Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
3.1.2.1.2 PORT CONFIGURATION
Each of the eight ports may be configured independently regarding framing (SF or ESF), line coding
(AMI or B8ZS).
There are additional parameters such as line termination and line build-out that may be varied. If a
fiber interface is installed for a port, the port configuration will automatically be adjusted to
accommodate for the fiber I/O.
Up to four ports may be configured for FLOF detection. Setting a port for FLOF does not force the
transmit function of that port to contain the Fast pattern, nor does it speed up any reframe functions.
What it does do is quickly detect when a port has gone bad so that appropriate action may be taken.
The actual reframe function continues to be accomplished in the multiplexer.
3.1.2.2 PORT FAILURE DETECTION
There are several conditions that may be used to determine if a port has a fault or not. The user has the
ability to individually select these criteria.
UA1: Unframed All Ones (also known as AIS, RBL, or ‘all ones’) is a definite sign that something is
wrong. This requires the presence of clocked data that is qualified as being consistent over time, so it
is unlikely to be mistakenly reported. However, as implied above, it is not detected extremely quickly.
LOD: Loss of Data (also known as RCL) is not the most robust fault detection method available. Due
to the (required) automatic gain in the front end of the framers, upon loss of signal ambient noise or
crosstalk may be interpreted as a signal. For this reason LOD is not reported by the DACS prior to
qualifying the detection with other information. As a result, this is also not a very quick, switch
criteria.
LOF: Loss of Frame is a fairly quick and reliable status indicator. It is somewhat more reliable than
the (more sensitive) FOS indicator and is normally enabled for switching purposes.
PCV: Path Code Violations (also known as bit errors), due to the random nature of the problem it is
intended to detect, is often less than ideal as a switching criteria. The user can vary the threshold
above which the DACS will initiate a switch. Often, however, a significant level of bit errors will be
accompanied by other, more serious, errors being reported. Microwave links are subject to fading and
other interference problems that the PCV detection may be helpful in detecting.
FLOF: Fast Loss Of Frame is fast and reliable, requires a dedicated a timeslot, and all multiplexers in
the network must be set for Fast Reframe.
M-DACS-T1 RFL Electronics Inc.
October 25, 2004 3-5 (973) 334-3100
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