1menu "DCCP CCIDs Configuration (EXPERIMENTAL)" 2 3config IP_DCCP_CCID2 4 tristate "CCID2 (TCP-Like)" 5 def_tristate IP_DCCP 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 20 also prefer CCID 2. See RFC 4341 for further details. 21 22 CCID2 is the default CCID used by DCCP. 23 24config IP_DCCP_CCID2_DEBUG 25 bool "CCID2 debugging messages" 26 depends on IP_DCCP_CCID2 27 ---help--- 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. 33 34 If in doubt, say N. 35 36config IP_DCCP_CCID3 37 tristate "CCID3 (TCP-Friendly)" 38 def_tristate IP_DCCP 39 select IP_DCCP_TFRC_LIB 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 51 CCID 3 is further described in RFC 4342, 52 http://www.ietf.org/rfc/rfc4342.txt 53 54 The TFRC congestion control algorithms were initially described in 55 RFC 3448. 56 57 This text was extracted from RFC 4340 (sec. 10.2), 58 http://www.ietf.org/rfc/rfc4340.txt 59 60 To compile this CCID as a module, choose M here: the module will be 61 called dccp_ccid3. 62 63 If in doubt, say M. 64 65if IP_DCCP_CCID3 66config IP_DCCP_CCID3_DEBUG 67 bool "CCID3 debugging messages" 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. 76 77config IP_DCCP_CCID3_RTO 78 int "Use higher bound for nofeedback timer" 79 default 100 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. 106endif # IP_DCCP_CCID3 107 108config IP_DCCP_TFRC_LIB 109 tristate 110 default n 111 112config IP_DCCP_TFRC_DEBUG 113 bool 114 depends on IP_DCCP_TFRC_LIB 115 default y if IP_DCCP_CCID3_DEBUG 116 117endmenu 118