Specifications

Chapter 1 Introduction Installation and Operation Manual
1-4 Functional Description FOM-E3/ETH, FOM-T3/ETH Ver. 1.0
1.3 Functional Description
Figure 1-2 illustrates the FOM-E3/ETH and FOM-T3/ETH functional diagram.
RxTx
Tx
TCDP +
RCDP +
TCDP -
RCDP -
Rx
TNRZ
RNRZ
TCLK
RCLK
Ethernet InterfaceCODE
C
Optical Interface
Internal Clock
Oscillator
Figure 1-3. FOM-E3/ETH and FOM-T3/ETH Functional Diagram
E3/T3 Fiber Optic Interface
The fiber optic interface uses an infrared light emitting diode or laser transmitter
to send a CDP-coded signal received from the CODEC over the fiber cable. At the
opposite end of the fiber, the fiber optic interface receives the optical
transmission and sends it to the CODEC for decoding.
CODEC
Coder/decoder (CODEC) converts an NRZ signal received from the electrical
interface into the CDP signal and sends it to the fiber optic interface for
transmission. At the opposite end of the fiber, the CODEC converts the CDP optic
signal into NRZ electrical signal.
Ethernet Interface
The Ethernet interface includes a high performance self-learning Ethernet bridge,
which is connected to the LAN via a single 10BaseT or 100BaseT port, operating
in full duplex. The Ethernet interface supports VLANs.
The module automatically learns the MAC addresses of the LAN to which it is
connected. Its LAN table stores up to 1,000 addresses with 5-minute automatic
aging.
Filtering and forwarding is performed at the maximum theoretical rate of
150,000 packets per second (wire speed). The buffer with 512 kbit SRAM can
hold 85 frames with a throughput latency of one frame. The forwarding of the
multicast messages from LAN to WAN can be disabled.