/share/man/man4/lmc.4
https://bitbucket.org/freebsd/freebsd-head/ · Forth · 764 lines · 764 code · 0 blank · 0 comment · 43 complexity · fe46c3a39ca47cfeb2562e80c8e81377 MD5 · raw file
- .\"
- .\" $FreeBSD$
- .\"
- .\" Copyright (c) 2002-2005 David Boggs. (boggs@boggs.palo-alto.ca.us)
- .\" All rights reserved.
- .\"
- .\" BSD License:
- .\"
- .\" Redistribution and use in source and binary forms, with or without
- .\" modification, are permitted provided that the following conditions
- .\" are met:
- .\" 1. Redistributions of source code must retain the above copyright
- .\" notice, this list of conditions and the following disclaimer.
- .\" 2. Redistributions in binary form must reproduce the above copyright
- .\" notice, this list of conditions and the following disclaimer in the
- .\" documentation and/or other materials provided with the distribution.
- .\"
- .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- .\" SUCH DAMAGE.
- .\"
- .\" GNU General Public License:
- .\"
- .\" This program is free software; you can redistribute it and/or modify it
- .\" under the terms of the GNU General Public License as published by the Free
- .\" Software Foundation; either version 2 of the License, or (at your option)
- .\" any later version.
- .\"
- .\" This program is distributed in the hope that it will be useful, but WITHOUT
- .\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- .\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- .\" more details.
- .\"
- .\" You should have received a copy of the GNU General Public License along with
- .\" this program; if not, write to the Free Software Foundation, Inc., 59
- .\" Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- .\"
- .Dd February 8, 2012
- .Dt LMC 4
- .Os
- .\"
- .Sh NAME
- .\"
- .Nm lmc
- .Nd device driver for
- .Tn LMC
- (now
- .Tn SBE )
- wide-area network interface cards
- .\"
- .Sh SYNOPSIS
- .\"
- To wire this driver into your kernel,
- add the following line to your kernel configuration file:
- .Bd -ragged -offset indent
- .Cd "device lmc"
- .Ed
- .Pp
- Alternatively, to load this module at boot time, add
- .Bd -literal -offset indent
- if_lmc_load="YES"
- .Ed
- .Pp
- to
- .Pa /boot/loader.conf ;
- see
- .Xr loader.conf 5 .
- .Pp
- To wire a line protocol into your kernel, add:
- .Bd -ragged -offset indent
- .Cd "options NETGRAPH"
- .Cd "device sppp"
- .Ed
- .Pp
- It is not necessary to wire line protocols into your kernel,
- they can be loaded later with
- .Xr kldload 8 .
- The driver can send and receive raw IP packets even if neither
- SPPP nor Netgraph are configured into the kernel.
- Netgraph and SPPP can both be enabled; Netgraph will be used if the
- .Va rawdata
- hook is connected.
- .\"
- .Sh DESCRIPTION
- .\"
- This is an open-source
- .Ux
- device driver for PCI-bus WAN interface cards.
- It sends and receives packets in HDLC frames over synchronous circuits.
- A generic PC plus
- .Ux
- plus some
- .Tn LMC / SBE
- cards makes an
- .Em open
- router.
- This driver works with
- .Fx ,
- .Nx ,
- .Ox ,
- .Bsx
- and
- .Tn Linux
- OSs.
- It has been tested on i386 (SMP 32-bit little-endian) and Sparc (64-bit big-endian)
- architectures.
- .Pp
- The
- .Nm
- driver works with the following cards:
- .Bl -bullet
- .It
- SBE wanADAPT-HSSI (LMC5200)
- .Pp
- High Speed Serial Interface,
- EIA612/613, 50-pin connector,
- 0 to 52 Mb/s, DTE only.
- .It
- SBE wanADAPT-T3 (LMC5245)
- .Pp
- T3: two 75-ohm BNC connectors,
- C-Parity or M13 Framing,
- 44.736 Mb/s, up to 950 ft.
- .It
- SBE wanADAPT-SSI (LMC1000)
- .Pp
- Synchronous Serial Interface,
- V.35, X.21, EIA449, EIA530(A), EIA232,
- 0 to 10 Mb/s, DTE or DCE.
- .It
- SBE wanADAPT-T1E1 (LMC1200)
- .Pp
- T1 or E1: RJ45 conn, 100 or 120 ohms,
- T1-ESF-B8ZS, T1-SF-AMI, E1-(many)-HDB3,
- 1.544 Mb/s or 2.048 Mb/s, up to 6 Kft.
- .El
- .Pp
- Cards contain a high-performance
- .Sy "PCI"
- interface, an
- .Sy "HDLC"
- function and
- either integrated
- .Sy "modems"
- (T1, T3) or
- .Sy "modem"
- interfaces (HSSI and SSI).
- .Bl -tag -width "Modem"
- .It Sy "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).
- .It Sy "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 it as a WAN PHY chip for Ethernet.
- .It Sy "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.
- .El
- .Pp
- Line protocols exist above device drivers and below internet protocols.
- They typically encapsulate packets in HDLC frames and deal with
- higher-level issues like protocol multiplexing and security.
- This driver is compatible with several line protocol packages:
- .Bl -tag -width "Generic HDLC"
- .It Sy "Netgraph"
- .Xr netgraph 4
- implements many basic packet-handling functions as kernel loadable modules.
- They can be interconnected in a graph to implement many protocols.
- Configuration is done from userland without rebuilding the kernel.
- Packets are sent and received through this interface if the driver's
- .Em rawdata
- hook is connected, otherwise the ifnet interface (SPPP and RawIP) is used.
- ASCII configuration control messages are
- .Em not
- currently supported.
- .It Sy "SPPP"
- .Xr sppp 4
- implements Synchronous-PPP, Frame-Relay and Cisco-HDLC in the kernel.
- .It Sy "RawIP"
- This null line protocol, built into the driver, sends and receives
- raw IPv4 and IPv6 packets in HDLC frames (aka IP-in-HDLC) with
- no extra bytes of overhead and no state at the end points.
- .El
- .\"
- .Sh EXAMPLES
- .\"
- .Ss "ifconfig and lmcconfig"
- .\"
- The program
- .Xr lmcconfig 8
- manipulates interface parameters beyond the scope of
- .Xr ifconfig 8 .
- In normal operation only a few arguments are needed:
- .Pp
- .Bl -tag -width ".Fl X" -offset indent -compact
- .It Fl X
- selects the external
- SPPP
- line protocol package.
- .It Fl x
- selects the built-in RawIP line protocol package.
- .It Fl Z
- selects PPP line protocol.
- .It Fl z
- selects Cisco-HDLC line protocol.
- .It Fl F
- selects Frame-Relay line protocol.
- .El
- .Bl -tag -width indent
- .It Li "lmcconfig lmc0"
- displays interface configuration and status.
- .It Li "lmcconfig lmc0 -D"
- enables debugging output from the device driver only.
- .It Li "ifconfig lmc0 debug"
- enables debugging output from the device driver and from
- the line protocol module above it.
- Debugging messages that appear on the console are also
- written to file
- .Pa "/var/log/messages" .
- .Em Caution :
- when things go very wrong, a torrent of debugging messages
- can swamp the console and bring a machine to its knees.
- .El
- .\"
- .Ss Operation
- .\"
- Activate a PPP link using SPPP and Netgraph with:
- .Bd -literal -offset indent
- ngctl mkpeer lmc0: sppp rawdata downstream
- ifconfig sppp0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- Activate a PPP link using only SPPP with:
- .Bd -literal -offset indent
- lmcconfig lmc0 -XYZ
- ifconfig lmc0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- Activate a Cisco-HDLC link using SPPP and Netgraph with:
- .Bd -literal -offset indent
- ngctl mkpeer lmc0: sppp rawdata downstream
- ifconfig sppp0 10.0.0.1 10.0.0.2 link2
- .Ed
- .Pp
- Activate a Cisco-HDLC link using only SPPP with:
- .Bd -literal -offset indent
- lmcconfig lmc0 -XYz
- ifconfig lmc0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- Activate a Cisco-HDLC link using only Netgraph with:
- .Bd -literal -offset indent
- ngctl mkpeer lmc0: cisco rawdata downstream
- ngctl mkpeer lmc0:rawdata iface inet inet
- ifconfig ng0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- Activate a Frame-Relay DTE link using SPPP with:
- .Bd -literal -offset indent
- lmcconfig lmc0 -XYF
- ifconfig lmc0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- (SPPP implements the ANSI T1.617 annex D LMI.)
- .Pp
- Activate a Frame-Relay DTE link using Netgraph with:
- .Bd -literal -offset indent
- ngctl mkpeer lmc0: frame_relay rawdata downstream
- ngctl mkpeer lmc0:rawdata lmi dlci0 auto0
- ngctl connect lmc0:rawdata dlci0 dlci1023 auto1023
- ngctl mkpeer lmc0:rawdata rfc1490 dlci500 downstream
- ngctl mkpeer lmc0:rawdata.dlci500 iface inet inet
- ifconfig ng0 10.0.0.1 10.0.0.2
- .Ed
- This is
- .Em ONE
- possible Frame Relay configuration; there are many.
- .Pp
- Activate a RAWIP link using only the driver with:
- .Bd -literal -offset indent
- lmcconfig lmc0 -x
- ifconfig lmc0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- Activate a RAWIP link using Netgraph with:
- .Bd -literal -offset indent
- ngctl mkpeer lmc0: iface rawdata inet
- ifconfig ng0 10.0.0.1 10.0.0.2
- .Ed
- .Pp
- If the driver is unloaded and then loaded, reconnect hooks by:
- .Pp
- .Dl "ngctl connect lmc0: ng0: rawdata inet"
- .\"
- .Sh TESTING
- .\"
- .Ss Testing with Loopbacks
- .\"
- Testing with loopbacks requires only one 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.
- .Pp
- Activate the card with
- .Xr ifconfig 8 :
- .Pp
- .Dl "ifconfig lmc0 10.0.0.1 10.0.0.1"
- .Pp
- 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
- .Xr lmcconfig 8
- for details.
- .Pp
- Loopback plugs test everything on the card.
- .Bl -tag -width ".Sy T1/E1"
- .It Sy HSSI
- Loopback plugs can be ordered from SBE (and others).
- Transmit clock is normally 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
- .Xr lmcconfig 8 :
- .Pp
- .Dl "lmcconfig lmc0 -a 2"
- .Pp
- .Dq Fl a Li 2
- selects the PCI bus clock as the transmit clock.
- .It Sy T3
- Connect the two BNC jacks with a short coax cable.
- .It Sy SSI
- Loopback plugs can be ordered from SBE (only).
- Transmit clock is normally supplied 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
- .Xr lmcconfig 8 :
- .Pp
- .Dl "lmcconfig lmc0 -E -f 10000000"
- .Pp
- .Fl E
- puts the card in DCE mode to source a transmit clock.
- .Dq Fl f Li 10000000
- sets the internal clock source to 10 Mb/s.
- .It Sy T1/E1
- A loopback plug is a modular plug with two wires
- connecting pin 1 to pin 4 and pin 2 to pin 5.
- .El
- .Pp
- 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 circuits can be tested; see
- .Xr lmcconfig 8
- for details.
- .\"
- .Ss Testing with a Modem
- .\"
- Testing with a modem requires two cards of different types.
- .Bl -tag -width ".Sy T3/HSSI"
- .It Sy T3/HSSI
- If you have a T3 modem with an HSSI interface
- (made by Digital Link, Larscom, Kentrox etc.\&)
- then use an HSSI card in one machine and a T3 card in the other machine.
- The T3 coax cables must use the null modem configuration (see below).
- .It Sy 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 in one machine and a T1 card in the other machine.
- Use a T1 null modem cable (see below).
- .El
- .\"
- .Ss Testing with a Null Modem Cable
- .\"
- Testing with a null modem cable requires two cards of the same type.
- .Bl -tag -width ".Sy T1/E1"
- .It Sy 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
- .Xr lmcconfig 8 :
- .Pp
- .Dl "lmcconfig lmc0 -a 2"
- .Pp
- .Dq Fl a Li 2
- selects the PCI bus clock as the transmit clock.
- .It Sy 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
- .Em usually
- work up to a few meters, but they will
- .Em not
- work for longer runs \[em] 75-ohm coax is
- .Em required .
- .It Sy 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
- .Xr lmcconfig 8 :
- .Pp
- .Dl "lmcconfig lmc0 -E -f 10000000"
- .Pp
- .Fl E
- puts the card in DCE mode to source a transmit clock.
- .Dq Fl f Li 10000000
- sets the internal clock source to 10 Mb/s.
- .It Sy 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.
- .El
- .\"
- .Sh OPERATION NOTES
- .\"
- .Ss Packet Lengths
- Maximum transmit and receive packet length is unlimited.
- Minimum transmit and receive packet length is one byte.
- .Pp
- 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.
- .Pp
- This 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
- .Pp
- .Dl "ifconfig lmc0 mtu 2000"
- .Pp
- SPPP enforces an MTU of (128..far-end-MRU) for PPP
- and 1500 bytes for Cisco-HDLC.
- RAWIP sets the default MTU to 4032 bytes,
- but it can be changed to anything.
- .\"
- .Ss BPF - Berkeley Packet Filter
- .\"
- This driver has hooks for
- .Xr bpf 4 ,
- the Berkeley Packet Filter.
- The line protocol header length reported to BPF is four bytes
- 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 boggs@boggs.palo-alto.ca.us