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- DCCP protocol
- ============
- 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. The specification mandates use of
- service codes (RFC 4340, sec. 8.1.2); if this socket option is not set,
- the socket will fall back to 0 (which means that no meaningful service code
- is present). Connecting sockets set at most one service option; for
- listening sockets, multiple service codes can be specified.
- 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.
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