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LMC(4)				   BSD Kernel Interfaces Manual 			   LMC(4)

NAME
     lmc -- device driver for LMC (and some SBE) wide-area network interface cards

SYNOPSIS
     This driver is built into the GENERIC kernel so it should "just work".

     The driver can be built into a kernel by adding the following to
     /sys/arch/ARCH/conf/YOURKERNEL:
	   lmc*      at pci?
	   options   ALTQ
	   options   ALTQ_HFSC # for altq example
	   pseudo-device sppp
	   pseudo-device bpfilter

     The driver can send and receive raw IP packets even if SPPP is not configured into the ker-
     nel.

DESCRIPTION
     This is an open-source Unix device driver for PCI-bus wide-area network interface cards.  It
     sends and receives packets in HDLC frames over synchronous circuits.  A computer plus UNIX
     plus some LMC cards makes an open wide-area network router.

     The lmc driver works with FreeBSD, NetBSD, OpenBSD, BSD/OS, and Linux OSs.  It has been
     tested on i386 (SMP 32-bit little-end), PowerPC (32-bit big-end), Alpha (64-bit little-end),
     and Sparc (64-bit big-end) architectures.

     The lmc driver works with the following cards:

	   LMC5200  HSSI--High Speed Serial Interface,
		    EIA612/613, 50-pin connector,
		    0 to 52 Mb/s, DTE only.

	   LMC5245  T3, 2xBNC conns, 75 ohm
		    C-Parity or M13 Framing,
		    DSX-3 up to 910 ft.

	   LMC1000  SSI--Synchronous Serial Interface,
		    V.35, X.21, EIA449, EIA530(A), EIA232,
		    0 to 10 Mb/s, DTE or DCE.

	   LMC1200  T1/E1, RJ45 conn, 100 or 120 ohms,
		    T1-B8ZS-ESF, T1-AMI-SF, E1-HDB3-many,
		    DSX-1 up to 1500 ft; CSU up to 6 Kft.

     LMC cards contain a high-performance PCI interface, an HDLC function and either integrated
     modems (T1, T3) or modem interfaces (HSSI and SSI).

	   PCI	  The PCI interface is a DEC 21140A Tulip Fast Ethernet chip.  This chip has an
		  efficient PCI implementation with scatter/gather DMA, and can run at 100 Mb/s
		  full duplex (twice as fast as needed here).

	   HDLC   The HDLC functions (ISO-3309: flags, bit-stuffing, CRC) are implemented in a
		  Field Programmable Gate Array (FPGA) which talks to the Ethernet chip through a
		  Media Independent Interface (MII).  The hardware in the FPGA translates between
		  Ethernet packets and HDLC frames on-the-fly; think of it as a WAN PHY chip for
		  Ethernet.

	   Modem  The modem chips are the main differences between cards.  HSSI cards use ECL10K
		  chips to implement the EIA-612/613 interface.  T3 cards use a TranSwitch
		  TXC-03401 framer chip.  SSI cards use Linear Technology LTC1343 modem interface
		  chips.  T1 cards use a BrookTree/Conexant/Mindspeed Bt8370 framer and line
		  interface chip.

     Line protocol stacks exist above device drivers and below internet protocol stacks.  They
     typically encapsulate packets in HDLC frames and deal with higher-level issues like protocol
     multiplexing and security.  The driver is compatible with several line protocol stacks:

	   SPPP 	sppp(4) implements Synchronous-PPP and Cisco-HDLC in the kernel.

	   RawIP	The null line protocol, built into the driver, sends and receives raw
			IPv4 and IPv6 packets in HDLC frames with no extra bytes of overhead and
			no state at the end points.

EXAMPLES
   ifconfig and lmcconfig
     The program lmcconfig(8) manipulates interface parameters beyond the scope of ifconfig(8).
     lmcconfig has many flags and options, but in normal operation only a few are needed.

	   lmcconfig lmc0
     displays interface configuration and status.

	   lmcconfig lmc0 -X 1
     selects the built-in RawIP line protocol stack.

	   lmcconfig lmc0 -X 2 -x 2
     selects the SPPP stack and the PPP protocol.

     Some configuration options are available through ifconfig as well as lmcconfig.
	   ifconfig -m lmc0
     lists the available media options.

	   ifconfig lmc0 mediaopt loopback
     loops the interface transmitter to the receiver for testing.  This loopback uses a path
     present in every card type.  lmcconfig can select card-specific loopbacks, such as outbound
     payload loopback.

	   ifconfig lmc0 debug
     enables debugging output from the device driver and from the line protocol stack above it.

	   lmcconfig lmc0 -D
     enables debugging output from the device driver.

     Debugging messages that appear on the console are also written to file /var/log/messages.
     Caution: when things go very wrong, a torrent of debugging messages can swamp the console
     and bring a machine to its knees.

   Operation
     Configure a PPP link using SPPP with
	   lmcconfig lmc0 -X 2 -x 2
	   ifconfig lmc0 10.0.0.1 10.0.0.2

     Configure a Cisco-HDLC link using SPPP with
	   lmcconfig lmc0 -X 2 -x 3
	   ifconfig lmc0 10.0.0.1 10.0.0.2

     Configure a RAWIP link with
	   lmcconfig lmc0 -X 1
	   ifconfig lmc0 10.0.0.1 10.0.0.2

TESTING
   Testing with Loopbacks
     Testing with loopbacks requires only one card and can test everything on that card.  Packets
     can be looped back at many points: in the PCI chip, in the modem chips, through a loopback
     plug, in the local external equipment, or at the far end of a circuit.

     All cards can be looped through the PCI chip.  Cards with internal modems can be looped
     through the modem framer and the modem line interface.  Cards for external modems can be
     looped through the driver/receiver chips.	See lmcconfig(8) for details.

     Configure the card with
	   ifconfig lmc0 10.0.0.1 10.0.0.1

	   HSSI   Loopback plugs can be ordered from SBE (and others).	Transmit clock is nor-
		  mally supplied by the external modem.  When an HSSI card is operated with a
		  loopback plug, the PCI bus clock must be used as the transmit clock, typically
		  33 MHz.  When testing an HSSI card with a loopback plug, configure it with
			lmcconfig lmc0 -a 2
		  ``-a 2'' selects the PCI bus clock as the transmit clock.

	   T3	  Connect the two BNC jacks with a short coax cable.

	   SSI	  Loopback plugs can be ordered from SBE (only).  Transmit clock is normally sup-
		  plied by the external modem.	When an SSI card is operated with a loopback
		  plug, the on-board clock synthesizer must be used.  When testing an SSI card
		  with a loopback plug, configure it with
			lmcconfig lmc0 -E -f 10000000
		  ``-E'' puts the card in DCE mode to source a transmit clock.	``-f 10000000''
		  sets the internal clock source to 10 Mb/s.

	   T1/E1  A loopback plug is a modular plug with two wires connecting pin 1 to pin 4 and
		  pin 2 to pin 5.

     One can also test by connecting to a local modem (HSSI and SSI) or NI (T1 and T3) configured
     to loop back.  Cards can generate signals to loopback remote equipment so that complete cir-
     cuits can be tested; see lmcconfig(8) for details.

   Testing with a Modem
     Testing with a modem requires two cards of different types.  The cards can be in the same
     machine or different machines.

     Configure the two cards with
	   ifconfig lmc0 10.0.0.1 10.0.0.2
	   ifconfig lmc1 10.0.0.2 10.0.0.1

	   T3/HSSI  If you have a T3 modem with an HSSI interface (made by Digital Link, Larscom,
		    Kentrox etc.) then use an HSSI card and a T3 card.	The coax cables between
		    the card and the modem must ``cross over'' (see below).

	   T1/V.35  If you have a T1 (or E1) modem with a V.35, X.21 or EIA530 interface, then
		    use an SSI card and a T1 card.  Use a T1 null modem cable (see below) between
		    the external modem and the T1 card.

   Testing with a Null Modem Cable
     Testing with a null modem cable requires two cards of the same type.  The cards can be in
     the same machine or different machines.

     Configure the two cards with
	   ifconfig lmc0 10.0.0.1 10.0.0.2
	   ifconfig lmc1 10.0.0.2 10.0.0.1

	   HSSI   Three-meter HSSI null-modem cables can be ordered from SBE.  In a pinch, a
		  50-pin SCSI-II cable up to a few meters will work as a straight HSSI cable (not
		  a null modem cable).	Longer cables should be purpose-built HSSI cables because
		  the cable impedance is different.  Transmit clock is normally supplied by the
		  external modem.  When an HSSI card is connected by a null modem cable, the PCI
		  bus clock can be used as the transmit clock, typically 33 MHz.  When testing an
		  HSSI card with a null modem cable, configure it with
			lmcconfig lmc0 -a 2
		  ``-a 2'' selects the PCI bus clock as the transmit clock.

	   T3	  T3 null modem cables are just 75-ohm coax cables with BNC connectors.  TX OUT
		  on one card should be connected to RX IN on the other card.  In a pinch, 50-ohm
		  thin Ethernet cables usually work up to a few meters, but they will not work
		  for longer runs--75-ohm coax is required.

	   SSI	  Three-meter SSI null modem cables can be ordered from SBE.  An SSI null modem
		  cable reports a cable type of V.36/EIA449.  Transmit clock is normally supplied
		  by the external modem.  When an SSI card is connected by a null modem cable, an
		  on-board clock synthesizer is used.  When testing an SSI card with a null modem
		  cable, configure it with
			lmcconfig lmc0 -E -f 10000000
		  ``-E'' puts the card in DCE mode to source a transmit clock.	``-f 10000000''
		  sets the internal clock source to 10 Mb/s.

	   T1/E1  A T1 null modem cable has two twisted pairs that connect pins 1 and 2 on one
		  plug to pins 4 and 5 on the other plug.  Looking into the cable entry hole of a
		  plug, with the locking tab oriented down, pin 1 is on the left.  A twisted pair
		  Ethernet cable makes an excellent straight T1 cable.	Alas, Ethernet cross-over
		  cables do not work as T1 null modem cables.

OPERATING NOTES
   LEDs
     HSSI and SSI cards should be operational if all three green LEDs are on (the upper-left one
     should be blinking) and the red LED is off.
	   RED	     upper-right    No Transmit clock
	   GREEN     upper-left     Device driver is alive if blinking
	   GREEN     lower-right    Modem signals are good
	   GREEN     lower-left     Cable is plugged in (SSI only)

     T1/E1 and T3 cards 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!
	   RED	     upper-right    Received signal is wrong
	   GREEN     upper-left     Device driver is alive if blinking
	   BLUE      lower-right    Alarm Information Signal (AIS)
	   YELLOW    lower-left     Remote Alarm Indication (RAI)

	   RED	     blinks if an outward loopback is active.
	   GREEN     blinks if the device driver is alive.
	   BLUE      blinks if sending AIS, on solid if receiving AIS.
	   YELLOW    blinks if sending RAI, on solid if receiving RAI.

   Packet Lengths
     Maximum transmit and receive packet length is unlimited.
     Minimum transmit and receive packet length is one byte.

     Cleaning up after one packet and setting up for the next packet involves making several DMA
     references.  This can take longer than the duration of a short packet, causing the adapter
     to fall behind.  For typical PCI bus traffic levels and memory system latencies, back-to-
     back packets longer than about 20 bytes will always work (53 byte cells work), but a burst
     of several hundred back-to-back packets shorter than 20 bytes will cause packets to be
     dropped.  This usually is not a problem since an IPv4 packet header is at least 20 bytes
     long.

     The device driver imposes no constraints on packet size.  Most operating systems set the
     default Maximum Transmission Unit (MTU) to 1500 bytes; the legal range is usually
     (72..65535).  This can be changed with
	   ifconfig lmc0 mtu 2000
     SPPP enforces an MTU of 1500 bytes for PPP and Cisco-HDLC.  RAWIP sets the default MTU to
     4032 bytes, but allows it to be changed to anything.

   ALTQ: Alternate Output Queue Disciplines
     The driver has hooks for altq(9), the Alternate Queueing package.	To see ALTQ in action,
     use your favorite traffic generation program to generate three flows sending down one T3
     circuit.  Without ALTQ, the speeds of the three connections will vary chaotically.  Enable
     ALTQ and two of the connections will run at about 20 Mb/s and the third will run at about 2
     Mb/s.

     Enable altqd(8) and add the following lines to /etc/altq.conf:
	   interface lmc0 bandwidth 44M hfsc
	   class hfsc lmc0 a root pshare 48
	   filter lmc0 a 10.0.0.2 12345 10.0.0.1 0 6
	   filter lmc0 a 10.0.0.1 0 10.0.0.2 12345 6
	   class hfsc lmc0 b root pshare 48
	   filter lmc0 b 10.0.0.2 12346 10.0.0.1 0 6
	   filter lmc0 b 10.0.0.1 0 10.0.0.2 12346 6
	   class hfsc lmc0 c root pshare 4 default
	   filter lmc0 c 10.0.0.2 12347 10.0.0.1 0 6
	   filter lmc0 c 10.0.0.1 0 10.0.0.2 12347 6

     The example above requires the altq(4) Hierarchical Fair Service Curve queue discipline to
     be configured in conf/YOURKERNEL:
	   options ALTQ
	   options ALTQ_HFSC.

   BPF: Berkeley Packet Filter
     The driver has hooks for bpf(4), the Berkeley Packet Filter, a protocol-independent raw
     interface to data link layers.

     To test the BPF kernel interface, bring up a link between two machines, then run ping(8) and
     tcpdump(8):
	   ping 10.0.0.1
     and in a different window:
	   tcpdump -i lmc0
     The output from tcpdump should look like this:
	   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
     Line protocol control packets may appear among the ping packets occasionally.

     The kernel must be configured with
	   options bpfilter

   SNMP: Simple Network Management Protocol
     The 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:
	   RFC-2233  Interfaces group
	   RFC-2496  DS3 interfaces
	   RFC-2495  DS1/E1 interfaces
	   RFC-1659  RS232-like interfaces

     An SNMP Agent is a user program, not a kernel function.  Agents can retrieve configuration
     and status information by using ioctl(2) system calls.  User programs should poll
     sc->cfg.ticks which increments once per second after the SNMP state has been updated.

   E1 Framing
     Phone companies usually insist that customers put a Frame Alignment Signal (FAS) in time
     slot 0.  A Cyclic Redundancy Checksum (CRC) can also ride in time slot 0.	Channel
     Associated Signalling (CAS) uses Time Slot 16.  In telco-speak 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).

   T3 Framing
     M13 is a technique for multiplexing 28 T1s into a T3.  Muxes use the C-bits for speed-match-
     ing 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 not supported.

   T1 & T3 Frame Overhead Functions
     Performance Report Messages (PRMs) are enabled in T1-ESF.
     Bit Oriented Protocol (BOP) messages are enabled in T1-ESF.
     In-band loopback control (framed or not) is enabled in T1-SF.
     Far End Alarm and Control (FEAC) msgs are enabled in T3-CPar.
     Far End Block Error (FEBE) reports are enabled in T3-CPar.
     Remote Alarm Indication (RAI) is enabled in T3-Any.
     Loopbacks initiated remotely time out after 300 seconds.

   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 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 bet-
     ter.  The default TS param, 0xFFFFFFFF, enables the maximum number of time slots for what-
     ever frame format is selected.  56 Kb/s time slots are not supported.

SEE ALSO
     ioctl(2), bpf(4), de(4), sppp(4), altq.conf(5), altqd(8), ifconfig(8), init(8),
     lmcconfig(8), modload(8), ping(8), tcpdump(8), altq(9), ifnet(9)

     http://www.sbei.net/

HISTORY
     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.  David Boggs designed the Ethernet-to-HDLC gate array
     and PC cards.  We did this at our company, LAN Media Corporation (LMC).  SBE Corporation
     acquired LMC and continues to make the cards.

     Since the cards use Tulip Ethernet chips, we started with Matt Thomas' ubiquitous de(4)
     driver.  Michael Graff stripped out the Ethernet stuff and added HSSI stuff.  Basil Gunn
     ported it to Solaris (lost) and Rob Braun ported it to Linux.  Andrew Stanley-Jones added
     support for three more cards.  David Boggs rewrote everything and now feels responsible for
     it.

AUTHORS
     David Boggs <boggs@boggs.palo-alto.ca.us>

BSD					  April 11, 2006				      BSD
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