Hi Folks,
I'll suggest CCID 3 because that's my lucky number. ;-)
Seriously, here is a relevant point from RFC 5238:
===vvv===
In addition to the retransmission issues, if the throughput needs of
the actual application data differ from the needs of the DTLS
handshake, it is possible that the handshake transference could leave
the DCCP congestion control in a state that is not immediately
suitable for the application data that will follow. For example,
DCCP Congestion Control Identifier (CCID) 2 ([RFC4341]) congestion
control uses an Additive Increase Multiplicative Decrease (AIMD)
algorithm similar to TCP congestion control. If it is used, then it
is possible that transference of a large handshake could cause a
multiplicative decrease that would not have happened with the
application data. The application might then be throttled while
waiting for additive increase to return throughput to acceptable
levels.
Applications where this might be a problem should consider using DCCP
CCID 3 ([RFC4342]). CCID 3 implements TCP-Friendly Rate Control
(TFRC, [RFC3448])). TFRC varies the allowed throughput more slowly
than AIMD and might avoid the discontinuities possible with CCID 2.
===^^^===
My reasoning for choosing CCID 3 is that when some devices start up they
will queue up syslog messages until the network is up, and then they will
start to deliver them. I don't want a large handshake to throttle that
initial burst of messages. (Please challenge this assumption if you have
a better understanding of the process.)
I'll suggest that the specific wording will need to be: "MUST implement
CCID 3 and SHOULD implement CCID 2 to ensure interoperability". Does that
sound OK to everyone?
Joe: can you look at Sean's second question and let us know about that?
Thanks,
Chris
On Thu, 8 Apr 2010, Sean Turner wrote:
I have one major comment and it relates to DCCP:
The DCCP chairs tell me that to specify the use of DCCP the ID needs to
decide which CCID it will use (CCID 2 is AIMD and CCID 3 is TFRC). I was
hoping that the DTLS over DCCP RFC addressed this, but that RFC doesn't pick
one it leaves this choice to the "application".
Can you also confirm that the Port # is used as the DCCP service code?
spt
_______________________________________________
Syslog mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/syslog
_______________________________________________
Syslog mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/syslog
