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119 lines
4.4 KiB
119 lines
4.4 KiB
menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
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depends on EXPERIMENTAL
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config IP_DCCP_CCID2
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tristate "CCID2 (TCP-Like) (EXPERIMENTAL)"
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def_tristate IP_DCCP
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select IP_DCCP_ACKVEC
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---help---
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CCID 2, TCP-like Congestion Control, denotes Additive Increase,
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Multiplicative Decrease (AIMD) congestion control with behavior
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modelled directly on TCP, including congestion window, slow start,
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timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
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bandwidth over the long term, consistent with the use of end-to-end
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congestion control, but halves its congestion window in response to
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each congestion event. This leads to the abrupt rate changes
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typical of TCP. Applications should use CCID 2 if they prefer
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maximum bandwidth utilization to steadiness of rate. This is often
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the case for applications that are not playing their data directly
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to the user. For example, a hypothetical application that
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transferred files over DCCP, using application-level retransmissions
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for lost packets, would prefer CCID 2 to CCID 3. On-line games may
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also prefer CCID 2. See RFC 4341 for further details.
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CCID2 is the default CCID used by DCCP.
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config IP_DCCP_CCID2_DEBUG
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bool "CCID2 debugging messages"
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depends on IP_DCCP_CCID2
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---help---
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Enable CCID2-specific debugging messages.
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When compiling CCID2 as a module, this debugging output can
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additionally be toggled by setting the ccid2_debug module
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parameter to 0 or 1.
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If in doubt, say N.
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config IP_DCCP_CCID3
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tristate "CCID3 (TCP-Friendly) (EXPERIMENTAL)"
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def_tristate IP_DCCP
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select IP_DCCP_TFRC_LIB
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---help---
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CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
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rate-controlled congestion control mechanism. TFRC is designed to
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be reasonably fair when competing for bandwidth with TCP-like flows,
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where a flow is "reasonably fair" if its sending rate is generally
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within a factor of two of the sending rate of a TCP flow under the
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same conditions. However, TFRC has a much lower variation of
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throughput over time compared with TCP, which makes CCID 3 more
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suitable than CCID 2 for applications such streaming media where a
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relatively smooth sending rate is of importance.
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CCID 3 is further described in RFC 4342,
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http://www.ietf.org/rfc/rfc4342.txt
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The TFRC congestion control algorithms were initially described in
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RFC 3448.
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This text was extracted from RFC 4340 (sec. 10.2),
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http://www.ietf.org/rfc/rfc4340.txt
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To compile this CCID as a module, choose M here: the module will be
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called dccp_ccid3.
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If in doubt, say M.
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config IP_DCCP_CCID3_DEBUG
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bool "CCID3 debugging messages"
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depends on IP_DCCP_CCID3
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---help---
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Enable CCID3-specific debugging messages.
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When compiling CCID3 as a module, this debugging output can
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additionally be toggled by setting the ccid3_debug module
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parameter to 0 or 1.
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If in doubt, say N.
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config IP_DCCP_CCID3_RTO
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int "Use higher bound for nofeedback timer"
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default 100
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depends on IP_DCCP_CCID3 && EXPERIMENTAL
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---help---
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Use higher lower bound for nofeedback timer expiration.
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The TFRC nofeedback timer normally expires after the maximum of 4
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RTTs and twice the current send interval (RFC 3448, 4.3). On LANs
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with a small RTT this can mean a high processing load and reduced
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performance, since then the nofeedback timer is triggered very
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frequently.
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This option enables to set a higher lower bound for the nofeedback
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value. Values in units of milliseconds can be set here.
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A value of 0 disables this feature by enforcing the value specified
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in RFC 3448. The following values have been suggested as bounds for
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experimental use:
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* 16-20ms to match the typical multimedia inter-frame interval
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* 100ms as a reasonable compromise [default]
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* 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4)
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The default of 100ms is a compromise between a large value for
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efficient DCCP implementations, and a small value to avoid disrupting
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the network in times of congestion.
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The purpose of the nofeedback timer is to slow DCCP down when there
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is serious network congestion: experimenting with larger values should
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therefore not be performed on WANs.
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config IP_DCCP_TFRC_LIB
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tristate
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default n
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config IP_DCCP_TFRC_DEBUG
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bool
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depends on IP_DCCP_TFRC_LIB
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default y if IP_DCCP_CCID3_DEBUG
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endmenu
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