Black Box MT721A-35T Manual De Usuario
CHAPTER 2: Introduction
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The Fradswitch employs a unique funneling method for controlling network congestion and moderating
feeder throughput speed.
feeder throughput speed.
CCLM and LMI management protocols are supported, and operation is in compliance with ANSI T1.606,
T1.619, T1.617 Annex D, and ITU Q.922, Annex A.
T1.619, T1.617 Annex D, and ITU Q.922, Annex A.
2.5 HDLC Link Features
The Fradswitch links can be programmed to operate with transparent HDLC allowing computers, bridges,
and HDLC communication devices to be connected over X.25 or Frame Relay networks. The HDLC
protocol is encapsulated over the X.25 or Frame Relay protocol, providing end-to-end transparent
operation. (See Figure 2-6.)
and HDLC communication devices to be connected over X.25 or Frame Relay networks. The HDLC
protocol is encapsulated over the X.25 or Frame Relay protocol, providing end-to-end transparent
operation. (See Figure 2-6.)
2.6 ASYNC Link Features
The Fradswitch links can be programmed to operate asynchronously, allowing connection of asynchronous
devices to the links. When programmed to operate as async, the links operate like Fradswitch series async
channels with all the standard facilities. (See Figure 2-3.)
devices to the links. When programmed to operate as async, the links operate like Fradswitch series async
channels with all the standard facilities. (See Figure 2-3.)
2.7 Buffer Capacity
The Fradswitch series uses dynamic on-demand allocation of data buffers, in accordance with the channels
and links traffic conditions. The Fradswitch series automatically changes the buffer allocation on-line,
to make the best possible use of the free RAM capacity.
and links traffic conditions. The Fradswitch series automatically changes the buffer allocation on-line,
to make the best possible use of the free RAM capacity.
The standard Fradswitch RAM size is 256 KB; as an option, the Fradswitch can be ordered with
1024 KB RAM, to increase the throughput in environments that generate high traffic volumes.
1024 KB RAM, to increase the throughput in environments that generate high traffic volumes.
2.8 Asynchronous Channel Interface Characteristics
Channel operation is asynchronous. The asynchronous word format is user-configurable, by means of
proprietary extension to the ITU X.28 basic set of commands. For flexibility in applications, flow control
can be performed either by software (X-ON/X-OFF) or by hardware handshaking.
proprietary extension to the ITU X.28 basic set of commands. For flexibility in applications, flow control
can be performed either by software (X-ON/X-OFF) or by hardware handshaking.
All of the Fradswitch channels have RS-232/V.24 DCE interfaces. Each channel has its own eight-pin
RJ-45 connector.
RJ-45 connector.
2.9 Channel PAD Characteristics
The Fradswitch includes eight essentially independent PADs, one for each channel. All the channel
PADs share the three X.25 physical links. The channel PADs support multiple sessions with independent,
user-selected session profiles. This means that any user connected to one of the Fradswitch channels can
simultaneously conduct several virtual circuits carried by different logical channels. The maximum number
of sessions per channel is up to 4.
PADs share the three X.25 physical links. The channel PADs support multiple sessions with independent,
user-selected session profiles. This means that any user connected to one of the Fradswitch channels can
simultaneously conduct several virtual circuits carried by different logical channels. The maximum number
of sessions per channel is up to 4.