
|
|
|
||
|
|
Missing features
|
||
|
|
================
|
||
|
|
|
||
|
|
The DCCP implementation does not currently have all the features that are in
|
||
|
|
the draft RFC.
|
||
|
|
|
||
|
|
In particular the following are missing:
|
||
|
|
- CCID2 support
|
||
|
|
- feature negotiation
|
||
|
|
|
||
|
|
When testing against other implementations it appears that elapsed time
|
||
|
|
options are not coded compliant to the specification.
|
||
|
|
|
||
|
|
Socket options
|
||
|
|
==============
|
||
|
|
|
||
|
|
DCCP_SOCKOPT_PACKET_SIZE is used for CCID3 to set default packet size for
|
||
|
|
calculations.
|
||
|
|
|
||
|
|
DCCP_SOCKOPT_SERVICE sets the service. This is compulsory as per the
|
||
|
|
specification. If you don't set it you will get EPROTO.
|
||
|
|
|
||
|
|
Notes
|
||
|
|
=====
|
||
|
|
|
||
|
|
SELinux does not yet have support for DCCP. You will need to turn it off or
|
||
|
|
else you will get EACCES.
|
||
|
|
|
||
|
|
DCCP does not travel through NAT successfully at present. This is because
|
||
|
|
the checksum covers the psuedo-header as per TCP and UDP. It should be
|
||
|
|
relatively trivial to add Linux NAT support for DCCP.
|