ATM on Linux HOWTO

Paul B Schroeder

IBM Corporation

paulsch@us.ibm.com

ATM support for Linux is currently in pre-alpha stage. There is an experimental
release, which supports raw ATM connections (PVCs and SVCs), IP over ATM, LAN
emulation, MPOA, Arequipa, and some other goodies.

2001-10-18

Revision History                                                               
Revision 2.4.0               2001-10-18           Revised by: PBS              
Converted from LaTeX to DocBook along with some other additions and changes.   

This document describes how to install, setup, and configure the necessary
drivers and tools to support ATM networking under Linux.

For the latest information, please check the ATM on Linux home page.

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------

Introduction

Acknowledgements and Thanks

This document is largely derived from the Usage Instructions document that was
included with the ATM on Linux distribution up until version 0.79. That
previous document was written by Werner Almesberger <wa@almsesberger.net> while
he was at the Institute for computer Communications and Applications (ICA).

The section Running Two ATM NICs Back-to-Back was primarily written by Richard
Jones <rjones@imcl.com>.

-------------------------------------------------------------------------------

Copyright

Copyright 2001 IBM Corporation

Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.1 or any later version
published by the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts, and with no Back-Cover Texts. A copy of the license can be
found at http://www.gnu.org/copyleft/fdl.html.

A large portion of this document is derived from the Usage Instructions
included with the ATM on Linux distribution up to version 0.79 which was
released under the BSD License, GNU General Public License (GPL), and GNU
Lesser General Public License (LGPL).

-------------------------------------------------------------------------------

Mailing List

There is also a mailing list on which to discuss ATM on Linux. If you have any
comments, questions, suggestions, or would just like to get involved, please
join the list. You can subscribe and unsubscribe to it at http://
lists.sourceforge.net/lists/listinfo/linux-atm-general.

The mailing list is archived at http://www.geocrawler.com/lists/3/SourceForge/
6487/0/.

-------------------------------------------------------------------------------

CVS Access

Users are encouraged to continue to use the releases instead of automatically
assuming they should grab the latest version out of CVS. However, if you like
living on the edge, here is how to do it.

First, log in anonymously:

% cvs -d:pserver:anonymous@cvs.linux-atm.sourceforge.net.:/cvsroot/linux-atm login

Just hit return when prompted for a password. Then, checkout the repository:

% cvs -z6 -d:pserver:anonymous@cvs.linux-atm.sourceforge.net.:/cvsroot/linux-atm co -P linux-atm

You may also specify a branch to check out specifically:

% cvs -z6 -d:pserver:anonymous@cvs.linux-atm.sourceforge.net.:/cvsroot/linux-atm co -r V2_5_0 linux-atm

In either case, this will create a directory called "linux-atm" with the latest
sources in it. When working inside this directory you will not need to specify
the '-d' option to CVS. For instance, you could just do

% cvs -z6 up -d

To grab any changes that have been put in the repository (the '-d' option in
the above example is to the "up" sub-command and is different than the '-d'
used to specify the CVS root directory)

After you have checked out the source tree, you will need to run the autotools
script in the top level directory before you can configure, build, and install
from that source tree:

# ./autotools 
Running aclocal...
Running autoconf...
Running autoheader...
Running automake...
automake: configure.in: installing `./install-sh'
automake: configure.in: installing `./mkinstalldirs'
automake: configure.in: installing `./missing'
configure.in: 26: required file `./ltconfig' not found
automake: Makefile.am: installing `./INSTALL'
automake: configure.in: installing `src/lane/ylwrap'
Finished...  Now run './configure' and 'make'...

 

 If you wish to create a tarred, gzipped distribution file or a RPM
distribution file, run make dist or make rpm respectively. The tarred, gzipped
file will be placed in the top level of the source tree and the RPM file will
be placed in the src/extra/RPMS directory.

The CVS archive may also be browsed on the web at: http://
cvs.linux-atm.sourceforge.net/cgi-bin/viewcvs.cgi/linux-atm/linux-atm/.

Finally, if you would like to receive email including every diff that is
committed to the repository as they go in, there is a mailing list called
"linux-atm-commits": http://lists.sourceforge.net/lists/listinfo/
linux-atm-commits.

This mailing list should be treated as receive-only. NO discussion or questions
are allowed (even of patches which are sent through that list). All discussion
should be kept on the linux-atm-general mailing list.

-------------------------------------------------------------------------------

Installation

In order to install this package, you'll need

  * the package itself from http://linux-atm.sourceforge.net/dist.php
   
  * the Linux kernel, version 2.4.x, e.g. from ftp://ftp.kernel.org/pub/linux/
    kernel/v2.4/
   
  * Perl, version 4 or 5
   
  * if you want memory debugging: MPR, e.g. from ftp://ibiblio.org/pub/Linux/
    devel/lang/c/
   
 

-------------------------------------------------------------------------------

The Binary RPMs

If you do not wish to futz with extracting and building the source yourself,
the ATM tools are also distributed in RPM format. The RPM can be installed as
follows:

rpm -ivh linux-atm-x.x.x-x.rpm

-------------------------------------------------------------------------------

The Source Tree

First, extract the ATM on Linux distribution:

tar xzvf linux-atm-x.x.x.tar.gz

When extracted the distribution will create the linux-atm-x.x.x/ directory with
several sub-directories. The following sub-directories are of note:

doc/
   
    Documentation (including this HOWTO) in SGML DocBook format
   
src/sigd/
   
    UNI 3.0, UNI 3.1, and UNI 4.0 signaling demon: atmsigd
   
src/saal/
   
    Signaling AAL library (SSCOP, SSCF, and SAAL)
   
src/qgen/
   
    Q.2931-style message handling
   
src/ilmid/
   
    ILMI address registration demon: ilmid
   
src/maint/
   
    ATM maintenance programs: atmaddr, atmdiag, atmdump, atmloop, atmtcp,
    enitune, esi, sonetdiag, saaldump, and zntune
   
src/test/
   
    Test programs: align, aping, aread, awrite, br, bw, isp, ttcp_atm, window
   
src/arpd/
   
    ATMARP tools and demon: atmarp, atmarpd
   
src/led/
   
    LAN Emulation demon: zeppelin
   
src/lane/
   
    LAN Emulation servers: bus, lecs, les
   
src/mpoad/
   
    Multi-Protocol Over ATM demon: mpcd
   
src/debug/
   
    Debugging tools: delay, ed, encopy, endump, svctor, zndump, and znth
   
src/lib/
   
    Libraries for applications and demons
   
src/man/
   
    Miscellaneous man pages
   
src/extra/
   
    Extra packages and RPM spec files.
   
src/config/
   
    Configuration and rc file examples
   
src/switch/
   
    Switch fabric control (under construction)
   
 

-------------------------------------------------------------------------------

Kernel Configuration

    NOTE: If you are not familiar with building and installing a new kernel,
    please see the The Linux Kernel HOWTO
   
After unpacking the kernel distribution, do the usual make config, make
menuconfig, or make xconfig in the top-level of your Linux kernel source tree.
First, enable
Prompt for development and/or incomplete code/drivers
  (CONFIG_EXPERIMENTAL)
You should then be able to find the following options:
Asynchronous Transfer Mode (ATM, EXPERIMENTAL) (CONFIG_ATM)
  Use "new" skb structure (CONFIG_ATM_SKB)
  Classical IP over ATM (CONFIG_ATM_CLIP)
    Do NOT send ICMP if no neighbour (CONFIG_ATM_CLIP_NO_ICMP)
  LAN Emulation (LANE) support (CONFIG_ATM_LANE)
    Multi-Protocol Over ATM (MPOA) support (CONFIG_ATM_MPOA)
ATM over TCP (CONFIG_ATM_TCP)
Efficient Networks ENI155P (CONFIG_ATM_ENI)
  Enable extended debugging (CONFIG_ATM_ENI_DEBUG)
  Fine-tune burst settings (CONFIG_ATM_ENI_TUNE_BURST)
    Enable 16W TX bursts (discouraged) (CONFIG_ATM_ENI_BURST_TX_16W)
    Enable 8W TX bursts (recommended) (CONFIG_ATM_ENI_BURST_TX_8W)
    Enable 4W TX bursts (optional) (CONFIG_ATM_ENI_BURST_TX_4W)
    Enable 2W TX bursts (optional) (CONFIG_ATM_ENI_BURST_TX_2W)
    Enable 16W RX bursts (discouraged) (CONFIG_ATM_ENI_BURST_RX_16W)
    Enable 8W RX bursts (discouraged) (CONFIG_ATM_ENI_BURST_RX_8W)
    Enable 4W RX bursts (recommended) (CONFIG_ATM_ENI_BURST_RX_4W)
    Enable 2W RX bursts (optional) (CONFIG_ATM_ENI_BURST_RX_2W)
ZeitNet ZN1221/ZN1225 (CONFIG_ATM_ZATM)
  Enable extended debugging (CONFIG_ATM_ZATM_DEBUG)
  Enable usec resolution timestamps (CONFIG_ATM_ZATM_EXACT_TS)
IDT 77201 (NICStAR) (CONFIG_ATM_NICSTAR)
  Use suni PHY driver (155Mbps) (CONFIG_ATM_NICSTAR_USE_SUNI)
  Use IDT77015 PHY driver (25Mbps) (CONFIG_ATM_NICSTAR_USE_IDT77105)
Madge Ambassador (Collage PCI 155 Server) (CONFIG_ATM_AMBASSADOR)
  Enable debugging messages (CONFIG_ATM_AMBASSADOR_DEBUG)
Madge Horizon [Ultra] (Collage PCI 25 and Collage PCI 155 Client)
  Enable debugging messages (CONFIG_ATM_HORIZON_DEBUG)
Interphase ATM PCI x575/x525/x531 (CONFIG_ATM_IA)
  Enable debugging messages (CONFIG_ATM_IA_DEBUG)

The burst settings of the ENI driver can be fine-tuned. This may be necessary
if the default settings lead to buffer overruns in the PCI chipset. See the
on-line help on "CONFIG_ATM_ENI_TUNE_BURST" for a detailed discussion of the
implications of changing the burst settings.

Note that the file drivers/atm/nicstar.h contains a few configurable settings
for the IDT 77201 driver.

Some drivers can also be used with certain compatible cards. The latest
information about compatible cards can be found at ATM on Linux information
page.

Then build your kernel and reboot.

-------------------------------------------------------------------------------

Driver Messages

If you've configured the ENI155p-MF driver, you should see two lines like these
(512kB for the -C version, 2048kB for the -S version.):

eni(itf 0): rev.0,base=0xff400000,irq=10,mem=512kB (00-20-EA-00-07-56)
eni(itf 0): FPGA,MMF

If you've configured the ZN1221/ZN1225 driver, you will get something like:

zatm(itf 0): rev.3,base=0xf800,irq=11,mem=128kB,MMF (00-20-D4-10-2A-80)
zatm(itf 0): uPD98401 0.5 at 30.024 MHz
zatm(itf 0): 16 shapers, 32 pools, 2048 RX, 3958 VCs

Note that your board needs to be at least at revision level 3 if you want to
use it in a Triton-based system.

Note that if you've configured only the ATM over TCP driver, there are no
messages at startup, because ATM over TCP devices are created later using the 
atmtcp command.

-------------------------------------------------------------------------------

Memory Debugging

If you want to enable debugging for options for memory allocations, you need to
install MPR before compiling the ATM tools.

If you chose to download the binary RPM package, you can install MPR like so:

rpm -ivh mpr-x.x-x.rpm

If you chose to download the source, extract mpr-x.x.tar.gz like so:

tar xzvf mpr-x.x.tar.gz

Then do:

cd mpr-x.x
./configure x86-linux
make
make install

Detection of some general mis-use of malloc and free is automatically performed
if the program was compiled with MPR present. Tracing of allocations is enabled
by setting MPRPC and MPRFI. See doc/mpr.html or doc/mpr.ps in the MPR
distribution for details.

Only little run-time overhead is incurred if memory debugging is included, but
those environment variables are not set.

-------------------------------------------------------------------------------

ATM Tools

Now, as the final step, configure and build the ATM tools. Configuration is
only necessary if your switch uses UNI 3.1 or 4.0, or if it has certain bugs.
The configuration options selected by passing the appropriate options to the ./
configure script in the linux-atm distribution.

   
    NOTE: Issue ./configure --help from the top-level directory of the
    linux-atm distribution to view all possible options.
   
The ATM tools are built with the following commands:

cd linux-atm-x.x.x
./configure
make
make install

Unless otherwise specified when invoking ./configure, make install will install
executables in the directory /usr/local/bin and /usr/local/sbin, respectively.
Configuration files (except for hosts.atm which is installed in /etc) are
installed in /usr/local/etc. Libraries and header files are installed in /usr/
local/lib and /usr/local/include, respectively. Man pages are installed in /usr
/local/man.

-------------------------------------------------------------------------------

Extra Packages

Some programs are based on large packages that are already distributed outside
of the ATM context. For some packages, patches are contained in the ATM on
Linux distribution. They are contained in the src/extra directory of the ATM on
Linux distribution.

Currently, the following extra packages are available:

tcpdump
   
    dumps network traffic (enhanced for ATM)
   
ANS
   
    ATM name server (based on named 4.9.5)
   
Note that text2atm automatically uses ANS if available, so ans only needs to be
installed on systems providing name server functionality or if ATM-aware
maintenance tools nslookup, etc.) are needed.

A script hosts2ans.pl to convert a /etc/hosts.atm file to ANS zone files are
provided in the src/extra/ANS/ directory. Its use is described at the beginning
of the file.

-------------------------------------------------------------------------------

Device Setup

This section describes device-specific configuration operations, and general
diagnostic procedures at the ATM or SONET level. Please see the adapter
documentation for details on hardware installation and diagnosis.

-------------------------------------------------------------------------------

ATM Over TCP Setup

If you have no real ATM hardware, you can still exercise the API by using the
ATM over TCP ``driver''. It emulates ATM devices which are directly wired to
remote devices (i.e. there is no VPI/VCI swapping).

To establish one (bidirectional) ``wire'', become root on both systems (or run
both sides on the same system to create two connected ``interfaces'') and run
the following command on one of them (let's call it ``a''):

# atmtcp virtual listen

Then, on the other system (``b''), run

# atmtcp virtual connect address_of_a

Both atmtcps will report on their progress and the kernel should display
messages like:

Link 0: virtual interface 2
Link 1: incoming ATMTCP connection from 127.0.0.1

and

Link 0: virtual interface 3
Link 1: ATMTCP connection to localhost

on the two systems. Note that atmtcp keeps running and that interrupting it
breaks the virtual wire.

Multiple ``wires'' can be attached to the same machine by specifying a port
number (default is 2812). Note that no AAL processing is performed. It is
therefore not possible to receive data using a different AAL (e.g. AAL0) than
the one with which the data was sent.

-------------------------------------------------------------------------------

ZN1221/ZN1225 Tuning

The ZeitNet ZN1221 and ZN1225 adapters use pre-allocated pools of free memory
buffers for receiving. Whenever a VC with a certain maximum SDU size is opened
for receiving, the corresponding pool is filled with free buffers by the device
driver. The adapter removes buffers while it receives data. When the number of
remaining buffers falls below a certain threshold, the device driver
replenishes the pool again.

The lower and the upper limits for the number of free buffers, and the
threshold for adapting to a new data offset (see below for details), can be set
using the zntune program. Usage:

zntune [-l low_water] [-h high_water] [-t threshold] itf [pool]

The changes are applied to all pools if no pool number is specified. Pool 2
stores 64 bytes packets, pool 3 stores 128 bytes packets, etc. Pools 0 and 1
are currently unused.

The current settings and some usage statistics can be obtained by invoking 
zntune without specifying new parameters:

zntune [-z] itf [pool]

The ``Size'' column shows the buffer size in Bytes. The ``Ref'' column shows
the number of open VCs using that pool. The ``Alarm'' column shows how many
times the number of free buffers has fallen below the low-water mark since the
counters were reset. Similarly, the ``Under'' column shows how many times an
incoming PDU had to be discarded because the corresponding pool was empty.

The columns ``Offs'', ``NxOf'', ``Count'' and ``Thres'' show the alignment
adaption status. ``Offs'' is the offset of user data the driver currently
expects in incoming PDUs. For single-copy, receive buffers are aligned
accordingly so that data is received at page boundaries. ``NxOf'' is the user
data offset of the most recently received PDU, where the offset differs from
the currently assumed offset. ``Count'' is the number of PDUs that have been
received in sequence with an offset of ``NxOf''. Finally, ``Thres'' is the
threshold value ``Count'' has to reach for ``NxOf'' to become the new current
offset.

Use the -z option to reset the ``Alarm'' and ``Under'' counters.

-------------------------------------------------------------------------------

Files in /proc/net/atm/

Some status information about the ATM subsystem can be obtained through files
in /proc/net/atm/. The file /proc/net/atm/arp contains information specific to
Classical IP over ATM, see section CLIP.

All active ATM devices are listed in /proc/net/atm/devices. For each device,
the interface number, the type label, the end system identifier (ESI), and
statistics are shown. The statistics correspond to the ones available via
atmdiag.

Individual ATM devices may register entries of the form type:number (e.g. eni:
0) which contain device-specific information.

The files /proc/net/atm/pvc and /proc/net/atm/svc list all PVC and SVC sockets.
For both types of sockets, the interface, VPI and VCI numbers are shown. For
PVCs, this is followed by the AAL and the traffic class and the selected PCR
for the receive and the transmit direction. For SVCs, the SVC state and the
address of the remote party are shown. SVCs with the interface number 999 are
used for special control purposes as indicated in the ``State'' column.

Furthermore, /proc/net/atm/vc shows buffer sizes and additional internal
information for all ATM sockets.

-------------------------------------------------------------------------------

ATM Diagnostics

Various counters of the ATM device drivers can be queried with the atmdiag
program. See the corresponding man page for details.

-------------------------------------------------------------------------------

SONET Diagnostics

The SONET diagnostics tool can be used to monitor link performance and to
simulate errors. In order to get current SONET statistics, run it with the ATM
interface number as the argument, e.g.

% sonetdiag 0

The counters can be reset with the -z option:

# sonetdiag -z 0

The following network failures can be simulated:[1]

sbip
   
    insert section errors (B1)
   
lbip
   
    insert line errors (B2)
   
pbip
   
    insert path errors (B3)
   
frame
   
    force (RX) frame loss
   
los
   
    insert loss of signal
   
lais
   
    insert line alarm indication signal
   
pais
   
    insert path alarm indication signal
   
hcs
   
    insert header checksum errors
   
A failure is enabled by adding the corresponding keyword on the command line.
The failure is cleared by prefixing the keyword with a minus sign, e.g.

a# sonetdiag -z 0 >/dev/null
b# sonetdiag -z 0 >/dev/null
a# sonetdiag 0 los
a# sonetdiag 0 -los
b# sonetdiag 0 | grep BIP
Section BIP errors:      56200
Line BIP errors:           342
Path BIP errors:           152
a# sonetdiag 0 | grep FEBE
Line FEBE:                 342
Path FEBE:                 152

If any diagnostic error insertions are active, their keywords are shown when
sonetdiag is used to obtain statistics. Note that some error insertions may be
automatically switched off by the hardware.

-------------------------------------------------------------------------------

Native ATM PVCs

PVCs can be used for machines that are either connected back to back or via a
switch. In the latter case, the cell forwarding has to be manually set up at
the switch.

-------------------------------------------------------------------------------

Traffic Tools

aread/awrite and br/bw are simple programs to access the ATM API. awrite sends
the text string passed as its second argument in an AAL5 PDU. aread receives
one AAL5 PDU and displays it in hex. Both programs also display the return
values of the corresponding system calls and the current values of errno.

bw either sends its standard input or a stream of blocks containing arbitrary
data (if a number is passed as its fourth argument) in 8 kB AAL5 PDUs. br
receives AAL5 PDUs and writes them to standard output.

The first argument of aread, awrite, br and bw is always the PVC address, i.e.
the ATM interface number, the VPI and the VCI number, with a dot between
elements. The interface number can be omitted if it is zero. Example:

% awrite 1.0.42 hi

Note that some adapters only support VPI == 0. Also, the VCI range may be
limited, e.g 0 to 1023. The interface number can be obtained from the
initialization message the driver printed during startup. atm0 is interface 0,
atm1 is interface 1, etc. If the system is equipped with a real ATM adapter
(e.g. not only atmtcp), that adapter is normally at atm0.

aping receives and sends small AAL5 PDUs on a PVC. It expects that messages it
sends are either echoed back or that a similar program on the other side
generates a stream of messages. aping reports an error if no messages are
received for too long. aping is invoked by specifying the PVC, like aread.

For "real" tests, you should use the modified version of ttcp that comes with
this package. The original is available at ftp://ftp.sgi.com/sgi/src/ttcp/. The
following options have been added:

-a
   
    use native ATM instead of UDP/TCP. The address must be in the format [itf.]
    vpi.vci for PVCs, or a valid ATM end system address for SVCs.
   
-P num
   
    use a CBR connection with a peak cell rate of num cells per second. Default
    is to use UBR.
   
-C
   
    disable (UDP) checksums
   
Example:

%a ttcp_atm -r -a -s 0.90
%b ttcp_atm -t -a -s 0.90

-------------------------------------------------------------------------------

Direct Cell Access

On adapters where the device driver supports access to raw cells (``AAL0''),
individual cells can be composed and received with the atmdump program. Here is
an example:

a% sleep 10; date | ./atmdump -t 1 -c 0.51
b% ./atmdump 0.51
825079645.192480: VPI=0 VCI=51, GFC=0x0, CLP=1, Data SDU 1 (PTI 1)
   46 72 69 20 46 65 62 20 32 33 20 31 32 3a 34 37 
   3a 32 35 20 47 4d 54 20 31 39 39 36 0a 00 00 00 
   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 

-------------------------------------------------------------------------------

Signaling

ATM Hosts File

Because ATM addresses are inconvenient to use, most ATM tools also accept names
instead of numeric addresses. The mapping between names and numbers is defined
in the file /etc/hosts.atm. The structure of this file is similar to the /etc/
hosts file:

numeric_address name(s)

e.g.

47.0005.80FFE1000000F21A26D8.0020EA000EE0.00 pc2-a.fqdn pc2-a
47.0005.80FFE1000000F21A26D8.0020D4102A80.00 pc3-a.fqdn pc3-a

The numeric address can be specified in any of the formats described in [api].
The numeric address(es) of a Linux system can be determined with the command 
atmaddr -n (see also section Manual Address Configuration).

Many ATM tools also attempt to find the corresponding name when displaying an
address. When translating from the numeric form to a name, the first applicable
name in the file is used.

In addition to ATM addresses for SVCs, also PVC addresses can be stored in /etc
/hosts.atm. If different address types are stored under the same name, the
first suitable one will be chosen, i.e. if an application explicitly requests
only SVC addresses, any PVC addresses will be ignored.

-------------------------------------------------------------------------------

ANS

If you have access to the ATM Name Service (ANS, e.g because you've installed
the ANS extension), you can use it instead of or in addition to the hosts file
by specifying the host that runs ANS in the /etc/resolv.conf file.

For performing reverse lookups of E.164 addresses, the list of telephony
country codes needs to be known. That list can be obtained from the 
International Telecommunications Union. The List of ITU-T Recommendation E.164
Assigned Country Codes is currently available in PDF and Word document formats.

   
    NOTE: Should the URL become out of date, the document should easily be
    found by searching for the document's title at the ITU web site.
   
The script src/lib/pdf2e164_cc.pl in the atm-linux distribution can be used to
create the E.164 county codes table with the PDF version of the country code
list, e.g.

perl pdf2e164_cc.pl e164_xxx.pdf >/etc/e164_cc

It should be noted that pdftotext needs to be available in order to run the
script above. It can be obtained with xpdf.

-------------------------------------------------------------------------------

Signaling Demon

Man pages: atmsigd(8) atmsigd.conf(4)

Note that atmsigd's support for point-to-multipoint is very limited: only
operation as a single leaf of a point-to-multipoint tree works.

By default, atmsigd is configured to conform to dynamically configure the UNI
version. It can be compiled for UNI 3.0, 3.1, or 4.0 specifically by passing
the --with-uni=VERSION to the ./configure script in the top-level directory of
the linux-atm source distribution.

Note that atmsigd is configured to be paranoid. If it detects unusual problems,
it frequently terminates. This will (obviously) change in the future.

atmsigd also looks for a configuration file at the location specified with the
-c option. The default location is /usr/local/etc/atmsigd.conf.

-------------------------------------------------------------------------------

ILMI Demon

ILMI provides a mechanism for automatic address configuration. If there is no
switch or if the switch doesn't support ILMI, the ATM addresses must be
configured manually (see section Manual Address Configuration). Note that the
ILMI demon should not be used on interfaces where addresses are manually
configured.

The ILMI demon is started as follows:

ilmid [-b] [-d] [-i local_ip] [-l log_file] [-q qos] [-u uni_version] [-v] [-x]
[itf]

-b
   
    background. Run in a forked child process after initializing.
   
-d
   
    enables debugging output. By default, ilmid is very quiet.
   
-i local_ip
   
    IP address to tell switch when asked for one. Can be in either dotted
    decimal or textual format. By default, ilmid uses some heuristics to select
    a local IP address.
   
-l logfile
   
    write diagnostic messages to the specified file instead of to standard
    error. The special name syslog is used to send diagnostics to the system
    logger.
   
-q qos
   
    configures the ILMI VC to use the specified quality of service. By default,
    UBR at link speed is used on the ILMI VC.
   
-u uni_version
   
    set UNI version. Possible values are 3.0, 3.1, and 4.0. The dot can be
    omitted. The default value depends on how ilmid was compiled. Typically, it
    is 3.0.
   
-v
   
    enables extensive debugging output.
   
-x
   
    disable inclusion of variable bindings in the ColdstartTrap. Some switches
    (e.g. the LS100) only work if this option is set.
   
 

If no interface number is specified, ilmid serves interface 0. You can check
whether address registration was successful with the atmaddr command (see
below).

The agent supports only the address registration procedures specified in
section 5.8 of the ATM Forum's UNI 3.1 specification. These procedures involve
the switch registering the network prefix on the host and the host registering
the final ATM address back on the switch. The host accomplishes this by
appending an ESI (End System Identifier) and a null selector byte to the
network prefix registered by the switch. The ESI is the physical or MAC address
of the ATM interface.

-------------------------------------------------------------------------------

Manual Address Configuration

If your switch doesn't support ILMI, you have to set the ATM address manually
on the switch and on the PC(s). On the Linux side, make sure that ilmid doesn't
interfere, then use the atmaddr command to set the address(es).

Man pages: atmaddr(8)

Manual configuration of ATM addresses on the switch depends on the brand. On a
Fore ASX-200, it can be done with the following command:

conf nsap route new nsap_addr 152 port vpi

e.g.

conf nsap route new 47000580ffe1000000f21510650020ea000ee000 152 1a2 0
                    |<---- NSAP prefix ----->||<--ESI--->|^^
                                                          SEL

The entire NSAP address always has to have a length of 40 digits. Note that you
can also use addresses with a different prefix and an ESI that doesn't
correspond to any ESI your adapters have. The value of the selector byte (SEL)
is ignored.

-------------------------------------------------------------------------------

Running Two ATM NICs Back-to-Back

It is also possible to run with two ATM NICs connected back-to-back, and no
switch in between. This is great for simple test environments.

First, if you're using UTP or STP-5, you need a suitable cable. Our experience
with standard 100Base-T back-to-back cables was not good. It appears that the
pin-out they use is different. After some false starts, we found that the
following cable works:

RJ45                            RJ45
   1        ------------        7
   2        ------------        8

   7        ------------        1
   8        ------------        2

Pins 3, 4, 5, 6 unconnected.

A better way to illustrate this may be to show the proper color schemes for the
RJ45 connectors at each end of the back-to-back cable. The first connector
should use the following scheme:

RJ45-1
   1 - Brown
   2 - White/Brown
   3 - Unconnected
   4 - Unconnected
   5 - Unconnected
   6 - Unconnected
   7 - Orange
   8 - White/Orange

And the second connector should use this scheme:

RJ45-2
   1 - Orange
   2 - White/Orange
   3 - Unconnected
   4 - Unconnected
   5 - Unconnected
   6 - Unconnected
   7 - Brown
   8 - White/Brown

 

You can also make up a loopback cable with 1 -- 7 and 2 -- 8 connected for
ultra-cheap setups.

Here we have two machines called ``virgil'' and ``nestor''. Substitute your own
names as necessary.

One side of the ATM connection needs to use the network version of atmsigd and
the other side should use the normal user version. So here on nestor we start
atmsigd with:

atmsigd -b -m network

and on virgil with:

atmsigd -b

Without a switch, you won't be able to use ILMI. Instead, create a /etc/
hosts.atm file containing two dummy addresses. Our ATM hosts file contains:

47.0005.80FFE1000000F21A26D8.0020EA000EE0.00    nestor-atm
47.0005.80FFE1000000F21A26D8.0020D4102A80.00    virgil-atm

These are completely spurious addresses, of course, but as long as you're not
connected to a public or private ATM network, I don't think it matters. To set
the address correctly in the driver, we use:

atmaddr -a virgil-atm

on virgil, and:

atmaddr -a nestor-atm

on nestor. Now start atmarpd on both machines in the normal way. Now you
(should) have a working ATM set-up. To get IP over ATM working, just follow the
instructions in section IP Over ATM.

-------------------------------------------------------------------------------

Q.2931 Message Dumper

The Q.2931 message compiler also generates a pretty-printer for Q.2931
messages. The executable is called q.dump is stored in the src/qgen directory.
Note that it is not copied elsewhere by make install.

q.dump expects a sequence of whitespace-separated hex bytes at standard input
and outputs the message structure if the message can be parsed. Example:

% echo 09 03 80 00 05 5A 80 00 06 08 80 00 02 81 83 00 48 \
  00 00 08 | ./q.dump
_pdsc = 9 "Q.2931 user-network call/connection control message"
_cr_len = 3
call_ref = 8388613 (0x800005)
msg_type = 0x5a "RELEASE COMPLETE"
_ext = 1
_flag = 0 "instruction field not significant"
_action_ind = 0 "clear call"
msg_len = 6 (0x6)
  _ie_id = 0x08 "Cause"
    _ext = 1
    cause_cs = 0 "ITU-T standardized"
    _flag = 0 "instruction field not significant"
    _action_ind = 0 "clear call"
    _ie_len = 2 (0x2)
      _ext = 1
      location = 1 "private network serving the local user"
      _ext = 1
      cause = 3 "no route to destination"

 

-------------------------------------------------------------------------------

IP Over ATM

IP over ATM is supported with Classical IP over ATM (CLIP, defined in RFC1577 [
RFC1577], LAN Emulation (LANE, defined in [lanev1] and [lanev2]) and
Multi-Protocol Over ATM (MPOA, client only, defined in [mpoav1]).

-------------------------------------------------------------------------------

CLIP

A demon process is used to generate and answer ARP queries. The actual kernel
part maintains a small lookup table only containing partial information.

Man pages: atmarpd(8), atmarp(8)

atmsigd and ilmid must already be running when atmarpd is started. Use the -b
option to make sure they're properly synchronized, e.g.

#!/bin/sh
atmsigd -b
ilmid -b
atmarpd -b
...

works, but

#!/bin/sh
atmsigd &
ilmid &
atmarpd &
...

frequently doesn't (yet).

The atmarp program is used to configure ATMARP. First, you have to start
atmsigd, ilmid, and atmarpd, then create an IP interface and configure it:

# atmarp -c interface_name
# ifconfig atm0 local_address possibly_more_options up

e.g.

# atmarp -c atm0
# ifconfig atm0 10.0.0.3 up

If only PVCs will be used, they can now be created with a command like

# atmarp -s 10.0.0.4 0.0.70

NULL encapsulation is used if the null keyword is specified. Note that ARP
requires LLC/SNAP encapsulation. NULL encapsulation can therefore only be used
for PVCs.

When using SVCs, some additional configuration work may be necessary. If the
machine is acting as the ATMARP server on that LIS, no additional configuration
is required. Otherwise, the ATM address of the ATMARP server has to be
configured. This is done by creating an entry for the network address with the
option arpsrv set, e.g.

# atmarp -s \
  10.0.0.0 47.0005.80.ffe100.0000.f215.1065.0020EA000756.00 \
  arpsrv

Note that the ATMARP server currently has to be started and configured before
any clients are configured.

The kernel ATMARP table can be read via \path{/proc/net/atm/arp}. The table
used by atmarpd is regularly printed on standard error if atmarpd is started
with the -d option. If atmarpd is invoked without -d, the table is written to
the file atmarpd.table in the dump directory (by default /var/run; can be
changed with -D), and it can be read with atmarp -a.

-------------------------------------------------------------------------------

LAN Emulation

Besides Classical IP over ATM, LAN Emulation (LANE) can be used to carry IP
over ATM. LANE emulates the characteristics of legacy LAN technology, such as
support for broadcasts. LANE server support is described in the src/lane/USAGE
file in the linux-atm distribution.

Man pages: bus(8), lecs(8), les(8), and zeppelin(8)

If you plan to run more than one LANE clients, LANE service or LANE clients and
LANE service, you need to specify different local ATM addresses for each demon.
Since all the LANE demons use similar service access points (SAPs) they need
different ATM addresses to differentiate between connections.

Just as with CLIP, the LANE client consists of two parts: a demon process
called zeppelin which takes care of the LANE protocol and kernel part which
contains LANE ARP cache.

atmsigd and ilmid must already be running when zeppelin is started. When
zeppelin starts, the kernel creates a new interface which can then be
configured:

# zeppelin possibly_more_options &
# ifconfig lec0 local_address possibly_more_options up

In the example below, two LANE clients are started. The first client uses
default interface lec0, default listen address and tries to join the default
ELAN. The other LANE client gets interface lec2 assigned to it, binds to local
address mybox3, tries to join ELAN called myelan and will bridge packets
between ELAN and Ethernet segments. Address mybox3 is defined in /etc/
hosts.atm. Rest of the bridging can be configured by reading the Bridging
mini-HOWTO. [bridge-howto]

# zeppelin &
# ifconfig lec0 10.1.1.42 netmask 255.255.255.0 \
                          broadcast 10.1.1.255 up
#
# zeppelin -i 2 -l mybox3 -n myelan -p &
# ifconfig lec2 10.1.2.42 netmask 255.255.255.0 \
                          broadcast 10.1.2.255 up

By default, zeppelin uses interface lec0, binds to local ATM address using
selector byte value 0, tries to contact LECS using Well-Known LECS address,
joins the default ELAN as defined by the LECS, accepts the MTU size as defined
by the LES and will not act as an proxy LEC. These parameters can be tailored
with command line options which are defined in zeppelin(8).

zeppelin will automatically join any ELANs which use higher MTU than the
default MTU of 1516 bytes. The MTU of the LANE interface will adjust itself
according to the MTU of the current ELAN.

The state of the LANE ARP cache entries can be monitored through /proc/net/atm/
lec. For each entry the MAC and ATM addresses and status is listed. If the
entry has an active connection, the connection identifiers are also listed.

The LANE service ( lecs(8), les(8), and bus(8)) is configured using
configuration files. The configuration file syntax is listed on the respective
manual pages.

A more detailed description of Linux LANE services is discussed in Marko
Kiiskil's Master's Thesis [kiis].  

-------------------------------------------------------------------------------

MPOA

The Linux MPOA client continues the tradition of user space -- kernel divided
ATM services. The demon process called mpcd processes MPOA control packets
while the kernel holds MPOA ingress and egress caches and does the packet
forwarding.

Man page: mpcd(8)

atmsigd and ilmid must already be running when mpcd is started. Since MPOA
detects IP layer flows from LANE traffic, you need to have zeppelin running
before MPOA can function. However, the order in which zeppelin and mpcd is
started is not fixed. You can kill any of the demons at your will and restart
it later without need to restart the other demon. The easiest way to disable
MPOA is to kill the running mpcd.

Below is the example from Section LAN Emulation which starts two LANE clients.
The configuration has been augmented with two MPOA clients which the LANE
clients will serve.

# zeppelin &
# ifconfig lec0 10.1.1.42 netmask 255.255.255.0 \
                          broadcast 10.1.1.255 up
# mpcd -s mybox1 -l mybox2 &
#
# zeppelin -i 2 -l mybox3 -n myelan -p &
# ifconfig lec2 10.1.2.42 netmask 255.255.255.0 \
                          broadcast 10.1.2.255 up
# mpcd -i 2 -s mybox4 -l mybox5 &

The MPOA demon needs two different local ATM addresses which it uses when
initiating and receiving data and control connections. The addresses can be the
same as with e.g. zeppelin but must be different among other mpcd demons. By
default, mpcd does not retrieve configuration information from the LECS. The
necessary command line options and an example of using LECS are shown on the
mpcd manual page. The manual page also lists the rest of the available options.

The contents of MPOA ingress and egress caches can be monitored through the /
proc/net/atm/mpc file.

The Linux MPOA client also supports CBR traffic class for shortcuts SVCs
instead of default UBR. The QoS specifications for future shortcuts can be set
and modified using /proc/net/atm/mpc.

# echo add 130.230.54.146 tx=80000,1600 rx=tx > /proc/net/atm/mpc
#             # generate enough traffic to trigger a shortcut
# cat /proc/net/atm/mpc 
QoS entries for shortcuts:
IP address
  TX:max_pcr pcr     min_pcr max_cdv max_sdu
  RX:max_pcr pcr     min_pcr max_cdv max_sdu
130.230.54.146  
     80000   0       0       0       1600   
     80000   0       0       0       1600   

Interface 2:

Ingress Entries:
IP address      State     Holding time  Packets fwded  VPI VCI
130.230.4.3     invalid   1160          0           
130.230.54.146  resolved  542           151            0   109
...

The shortcut to IP address 130.230.54.146 was established with the parameters
shown above. There also exist patches which extend the flow detection to fully
support layer 4 flows. The layer 4 flows are expressed as a 5 tuple (proto,
local addr, local port, remote addr, remote port) and they identify application
to application flows. If you are interested, see ftp://sunsite.tut.fi/pub/Local
/linux-atm/mpoa/ for the latest patch.

Bibliography

References

[api] Linux ATM API, Werner Almesberger, http://linux-atm.sourceforge.net/API/
, July 1996.

[RFC1577] Classical IP and ARP over ATM (RFC1577), Mark Laubach, January 1994.

[lanev1] LAN Emulation Over ATM -- Version 1.0, ATM Forum, February 1996.

[lanev2] LAN Emulation Over ATM -- Version 2 -- LUNI Specification, ATM Forum,
July 1997.

[mpoav1] Multi-Protocol Over ATM -- Version 1.0, ATM Forum, July 1997.

[bridge-howto] Bridging mini-Howto, Christopher Cole, http://www.linuxdoc.org/
HOWTO/mini/Bridge.html , March, 2001.

[kiis] Implementation of LAN Emulation Over ATM in Linux, Marko Kiiskil, ftp:/
/sunsite.tut.fi/pub/Local/linux-atm/misc/ , October 1996.

Notes

[1]  Some adapters may only support a subset of this.