MX-2100/2104
Installation and Operation Manual
Chapter 1 General Information
Functional Description
1-3
The MX-2104 system can be equipped with only one main link. The 3U high
MX-2100 system can be equipped with two main link modules. Two main link
modules in an MX-2100 system, can be used in several ways:
•
To provide hot-standby redundancy (backup) for the main link, with automatic or
manual switchover in case one of the links fails. For maximum flexibility, MX-2100
allows the preparation of a different configuration for use on the backup link. The
backup link can also use a switched data circuit. The switched circuit can be
established on a PSTN line, using analog modems, or on an ISDN line using an S
or U interface.
•
To provide two independent links from the same MX-2100 enclosure. The two
links can operate at different data rates. The dual-link mode can also be used
for providing the equivalent of hot standby protection to critical data channels
(by enabling the priority bumping feature).
•
To provide multidrop and bypass capabilities (using a dedicated KDI module).
In addition to main link redundancy, the MX-2100 system reliability can be further
enhanced by installing an additional power supply unit in the enclosure. The
power supplies share the load current, therefore when one of them fails or its
input voltage is disconnected, the other takes over the full load without
disturbance to MX-2100 operation.
The MX-2100/2104 system provides flexible system timing options, with several
main link, and channel timing modes.
The main link timing modes are DTE, DCE, and external DCE. In the DCE and
external DCE modes, the timing reference source can be selected by the user:
•
Internal oscillator
•
External (timing locked to one of the data channels)
•
The other main link module (provided a KDI module is installed).
In addition to the main timing source, a fallback source can be selected. When the
timing mode is DTE or external DCE, buffers are inserted in the main link signal
paths, to absorb the expected jitter and timing instabilities. Normal buffer size is
±
8 bits; for operation over satellite links, the receive buffer size can be increased to
±
256 bits.
The timing modes available for the data channels are programmable, thereby
permitting each channel to be configured as either DCE (supplies receive and
transmit clocks to the user's equipment), DTE1 (supplies the receive clock and
accept a transmit clock), or DTE2 (accepts receive and transmit clocks from the
user's equipment), with buffered retiming of the received data. Connection to the
national network and to common-carrier data lines is also supported, with the
external clock selectable as the source for system timing.
For modules with ISDN, T1, E1, and fiber-optic interfaces, a loopback timing
mode is available. This mode enables locking the MX-2100 timing to the accurate
timing provided by the network to which the interface is connected.
