Lucent Technologies PortMaster - Manual (Page 104)

Synchronous Port Uses
6-2 PortMaster Configuration Guide
dozen field offices with 56Kbps or fractional T1 Frame Relay connections can connect to
a central office using a fractional T1 or T1 Frame Relay connection. The central office
requires only one CSU/DSU and synchronous port on the router, instead of 12. For
more information, see Chapter 13, “Using Frame Relay.”
Routing over Switched 56Kbps. Switched 56Kbps can be less expensive than Frame
Relay in applications where short bursts of connectivity are required but dial-up
modems do not provide enough bandwidth. V.25bis dialing is used to establish a link
over a switched network, and the link is brought down after a specified period with no
traffic. For more information, see Chapter 14, “Using Synchronous V.25bis
Connections.”
Routing over ISDN. Integrated Services Digital Network (ISDN) provides fast dial-up
connectivity for applications where the expense of a dedicated Frame Relay or leased
line connection is not called for by the amount and nature of the traffic. For more
information, see Chapter 12, “Using ISDN BRI.”