1menu "DCCP CCIDs Configuration (EXPERIMENTAL)" 2 depends on EXPERIMENTAL 3 4config IP_DCCP_CCID2 5 tristate "CCID2 (TCP-Like) (EXPERIMENTAL)" 6 def_tristate IP_DCCP 7 select IP_DCCP_ACKVEC 8 ---help--- 9 CCID 2, TCP-like Congestion Control, denotes Additive Increase, 10 Multiplicative Decrease (AIMD) congestion control with behavior 11 modelled directly on TCP, including congestion window, slow start, 12 timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum 13 bandwidth over the long term, consistent with the use of end-to-end 14 congestion control, but halves its congestion window in response to 15 each congestion event. This leads to the abrupt rate changes 16 typical of TCP. Applications should use CCID 2 if they prefer 17 maximum bandwidth utilization to steadiness of rate. This is often 18 the case for applications that are not playing their data directly 19 to the user. For example, a hypothetical application that 20 transferred files over DCCP, using application-level retransmissions 21 for lost packets, would prefer CCID 2 to CCID 3. On-line games may 22 also prefer CCID 2. See RFC 4341 for further details. 23 24 CCID2 is the default CCID used by DCCP. 25 26config IP_DCCP_CCID2_DEBUG 27 bool "CCID2 debugging messages" 28 depends on IP_DCCP_CCID2 29 ---help--- 30 Enable CCID2-specific debugging messages. 31 32 When compiling CCID2 as a module, this debugging output can 33 additionally be toggled by setting the ccid2_debug module 34 parameter to 0 or 1. 35 36 If in doubt, say N. 37 38config IP_DCCP_CCID3 39 tristate "CCID3 (TCP-Friendly) (EXPERIMENTAL)" 40 def_tristate IP_DCCP 41 select IP_DCCP_TFRC_LIB 42 ---help--- 43 CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based 44 rate-controlled congestion control mechanism. TFRC is designed to 45 be reasonably fair when competing for bandwidth with TCP-like flows, 46 where a flow is "reasonably fair" if its sending rate is generally 47 within a factor of two of the sending rate of a TCP flow under the 48 same conditions. However, TFRC has a much lower variation of 49 throughput over time compared with TCP, which makes CCID 3 more 50 suitable than CCID 2 for applications such streaming media where a 51 relatively smooth sending rate is of importance. 52 53 CCID 3 is further described in RFC 4342, 54 http://www.ietf.org/rfc/rfc4342.txt 55 56 The TFRC congestion control algorithms were initially described in 57 RFC 3448. 58 59 This text was extracted from RFC 4340 (sec. 10.2), 60 http://www.ietf.org/rfc/rfc4340.txt 61 62 To compile this CCID as a module, choose M here: the module will be 63 called dccp_ccid3. 64 65 If in doubt, say M. 66 67config IP_DCCP_CCID3_DEBUG 68 bool "CCID3 debugging messages" 69 depends on IP_DCCP_CCID3 70 ---help--- 71 Enable CCID3-specific debugging messages. 72 73 When compiling CCID3 as a module, this debugging output can 74 additionally be toggled by setting the ccid3_debug module 75 parameter to 0 or 1. 76 77 If in doubt, say N. 78 79config IP_DCCP_CCID3_RTO 80 int "Use higher bound for nofeedback timer" 81 default 100 82 depends on IP_DCCP_CCID3 && EXPERIMENTAL 83 ---help--- 84 Use higher lower bound for nofeedback timer expiration. 85 86 The TFRC nofeedback timer normally expires after the maximum of 4 87 RTTs and twice the current send interval (RFC 3448, 4.3). On LANs 88 with a small RTT this can mean a high processing load and reduced 89 performance, since then the nofeedback timer is triggered very 90 frequently. 91 92 This option enables to set a higher lower bound for the nofeedback 93 value. Values in units of milliseconds can be set here. 94 95 A value of 0 disables this feature by enforcing the value specified 96 in RFC 3448. The following values have been suggested as bounds for 97 experimental use: 98 * 16-20ms to match the typical multimedia inter-frame interval 99 * 100ms as a reasonable compromise [default] 100 * 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4) 101 102 The default of 100ms is a compromise between a large value for 103 efficient DCCP implementations, and a small value to avoid disrupting 104 the network in times of congestion. 105 106 The purpose of the nofeedback timer is to slow DCCP down when there 107 is serious network congestion: experimenting with larger values should 108 therefore not be performed on WANs. 109 110config IP_DCCP_TFRC_LIB 111 tristate 112 default n 113 114config IP_DCCP_TFRC_DEBUG 115 bool 116 depends on IP_DCCP_TFRC_LIB 117 default y if IP_DCCP_CCID3_DEBUG 118 119endmenu 120