.\"
.\" ===================================
.\" HARP  |  Host ATM Research Platform
.\" ===================================
.\"
.\"
.\" This Host ATM Research Platform ("HARP") file (the "Software") is
.\" made available by Network Computing Services, Inc. ("NetworkCS")
.\" "AS IS".  NetworkCS does not provide maintenance, improvements or
.\" support of any kind.
.\"
.\" NETWORKCS MAKES NO WARRANTIES OR REPRESENTATIONS, EXPRESS OR IMPLIED,
.\" INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY
.\" AND FITNESS FOR A PARTICULAR PURPOSE, AS TO ANY ELEMENT OF THE
.\" SOFTWARE OR ANY SUPPORT PROVIDED IN CONNECTION WITH THIS SOFTWARE.
.\" In no event shall NetworkCS be responsible for any damages, including
.\" but not limited to consequential damages, arising from or relating to
.\" any use of the Software or related support.
.\"
.\" Copyright 1994-1998 Network Computing Services, Inc.
.\"
.\" Copies of this Software may be made, however, the above copyright
.\" notice must be reproduced on all copies.
.\"
.\" @(#) $FreeBSD$
.\"
.\"
.Dd August 21, 1998
.Dt SCSPD 8
.Os
.Sh NAME
.Nm scspd
.Nd "SCSP daemon"
.Sh SYNOPSIS
.Nm
.Op Fl f Aq Ar cfg\-file
.Op Fl d
.Op Fl T Ns Aq Ar options
.Sh DESCRIPTION
.Nm Scspd
is an implementation of the Server Cache Synchronization
Protocol (SCSP) for the Host ATM Research Platform (HARP)
networking software.
.Nm Scspd
synchronizes the cache(s) of server(s)
running on a host with the caches of servers on remote hosts.
SCSP is defined for a number of different protocols, but the present
version of
.Nm
only supports ATMARP.
.Pp
By using
.Nm
and
.Xr atmarpd 8 ,
one can provide multiple
ATMARP servers in a single ATM LIS.
This might be useful, for example, when a LIS consists of a number of
local-area ATM networks connected by long-distance links.
Each local-area network could have its own ATMARP server, with all the
servers' caches being synchronized by SCSP.
Then, if a long-distance link fails, hosts on a local-area network
will still have connectivity to other local hosts (since they all use
the local ATMARP server); when the long-distance link is restored,
SCSP will re-synchronize the servers' caches, restoring
connectivity to remote hosts.
Both
.Nm
and
.Xr atmarpd 8
must be running before any ATMARP
cache synchronization can take place.
.Pp
.Nm Scspd
implements SCSP as specified in RFC 2334,
.%T "Server Cache Synchronization Protocol (SCSP)"
and
.Pa draft\-ietf\-ion\-scspd\-atmarpd\-00.txt ,
.%T "A Distributed ATMARP Service using SCSP" .
.Pp
When
.Nm
starts, it parses its command line and puts
itself into the background.
.Sh TERMINOLOGY
Some of the vocabulary associated with SCSP can be confusing.
In this document, the following definitions are used:
.Pp
.Em "Client server"
or
.Em "local server"
means the server running on
the same host as
.Nm
whose cache is to be synchronized with that
of one or more remote servers.
When the word
.Em server
is used alone, it means
.Em "client server" .
.Pp
.Em "Remote server"
means a server running on some host other than
the one where
.Nm
is running.
.Pp
.Em "Directly Connected Server"
(DCS) means a remote server that
.Nm
communicates with directly.
The remote server will also be running an implementation of SCSP.
.Pp
.Em "Cache Alignment"
(CA) has two meanings.
The Cache Alignment protocol is a part of the SCSP protocol
specification, and the Cache Alignment finite state machine (FSM)
is a finite state machine that implements the Cache Alignment
protocol.
.Pp
.Sh OPTIONS
The command-line options are:
.Bl -tag -width "-f <cfg\-file>"
.It Fl f Aq Ar cfg\-file
Specifies the name of the configuration file.
If this option is not specified,
.Nm
looks for the
file
.Pa /etc/scspd.conf .
.It Fl d
Specifies that
.Nm
is to be run in debug mode.
In debug mode, the daemon is not put into the background.
Log messages are written to standard output instead of to
the log file specified in the configuration file.
.It Fl T Ns Aq Ar options
Specifies that
.Nm
will trace specified events and messages
as it executes.
The
.Fl T
flag is followed by one or more of the following
options:
.Pp
.Bl -tag -width 4n -compact
.It Cm c
trace
.Nm Ns 's
CA Finite State Machine (FSM),
.It Cm h
trace
.Nm Ns 's
Hello FSM,
.It Cm i
trace
.Nm Ns 's
Client Interface FSM,
.It Cm C
trace CA, CSUS, CSU Request, and CSU Reply messages,
.It Cm H
trace Hello messages,
.It Cm I
trace interface messages to and from
.Nm Ns 's
clients.
.El
.El
.Sh CONFIGURATION
The configuration file consists of a sequence of configuration
statements.
These statements specify information about the servers,
both local and remote, whose
caches are to be synchronized by
.Nm .
RFC 2334,
.%T "Server Cache Synchronization Protocol (SCSP)"
and
.Pa draft\-ietf\-ion\-scspd\-atmarpd\-00.txt ,
.%T "A Distributed ATMARP Service using SCSP"
will be valuable in understanding how to configure
.Nm .
.Pp
A configuration statement other than a comment is terminated by a
semicolon.
Some statements contain blocks, delimited by braces
.No ( Dq Li {
and
.Dq Li } ) .
Configuration statement keywords are not case-sensitive,
but some parameters (e.g. interface names) are.
Configuration statements can span multiple lines.
.Ss Comments
Three types of comments are allowed:
.Bl -hang
.It Sy "# comments" :
any characters from
.Dq Li #
to the end of the line are ignored.
.It Sy "C comments" :
any characters between
.Dq Li /*
and
.Dq Li */
are ignored.
.It Sy "C++ comments" :
any characters from
.Dq Li //
to the end of the line are ignored.
.El
.Ss Statements
The configuration statements recognized by
.Nm
are:
.Bd -literal
Server <name> {
	Protocol <protocol ID>;
	Netif <if_name>;
	ServerGroupID <ID>;
	FamilyID <ID>;
	DCS {
		ATMaddr <ATM address>;
		ID <host>;
		CAReXmitInt <int>;
		CSUSReXmitInt <int>;
		CSUReXmitInt <int>;
		CSUReXmitMax <cnt>;
		HelloDead <cnt>;
		HelloInt <int>;
		Hops <cnt>;
	};
};

Log {
	File <file name>;
	Syslog;
};
.Ed
.Pp
Where a host address needs to be specified in the configuration file,
either a DNS name or an IP address in dotted decimal format can
be used.
.Pp
ATM addresses are specified as strings of hex digits, with an
optional leading
.Dq Li 0x .
Fields within the address may be separated by periods, but periods
are for readability only and are ignored.
ATM addresses are 20 bytes long.
The full address, including any leading zeroes, must be given.
For example:
.Pp
.Dl "0x47.0005.80.ffe100.0000.f21a.0170.0020481a0170.00"
.Ss "Server Statement"
The
.Ic server
statement specifies a client server whose cache
to be synchronized with the caches of other servers
running on remote hosts.
There will be one
.Ic server
statement in the configuration file
for each client server whose cache is to be synchronized by
.Nm .
The format of the
.Ic server
statement is:
.Bd -ragged -offset indent
.Ic Server
.Aq Ar name
{
.Aq Ar statements
};
.Ed
.Pp
A
.Ar name
must be specified on the
.Ic server
statement, but it is
not used by
.Nm .
It is expected to give a brief description of the server's purpose.
.Pp
The
.Ic server
statement has several sub-statements
that specify the details of the
.Nm Ns 's
configuration.
They are:
.Bl -tag -width indent
.It Ic Protocol Cm ATMARP ;
The only protocol supported by the current version of
.Nm
is
.Cm ATMARP .
The
.Ic protocol
statement must always be specified.
.It Ic Netif Aq Ar intf ;
The
.Ic netif
statement specifies the name of the ATM network
interface on which a client server is providing service.
The
.Ic netif
statement must always be specified.
.It Ic ServerGroupID Aq Ar ID ;
The
.Ic ServerGroupID
statement specifies an identifier for the
group of servers being synchronized by
.Nm .
The
.Ar ID
is specified as a decimal number in the range 0 - 65,535.
The server group ID must be the same for all servers whose caches
are being synchronized by an SCSP session.
That is, the server group ID for a host must be the same for all
Directly Connected Servers (DCSs) pointed to within a
.Ic server
statement.
The
.Ic ServerGroupID
statement must always be specified.
.It Ic FamilyID Aq Ar ID ;
The
.Ic familyID
statement specifies an identifier for a family
of parallel SCSP sessions running between a group of hosts (i.e. a
set of SCSP sessions with different protocol IDs but the same set
of servers).
The
.Ar ID
is specified as a decimal number in the range 0 - 65,535.
The family ID is currently not used by
.Nm .
.El
.Ss "DCS Statement"
The
.Ic DCS
statement is a sub-statement of the
.Ic server
statement
that specifies the characteristics of a Directly Connected Server (DCS).
The
.Ic server
statement will have one
.Ic DCS
statement for
each DCS that
.Nm
is to exchange information with.
The
.Ic DCS
statement has a number of sub-statements that specify the
details of the configuration for the DCS.
They are:
.Bl -tag -width indent
.It Ic ATMaddr Aq Ar ATM\ address ;
The
.Ic ATMaddr
statement specifies the ATM address of the DCS.
The
.Ic ATMaddr
statement must always be specified.
.It Ic ID Aq Ar host ;
The
.Ic ID
statement specifies the SCSP identifier of the DCS.
For ATMARP, the ID is the IP address or DNS name associated with the
ATM interface of the DCS.
The
.Ic ID
statement must always be specified.
.It Ic CAReXmitInt Aq Ar int ;
The
.Ic CAReXmitInt
statement specifies the interval that is
allowed to elapse between retransmissions of CA messages.
If a CA message is sent and an acknowledgement is not received within
.Ic CAReXmitInt
seconds, the message will be retransmitted.
The default value for
.Ic CAReXmitInt
is 3 seconds.
.It Ic CSUSReXmitInt Aq Ar int ;
The
.Ic CSUSReXmitInt
statement specifies the interval that is
allowed to elapse between retransmissions of CSU Solicit messages.
When a CSUS message is sent, any Cache State Advertisements (CSAs)
requested by the CSUS that have
not been received within
.Ic CSUSReXmitInt
seconds will be requested
again by another CSUS message.
The default value for
.Ic CSUSReXmitInt
is 3 seconds.
Be careful not to confuse
.Ic CSUSReXmitInt
and
.Ic CSUReXmitInt .
.It Ic CSUReXmitInt Aq Ar int ;
The
.Ic CSUReXmitInt
statement specifies the interval that is
allowed to elapse between retransmissions of CSU Request messages.
When a CSU Request message is sent, any CSAs that are not acknowledged
by a CSU Reply message within
.Ic CSUReXmitInt
seconds will
be retransmitted.
The default value for
.Ic CSUReXmitInt
is 2 seconds.
Be careful not to confuse
.Ic CSUReXmitInt
and
.Ic CSUSReXmitInt .
.It Ic CSUReXmitMax Aq Ar cnt ;
The
.Ic CSUReXmitMax
statement specifies the number of times that
a CSA will be retransmitted as described above before SCSP gives up
on the CSA and discards it.
The default value for
.Ic CSUReXmitMax
is 5.
.It Ic HelloDead Aq Ar cnt ;
The
.Ic HelloDead
statement specifies the Hello Dead Factor that
will be sent to the DCS in Hello messages.
A
.Dq "DCS down"
condition will be detected when nothing is received from
a DCS in
.Ic HelloDead No * Ic HelloInt
seconds.
The default value for
.Ic HelloDead
is 3.
.It Ic HelloInt Aq Ar int ;
The
.Ic HelloInt
statement specifies the Hello Interval that
will be sent to the DCS in Hello messages.
The default value for
.Ic HelloInt
is 3 seconds.
.It Ic Hops Aq Ar cnt ;
The
.Ic Hops
statement specifies the number of hops (DCS to DCS)
that will be specified in CSAs originating from the local server.
This number must be at least as large as the diameter of the
server group.
That is, it must be large enough for a CSA to be propagated from
server to server all the way across the server group.
The default value for
.Ic Hops
is 3.
.El
.Ss "Log Statement"
The
.Ic log
statement specifies how
.Nm
is to log
information about its operation.
.Nm Scspd
can write log information to a file, to the system log,
or both.
.Bl -tag -width indent
.It Ic File Aq Ar file\ name ;
The
.Ic file
statement specifies that
.Nm
is to write
its log messages to the named file.
Log messages will be appended to the end of the file if
it already exists.
.It Ic Syslog ;
The
.Ic syslog
statement specifies that
.Nm
is to write
its log messages to the syslog facility.
.Nm Scspd
writes its messages to syslog with a facility code
of
.Dv LOG_DAEMON .
.El
.Pp
If no
.Ic log
statement is specified,
.Nm
writes log
messages to the system log.
If both
.Ic file
and
.Ic syslog
are specified,
.Nm
will
write log messages to both the named file and the system log.
.Ss Examples
An example of a simple configuration file for
.Nm
might be:
.Bd -literal -offset indent
server atmarp_ni0 {
     protocol ATMARP;
     netif ni0;
     ServerGroupID 23;
     DCS {
          ID 10.1.1.2;
          ATMaddr 0x47.0005.80.ffdc00.0000.0002.0001.002048061de7.00;
          hops 2;
     };
};
.Ed
.Pp
This configuration would synchronize the cache of the ATMARP server
operating on network interface ni0 with the cache of a second server
running on a host whose IP address is 10.1.1.2.
Log messages would be written to the system log.
.Sh SIGNAL PROCESSING
The following signals can be used to control
.Nm :
.Bl -tag -width indent
.It Dv SIGHUP
Reread the configuration file and restart
.Nm .
.It Dv SIGINT
Dump debugging information to a file.
When it receives a
.Dv SIGINT
signal,
.Nm
dumps a summary of
its control blocks to a text file (see
.Sx FILES ) .
.El
.Sh FILES
.Bl -tag -width indent
.It Pa /etc/scspd.conf
.Nm Scspd
default configuration file name.
A different file name can be specified with the
.Fl f
command-line
option.
.It Xo
.Sm off
.Pa /tmp/scspd.
.Aq Ar pid
.Pa \&.
.Aq Ar seq
.Pa .out
.Sm on
.Xc
Debugging information dump file name.
.Nm Scspd
writes a summary of its control blocks to this file
when it receives a
.Dv SIGINT
signal.
.Aq Ar pid
is the process ID of the daemon and
.Aq Ar seq
is a sequence
number which is incremented every time a dump is taken.
.It Xo
.Sm off
.Pa /tmp/scspd.
.Aq Ar pid
.Pa .trace
.Sm on
.Xc
Trace file.
.Nm Scspd
writes trace information to this file if the
.Fl T
option is specified on the command line.
.El
.Sh SEE ALSO
.Xr atm 8 ,
.Xr atmarpd 8
.Rs
.%O "RFC 2334"
.%T "Server Cache Synchronization Protocol (SCSP)"
.Re
.Rs
.%O "draft\-ietf\-ion\-scsp\-atmarpd\-00.txt"
.%T "A Distributed ATMARP Service Using SCSP"
.Re
.Sh BUGS
If
.Nm
terminates and is restarted, there will be a period of
instability while previously-synchronized cache entries time out and are
refreshed.
.Pp
Please report any bugs to
.Aq harp\-bugs@magic.net .
.Sh COPYRIGHT
Copyright (c) 1994-1998, Network Computing Services, Inc.
.Sh AUTHORS
.An John Cavanaugh ,
Network Computing Services, Inc.
.An Mike Spengler ,
Network Computing Services, Inc.
.An Joe Thomas ,
Network Computing Services, Inc.
.Sh ACKNOWLEDGMENTS
This software was developed with the support of the Defense
Advanced Research Projects Agency (DARPA).