Lucent Technologies PortMaster, Configuration Manual

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19-1
Using Synchronous Leased Lines
19
This chapter uses an example to demonstrate how to configure the PortMaster to
connect to a synchronous leased line at speeds up to T1 (1.544Mbps) or E1
(2.048Mbps). This chapter also describes how to configure a dial backup connection for
your synchronous line. The example described in this chapter connects a PortMaster
router located in one office with a PortMaster router located in another office using a
dedicated leased line.
The following topics are described:
• “Overview of Leased Line Connections” on page 19-1
• “Configuration Steps for Leased Line Connections” on page 19-3
• “Troubleshooting a Leased Line Connection” on page 19-8
See the PortMaster Command Line Reference for more detailed command descriptions and
instructions.
Overview of Leased Line Connections
Leased line connections use leased or dedicated lines to establish a permanent
connection between two routers. Once the connection is established, it remains
available on a continuous basis whether there is network traffic between the two
locations or not. Leased line connections require a digital service unit/channel service
unit (DSU/CSU) connected between the router and the dedicated line. The DSU/CSU
takes digital data in the format used by the router and translates it into the digital
format used by the leased line. Leased line connections also require a carrier that
provides an external clock signal.
PortMaster routers support leased line connections using synchronous ports and the PPP
protocol. In this configuration, one PortMaster is usually connected to another
PortMaster or other router over a leased line where each router uses its own Ethernet
address for the serial link—known as
IP unnumbered—and the address of the other end
is discovered dynamically. In this way, a dedicated high-speed connection is established
between two routers located at separate sites. Figure 19-1 shows an example of the
leased line connection.