tp.4p

早期freebsd实现

means that upon receipt of the packet that represents
the high edge of the last window advertised, and AK TPDU is generated.
.\" ******************8
.TP 25
p_rx_strat
4 bit mask
[ TPRX_USE_CW | TPRX_FASTSTART over
connectionless network protocols ]
[ TPRX_USE_CW over
connection-oriented network protocols ]
.IP
This parameter applies only to class 4.
The bit mask may include the following values:
.IP
TPRX_EACH: When a retransmission timer expires, retransmit
each packet in the send window rather than
just the first unacknowledged packet.
.IP
TPRX_USE_CW: Use a "congestion window" strategy borrowed
from Van Jacobson's congestion window strategy for TCP.
The congestion window size is set to one whenever
a retransmission occurs.
.IP
TPRX_FASTSTART: Begin sending the maximum amount of data permitted
by the peer (subject to availability).
The alternative is to start sending slowly by 
pretending the peer's window is smaller than it is, and letting
it slowly grow up to the real peer's window size.
This is to smooth the effect of new connections on a congested network
by preventing a transport connection from suddenly 
overloading the network with a burst of packets.
This strategy is also due to Van Jacobson.
.\" ******************8
.TP 25
p_class
5 bit mask
[ TP_CLASS_4 | TP_CLASS_0 ]
.IP
Bit mask including one or both of the values TP_CLASS_4 and TP_CLASS_0.
The higher class indicated is the preferred class.
If only one class is indicated, negotiation will not occur
during connection establishment.
.\" ******************8
.TP 25
p_xtd_format
Boolean.
[ false ]
.IP
Boolean indicating that extended format shall be negotiated.
This parameter applies only to class 4.
.\" ******************8
.TP 25
p_xpd_service
Boolean.
[ true ]
.IP
Boolean indicating that 
the expedited data transport service will be negotiated.
This parameter applies only to class 4.
.\" ******************8
.TP 25
p_use_checksum
Boolean.
[ true ]
.IP
Boolean indicating the the use of checksums will be negotiated.
This parameter applies only to class 4.
.\" ******************8
.TP 25
p_use_nxpd
Reserved for future use.
.\" ******************8
.TP 25
p_use_rcc
Reserved for future use.
.\" ******************8
.TP 25
p_use_efc
Reserved for future use.
.\" ******************8
.TP 25
p_no_disc_indications
Boolean.
[ false ]
.IP
Boolean indicating that the local TP entity shall not issue
indications (signals) when a TP connection is disconnected.
.\" ******************8
.TP 25
p_dont_change_params
Boolean.
[ false ]
.IP
If \fBtrue\fR the TP entity will not override
any of the other values given in this structure.
If the values cannot be used, the TP entity will drop, disconnect,
or refuse to establish the connection to which this structure pertains.
.\" ******************8
.TP 25
p_netservice
One of { ISO_CLNS, ISO_CONS, ISO_COSNS, IN_CLNS }.
[ ISO_CLNS ]
.IP
Indicates which network service is to be used.
.IP
ISO_CLNS indicates the connectionless network service provided
by CLNP (ISO 8473).
.IP
ISO_CONS indicates the connection-oriented network service provided
by X.25 (ISO 8208) and ISO 8878.
.IP
ISO_COSNS indicates the 
connectionless network service running over a
connection-oriented subnetwork service : CLNP (ISO 8473) over X.25 (ISO 8208).
.IP
IN_CLNS indicates the 
DARPA Internet connectionless network service provided by IP (RFC 791).
.\" ******************8
.TP 25
p_dummy
Reserved for future use.
.sp 1
.PP
The TPOPT_FLAGS option is used for obtaining
various boolean-valued options.
Its meaning is as follows.
The bit numbering used is that of the PC/RT, which means that bit
0 is the most significant bit, while bit 8 is the least significant bit.
.nf
.sp 1
\fIValues for TPOPT_FLAGS:\fR
.fi
.TP 10
\fBBits\fR
\fBDescription [Default]\fR
.TP 10
0
TPFLAG_NLQOS_PDN : set when the quality of the 
network service is
similar to that of a public data network.
.TP 10
1
TPFLAG_PEER_ON_SAMENET : set when the peer TP entity
is considered to be on the same network as the local
TP entity.
.TP 10
2
Not used.
.TP 10
3
TPFLAG_XPD_PRES : set when expedited data are present
[ 0 ]
.TP 10
4..7
Reserved.
.\".TP 10
.\"4
.\"Reserved.
.\".TP 10
.\"5
.\"TPFLAG_DISC_DATA_IN : read only flag, if set indicates that
.\"data from a disconnect TPDU are present.
.\".TP 10
.\"6
.\"Reserved.
.\".TP 10
.\"7
.\"TPFLAG_CONN_DATA_IN : read only flag, if set indicates that
.\"data from a connect TPDU are present.
.SH "LIBRARIES
.PP
The new system calls \fIrecvv\fR and \fIsendv\fR are supported by a
library, \fIlibtp.a\fR (rather than a modified C library).  
Also in this
library are new optional interfaces to the \fIconnect\fR and \fIaccept\fR
system calls.  See LIBTP(3).
.SH FILES
.PP
The following files in have entries necessary for the correct operation
of the TP utilities.
.nf
\fC
	/etc/isodir
	/etc/protocols
\fR
.fi
.PP
The symbolic link is needed for users to write programs using IPC
with TP:
.nf
\fC
	/usr/include/netargo@  ->  /sys/netargo
\fR
.fi
.PP
The following utilities have changed:
.nf
	netstat
	ifconfig
	config
.fi
.PP
The following are new utilities and daemons:
.nf
	isoroute
	rlogin.iso, rcp.iso, rsh.iso, isod, rlogind
	tpdiscard
	tpping
	tppt (for maintenance and debugging)
	bark (for maintenance and debugging)
	tpfileget, tpfileput (for debugging)
	tpstat, tpmon
	tpset
	tppkt
	viid
.fi
.PP
In the kernel source, many files have changed or been added.
For a list of these, see the installation guide,
"Installing Wisconsin ARGO 1.0 on Academic Operating System 4.3
Release 2".
.SH "ERROR VALUES
.PP
The TP entity returns \fIerrno\fR error values as defined in
\fB<sys/errno.h>\fR
and
\fB<netargo/iso_errno.h>\fR.
User programs may print messages associated with these value by
using an expanded version of \fIperror()\fR
found in the ISO library, \fIlibisodir.a\fR.
.PP
If the TP entity encounters asynchronous events
that will cause a transport connection to be closed,
such as
timing out while retransmitting a connect request TPDU,
or receiving a DR TPDU,
the TP entity issues a SIGURG signal, indicating that
disconnection has occurred.
If the signal is issued during a 
a system call, the system call may be interrupted,
in which case the
\fIerrno\fR value upon return from the system call is EINTR.
If the signal SIGURG
is being handled by reading
from the socket, and it was a \fIaccept()\fR that
timed out, the read may result in ENOTSOCK,
because the \fIaccept()\fR call had not yet returned a
legitimate socket descriptor when the signal was handled.
ETIMEDOUT (or a some other errno value appropriate to the
type of error) is returned if SIGURG is blocked
for the duration of the system call.
A user program should take one of the following approaches:
.IP "Block SIGURG." 5
If the program is servicing
only one connection, it can block or ignore SIGURG during connection 
establishment.
The advantage of this is that the \fIerrno\fR value
returned is somewhat meaningful.
The disadvantage of this is that
if ignored, disconnection and expedited data indications could be
missed.
For some programs this is not a problem.
.IP "Handle SIGURG." 5
If the program is servicing more than one connection at a time
or expedited data may arrive or both, the program must
service SIGURG.
It can use the \fIgetsockopt(...TPOPT_FLAGS...)\fR system 
call to see if the signal
was due to the arrival of expedited data or due to a disconnection.
In the latter case, 
\fIgetsockopt()\fR
will return ENOTCONN.
.SH BUGS
.PP
When running TP over the token ring, if checksumming
is NOT used, the TP entity sents packets to the lan driver faster than
the driver can reasonably handle them.
A bug in the lan driver causes it to reorder the packets in this
situation, causing an overall degradation of TP performance.
In general, this is not a problem because very few applications
will actually be able to send packets this fast.
Nevertheless,
in order to prevent this reordering, 
one may induce a delay in the TP entity by setting the 1-byte
value
\fItp_delay\fR
to 1
using the debugger.
Hit the <pause> key, then
type \fB/b tp_delay\fR followed by the <enter key>.
The debugger will print the value 00.  
You then type \fB1\fR followed by the <enter key>.
Then type \fBend\fR <enter key>.
Then type \fBgo\fR <enter key>.
.SH SEE ALSO
.PP
tcp(4P), sendv(2), recvv(2), libtp(3),
isodir(3), isodir(5), netstat(1),
iso(4F), clnp(4P), viid(8)
tppt(8), tpstat(8), bark(8), tppkt(8), tpset(8), tpperf(8)
isoroute(8), ifconfig(8), isod(8), rlogin.iso(1),
"Installing Wisconsin ARGO 1.0 on Academic Operating System 4.3
Release 2",
"ARGO 1.0 Kernel Programmer's Manual"