Black Box MT722AE-X21T Manual De Usuario

The Fradswitch-8A, Fradswitch-16A, and Fradswitch-24A are combinations of a high-performance
X.25/Frame Relay PAD (Packet Assembler/Disassembler) and a Packet Switch, for concentrating and
switching data in an X.25/Frame Relay environment. A Fradswitch can connect up to eight, sixteen, or
twenty-four asynchronous channels, and up to three synchronous links, and perform packet-switching
functions between all links (X.25 to X.25, X.25 to Frame Relay, and Frame Relay to Frame Relay). The
Fradswitch can also encapsulate various protocols over Frame Relay and over X.25.

The Fradswitch operates on 115- or 230-VAC, depending on which model you ordered, and has very low
power consumption. It’s built into a compact case that can be placed on desktops or shelves. Optional
rackmounting allows installation in a 19-inch rack.

When operating as a PAD, the Fradswitch assembles the data from the asynchronous channels into X.25
packets. The concentrated packetized data stream is transferred to the routing module which then forwards
the packets to the appropriate X.25 link.

When operating as an X.25 switch, packets received over the X.25 link are rerouted to the appropriate link.
If the destination is a Fradswitch asynchronous port, the packets are disassembled into asynchronous data
and then routed to the destination port.

The Fradswitch links can be programmed to operate asynchronously, allowing connection of asynchronous
devices to a link. When programmed to operate in async mode, the link operates like a Fradswitch async
channel with all the X.28 standard facilities.

The Fradswitch can easily expand a network by remote connection of an STM (Statistical Multiplexor) 
to one or more of its synchronous links. When one or more STMs are connected to the Fradswitch links, 
the asynchronous ports of the STM have all the functionality of PAD ports.

The Fradswitch is compatible with ITU X.2, X.3, X.25, X.28, X.29, and X.121 (Blue Book, 1988). 
It supports both switched and permanent virtual circuits. Each channel has multiple-session capabilities. 
The Fradswitch provides a variety of call-setup options, including automatic and mnemonic dialing.

The Fradswitch supports a wide range of applications:

• Backbone for a low-cost private X.25 network with optional connection to the public network. 

(See Figure 2-1.)

• Expansion of the number of asynchronous inputs, using statistical multiplexors (proprietary). 

(See Figure 2-2.)

• Public Network access via redundant links. (See Figure 2-3.)

• Running asynchronous data in X.25 packets over Frame Relay. (See Figure 2-4, part a.)

• Running asynchronous data directly over Frame Relay (SLIP protocol over Frame Relay). 

(See Figure 2-4, part b.)

2. Introduction