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CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN235"
>5. A note on callsigns, addresses and things before we start</A
></H1
><P
>Each AX.25 and NET/ROM port on your system must have a callsign/ssid allocated
to it. These are configured in the configuration files that will be described
in detail later on.</P
><P
>Some AX.25 implementations such as NOS and BPQ will allow you to configure
the same callsign/ssid on each AX.25 and NET/ROM port. For somewhat complicated
technical reasons Linux does not allow this. This isn't as big a problem in
practice as it might seem.</P
><P
>This means that there are things you should be aware of and take into
consideration when doing your configurations.</P
><P
>&#13;<P
></P
><OL
TYPE="1"
><LI
><P
>Each AX.25 and NET/ROM port must be configured with a unique callsign/ssid.</P
></LI
><LI
><P
>TCP/IP will use the callsign/ssid of the AX.25 port it is being
transmitted or received by, ie the one you configured for the AX.25 interface
in point 1.</P
></LI
><LI
><P
>NET/ROM will use the callsign/ssid specified for it in its
configuration file, but this callsign is only used when your NET/ROM is
speaking to another NET/ROM, this is <EM
>not</EM
> the
callsign/ssid that AX.25 users who wish to use your NET/ROM `node' will
use. More on this later.</P
></LI
><LI
><P
>ROSE will, by default, use the callsign/ssid of the AX.25 port, unless
the ROSE callsign has been specifically set using the
`<EM
>rsparms</EM
>' command. If you set a callsign/ssid
using the `<EM
>rsparms</EM
>' command then ROSE will use
this callsign/ssid on all ports.</P
></LI
><LI
><P
>Other programs, such as the `<EM
>ax25d</EM
>' program can listen using
any callsign/ssid that they wish and these may be duplicated across different
ports.</P
></LI
><LI
><P
>If you are careful with routing you can configure the same IP address on
all ports if you wish.</P
></LI
></OL
>&#13;</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN258"
>5.1. What are all those T1, T2, N2 and things ?</A
></H2
><P
>Not every AX.25 implementation is a TNC2. Linux uses nomenclature that
differs in some respects from that you will be used to if your sole
experience with packet is a TNC. The following table should help you
interpret what each of the configurable items are, so that when you come
across them later in this text you'll understand what they mean.</P
><P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN262"
></A
><P
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Linux</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>TAPR TNC</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T1</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>FRACK</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>How long to wait before retransmitting an unacknowledged frame.</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T2</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>RESPTIME</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>The minimum amount of time to wait for another frame to be received
before transmitting an acknowledgement.</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T3</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>CHECK</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>The period of time we wait between sending a check that the link is still active.</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>N2</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>RETRY</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>How many times to retransmit a frame before assuming the connection has failed.</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Idle</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>The period of time a connection can be idle before we close it down.</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Window</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>MAXFRAME</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>The maximum number of unacknowledged transmitted frames.</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN294"
>5.2. Run time configurable parameters</A
></H2
><P
>The kernel allows you to change many parameters at run time. If you
take a careful look at the <TT
CLASS="LITERAL"
>/proc/sys/net/</TT
> directory
structure you will see many files with useful names that describe
various parameters for the network configuration. The files in the
<TT
CLASS="LITERAL"
>/proc/sys/net/ax25/</TT
> directory each represent one
configured AX.25 port. The name of the file relates to the name of the
port.</P
><P
>The structure of the files in
<TT
CLASS="LITERAL"
>/proc/sys/net/ax25/<TT
CLASS="REPLACEABLE"
><I
>portname</I
></TT
>/</TT
>
is as follows:</P
><P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN303"
></A
><P
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Filename</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Meaning</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Values</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Default</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>ip_default_mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>IP Default Mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0=DG 1=VC</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>ax25_default_mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>AX.25 Default Mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0=Normal 1=Extended</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>backoff_type</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Backoff</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0=Linear 1=Exponential</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>connect_mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Connected Mode</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0=No 1=Yes</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>standard_window_size</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Standard Window</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1 .. 7</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>2</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>extended_window_size</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Extended Window</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1 .. 63</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>32</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>t1_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T1 Timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1s .. 30s</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>10s</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>t2_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T2 Timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1s .. 20s</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>3s</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>t3_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>T3 Timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0s .. 3600s</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>300s</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>idle_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Idle Timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>0m or greater</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>20m</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>maximum_retry_count</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>N2</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1 .. 31</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>10</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>maximum_packet_length</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>AX.25 Frame Length</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1 .. 512</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>256</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></P
><P
>In the table T1, T2 and T3 are given in seconds, and the Idle Timeout
is given in minutes. But please note that the values used in the sysctl
interface are given in internal units where the time in seconds is
multiplied by 10, this allows resolution down to 1/10 of a second. With
timers that are allowed to be zero, e.g. T3 and Idle, a zero value indicates
that the timer is disabled.</P
><P
>The structure of the files in <TT
CLASS="LITERAL"
>/proc/sys/net/netrom/</TT
>
is as follows:</P
><P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN376"
></A
><P
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Filename</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Meaning</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Values</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Default</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>default_path_quality</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>10</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>link_fails_count</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>2</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>network_ttl_initialiser</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>16</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>obsolescence_count_initialiser</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>6</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>routing_control</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>transport_acknowledge_delay</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>50</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>transport_busy_delay</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1800</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>transport_maximum_tries</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>3</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>transport_requested_window_size</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>4</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>transport_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1200</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></P
><P
>The structure of the files in <TT
CLASS="LITERAL"
>/proc/sys/net/rose/</TT
>
is as follows:</P
><P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN438"
></A
><P
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Filename</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Meaning</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Values</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Default</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>acknowledge_hold_back_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>50</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>call_request_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>2000</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>clear_request_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1800</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>link_fail_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1200</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>maximum_virtual_circuits</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>50</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>reset_request_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1800</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>restart_request_timeout</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1800</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>routing_control</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>1</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>window_size</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>3</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></P
><P
>To set a parameter all you need to do is write the desired value to the file
itself, for example to check and set the ROSE window size you'd use something
like:</P
><P
><TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
># cat /proc/sys/net/rose/window_size
3
# echo 4 &#62;/proc/sys/net/rose/window_size
# cat /proc/sys/net/rose/window_size
4</PRE
></FONT
></TD
></TR
></TABLE
></P
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