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<HTML
><HEAD
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>IP Over ATM</TITLE
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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="IP-OVER-ATM"
>6. IP Over ATM</A
></H1
><P
>IP over ATM is supported with Classical IP over ATM (CLIP, defined in
RFC1577 [<A
HREF="bibliography.html#RFC1577"
>RFC1577</A
>], LAN Emulation (LANE, defined in
[<A
HREF="bibliography.html#LANEV1"
>lanev1</A
>] and [<A
HREF="bibliography.html#LANEV2"
>lanev2</A
>])
and Multi-Protocol Over ATM (MPOA, client only, defined in
[<A
HREF="bibliography.html#MPOAV1"
>mpoav1</A
>]).</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="IP-OVER-ATM.CLIP"
>6.1. CLIP</A
></H2
><P
>A demon process is used to generate and answer ARP queries.
The actual kernel part maintains a small lookup table only containing partial
information.</P
><P
>Man pages:
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>atmarpd</SPAN
>(8)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>atmarp</SPAN
>(8)</SPAN
></P
><P
><SPAN
CLASS="APPLICATION"
>atmsigd</SPAN
> and <SPAN
CLASS="APPLICATION"
>ilmid</SPAN
>
must already be running when <SPAN
CLASS="APPLICATION"
>atmarpd</SPAN
> is
started. Use the <TT
CLASS="PARAMETER"
><I
>-b</I
></TT
>
option to make sure they're properly synchronized,
e.g.
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN744"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
>#!/bin/sh
atmsigd -b
ilmid -b
atmarpd -b
...</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
>
works, but
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN746"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
>#!/bin/sh
atmsigd &#38;
ilmid &#38;
atmarpd &#38;
...</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
>
frequently doesn't (yet).</P
><P
>The <SPAN
CLASS="APPLICATION"
>atmarp</SPAN
> program is used to configure ATMARP.
First, you have to
start <SPAN
CLASS="APPLICATION"
>atmsigd</SPAN
>, <SPAN
CLASS="APPLICATION"
>ilmid</SPAN
>, and
<SPAN
CLASS="APPLICATION"
>atmarpd</SPAN
>, then create an IP
interface and configure it:
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN753"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># atmarp -c <TT
CLASS="REPLACEABLE"
><I
>interface_name</I
></TT
>
# ifconfig atm0 <TT
CLASS="REPLACEABLE"
><I
>local_address</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>possibly_more_options</I
></TT
> up</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
>
e.g.
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN758"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># atmarp -c atm0
# ifconfig atm0 10.0.0.3 up</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>If only PVCs will be used, they can now be created with a command like
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN761"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># atmarp -s 10.0.0.4 0.0.70</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>NULL encapsulation is used if the <TT
CLASS="PARAMETER"
><I
>null</I
></TT
>
keyword is specified.
Note that ARP requires LLC/SNAP encapsulation. NULL encapsulation can
therefore only be used for PVCs.</P
><P
>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 <TT
CLASS="PARAMETER"
><I
>arpsrv</I
></TT
>
set, e.g.
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN767"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># atmarp -s \
10.0.0.0 47.0005.80.ffe100.0000.f215.1065.0020EA000756.00 \
arpsrv</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>Note that the ATMARP server currently has to be started and configured
before any clients are configured.</P
><P
>The kernel ATMARP table can be read via \path{/proc/net/atm/arp}. The table
used by <SPAN
CLASS="APPLICATION"
>atmarpd</SPAN
>
is regularly printed on standard error if <SPAN
CLASS="APPLICATION"
>atmarpd</SPAN
>
is started with the <TT
CLASS="PARAMETER"
><I
>-d</I
></TT
> option.
If <SPAN
CLASS="APPLICATION"
>atmarpd</SPAN
> is invoked without
<TT
CLASS="PARAMETER"
><I
>-d</I
></TT
>, the table is written to the file
<TT
CLASS="FILENAME"
>atmarpd.table</TT
> in the dump
directory (by default <TT
CLASS="FILENAME"
>/var/run</TT
>; can be
changed with <TT
CLASS="PARAMETER"
><I
>-D</I
></TT
>), and
it can be read with <B
CLASS="COMMAND"
>atmarp -a</B
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="IP-OVER-ATM.LAN-EMULATION"
>6.2. LAN Emulation</A
></H2
><P
>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 <TT
CLASS="FILENAME"
>src/lane/USAGE</TT
> file in the linux-atm
distribution.</P
><P
>Man pages:
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>bus</SPAN
>(8)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lecs</SPAN
>(8)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>les</SPAN
>(8)</SPAN
>, and
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>zeppelin</SPAN
>(8)</SPAN
></P
><P
>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.</P
><P
>Just as with CLIP, the LANE client consists of two parts: a demon
process called <SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
>
which takes care of the LANE protocol
and kernel part which contains LANE ARP cache.</P
><P
><SPAN
CLASS="APPLICATION"
>atmsigd</SPAN
> and <SPAN
CLASS="APPLICATION"
>ilmid</SPAN
>
must already be running when
<SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
> is started. When
<SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
> starts, the kernel
creates a new interface which can then be configured:
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN805"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># zeppelin <TT
CLASS="REPLACEABLE"
><I
>possibly_more_options</I
></TT
> &#38;
# ifconfig lec0 <TT
CLASS="REPLACEABLE"
><I
>local_address</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>possibly_more_options</I
></TT
> up</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>In the example below, two LANE clients are started. The first client
uses default interface <SPAN
CLASS="INTERFACE"
>lec0</SPAN
>,
default listen address and tries to
join the default ELAN. The other LANE client gets interface
<SPAN
CLASS="INTERFACE"
>lec2</SPAN
>
assigned to it, binds to local address
<TT
CLASS="PARAMETER"
><I
>mybox3</I
></TT
>, tries to join
ELAN called <TT
CLASS="PARAMETER"
><I
>myelan</I
></TT
>
and will bridge packets between ELAN and
Ethernet segments. Address <TT
CLASS="PARAMETER"
><I
>mybox3</I
></TT
>
is defined in
<TT
CLASS="FILENAME"
>/etc/hosts.atm</TT
>. Rest of the bridging can be configured
by reading the Bridging mini-HOWTO. [<A
HREF="bibliography.html#BRIDGE-HOWTO"
>bridge-howto</A
>]
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN818"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># zeppelin &#38;
# 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 &#38;
# ifconfig lec2 10.1.2.42 netmask 255.255.255.0 \
broadcast 10.1.2.255 up</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>By default, <SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
> uses interface
<SPAN
CLASS="INTERFACE"
>lec0</SPAN
>, 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
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>zeppelin</SPAN
>(8)</SPAN
>.</P
><P
><SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
> 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.</P
><P
>The state of the LANE ARP cache entries can be monitored through
<TT
CLASS="FILENAME"
>/proc/net/atm/lec</TT
>.
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.</P
><P
>The LANE service (
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lecs</SPAN
>(8)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>les</SPAN
>(8)</SPAN
>, and
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>bus</SPAN
>(8)</SPAN
>)
is
configured using configuration files. The configuration file syntax is
listed on the respective manual pages.</P
><P
>A more detailed description of Linux LANE services is discussed in
Marko Kiiskil<69>'s Master's Thesis
[<A
HREF="bibliography.html#KIIS"
>kiis</A
>].
&#13;</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="IP-OVER-ATM.MPOA"
>6.3. MPOA</A
></H2
><P
>The Linux MPOA client continues the tradition of user space -- kernel
divided ATM services. The demon process called
<SPAN
CLASS="APPLICATION"
>mpcd</SPAN
> processes
MPOA control packets while the kernel holds MPOA ingress and egress
caches and does the packet forwarding.</P
><P
>Man page:
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>mpcd</SPAN
>(8)</SPAN
></P
><P
><SPAN
CLASS="APPLICATION"
>atmsigd</SPAN
> and <SPAN
CLASS="APPLICATION"
>ilmid</SPAN
>
must already be running when
<SPAN
CLASS="APPLICATION"
>mpcd</SPAN
> is started.
Since MPOA detects IP layer flows from LANE
traffic, you need to have <SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
>
running before MPOA can
function. However, the order in which <SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
>
and <SPAN
CLASS="APPLICATION"
>mpcd</SPAN
>
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
<SPAN
CLASS="APPLICATION"
>mpcd</SPAN
>.</P
><P
>Below is the example from Section
<A
HREF="ip-over-atm.html#IP-OVER-ATM.LAN-EMULATION"
><I
>LAN Emulation</I
></A
>
which starts two LANE
clients. The configuration has been augmented with two MPOA clients
which the LANE clients will serve.
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN860"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># zeppelin &#38;
# ifconfig lec0 10.1.1.42 netmask 255.255.255.0 \
broadcast 10.1.1.255 up
# mpcd -s mybox1 -l mybox2 &#38;
#
# zeppelin -i 2 -l mybox3 -n myelan -p &#38;
# ifconfig lec2 10.1.2.42 netmask 255.255.255.0 \
broadcast 10.1.2.255 up
# mpcd -i 2 -s mybox4 -l mybox5 &#38;</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
></P
><P
>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.
<SPAN
CLASS="APPLICATION"
>zeppelin</SPAN
> but must be
different among other <SPAN
CLASS="APPLICATION"
>mpcd</SPAN
> demons. By default,
<SPAN
CLASS="APPLICATION"
>mpcd</SPAN
> does
not retrieve configuration information from the LECS. The necessary
command line options and an example of using LECS are shown on the
<SPAN
CLASS="APPLICATION"
>mpcd</SPAN
> manual page.
The manual page also lists the rest of the available options.</P
><P
>The contents of MPOA ingress and egress caches can be monitored
through the <TT
CLASS="FILENAME"
>/proc/net/atm/mpc</TT
> file.</P
><P
>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
<TT
CLASS="FILENAME"
>/proc/net/atm/mpc</TT
>.
<DIV
CLASS="INFORMALEXAMPLE"
><A
NAME="AEN871"
></A
><P
></P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># echo add 130.230.54.146 tx=80000,1600 rx=tx &#62; /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
...</PRE
></FONT
></TD
></TR
></TABLE
><P
></P
></DIV
>
The shortcut to IP address <TT
CLASS="PARAMETER"
><I
>130.230.54.146</I
></TT
>
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
<A
HREF="ftp://sunsite.tut.fi/pub/Local/linux-atm/mpoa/"
TARGET="_top"
>ftp://sunsite.tut.fi/pub/Local/linux-atm/mpoa/</A
>
for the latest
patch.</P
></DIV
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