Installing and Administering PPP

Chapter 2 41
Setting Up PPP Connections
Additional Information
Bring up the connection for any traffic other than
Network Time Protocol (NTP) packets, ICMP Network
Unreachable messages, and packets from the in.rwhod
daemon.
(!send) (!ntp) (!3/icmp) (!who)
Keep up the link for all packets except those sent by
robin and those that will not bring up the connection.
(!route)
Pass all packets except for RIP routing messages
between routed daemons.
(tcp/syn/recv) (!nntp)
Log messages when an inbound TCP session is
established except for NNTP connections.
Note on Systems and Devices Entries
In both the Systems and Devices files, pppd selects the first line that
matches its search criteria. If the connection attempt fails while using
the method described by that line, pppd will search for the next
matching line. pppd will report a failure only when all the
criteria-matching lines have been tried and exhausted.
For example, suppose two lines in the Systems file differed only by the
values in the telephone number field like this:
lark Any;50 ACU 38400 5551212 in:--in: Probin word: mypasswd
lark Any;50 ACU 38400 5551223 in:--in: Probin word: mypasswd
pppd would first try to connect by dialing 5551212. If pppd received a
BUSY from the modem, it would dial the second number, 5551223.
Similarly, suppose a host has two different modems attached which can
be used for outbound calls. The Devices entries might look like this:
T3000 cuh00 38400
USRv32bis cul00 38400
pppd would try to call out through /dev/cuh00. But suppose it is busy
because an incoming UUCP connection is on /dev/ttya00. pppd will
try /dev/cul00 instead.