765 lines
23 KiB
Groff
765 lines
23 KiB
Groff
.\"
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.\" $FreeBSD$
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.\"
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.\" Copyright (c) 2002-2005 David Boggs. (boggs@boggs.palo-alto.ca.us)
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.\" All rights reserved.
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.\"
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.\" BSD License:
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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, this list of conditions and the following 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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.\" GNU General Public License:
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.\"
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.\" This program is free software; you can redistribute it and/or modify it
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.\" under the terms of the GNU General Public License as published by the Free
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.\" Software Foundation; either version 2 of the License, or (at your option)
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.\" any later version.
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.\"
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.\" This program is distributed in the hope that it will be useful, but WITHOUT
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.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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.\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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.\" more details.
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.\"
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.\" You should have received a copy of the GNU General Public License along with
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.\" this program; if not, write to the Free Software Foundation, Inc., 59
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.\" Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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.\"
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.Dd February 8, 2012
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.Dt LMC 4
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.Os
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.\"
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.Sh NAME
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.\"
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.Nm lmc
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.Nd device driver for
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.Tn LMC
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(now
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.Tn SBE )
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wide-area network interface cards
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.\"
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.Sh SYNOPSIS
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.\"
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To wire this driver into your kernel,
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add the following line to your kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device lmc"
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.Ed
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.Pp
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Alternatively, to load this module at boot time, add
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.Bd -literal -offset indent
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if_lmc_load="YES"
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.Ed
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.Pp
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to
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.Pa /boot/loader.conf ;
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see
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.Xr loader.conf 5 .
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.Pp
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To wire a line protocol into your kernel, add:
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.Bd -ragged -offset indent
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.Cd "options NETGRAPH"
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.Cd "device sppp"
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.Ed
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.Pp
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It is not necessary to wire line protocols into your kernel,
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they can be loaded later with
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.Xr kldload 8 .
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The driver can send and receive raw IP packets even if neither
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SPPP nor Netgraph are configured into the kernel.
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Netgraph and SPPP can both be enabled; Netgraph will be used if the
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.Va rawdata
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hook is connected.
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.\"
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.Sh DESCRIPTION
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.\"
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This is an open-source
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.Ux
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device driver for PCI-bus WAN interface cards.
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It sends and receives packets in HDLC frames over synchronous circuits.
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A generic PC plus
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.Ux
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plus some
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.Tn LMC / SBE
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cards makes an
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.Em open
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router.
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This driver works with
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.Fx ,
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.Nx ,
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.Ox ,
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.Bsx
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and
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.Tn Linux
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OSs.
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It has been tested on i386 (SMP 32-bit little-endian) and Sparc (64-bit big-endian)
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architectures.
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.Pp
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The
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.Nm
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driver works with the following cards:
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.Bl -bullet
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.It
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SBE wanADAPT-HSSI (LMC5200)
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.Pp
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High Speed Serial Interface,
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EIA612/613, 50-pin connector,
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0 to 52 Mb/s, DTE only.
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.It
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SBE wanADAPT-T3 (LMC5245)
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.Pp
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T3: two 75-ohm BNC connectors,
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C-Parity or M13 Framing,
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44.736 Mb/s, up to 950 ft.
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.It
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SBE wanADAPT-SSI (LMC1000)
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.Pp
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Synchronous Serial Interface,
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V.35, X.21, EIA449, EIA530(A), EIA232,
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0 to 10 Mb/s, DTE or DCE.
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.It
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SBE wanADAPT-T1E1 (LMC1200)
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.Pp
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T1 or E1: RJ45 conn, 100 or 120 ohms,
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T1-ESF-B8ZS, T1-SF-AMI, E1-(many)-HDB3,
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1.544 Mb/s or 2.048 Mb/s, up to 6 Kft.
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.El
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.Pp
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Cards contain a high-performance
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.Sy "PCI"
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interface, an
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.Sy "HDLC"
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function and
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either integrated
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.Sy "modems"
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(T1, T3) or
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.Sy "modem"
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interfaces (HSSI and SSI).
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.Bl -tag -width "Modem"
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.It Sy "PCI"
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The PCI interface is a DEC 21140A "Tulip" Fast Ethernet chip.
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This chip has an efficient PCI implementation with scatter/gather DMA,
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and can run at 100 Mb/s full duplex (twice as fast as needed here).
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.It Sy "HDLC"
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The HDLC functions (ISO-3309: flags, bit-stuffing, CRC) are implemented
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in a Field Programmable Gate Array (FPGA) which talks to the Ethernet
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chip through a Media Independent Interface (MII).
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The hardware in the FPGA translates between Ethernet packets and
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HDLC frames on-the-fly; think it as a WAN PHY chip for Ethernet.
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.It Sy "Modem"
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The modem chips are the main differences between cards.
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HSSI cards use ECL10K chips to implement the EIA-612/613 interface.
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T3 cards use a TranSwitch TXC-03401 framer chip.
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SSI cards use Linear Technology LTC1343 modem interface chips.
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T1 cards use a BrookTree/Conexant/Mindspeed Bt8370 framer
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and line interface chip.
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.El
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.Pp
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Line protocols exist above device drivers and below internet protocols.
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They typically encapsulate packets in HDLC frames and deal with
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higher-level issues like protocol multiplexing and security.
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This driver is compatible with several line protocol packages:
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.Bl -tag -width "Generic HDLC"
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.It Sy "Netgraph"
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.Xr netgraph 4
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implements many basic packet-handling functions as kernel loadable modules.
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They can be interconnected in a graph to implement many protocols.
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Configuration is done from userland without rebuilding the kernel.
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Packets are sent and received through this interface if the driver's
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.Em rawdata
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hook is connected, otherwise the ifnet interface (SPPP and RawIP) is used.
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ASCII configuration control messages are
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.Em not
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currently supported.
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.It Sy "SPPP"
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.Xr sppp 4
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implements Synchronous-PPP, Frame-Relay and Cisco-HDLC in the kernel.
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.It Sy "RawIP"
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This null line protocol, built into the driver, sends and receives
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raw IPv4 and IPv6 packets in HDLC frames (aka IP-in-HDLC) with
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no extra bytes of overhead and no state at the end points.
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.El
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.\"
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.Sh EXAMPLES
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.\"
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.Ss "ifconfig and lmcconfig"
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.\"
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The program
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.Xr lmcconfig 8
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manipulates interface parameters beyond the scope of
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.Xr ifconfig 8 .
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In normal operation only a few arguments are needed:
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.Pp
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.Bl -tag -width ".Fl X" -offset indent -compact
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.It Fl X
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selects the external
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SPPP
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line protocol package.
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.It Fl x
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selects the built-in RawIP line protocol package.
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.It Fl Z
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selects PPP line protocol.
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.It Fl z
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selects Cisco-HDLC line protocol.
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.It Fl F
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selects Frame-Relay line protocol.
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.El
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.Bl -tag -width indent
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.It Li "lmcconfig lmc0"
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displays interface configuration and status.
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.It Li "lmcconfig lmc0 -D"
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enables debugging output from the device driver only.
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.It Li "ifconfig lmc0 debug"
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enables debugging output from the device driver and from
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the line protocol module above it.
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Debugging messages that appear on the console are also
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written to file
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.Pa "/var/log/messages" .
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.Em Caution :
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when things go very wrong, a torrent of debugging messages
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can swamp the console and bring a machine to its knees.
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.El
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.\"
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.Ss Operation
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.\"
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Activate a PPP link using SPPP and Netgraph with:
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.Bd -literal -offset indent
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ngctl mkpeer lmc0: sppp rawdata downstream
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ifconfig sppp0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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Activate a PPP link using only SPPP with:
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.Bd -literal -offset indent
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lmcconfig lmc0 -XYZ
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ifconfig lmc0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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Activate a Cisco-HDLC link using SPPP and Netgraph with:
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.Bd -literal -offset indent
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ngctl mkpeer lmc0: sppp rawdata downstream
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ifconfig sppp0 10.0.0.1 10.0.0.2 link2
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.Ed
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.Pp
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Activate a Cisco-HDLC link using only SPPP with:
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.Bd -literal -offset indent
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lmcconfig lmc0 -XYz
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ifconfig lmc0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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Activate a Cisco-HDLC link using only Netgraph with:
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.Bd -literal -offset indent
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ngctl mkpeer lmc0: cisco rawdata downstream
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ngctl mkpeer lmc0:rawdata iface inet inet
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ifconfig ng0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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Activate a Frame-Relay DTE link using SPPP with:
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.Bd -literal -offset indent
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lmcconfig lmc0 -XYF
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ifconfig lmc0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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(SPPP implements the ANSI T1.617 annex D LMI.)
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.Pp
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Activate a Frame-Relay DTE link using Netgraph with:
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.Bd -literal -offset indent
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ngctl mkpeer lmc0: frame_relay rawdata downstream
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ngctl mkpeer lmc0:rawdata lmi dlci0 auto0
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ngctl connect lmc0:rawdata dlci0 dlci1023 auto1023
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ngctl mkpeer lmc0:rawdata rfc1490 dlci500 downstream
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ngctl mkpeer lmc0:rawdata.dlci500 iface inet inet
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ifconfig ng0 10.0.0.1 10.0.0.2
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.Ed
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This is
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.Em ONE
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possible Frame Relay configuration; there are many.
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.Pp
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Activate a RAWIP link using only the driver with:
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.Bd -literal -offset indent
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lmcconfig lmc0 -x
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ifconfig lmc0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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Activate a RAWIP link using Netgraph with:
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.Bd -literal -offset indent
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ngctl mkpeer lmc0: iface rawdata inet
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ifconfig ng0 10.0.0.1 10.0.0.2
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.Ed
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.Pp
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If the driver is unloaded and then loaded, reconnect hooks by:
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.Pp
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.Dl "ngctl connect lmc0: ng0: rawdata inet"
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.\"
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.Sh TESTING
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.\"
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.Ss Testing with Loopbacks
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.\"
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Testing with loopbacks requires only one card.
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Packets can be looped back at many points: in the PCI chip,
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in the modem chips, through a loopback plug, in the
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local external equipment, or at the far end of a circuit.
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.Pp
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Activate the card with
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.Xr ifconfig 8 :
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.Pp
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.Dl "ifconfig lmc0 10.0.0.1 10.0.0.1"
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.Pp
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All cards can be looped through the PCI chip.
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Cards with internal modems can be looped through
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the modem framer and the modem line interface.
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Cards for external modems can be looped through
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the driver/receiver chips.
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See
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.Xr lmcconfig 8
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for details.
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.Pp
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Loopback plugs test everything on the card.
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.Bl -tag -width ".Sy T1/E1"
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.It Sy HSSI
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Loopback plugs can be ordered from SBE (and others).
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Transmit clock is normally supplied by the external modem.
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When an HSSI card is operated with a loopback plug, the PCI bus
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clock must be used as the transmit clock, typically 33 MHz.
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When testing an HSSI card with a loopback plug,
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configure it with
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.Xr lmcconfig 8 :
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.Pp
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.Dl "lmcconfig lmc0 -a 2"
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.Pp
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.Dq Fl a Li 2
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selects the PCI bus clock as the transmit clock.
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.It Sy T3
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Connect the two BNC jacks with a short coax cable.
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.It Sy SSI
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Loopback plugs can be ordered from SBE (only).
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Transmit clock is normally supplied by the external modem.
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When an SSI card is operated with a loopback plug,
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the on-board clock synthesizer must be used.
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When testing an SSI card with a loopback plug,
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configure it with
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.Xr lmcconfig 8 :
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.Pp
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.Dl "lmcconfig lmc0 -E -f 10000000"
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.Pp
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.Fl E
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puts the card in DCE mode to source a transmit clock.
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.Dq Fl f Li 10000000
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sets the internal clock source to 10 Mb/s.
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.It Sy T1/E1
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A loopback plug is a modular plug with two wires
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connecting pin 1 to pin 4 and pin 2 to pin 5.
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.El
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.Pp
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One can also test by connecting to a local modem (HSSI and SSI)
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or NI (T1 and T3) configured to loop back.
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Cards can generate signals to loopback remote equipment
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so that complete circuits can be tested; see
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.Xr lmcconfig 8
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for details.
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.\"
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.Ss Testing with a Modem
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.\"
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Testing with a modem requires two cards of different types.
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.Bl -tag -width ".Sy T3/HSSI"
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.It Sy T3/HSSI
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If you have a T3 modem with an HSSI interface
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(made by Digital Link, Larscom, Kentrox etc.\&)
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then use an HSSI card in one machine and a T3 card in the other machine.
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The T3 coax cables must use the null modem configuration (see below).
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.It Sy T1/V.35
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If you have a T1 (or E1) modem with a V.35, X.21 or EIA530 interface,
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then use an SSI card in one machine and a T1 card in the other machine.
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Use a T1 null modem cable (see below).
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.El
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.\"
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.Ss Testing with a Null Modem Cable
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.\"
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Testing with a null modem cable requires two cards of the same type.
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.Bl -tag -width ".Sy T1/E1"
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.It Sy HSSI
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Three-meter HSSI null-modem cables can be ordered from SBE.
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In a pinch, a 50-pin SCSI-II cable up to a few meters will
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work as a straight HSSI cable (not a null modem cable).
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Longer cables should be purpose-built HSSI cables because
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the cable impedance is different.
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Transmit clock is normally supplied by the external modem.
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When an HSSI card is connected by a null modem cable, the PCI bus
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clock can be used as the transmit clock, typically 33 MHz.
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When testing an HSSI card with a null modem cable, configure it
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with
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.Xr lmcconfig 8 :
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.Pp
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.Dl "lmcconfig lmc0 -a 2"
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.Pp
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.Dq Fl a Li 2
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selects the PCI bus clock as the transmit clock.
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.It Sy T3
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T3 null modem cables are just 75-ohm coax cables with BNC connectors.
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TX OUT on one card should be connected to RX IN on the other card.
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In a pinch, 50-ohm thin Ethernet cables
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.Em usually
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work up to a few meters, but they will
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.Em not
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work for longer runs \[em] 75-ohm coax is
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.Em required .
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.It Sy SSI
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Three-meter SSI null modem cables can be ordered from SBE.
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An SSI null modem cable reports a cable type of V.36/EIA449.
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Transmit clock is normally supplied by the external modem.
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When an SSI card is connected by a null modem cable,
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an on-board clock synthesizer is used.
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When testing an SSI card with a null modem cable, configure it
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with
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.Xr lmcconfig 8 :
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.Pp
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.Dl "lmcconfig lmc0 -E -f 10000000"
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.Pp
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.Fl E
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puts the card in DCE mode to source a transmit clock.
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.Dq Fl f Li 10000000
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sets the internal clock source to 10 Mb/s.
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.It Sy T1/E1
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A T1 null modem cable has two twisted pairs that connect
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pins 1 and 2 on one plug to pins 4 and 5 on the other plug.
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Looking into the cable entry hole of a plug,
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with the locking tab oriented down,
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pin 1 is on the left.
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A twisted pair Ethernet cable makes an excellent straight T1 cable.
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Alas, Ethernet cross-over cables do not work as T1 null modem cables.
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.El
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.\"
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.Sh OPERATION NOTES
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.\"
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.Ss Packet Lengths
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Maximum transmit and receive packet length is unlimited.
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Minimum transmit and receive packet length is one byte.
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.Pp
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Cleaning up after one packet and setting up for the next
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packet involves making several DMA references.
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This can take longer than the duration of a short packet,
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causing the adapter to fall behind.
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For typical PCI bus traffic levels and memory system latencies,
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back-to-back packets longer than about 20 bytes will always
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work (53 byte cells work), but a burst of several hundred
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back-to-back packets shorter than 20 bytes will cause packets
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to be dropped.
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This usually is not a problem since an IPv4 packet header is
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at least 20 bytes long.
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.Pp
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This device driver imposes no constraints on packet size.
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Most operating systems set the default Maximum Transmission
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Unit (MTU) to 1500 bytes; the legal range is usually (72..65535).
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This can be changed with
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.Pp
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.Dl "ifconfig lmc0 mtu 2000"
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.Pp
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SPPP enforces an MTU of (128..far-end-MRU) for PPP
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and 1500 bytes for Cisco-HDLC.
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RAWIP sets the default MTU to 4032 bytes,
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but it can be changed to anything.
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.\"
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.Ss BPF - Berkeley Packet Filter
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.\"
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This driver has hooks for
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.Xr bpf 4 ,
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the Berkeley Packet Filter.
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|
The line protocol header length reported to BPF is four bytes
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for SPPP and P2P line protocols and zero bytes for RawIP.
|
|
.Pp
|
|
To include BPF support into your kernel,
|
|
add the following line to
|
|
.Pa conf/YOURKERNEL :
|
|
.Pp
|
|
.Dl "device bpf"
|
|
.Pp
|
|
To test the BPF kernel interface,
|
|
bring up a link between two machines, then run
|
|
.Xr ping 8
|
|
and
|
|
.Xr tcpdump 1 :
|
|
.Pp
|
|
.Dl "ping 10.0.0.1"
|
|
.Pp
|
|
and in a different window:
|
|
.Pp
|
|
.Dl "tcpdump -i lmc0"
|
|
.Pp
|
|
The output from
|
|
.Xr tcpdump 1
|
|
should look like this:
|
|
.Bd -literal -offset indent
|
|
03:54:35.979965 10.0.0.2 > 10.0.0.1: icmp: echo request
|
|
03:54:35.981423 10.0.0.1 > 10.0.0.2: icmp: echo reply
|
|
.Ed
|
|
.Pp
|
|
Line protocol control packets will appear among the
|
|
.Xr ping 8
|
|
packets occasionally.
|
|
.\"
|
|
.Ss Device Polling
|
|
.\"
|
|
A T3 receiver can generate over 100K interrupts per second,
|
|
this can cause a system to
|
|
.Dq live-lock :
|
|
spend all of its
|
|
time servicing interrupts.
|
|
.Fx
|
|
has a polling mechanism to prevent live-lock.
|
|
.Pp
|
|
.Fx Ns 's
|
|
mechanism permanently disables interrupts from the card
|
|
and instead the card's interrupt service routine is called each
|
|
time the kernel is entered (syscall, timer interrupt, etc.\&) and
|
|
from the kernel idle loop; this adds some latency.
|
|
The driver is permitted to process a limited number of packets.
|
|
The percentage of the CPU that can be consumed this way is settable.
|
|
.Pp
|
|
See the
|
|
.Xr polling 4
|
|
manpage for details on how to enable the polling mode.
|
|
.\"
|
|
.Ss SNMP: Simple Network Management Protocol
|
|
.\"
|
|
This driver is aware of what is required to be a Network Interface
|
|
Object managed by an Agent of the Simple Network Management Protocol.
|
|
The driver exports SNMP-formatted configuration and status
|
|
information sufficient for an SNMP Agent to create MIBs for:
|
|
.Pp
|
|
.Bl -item -offset indent -compact
|
|
.It
|
|
.%T "RFC-2233: Interfaces group" ,
|
|
.It
|
|
.%T "RFC-2496: DS3 interfaces" ,
|
|
.It
|
|
.%T "RFC-2495: DS1/E1 interfaces" ,
|
|
.It
|
|
.%T "RFC-1659: RS232-like interfaces" .
|
|
.El
|
|
.Pp
|
|
An SNMP Agent is a user program, not a kernel function.
|
|
Agents can retrieve configuration and status information
|
|
by using
|
|
Netgraph control messages or
|
|
.Xr ioctl 2
|
|
system calls.
|
|
User programs should poll
|
|
.Va sc->cfg.ticks
|
|
which increments once per second after the SNMP state has been updated.
|
|
.\"
|
|
.Ss HSSI and SSI LEDs
|
|
.\"
|
|
The card should be operational if all three green LEDs are on
|
|
(the upper-left one should be blinking) and the red LED is off.
|
|
All four LEDs turn on at power-on and module unload.
|
|
.Pp
|
|
.Bl -column -compact -offset indent "YELLOW" "upper-right" "Software"
|
|
.It "RED" Ta "upper-right" Ta "No Transmit clock"
|
|
.It "GREEN" Ta "upper-left" Ta "Device driver is alive if blinking"
|
|
.It "GREEN" Ta "lower-right" Ta "Modem signals are good"
|
|
.It "GREEN" Ta "lower-left" Ta "Cable is plugged in (SSI only)"
|
|
.El
|
|
.\"
|
|
.Ss T1E1 and T3 LEDs
|
|
.\"
|
|
The card should be operational if the upper-left green LED is blinking
|
|
and all other LEDs are off.
|
|
For the T3 card, if other LEDs are on or
|
|
blinking, try swapping the coax cables!
|
|
All four LEDs turn on at power-on and module unload.
|
|
.Pp
|
|
.Bl -column -compact -offset indent "YELLOW" "upper-right" "Received"
|
|
.It "RED" Ta "upper-right" Ta "Received signal is wrong"
|
|
.It "GREEN" Ta "upper-left" Ta "Device driver is alive if blinking"
|
|
.It "BLUE" Ta "lower-right" Ta "Alarm Information Signal (AIS)"
|
|
.It "YELLOW" Ta "lower-left" Ta "Remote Alarm Indication (RAI)"
|
|
.El \" YELLOW
|
|
.Pp
|
|
.Bl -column -compact "The yellow" "LED"
|
|
.It "The green" Ta "LED blinks if the device driver is alive."
|
|
.It "The red" Ta "LED blinks if an outward loopback is active."
|
|
.It "The blue" Ta "LED blinks if sending AIS, on solid if receiving AIS."
|
|
.It "The yellow" Ta "LED blinks if sending RAI, on solid if receiving RAI."
|
|
.El \" LED
|
|
.\"
|
|
.Ss E1 Framing
|
|
.\"
|
|
Phone companies usually insist that customers put a
|
|
.Em Frame Alignment Signal
|
|
(FAS) in time slot 0.
|
|
A Cyclic Redundancy Checksum (CRC) can also ride in time slot 0.
|
|
.Em Channel Associated Signalling
|
|
(CAS) uses Time Slot 16.
|
|
In telco-speak
|
|
.Em signalling
|
|
is on/off hook, ringing, busy, etc.
|
|
Signalling is not needed here and consumes 64 Kb/s.
|
|
Only use E1-CAS formats if the other end insists on it!
|
|
Use E1-FAS+CRC framing format on a public circuit.
|
|
Depending on the equipment installed in a private circuit,
|
|
it may be possible to use all 32 time slots for data (E1-NONE).
|
|
.\"
|
|
.Ss T3 Framing
|
|
.\"
|
|
M13 is a technique for multiplexing 28 T1s into a T3.
|
|
Muxes use the C-bits for speed-matching the tributaries.
|
|
Muxing is not needed here and usurps the FEBE and FEAC bits.
|
|
Only use T3-M13 format if the other end insists on it!
|
|
Use T3-CParity framing format if possible.
|
|
Loop Timing, Fractional T3, and HDLC packets in
|
|
the Facility Data Link are
|
|
.Em not
|
|
supported.
|
|
.\"
|
|
.Ss T1 & T3 Frame Overhead Functions
|
|
.\"
|
|
.Bl -item -compact
|
|
.It
|
|
Performance Report Messages (PRMs) are enabled in T1-ESF.
|
|
.It
|
|
Bit Oriented Protocol (BOP) messages are enabled in T1-ESF.
|
|
.It
|
|
In-band loopback control (framed or not) is enabled in T1-SF.
|
|
.It
|
|
Far End Alarm and Control (FEAC) msgs are enabled in T3-CPar.
|
|
.It
|
|
Far End Block Error (FEBE) reports are enabled in T3-CPar.
|
|
.It
|
|
Remote Alarm Indication (RAI) is enabled in T3-Any.
|
|
.It
|
|
Loopbacks initiated remotely time out after 300 seconds.
|
|
.El
|
|
.\"
|
|
.Ss T1/E1 'Fractional' 64 kb/s Time Slots
|
|
.\"
|
|
T1 uses time slots 24..1; E1 uses time slots 31..0.
|
|
E1 uses TS0 for FAS overhead and TS16 for CAS overhead.
|
|
E1-NONE has
|
|
.Em no
|
|
overhead, so all 32 TSs are available for data.
|
|
Enable/disable time slots by setting 32 1s/0s in a config param.
|
|
Enabling an E1 overhead time slot,
|
|
or enabling TS0 or TS25-TS31 for T1,
|
|
is ignored by the driver, which knows better.
|
|
The default TS param, 0xFFFFFFFF, enables the maximum number
|
|
of time slots for whatever frame format is selected.
|
|
56 Kb/s time slots are
|
|
.Em not
|
|
supported.
|
|
.\"
|
|
.Ss T1 Raw Mode
|
|
.\"
|
|
Special gate array microcode exists for the T1/E1 card.
|
|
Each T1 frame of 24 bytes is treated as a packet.
|
|
A raw T1 byte stream can be delivered to main memory
|
|
and transmitted from main memory.
|
|
The T1 card adds or deletes framing bits but does not
|
|
touch the data.
|
|
ATM cells can be transmitted and received this way, with
|
|
the software doing all the work.
|
|
But that is not hard; after all it is only 1.5 Mb/s second!
|
|
.\"
|
|
.Ss T3 Circuit Emulation Mode
|
|
.\"
|
|
Special gate array microcode exists for the T3 card.
|
|
Each T3 frame of 595 bytes is treated as a packet.
|
|
A raw T3 signal can be
|
|
.Em packetized ,
|
|
transported through a
|
|
packet network (using some protocol) and then
|
|
.Em reconstituted
|
|
as a T3 signal at the far end.
|
|
The output transmitter's
|
|
bit rate can be controlled from software so that it can be
|
|
.Em frequency locked
|
|
to the distant input signal.
|
|
.\"
|
|
.Ss HSSI and SSI Transmit Clocks
|
|
.\"
|
|
Synchronous interfaces use two transmit clocks to eliminate
|
|
.Em skew
|
|
caused by speed-of-light delays in the modem cable.
|
|
DCEs (modems) drive ST, Send Timing, the first transmit clock.
|
|
DTEs (hosts) receive ST and use it to clock transmit data, TD,
|
|
onto the modem cable.
|
|
DTEs also drive a copy of ST back towards the DCE and call it TT,
|
|
Transmit Timing, the second transmit clock.
|
|
DCEs receive TT and TD and use TT to clock TD into a flip flop.
|
|
TT experiences the same delay as (and has no
|
|
.Em skew
|
|
relative to) TD.
|
|
Thus, cable length does not affect data/clock timing.
|
|
.\"
|
|
.Sh SEE ALSO
|
|
.\"
|
|
.Xr tcpdump 1 ,
|
|
.Xr ioctl 2 ,
|
|
.Xr bpf 4 ,
|
|
.Xr kld 4 ,
|
|
.Xr netgraph 4 ,
|
|
.Xr polling 4 ,
|
|
.Xr sppp 4 ,
|
|
.Xr loader.conf 5 ,
|
|
.Xr ifconfig 8 ,
|
|
.Xr lmcconfig 8 ,
|
|
.Xr mpd 8 Pq Pa ports/net/mpd ,
|
|
.Xr ngctl 8 ,
|
|
.Xr ping 8 ,
|
|
.Xr ifnet 9
|
|
.\"
|
|
.Sh HISTORY
|
|
.\"
|
|
.An Ron Crane
|
|
had the idea to use a Fast Ethernet chip as a PCI interface
|
|
and add an Ethernet-to-HDLC gate array to make a WAN card.
|
|
.An David Boggs
|
|
designed the Ethernet-to-HDLC gate array and PC cards.
|
|
We did this at our company, LAN Media Corporation
|
|
.Tn (LMC) .
|
|
.Tn SBE
|
|
Corp.\& acquired
|
|
.Tn LMC
|
|
and continues to make the cards.
|
|
.Pp
|
|
Since the cards use Tulip Ethernet chips, we started with
|
|
.An Matt Thomas Ns '
|
|
ubiquitous
|
|
.Xr de 4
|
|
driver.
|
|
.An Michael Graff
|
|
stripped out the Ethernet stuff and added HSSI stuff.
|
|
.An Basil Gunn
|
|
ported it to
|
|
.Tn Solaris
|
|
(lost) and
|
|
.Tn Rob Braun
|
|
ported it to
|
|
.Tn Linux .
|
|
.An Andrew Stanley-Jones
|
|
added support
|
|
for three more cards and wrote the first version of
|
|
.Xr lmcconfig 8 .
|
|
.An David Boggs
|
|
rewrote everything and now feels responsible for it.
|
|
.\"
|
|
.Sh AUTHORS
|
|
.\"
|
|
.An David Boggs Aq Mt boggs@boggs.palo-alto.ca.us
|