default or selected kernelversion does not have config value CONFIG_IP_DCCP_CCID2.
Result is shown for kernelversion 5.3.7
CCID2 (TCP-Like) (EXPERIMENTAL)
modulename: dccp_ccid2.ko
configname: CONFIG_IP_DCCP_CCID2
Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>The DCCP Protocol (EXPERIMENTAL)
└─>DCCP CCIDs Configuration (EXPERIMENTAL)
└─>CCID2 (TCP-Like) (EXPERIMENTAL)
In linux kernel since version 2.6.17 (release Date: 2006-06-17)
CCID 2, TCP-like Congestion Control, denotes Additive Increase,
Multiplicative Decrease (AIMD) congestion control with behavior
modelled directly on TCP, including congestion window, slow start,
timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
bandwidth over the long term, consistent with the use of end-to-end
congestion control, but halves its congestion window in response to
each congestion event. This leads to the abrupt rate changes
typical of TCP. Applications should use CCID 2 if they prefer
maximum bandwidth utilization to steadiness of rate. This is often
the case for applications that are not playing their data directly
to the user. For example, a hypothetical application that
transferred files over DCCP, using application-level retransmissions
for lost packets, would prefer CCID 2 to CCID 3. On-line games may
also prefer CCID 2. See RFC 4341 for further details.
CCID2 is the default CCID used by DCCP.
Multiplicative Decrease (AIMD) congestion control with behavior
modelled directly on TCP, including congestion window, slow start,
timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
bandwidth over the long term, consistent with the use of end-to-end
congestion control, but halves its congestion window in response to
each congestion event. This leads to the abrupt rate changes
typical of TCP. Applications should use CCID 2 if they prefer
maximum bandwidth utilization to steadiness of rate. This is often
the case for applications that are not playing their data directly
to the user. For example, a hypothetical application that
transferred files over DCCP, using application-level retransmissions
for lost packets, would prefer CCID 2 to CCID 3. On-line games may
also prefer CCID 2. See RFC 4341 for further details.
CCID2 is the default CCID used by DCCP.