Silicon Graphics IRIS Workstation User Manual page 138

132 IRIS WORKSTATION GUIDE
granted to outside machines by each of the systems on the private network.
Alternatively, access to/from the outside world can be confined to only one
processor. This is frequently done to minimize the effort in keeping access
information (passwords, phone numbers, login sequences, etc.) updated and to
minimize the number of security holes for the private network.
Hardware and Line Speeds
There are three supported means of interconnection by uucp(1),
1. Direct connection using a null modem.
2. Connection over the Direct Distance Dialing (DDD) network.
3. Ethernet with XNS protocols.
In choosing hardware, the equipment used by other processors on the network
must be considered. For example, if some systems on the network have only
102-type (300-baud) data sets, then communication with them is not possible
unless the local system has a 300-baud data set connected to a calling unit.
(Most data sets available on systems are 1200-baud.) If hard-wired connections
are to be used between systems, then the distance between systems must be
considered since a null modem cannot be used when the systems are separated
by more than several hundred feet. The limit for communication at 9600-baud
is about 800 to 1000 feet. However, the RS232 specification and Western
Electric Support Groups only allow for less than 50 feet. Limited distance
modems must be used beyond 50 feet as noise on the lines becomes a problem.
Maintenance and Administration
There is a minimum amount of maintenance that must be provided on each
system to keep the access files updated, to ensure that the network is running
properly, and to track down line problems. When more than one system is
involved, the job becomes more difficult because there are more files to update
and because users are much less patient when failures occur between machines
that are under local control.
I.3 UUCP Software
The uucp(1) or uux(1) command queues user 's requests and spawns the uucico
daemon to call another system. Uucico initiates the call to another system and
performs the file transfer. On the receiving side, uucico is invoked to receive
the transfer. Remote execution jobs are actually done by transferring a
command file to the remote system and invoking a daemon (uuxqt) to execute
that command file and return the results.
Appendix I:
Version 1.0