2 .\" Author: Alexander Motin <mav@alkar.net>
4 .\" Copyright (c) 2006, Alexander Motin <mav@alkar.net>
5 .\" All rights reserved.
7 .\" Redistribution and use in source and binary forms, with or without
8 .\" modification, are permitted provided that the following conditions
10 .\" 1. Redistributions of source code must retain the above copyright
11 .\" notice unmodified, this list of conditions, and the following
13 .\" 2. Redistributions in binary form must reproduce the above copyright
14 .\" notice, this list of conditions and the following disclaimer in the
15 .\" documentation and/or other materials provided with the distribution.
17 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 .Nd Deflate PPP compression (RFC 1979) netgraph node type
39 .In netgraph/ng_deflate.h
43 node type implements the Deflate sub-protocols of the Compression Control
46 The node has two hooks,
51 Only one of them can be connected at the same time, specifying node's
53 Typically that hooks would be connected to the
55 node type hook of the same name.
58 node hook must be switched to
59 .Dv NG_PPP_DECOMPRESS_FULL
60 mode to permit sending uncompressed frames.
62 This node type supports the following hooks:
64 .Bl -tag -compact -width decomp
70 Incoming frames are compressed (if possible) and sent back out the same hook.
76 Incoming frames are decompressed (if they are compressed), and sent
77 back out the same hook.
80 Only one hook can be connected at the same time, specifying node's
83 This node type supports the generic control messages, plus the following:
85 .It Dv NGM_DEFLATE_CONFIG Pq Li config
86 This command resets and configures the node for a session
87 (i.e., for compression or decompression).
89 .Vt "struct ng_deflate_config"
91 .Bd -literal -offset 0n
92 struct ng_deflate_config {
93 u_char enable; /* node enabled */
94 u_char windowBits; /* log2(Window size) */
99 field enables traffic flow through the node.
102 specify compression windows size as negotiated by the
103 Compression Control Protocol (CCP) in PPP.
105 .It Dv NGM_DEFLATE_RESETREQ Pq Li resetreq
106 This message contains no arguments, and is bi-directional.
107 If an error is detected during decompression, this message is sent by the
108 node to the originator of the
109 .Dv NGM_DEFLATE_CONFIG
110 message that initiated the session.
111 The receiver should respond by sending a PPP CCP Reset-Request to the peer.
113 This message may also be received by this node type when a CCP Reset-Request
114 or Reset-Ack is received by the local PPP entity.
115 The node will respond by flushing its compression state so the sides
117 .It Dv NGM_DEFLATE_GET_STATS Pq Li getstats
118 This control message obtains statistics for a given hook.
119 The statistics are returned in
120 .Vt "struct ng_deflate_stats" :
122 struct ng_deflate_stats {
123 uint64_t FramesPlain;
125 uint64_t FramesUncomp;
131 .It Dv NGM_DEFLATE_CLR_STATS Pq Li clrstats
132 This control message clears statistics for a given hook.
133 .It Dv NGM_DEFLATE_GETCLR_STATS Pq Li getclrstats
134 This control message obtains and clears statistics for a given hook.
137 This node shuts down upon receipt of a
139 control message, or when hook have been disconnected.
146 .%T "PPP Deflate Protocol"
151 .%T "The Point-to-Point Protocol (PPP)"
155 .An Alexander Motin Aq mav@alkar.net
157 Due to nature of netgraph PPP implementation there are possible race conditions
158 between data packet and ResetAck CCP packet in case of packet loss. As result,
159 packet loss can produce bigger performance degradation than supposed by protocol.