2FSU User Manual 61200.130L1-1
Chapter 1. Introduction
equipment. This DLCI is valid until the call is disconnected and
may be assigned a different value each time a call is requested.
PRODUCT OVERVIEW
The FSU provides a low cost solution for the CPE equipment in a
private or public frame relay network. The FSU connects to the
frame relay network via 56/64k DDS (digital data service) or
T1/FT1 access links. Connections to 56/64k DDS are made
using an integral 56/64k DSU or an external DSU. T1/FT1
connections are made using an external T1 DSU/CSU through a
V.35 interface.
The FSU provides connections to the user equipment through
two independent ports emulating a DCE device. These ports can
be configured for either RS-232 or V.35 signal specifications.
Synchronous protocol speeds up to 512 kbps and asynchronous
protocol speeds up to 38.4 kbps are supported.
The FSU handles each frame of the user data in a three-step
manner. The first step is terminating the user protocol. The
layer at which this termination occurs varies depending on the
user protocol selection for a given port. The next step is examin-
ing the user protocol destination address and routing to the
destination port and virtual circuit. The last step involves
encapsulating the information field of each frame and re-
encapsulating based on the destination port configuration. A
similar process is used for frame relay frames received on the
network port.
The major features of the FSU are as follows:
• Two DTE (data terminal equipment) ports for use on a single
frame relay network interface.
• Support for IP (internet protocol), SDLC (synchronous data
link control), Bisync, SLIP (serial link IP), PPP (point-to-point
protocol) both sync and async, frame relay, BOP (bit-oriented
protocol), and async protocols.
• SNMP (simple network management protocol) management
capability provided inband with support for RFC 1315 (frame