Using Synchronous Leased Lines; Overview Of Leased Line Connections - Lucent Technologies PortMaster 4 Configuration Manual

Using Synchronous Leased Lines

This chapter describes how to set up a synchronous leased line between a PortMaster 4
and another PortMaster product. The chapter provides guidelines for configuring both
ends of the connection and includes the following topics:
• "Overview of Leased Line Connections" on page 13-1
• "Configuring a Leased Line Connection" on page 13-2
• "Troubleshooting a Leased Line Connection" on page 13-4
See the PortMaster 4 Command Line Reference for more information about commands used
in the chapter.
You can also configure the PortMaster 4 using the PMVision application for Microsoft
Windows, UNIX, and other platforms supporting the Java Virtual Machine (JVM).
PMVision replaces the PMconsole interface to ComOS.

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 or not network traffic exists between the two
locations. Leased line connections have the required channel service unit/digital service
unit (CSU/DSU) built in. The CSU/DSU 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.
If you are connecting two networks together for the first time, make sure the networks
are not overlapping subnets. For more information on network numbers and
subnetting, see Appendix A, "Networking Concepts."
In the leased line configuration described in this chapter, the Ethernet address of the
PortMaster routers is used as the address for the serial link in a point-to-point
unnumbered serial connection. Because the PortMaster relies on an external clock
signal, you do not need to set the speed on the synchronous port. The port speed is
whatever the carrier sends. If you choose to set a speed, it is used for administrative
notation only and does not affect the operation of the port.
PortMaster synchronous ports support leased line connections from 9600bps to T1
(1.544Mbps) or E1 (2.048Mbps) speeds. Synchronous ports used for leased line
connections are configured for PPP operation and can have input and output filters for
network security.
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