ATM on Linux HOWTOATM 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.
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).
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:
Just hit return when prompted for a password. Then, checkout the repository:
You may also specify a branch to check out specifically:
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
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:
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.
In order to install this package, you'll need
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:
First, extract the ATM on Linux distribution:
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)
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.
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.):
If you've configured the ZN1221/ZN1225 driver, you will get something like:
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.
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:
If you chose to download the source, extract
mpr-x.x.tar.gz like so:
Then do:
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.
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:
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.
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.
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.
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''):
Then, on the other system (``b''), run
Both atmtcps will report on their progress and the kernel
should display messages like:
and
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.
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.
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.
Various counters of the ATM device drivers can be queried with the
atmdiag program. See the corresponding man page
for details.
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.
The counters can be reset with the -z
option:
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.
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.
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.
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:
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:
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:
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:
e.g.
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.
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.
It should be noted that pdftotext needs to be
available in order to run the script above. It can be obtained with
xpdf.
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 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.
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:
e.g.
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.
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:
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:
And the second connector should use this scheme:
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:
and on virgil with:
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:
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:
on virgil, and:
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.
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:
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]).
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.
works, but
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:
e.g.
If only PVCs will be used, they can now be created with a command like
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.
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.
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:
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]
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 Kiiskilä's Master's Thesis
[kiis].
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.
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.
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.
[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 Kiiskilä, ftp://sunsite.tut.fi/pub/Local/linux-atm/misc/
, October 1996. |
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