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147 lines
4.5 KiB
Groff
147 lines
4.5 KiB
Groff
.\"
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.\" Copyright (c) 2006, Alexander Motin <mav@alkar.net>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice unmodified, this list of conditions, and the following
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.\" disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 24, 2006
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.Dt NG_PRED1 4
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.Os
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.Sh NAME
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.Nm ng_pred1
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.Nd Predictor-1 PPP compression (RFC 1978) netgraph node type
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.Sh SYNOPSIS
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.In sys/types.h
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.In netgraph/ng_pred1.h
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.Sh DESCRIPTION
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The
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.Nm pred1
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node type implements the Predictor-1 sub-protocols of the Compression Control
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Protocol (CCP).
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.Pp
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The node has two hooks,
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.Va comp
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for compression and
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.Va decomp
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for decompression.
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Only one of them can be connected at the same time, specifying node's
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operation mode.
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Typically that hooks would be connected to the
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.Xr ng_ppp 4
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node type hook of the same name.
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.Sh HOOKS
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This node type supports the following hooks:
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.Pp
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.Bl -tag -compact -width ".Va decomp"
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.It Va comp
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Connection to
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.Xr ng_ppp 4
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.Va compress
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hook.
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Incoming frames are compressed and sent back out the same hook.
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.It Va decomp
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Connection to
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.Xr ng_ppp 4
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.Va decompress
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hook.
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Incoming frames are decompressed and sent back out the same hook.
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.El
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.Pp
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Only one hook can be connected at the same time,
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specifying node's operation mode.
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.Sh CONTROL MESSAGES
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This node type supports the generic control messages, plus the following:
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.Bl -tag -width foo
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.It Dv NGM_PRED1_CONFIG Pq Ic config
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This command resets and configures the node for a session
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(i.e., for compression or decompression).
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This command takes a
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.Vt "struct ng_pred1_config"
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as an argument:
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.Bd -literal -offset 0n
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struct ng_pred1_config {
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u_char enable; /* node enabled */
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};
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.Ed
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The
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.Ft enable
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field enables traffic flow through the node.
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.It Dv NGM_PRED1_RESETREQ Pq Ic resetreq
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This message contains no arguments, and is bi-directional.
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If an error is detected during decompression, this message is sent by the
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node to the originator of the
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.Dv NGM_PRED1_CONFIG
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message that initiated the session.
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The receiver should respond by sending a PPP CCP Reset-Request to the peer.
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.Pp
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This message may also be received by this node type when a CCP Reset-Request
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or Reset-Ack is received by the local PPP entity.
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The node will respond by flushing its compression state so the sides
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can resynchronize.
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.It Dv NGM_PRED1_GET_STATS Pq Ic getstats
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This control message obtains statistics for a given hook.
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The statistics are returned in
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.Vt "struct ng_pred1_stats" :
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.Bd -literal
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struct ng_pred1_stats {
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uint64_t FramesPlain;
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uint64_t FramesComp;
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uint64_t FramesUncomp;
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uint64_t InOctets;
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uint64_t OutOctets;
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uint64_t Errors;
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};
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.Ed
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.It Dv NGM_PRED1_CLR_STATS Pq Ic clrstats
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This control message clears statistics for a given hook.
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.It Dv NGM_PRED1_GETCLR_STATS Pq Ic getclrstats
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This control message obtains and clears statistics for a given hook.
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.El
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or when hook have been disconnected.
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.Sh SEE ALSO
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.Xr netgraph 4 ,
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.Xr ng_ppp 4 ,
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.Xr ngctl 8
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.Rs
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.%A D. Rand
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.%T "PPP Predictor Compression Protocol"
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.%O RFC 1978
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.Re
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.Rs
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.%A W. Simpson
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.%T "The Point-to-Point Protocol (PPP)"
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.%O RFC 1661
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.Re
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.Sh AUTHORS
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.An Alexander Motin Aq Mt mav@alkar.net
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.Sh BUGS
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Due to nature of netgraph PPP implementation there are possible race conditions
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between data packet and ResetAck CCP packet in case of packet loss.
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As result,
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packet loss can produce bigger performance degradation than supposed by protocol.
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