1.\" 2.\" Copyright (c) 2006, Alexander Motin <mav@alkar.net> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice unmodified, this list of conditions, and the following 10.\" disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd December 24, 2006 30.Dt NG_PRED1 4 31.Os 32.Sh NAME 33.Nm ng_pred1 34.Nd Predictor-1 PPP compression (RFC 1978) netgraph node type 35.Sh SYNOPSIS 36.In sys/types.h 37.In netgraph/ng_pred1.h 38.Sh DESCRIPTION 39The 40.Nm pred1 41node type implements the Predictor-1 sub-protocols of the Compression Control 42Protocol (CCP). 43.Pp 44The node has two hooks, 45.Va comp 46for compression and 47.Va decomp 48for decompression. 49Only one of them can be connected at the same time, specifying node's 50operation mode. 51Typically that hooks would be connected to the 52.Xr ng_ppp 4 53node type hook of the same name. 54.Sh HOOKS 55This node type supports the following hooks: 56.Pp 57.Bl -tag -compact -width ".Va decomp" 58.It Va comp 59Connection to 60.Xr ng_ppp 4 61.Va compress 62hook. 63Incoming frames are compressed and sent back out the same hook. 64.It Va decomp 65Connection to 66.Xr ng_ppp 4 67.Va decompress 68hook. 69Incoming frames are decompressed and sent back out the same hook. 70.El 71.Pp 72Only one hook can be connected at the same time, 73specifying node's operation mode. 74.Sh CONTROL MESSAGES 75This node type supports the generic control messages, plus the following: 76.Bl -tag -width foo 77.It Dv NGM_PRED1_CONFIG Pq Ic config 78This command resets and configures the node for a session 79(i.e., for compression or decompression). 80This command takes a 81.Vt "struct ng_pred1_config" 82as an argument: 83.Bd -literal -offset 0n 84struct ng_pred1_config { 85 u_char enable; /* node enabled */ 86}; 87.Ed 88The 89.Ft enable 90field enables traffic flow through the node. 91.It Dv NGM_PRED1_RESETREQ Pq Ic resetreq 92This message contains no arguments, and is bi-directional. 93If an error is detected during decompression, this message is sent by the 94node to the originator of the 95.Dv NGM_PRED1_CONFIG 96message that initiated the session. 97The receiver should respond by sending a PPP CCP Reset-Request to the peer. 98.Pp 99This message may also be received by this node type when a CCP Reset-Request 100or Reset-Ack is received by the local PPP entity. 101The node will respond by flushing its compression state so the sides 102can resynchronize. 103.It Dv NGM_PRED1_GET_STATS Pq Ic getstats 104This control message obtains statistics for a given hook. 105The statistics are returned in 106.Vt "struct ng_pred1_stats" : 107.Bd -literal 108struct ng_pred1_stats { 109 uint64_t FramesPlain; 110 uint64_t FramesComp; 111 uint64_t FramesUncomp; 112 uint64_t InOctets; 113 uint64_t OutOctets; 114 uint64_t Errors; 115}; 116.Ed 117.It Dv NGM_PRED1_CLR_STATS Pq Ic clrstats 118This control message clears statistics for a given hook. 119.It Dv NGM_PRED1_GETCLR_STATS Pq Ic getclrstats 120This control message obtains and clears statistics for a given hook. 121.El 122.Sh SHUTDOWN 123This node shuts down upon receipt of a 124.Dv NGM_SHUTDOWN 125control message, or when hook have been disconnected. 126.Sh SEE ALSO 127.Xr netgraph 4 , 128.Xr ng_ppp 4 , 129.Xr ngctl 8 130.Rs 131.%A D. Rand 132.%T "PPP Predictor Compression Protocol" 133.%O RFC 1978 134.Re 135.Rs 136.%A W. Simpson 137.%T "The Point-to-Point Protocol (PPP)" 138.%O RFC 1661 139.Re 140.Sh AUTHORS 141.An Alexander Motin Aq mav@alkar.net 142.Sh BUGS 143Due to nature of netgraph PPP implementation there are possible race conditions 144between data packet and ResetAck CCP packet in case of packet loss. As result, 145packet loss can produce bigger performance degradation than supposed by protocol. 146