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AX25
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1996-07-19
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ax25 <subcommands>
All AX.25 parameters are configurable per interface. Commands of
the form 'ax25 <command>' set the default or global values. Use
the 'ifconfig <iface> ax25 <command>' form to set or show the
interface-specific values.
To set the system default ax.25 parameters, you must do so BEFORE
attaching interfaces. After attachment, you must use the 'ifconfig
<iface> ax25' command form to show or change values for that interface.
THIS IS A CHANGE FROM THE BEHAVIOUR EXHIBITED PRIOR TO JNOS VERSION
1.10X16, RELEASED 08FEB94.
ax25 alias <aliascall>
The alias command shows or sets the system's alias call. If
netrom is enabled, this modifies the same call as the 'netrom
alias' command. The 'ax25 alias' command is NOT needed in that
case! If netrom is not used, this command allows an alias name
to be set such that users can connect to it. The alias is typically
a short string and should not be a valid callsign, since any SSID
is ignored when matching against <aliascall>.
Example: ax25 alias knx
ax25 bbscall [<bbs_call>]
The bbscall subcommand sets or shows the current bbs callsign.
Connects to this callsign, when set properly, will "jump-start"
the mailbox. That is, after the connect no additional packet
need be sent to obtain the mailbox greeting. This subcommand
will automatically set the bbscall for all currently-attached
AX.25-class interfaces with no bbscall set. For bbscall to
function properly, it must differ from the system alias/netrom
alias, as well as the link address of the interface (usually
set by 'ax25 mycall').
See also 'ifconfig <iface> bbscall <bbs_call>'.
#Example: (in the following order)
'ax25 mycall N5KNX-1'
'ax25 alias KNX'
'ax25 bbscall N5KNX'
'attach <(all interfaces)>'
or
'ifconfig <name> bbscall <bbscall>' sets only iface <name>
ax25 bc <iface>
The bc command forces an immediate broadcast on the given
interface. The particular interface or port must have been
enabled with the ax25 bcport command first. If this is so, the ID
will be broadcast as set with the ax25 bctext commands.
ax25 bc port1
ax25 bcinterval [<seconds>]
(B) The bcinterval displays or sets the time in seconds between
broadcasts. On display, both the interval and the countdown
values are shown. Default = 600 (10 minutes).
ax25 bcport [<iface> [on | OFF]]
Display or set the active interfaces for ax.25 broadcasting (i.e.
beacons). If no interface is given, all interfaces with ax.25
beaconing enabled will be listed. If interface is given, the
status of beaconing for that interface is shown, or set according
to the following on or off option. Initial state is off.
ax25 bcport port1 on
ax25 bctext ["broadcast text"]
Display or set the default text to be sent for broadcast messages
sent out every ax25 bcinterval seconds. To compose a multi-line
message, use \r between the text of each line, ie, "line1\rline2".
See also 'ifconfig <iface> bctext ["bctext"].
ax25 bctext "This is the beacon text!"
ax25 blimit [<value>] Default: 30
(B) Display or set the default AX25 retransmission backoff
limit. Normally each successive AX25 retransmission is delayed
by twice the value of the previous interval; this is called
binary exponential backoff. When 2^(retrycount) reaches or ex-
ceeds the blimit <value>, the retry interval is no longer increased.
To prevent the possibility of "congestive collapse" on a loaded
channel, blimit should be set at least as high as the number of
stations sharing the channel. Note that this is applicable only
on actual AX25 connections; UI frames will never be retransmitted
by the AX25 layer. See also ax25 maxwait, and ax25 timertype.
#Set ax25 blimit to 15
ax25 blimit 15
ax25 dest [<iface>]
Display the destinations saved in the heard list, for all interfaces
with heard list maintenance enabled, or for the just the specified
interface. See also "ax25 heard".
ax25 digipeat [<iface> [ON | off]]
Display or set digipeating per interface. If no interface is
given, all interfaces with digipeating enabled will be listed. If
interface is given, the status of digipeating for that interface
is shown, or set according to the following on or off option. If
cross-band or AXIP digipeating is to be allowed, digipeating must
be enabled on both interfaces involved. Default is on.
# Display digipeat status of port1
ax25 digipeat port1
ax25 filter N Default: 0
Sets the ax.25 heard list filtering value. This is a global value
that affects all ports with heard list maintenance set to ON.
0 => log both source and destination callsigns
1 => do not log source callsign
2 => do not log destination callsign
3 => do not log any callsign, ie, disable all heard list updates
ax25 flush
Clears the AX.25 "heard" list (see ax25 heard and ax25 hport)
ax25 heard [<iface>]
Display the AX.25 "heard" list. For each interface that is
configured to use AX.25 heard listing (see 'ax25 hport'), a list
of all ax25_source addresses heard on that interface is shown,
along with a count of the number of packets heard from each
station and the time since each station was last heard. The
maximum length of the heard table can be set with the 'ax25
hsize' command. If interface is given, only the heard list for
that interface is displayed.
ax25 heard port1
ax25 hport [<iface> [ON | off]]
Display or set the status of the ax.25 heard feature. If no
interface is given, all interfaces with ax.25 heard enabled will
be listed. If interface is given, the status of ax.25 heard for
that interface is shown, or set according to the following on or
off option. Default is on.
#Display port1 status
ax25 hport port1
ax25 hsize [<size>]
Set or display the size of the heard list table. Default is 0
which means no limit.
ax25 irtt [<milliseconds>]
(B) Display or set the initial value of smoothed round trip time
to be used when a new AX25 connection is created. The actual
round trip time will be learned by measurement once the
connection has been established. Default is 5000ms.
#Set irtt to 10 seconds (10000 milliseconds)
ax25 irtt 10000
ax25 kick <axcb>
Force a retransmission on the specified AX.25 control block. The
control block address can be found with the ax25 status command.
This is useful to reactivate connections that have long time-out
values.
ax25 maxframe [<count>]
(B) Establish the maximum number of frames that will be allowed
to remain unacknowledged at one time on new AX.25 connections.
This number cannot be greater than 7. Without <count> it will
display the current setting. Note that the maximum outstanding
frame count only works with virtual connections. UI frames are
not affected. Also note that for optimal performance, a value of
1 should be used. Default is 1 frame.
ax25 maxwait [<msec>]
Sets a limit (in msec) to the retry timeout values. Default =
30000 (30 secs). A value of 0 disables maxwait.
ax25 mycall [<ax25call>]
Display or set the default local AX.25 address. The standard
format is used, (e.g. WG7J or KA7EHK-5). This command must be
given before any attach commands using AX.25 mode are given.
ax25 mycall wg7j-3
ax25 paclen [<size>]
(B) This sets the default paclen used when attaching interfaces
that will carry AX.25 connections. See also 'ifconfig <iface> ax25
paclen'. Default is 256 bytes.
This parameter limits the size of I-fields on new AX.25
connections. If IP datagrams or fragments of datagrams larger
than paclen are transmitted, they will be transparently
fragmented at the AX.25 level, sent as a series of I frames, and
reassembled back into a complete IP datagram or fragment at the
other end of the link. IP datagrams will not be affected if this
parameter is greater than or equal to the MTU of the associated
interface.
If NET/ROM communication is configured, the NetRom MTU value
should be Paclen - 20. !!! The Net/Rom header takes 20 bytes,
and is part of the AX25 data. Default netrom mtu is 236.
Note1: the AX.25 Level 2 Version 2 definition specifies a
maximum paclen of 256 bytes. Some systems are not equipped to
handle larger packets (e.g. G8BPQ based systems), so be careful
when using this parameter.
Note2: see also the section 'Of PACLEN, MTU, MSS, and More'
in the JNOS40 Configuration Manual.
ax25 pthresh [<size>]
(B) Display or set the poll threshold to be used for new AX.25
Version 2 connections. The poll threshold controls
retransmission behavior as follows. If the oldest unacknowledged
I-frame size is less than the poll threshold, it will be sent
with the poll (P) bit set if a time-out occurs. If the oldest
unacked I-frame size is equal to or greater than the threshold,
then a RR or RNR frame, as appropriate, with the poll bit set
will be sent if a time-out occurs.
The idea behind the poll threshold is that the extra time needed
to send a "small" I-frame instead of a supervisory frame when
polling after a time-out is small, and since there's a good
chance the I-frame will have to be sent anyway (i.e., if it were
lost previously) then you might as well send it as the poll. But
if the I-frame is large, send a supervisory (RR/RNR) poll instead
to determine first if retransmitting the oldest unacknowledged I-
frame is necessary; the time-out might have been caused by a lost
acknowledgment. This is obviously a tradeoff, so experiment with
the poll threshold setting. The default is 128 bytes, one half
the default value of <paclen>
ax25 reset <axcb>
Delete the AX.25 connection control block at the specified
address. This deletes a connection and everything associated with
it. The control block address can be found with the 'ax25 status'
command.
ax25 retries [<count>]
(B) Limit the number of successive unsuccessful retransmission
attempts on new AX.25 connections. If this limit is
exceeded, link re-establishment is attempted. If the link can't
be re-established in <count> times, then the connection is
abandoned and all queued data is deleted. Default is 5.
ax25 route [<subcommand>]
Without optional subcommands, display the AX.25 routing table
that specifies the digipeaters to be used in reaching a given
station.
ax25 route add <target> <iface> [[via] digis ...]
ax25 route perm <target> <iface> [[via] digis ...]
Add an entry to the AX.25 routing table. The route added may
be replaced automatically by a new one, unless "perm" is used
instead of "add". Replacement may occur when digipeaters are
specified in an AX25 link from the node or a connection is
received from a remote station via digipeaters. Such automatic
replacement is usually desirable; use "route add perm ..." to
prevent this where necessary.
<target> is the destination call to reach via digipeaters.
<iface> is the interface to use for this route, i.e. Jnos allows
different digi routes for different interfaces.
[digis...] is a list of one or more digipeaters, separated by
spaces and/or commas. The keyword "via" is optional.
ax25 route add k7uyx-1 port1 wg7j wa7tas n7dva
ax25 route perm k7uyx-1 port1 wg7j wa7tas n7dva
ax25 route drop <target> <iface>
Drop an entry for <target> from the AX.25 routing table.
ax25 route drop k7uyx-1 port1
ax25 route mode <target> <iface> [vc|dg|interface]
Sets the interface ip mode to one of vc | datagram |
interface for target. This indicates how ip links to the
destination call <target> should be established. If nothing
is given for a certain destination or target, the interface
default mode is used, which defaults to datagram. (See also
the 'mode' command).
vc is a virtual circuit (ax25 connected mode, meaning
that ip frames are sent using ax.25 connections)
datagram is unconnected mode, (AX25 UI frames).
interface is the default interface mode, as set with the
'mode' command.
ax25 route mode k7uyx-1 port1 vc
ax25 status [<axcb>]
Without an argument, display a one-line summary of each AX.25
control block. If the address of a particular control block is
specified, the contents of that control block is shown in more
detail. Note that the send queue units are frames, while the
receive queue units are bytes.
ax25 t2 [<milliseconds>] Default: 1000
Display or set the AX.25 "resptime" timer. Value is in milli-
seconds. Default is 1000ms, and minimum is 0ms. This timer lets
Jnos eliminate some redundant transmissions and optimize what it
sends by possibly adding ACKs to I-frames, by delaying the trans-
mission of packets. A value of zero disables the use of the t2
timer, as does the use of datagram mode (UI) [see mode command].
ax25 t3 [<milliseconds>] Default: 0
(B) Display or set the AX.25 idle "keep alive" timer. Value is
in milliseconds. Default is 0, i.e. no 'keep-alive' polling.
ax25 t4 [<seconds>] Default: 300
(B) Display or set the AX.25 Link "redundancy" timer. Value is
in seconds. When no exchange has been had during this time the
link is reset and closed. Default = 300 seconds (5 minutes).
ax25 timertype [LINEAR|exponential|original]
(B) Sets or displays the type of timer used for retransmission
and recovery. Linear means that each retry will use a time-out
that is RTT greater then the previous time-out. I.e. 4 sec, 8
sec, 12 sec, 16 seconds etc. Exponential means that each retry
will use a time-out that is twice as large as the previous time-
out. I.e. 4 seconds, 8 seconds, 16 seconds, 32 seconds etc.
Original means that each retry will use a time out that is twice
the RTT, i.e. 4 seconds, 8 seconds, 8 seconds, 8 seconds, etc.
Default is linear.
ax25 timertype exponential
ax25 ttycall [ttycall]
Set or display the tty-link call for direct keyboard access.
Remember to have both 'attended on' and 'mbox attend on' to be
able to use this function.
ax25 version [n]
(B) Display or set the version of the AX.25 protocol to attempt
to use on new connections. Version 1 is the version that does
not use the poll/final bits. Default is version 2.
ax25 window [<size>] Default: 512 bytes
(B) Set the number of bytes that can be pending on an AX.25
receive queue beyond which I frames will be answered with RNR
(Receiver Not Ready) responses. This presently applies only to
suspended interactive AX.25 sessions, since incoming I-frames
containing network (IP, NET/ROM) packets are always processed
immediately and are not placed on the receive queue. However,
when an AX.25 connection carries both interactive and network packet
traffic, an RNR generated because of backlogged interactive traffic
will also stop network packet traffic from being sent.