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.\" Copyright (c) 1997, 2002 Hellmuth Michaelis. All rights reserved.
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.\" $FreeBSD$
.\"
.\"	last edit-date: [Sun Jul 28 12:43:22 2002]
.\"
.Dd July 28, 2002
.Dt I4BISPPP 4
.Os
.Sh NAME
.Nm i4bisppp
.Nd isdn4bsd synchronous PPP over ISDN B-channel network driver
.Sh SYNOPSIS
.Cd device \&"i4bisppp\&" Op count
.Cd device sppp
.Sh DESCRIPTION
The
.Nm
driver interfaces the IP subsystem of the operating system with the
isdn4bsd package so that a transport of IP packets over an ISDN link
is possible.
.Pp
The driver is just a glue layer between the
.Xr sppp 4
backend and the ISDN4BSD package and needs the
.Xr sppp 4
driver configured into the kernel.
.Pp
The network interfaces provided by this driver are named
.Em isp<n> ,
where <n> is a number between 0 and count-1 from the kernel config line.
.Pp
For configuration of the i4bsppp driver, either the
.Xr spppcontrol 8
utility is used or the driver can be configured via
.Xr isdnd 8
and its associated
.Xr isdnd.rc 5
file.
.Pp
In case an IP packet for a remote side arrives in the driver and no
connection is 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 1
with the
.Nm isp
interfaces.
.Pp
.Sh LINK0 and LINK1
The
.Em link0
and
.Em link1
flags given as parameters to
.Xr ifconfig 8
have the following meaning for the
.Em isp<n>
devices:
.Bl -tag -width link0 -compact
.Pp
.It Li link0
wait passively for connection
.Pp
.It Li link1
auto-dial on output
.El
.Pp
The
.Em link0
and
.Em link1
flags are set to
.Em off
by default.
.Pp
See
.Xr sppp 4
for a more detailed discussion of the flags.
.Sh SEE ALSO
.Xr tcpdump 1 ,
.Xr bpf 4 ,
.Xr sppp 4 ,
.Xr isdnd.rc 5 ,
.Xr isdnd 8 ,
.Xr spppcontrol 8
.Sh AUTHORS
.An -nosplit
The
.Nm
device driver was written by
.An Joerg Wunsch Aq joerg@FreeBSD.org
and then added to ISDN4BSD by
.An Gary Jennejohn Aq gj@FreeBSD.org .
.Pp
This manpage was written by
.An Hellmuth Michaelis Aq hm@FreeBSD.org .