Excalibur ISX 5312, Руководство по эксплуатации

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Excalibur ISX 5312/5314 T-1 Multiplexer Installation and Operation
1-14
Green and yellow LED indicators are located on the Ethernet interface. The green
indicator allows you to monitor the Ethernet link’s operating status at a glance. The
yellow indicator is On for a short period each time the Ethernet controller transmits a
packet.
External Dial Backup
The External Dial Backup feature is available only with Excalibur ISX 5312/5314
multiplexer models equipped with one network interface. It is not provided for models
equipped with two long-haul network interfaces.
The External Dial Backup feature operates in both T-1 and FT-1 environments. You can
configure one DTE port (ISX 5312) or two DTE ports (ISX 5314) to provide dial backup
for the unit’s dedicated DTE port(s). The dedicated DTE port(s) are connected to the
DS1 line. The dial backup DTE port(s) are connected to an external dial backup device,
such as an Integrated Services Digital Network (ISDN) terminal adapter or a Switched
56 Kbps unit. The dial backup device must have a V.35 interface, accept N x 56 or
N x 64 Kbps (N=1 to 24) data rates, supply a clock source, support DTR dialing, and
provide DSR in response to an incoming call.
In a T-1 environment, when the DS1 line fails (based on user-definable criteria), the
ISX 5312/5314 automatically routes data from its dedicated DTE port(s) to the external
device connected to the backup port(s). The external device restores communication by
transmitting the data over the dial backup line. (See Figure 1-10.) When the DS1 line is
restored (based on user-definable criteria), the dial backup connection is terminated, and
communication is returned to the DS1 line. Dial backup operation can also be initiated
and terminated manually by entering the appropriate commands.
In an FT-1 environment, a central ISX 5312 can provide dial backup to one remote unit,
while a central ISX 5314 can provide dial backup to up to two remote units. When the
Loss of Remote Communications (LRC) alarm is enabled, the central unit sends a
heartbeat message, via a portion of the remote T7 bandwidth, to the remote ISX
5312/5314 unit(s) to communicate the primary line connectivity. For example, in Figure
1-11 the central ISX 5314 maintains a heartbeat signal between the two remote ISX 5312
units. If the heartbeat signal is not present for a user-specified amount of time, the ISX
5314 goes into dial backup mode. When the DS1 line is restored (based on user-
definable criteria), the dial backup connection is terminated, and communication is
returned to the DS1 line. Dial backup operation can also be initiated and terminated
manually by entering the appropriate commands.