.\" $NetBSD: irip.4,v 1.3 2006/07/08 20:51:35 tsutsui Exp $
.\"
.\" Copyright (c) 1997, 1999 Hellmuth Michaelis. All rights reserved.
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.\"	$Id: irip.4,v 1.3 2006/07/08 20:51:35 tsutsui Exp $
.\"
.\" $FreeBSD$
.\"
.\"	last edit-date: [Mon Dec 13 23:10:25 1999]
.\"
.Dd July 6, 1998
.Dt IRIP 4
.Os
.Sh NAME
.Nm irip
.Nd Raw IP over ISDN network driver
.Sh SYNOPSIS
.Cd "pseudo-device irip" Ar count
.Sh DESCRIPTION
The
.Nm
driver interfaces the IP subsystem of the operating system with the
ISDN layer so that transport of IP packets over an ISDN link
is possible.
.Pp
The driver just packs IP packets without anything appended or prepended
into raw HDLC packets on the B channel and transfers them to a remote site.
IP packets received from the remote site are queued into the local IP
protocol stack.
.Pp
The format of the resulting packet on the B channel is:
.Pp
.Dl (HDLC opening flag) (IP-packet) (CRC) (HDLC closing flag)
.Pp
In the case where an IP packet for a remote site arrives in the driver and no
connection has been established yet, the driver communicates with the
.Xr isdnd 8
daemon to establish a connection.
.Pp
The driver has support for interfacing to the
.Xr bpf 4
subsystem for using
.Xr tcpdump 8
with the
.Nm
interfaces.
.Pp
The driver optionally (when compiled with the IRIP_VJ option) provides Van
Jacobson header compression, under control of the link0 and link1 options to
.Xr ifconfig 8 :
.Pp
.Bl -tag -width 15n -offset indent -compact
.It link0
Apply VJ compression to outgoing packets on this interface, and assume that
incoming packets require decompression.
.It link1
Check incoming packets for Van Jacobson compression; if they appear to be
compressed, automatically set link0.
.El
.Pp
The default values are
.Em on
for
.Em link1
and
.Em off
for
.Em link0 .
.Sh SEE ALSO
.Xr bpf 4 ,
.Xr isdnd.rc 5 ,
.Xr isdnd 8 ,
.Xr tcpdump 8
.Sh AUTHORS
The
.Nm
device driver and this man page were written by
.An Hellmuth Michaelis Aq hm@kts.org .