AL211 Allayer Communications, AL211 Datasheet - Page 8

• Manufacturer Part Number: AL211
• Description: Fast Ethernet Fiber to TP Media Converter
• Manufacturer: Allayer Communications

Figure 1-4
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2. Functional Description
The AL211 contains a physical layer interface (PHY) device for IEEE 802.3 100Base-TX and a
PHY for 100Base-FX networks. The PHY contains all the necessary functions such as elastic store
and driver circuits to complete a media converter design. The device converts the MLT3 scrambled
symbols from the twisted pair (TP) input port into 4B5B NRZI encoded data and transmits it over
the fiber media. The 4B5B NRZI encoded data from the fiber-input port is converted to a scrambled
MLT3 symbol stream for TP transmission.
The AL211 does not encode or decode the 4B5B symbols, therefore all errors and signaling are
preserved and propagated. In addition, the benefit of a “straight-through” conversion is that the
latency can be as low as 8-bit time (BT). The device also supports Far-End Fault Detection (fiber
only) and Link Status Propagation. If any port is in a link-fail state, the device will cease to transmit
data and disables the appropriate output port. In essence, the device is transparent in regard to the
connecting links.
The AL211 provides a PECL interface for interfacing either to an equalizer chip or a fiber module.
An elastic store is provided by the media converter to retime the received signal. The elastic store
can be disabled to reduce latency of the converter.
The AL211 supports redundant link applications. A redundant link can be formed by either a switch
with 100Base-FX transceiver that supports far-end fault signaling or two AL211’s. In the event of a
link-failure, the redundant link will be established automatically.
AL211 Applications
RJ45
FO Module
1x9
Xfmr
Reference Only / Allayer Confidential
FX to SX or FX single mode to FX multimode conversion
100BASE-TX to 100BASE-FX (1300 nm) media conversion
MLT3
PECL
TX
RX
AL211
AL211
PECL
PECL
FO Module
FO Module
1x9
1x9
8