[mirror_ubuntu-artful-kernel.git] / net / dccp / ccids / Kconfig

menu "DCCP CCIDs Configuration (EXPERIMENTAL)"

config IP_DCCP_CCID2
	tristate "CCID2 (TCP-Like)"
	def_tristate IP_DCCP
	---help---
	  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.

config IP_DCCP_CCID2_DEBUG
	  bool "CCID2 debugging messages"
	  depends on IP_DCCP_CCID2
	  ---help---
	    Enable CCID2-specific debugging messages.

	    When compiling CCID2 as a module, this debugging output can
	    additionally be toggled by setting the ccid2_debug module
	    parameter to 0 or 1.

	    If in doubt, say N.

config IP_DCCP_CCID3
	tristate "CCID3 (TCP-Friendly)"
	def_tristate IP_DCCP
	select IP_DCCP_TFRC_LIB
	---help---
	  CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
	  rate-controlled congestion control mechanism.  TFRC is designed to
	  be reasonably fair when competing for bandwidth with TCP-like flows,
	  where a flow is "reasonably fair" if its sending rate is generally
	  within a factor of two of the sending rate of a TCP flow under the
	  same conditions.  However, TFRC has a much lower variation of
	  throughput over time compared with TCP, which makes CCID 3 more
	  suitable than CCID 2 for applications such streaming media where a
	  relatively smooth sending rate is of importance.

	  CCID 3 is further described in RFC 4342,
	  http://www.ietf.org/rfc/rfc4342.txt

	  The TFRC congestion control algorithms were initially described in
	  RFC 3448.

	  This text was extracted from RFC 4340 (sec. 10.2),
	  http://www.ietf.org/rfc/rfc4340.txt
	  
	  To compile this CCID as a module, choose M here: the module will be
	  called dccp_ccid3.

	  If in doubt, say M.

if IP_DCCP_CCID3
config IP_DCCP_CCID3_DEBUG
	  bool "CCID3 debugging messages"
	  ---help---
	    Enable CCID3-specific debugging messages.

	    When compiling CCID3 as a module, this debugging output can
	    additionally be toggled by setting the ccid3_debug module
	    parameter to 0 or 1.

	    If in doubt, say N.

config IP_DCCP_CCID3_RTO
	  int "Use higher bound for nofeedback timer"
	  default 100
	  ---help---
	    Use higher lower bound for nofeedback timer expiration.

	    The TFRC nofeedback timer normally expires after the maximum of 4
	    RTTs and twice the current send interval (RFC 3448, 4.3). On LANs
	    with a small RTT this can mean a high processing load and reduced
	    performance, since then the nofeedback timer is triggered very
	    frequently.

	    This option enables to set a higher lower bound for the nofeedback
	    value. Values in units of milliseconds can be set here.

	    A value of 0 disables this feature by enforcing the value specified
	    in RFC 3448. The following values have been suggested as bounds for
	    experimental use:
	    	* 16-20ms to match the typical multimedia inter-frame interval
	    	* 100ms as a reasonable compromise [default]
	    	* 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4)

	    The default of 100ms is a compromise between a large value for
	    efficient DCCP implementations, and a small value to avoid disrupting
	    the network in times of congestion.

	    The purpose of the nofeedback timer is to slow DCCP down when there
	    is serious network congestion: experimenting with larger values should
	    therefore not be performed on WANs.
endif	# IP_DCCP_CCID3

config IP_DCCP_TFRC_LIB
	tristate
	default n

config IP_DCCP_TFRC_DEBUG
	bool
	depends on IP_DCCP_TFRC_LIB
	default y if IP_DCCP_CCID3_DEBUG

endmenu
Commit	Line	Data
7c657876	1	menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
7c657876	2
2a91aa39	3	config IP_DCCP_CCID2
891e4d8a	4	tristate "CCID2 (TCP-Like)"
057fc675	5	def_tristate IP_DCCP
2a91aa39 AB	6	---help---
	7	CCID 2, TCP-like Congestion Control, denotes Additive Increase,
	8	Multiplicative Decrease (AIMD) congestion control with behavior
	9	modelled directly on TCP, including congestion window, slow start,
	10	timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
	11	bandwidth over the long term, consistent with the use of end-to-end
	12	congestion control, but halves its congestion window in response to
	13	each congestion event. This leads to the abrupt rate changes
	14	typical of TCP. Applications should use CCID 2 if they prefer
	15	maximum bandwidth utilization to steadiness of rate. This is often
	16	the case for applications that are not playing their data directly
	17	to the user. For example, a hypothetical application that
	18	transferred files over DCCP, using application-level retransmissions
	19	for lost packets, would prefer CCID 2 to CCID 3. On-line games may
e333b3ed	20	also prefer CCID 2. See RFC 4341 for further details.
2a91aa39	21
e333b3ed	22	CCID2 is the default CCID used by DCCP.
2a91aa39	23
8d424f6c	24	config IP_DCCP_CCID2_DEBUG
84116716	25	bool "CCID2 debugging messages"
8d424f6c AB	26	depends on IP_DCCP_CCID2
8d424f6c AB	27	---help---
84116716 GR	28	Enable CCID2-specific debugging messages.
	29
	30	When compiling CCID2 as a module, this debugging output can
	31	additionally be toggled by setting the ccid2_debug module
	32	parameter to 0 or 1.
8d424f6c AB	33
	34	If in doubt, say N.
	35
7c657876	36	config IP_DCCP_CCID3
891e4d8a	37	tristate "CCID3 (TCP-Friendly)"
057fc675	38	def_tristate IP_DCCP
c40616c5	39	select IP_DCCP_TFRC_LIB
7c657876 ACM	40	---help---
	41	CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
	42	rate-controlled congestion control mechanism. TFRC is designed to
	43	be reasonably fair when competing for bandwidth with TCP-like flows,
	44	where a flow is "reasonably fair" if its sending rate is generally
	45	within a factor of two of the sending rate of a TCP flow under the
	46	same conditions. However, TFRC has a much lower variation of
	47	throughput over time compared with TCP, which makes CCID 3 more
	48	suitable than CCID 2 for applications such streaming media where a
	49	relatively smooth sending rate is of importance.
	50
0e64e94e GR	51	CCID 3 is further described in RFC 4342,
0e64e94e GR	52	http://www.ietf.org/rfc/rfc4342.txt
2a91aa39 AB	53
	54	The TFRC congestion control algorithms were initially described in
	55	RFC 3448.
7c657876	56
0e64e94e GR	57	This text was extracted from RFC 4340 (sec. 10.2),
0e64e94e GR	58	http://www.ietf.org/rfc/rfc4340.txt
7c657876	59
84116716 GR	60	To compile this CCID as a module, choose M here: the module will be
	61	called dccp_ccid3.
	62
7c657876 ACM	63	If in doubt, say M.
7c657876 ACM	64
891e4d8a	65	if IP_DCCP_CCID3
56724aa4 GR	66	config IP_DCCP_CCID3_DEBUG
56724aa4 GR	67	bool "CCID3 debugging messages"
56724aa4 GR	68	---help---
	69	Enable CCID3-specific debugging messages.
	70
	71	When compiling CCID3 as a module, this debugging output can
	72	additionally be toggled by setting the ccid3_debug module
	73	parameter to 0 or 1.
	74
	75	If in doubt, say N.
8a508ac2 GR	76
	77	config IP_DCCP_CCID3_RTO
	78	int "Use higher bound for nofeedback timer"
	79	default 100
8a508ac2 GR	80	---help---
	81	Use higher lower bound for nofeedback timer expiration.
	82
	83	The TFRC nofeedback timer normally expires after the maximum of 4
	84	RTTs and twice the current send interval (RFC 3448, 4.3). On LANs
	85	with a small RTT this can mean a high processing load and reduced
	86	performance, since then the nofeedback timer is triggered very
	87	frequently.
	88
	89	This option enables to set a higher lower bound for the nofeedback
	90	value. Values in units of milliseconds can be set here.
	91
	92	A value of 0 disables this feature by enforcing the value specified
	93	in RFC 3448. The following values have been suggested as bounds for
	94	experimental use:
	95	* 16-20ms to match the typical multimedia inter-frame interval
	96	* 100ms as a reasonable compromise [default]
	97	* 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4)
	98
	99	The default of 100ms is a compromise between a large value for
	100	efficient DCCP implementations, and a small value to avoid disrupting
	101	the network in times of congestion.
	102
	103	The purpose of the nofeedback timer is to slow DCCP down when there
	104	is serious network congestion: experimenting with larger values should
	105	therefore not be performed on WANs.
891e4d8a	106	endif # IP_DCCP_CCID3
8a508ac2	107
c40616c5 GR	108	config IP_DCCP_TFRC_LIB
	109	tristate
	110	default n
	111
	112	config IP_DCCP_TFRC_DEBUG
	113	bool
	114	depends on IP_DCCP_TFRC_LIB
	115	default y if IP_DCCP_CCID3_DEBUG
8a508ac2	116
7c657876	117	endmenu