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Fast Ethernet standard defines the 100-Mbps Fast Ethernet system which operates over twisted-pair and fiber optic media. The Fast Ethernet specifications include mechanisms for Auto-Negotiation of the media speed. This makes it possible for vendors to provide dual-speed Ethernet interfaces that can be installed and run at either 10-Mbps or 100-Mbps automatically. There are three media varieties that have been specified for transmitting 100-Mbps Ethernet signals.

* The "T4" segment type is a twisted-pair segment that uses four pairs of telephone-grade twisted-pair wire. This is not much used.
* The "TX" segment type is a twisted-pair segment that uses two pairs of wires and is based on the data grade (Category 5) twisted-pair physical medium. This is the most widely used version. The 100BASE-TX system operates over two pairs of wires (unshielded or shielded), one pair for receive data signals and the other pair for transmit data signals. The most popular wiring used today is Category 5 unshielded twisted-pair cable.
* The "FX" segment type is a fiber optic link segment based on the fiber optic physical medium standard developed by ANSI and that uses two strands of fiber cable.

The TX and FX medium standards are collectively known as 100BASE-X.The 100BASE-TX Ethernet segments are defined as link segments in the Ethernet specifications. A link segment is formally defined as a point-to-point medium that connects two and only two devices. A typical installation uses multiport repeater hubs, or packet switching hubs, to provide a connection between a larger number of link segments. You connect the Ethernet interface in your computer to one end of the link segment, and the other end of the link segment is connected to the hub. That way you can attach as many link segments with their associated computers as you have hub ports, and the computers all communicate via the hub. This means that the physical topology supported by twisted-pair link segments is the star. In this topology a set of link segments are connected to a hub, radiating out from the hub to the computers like the rays from a star. The 100BASE-TX specifications allow a segment of up to 100 meters. Two 100 meter 100BASE-TX segments can be connected together through a single Class I or Class II repeater. This provides a system with a total diameter of 200 meters between two communicating devices. If longer distances are needed, an Ethernet switch is needed in between (this breaks the network to two part with their own 200 meter limits). In 100BASE-T, the signal is encoded using a 125 MHz clock. 100BASE-T standard adopts a 3-level from of data encoding called MLT-3. Here, the output (encoded) signal is selected from a repeating 4-state pattern of {1, 0, -1, 0}. If the next data bit is a 1, the output transitions to the next state in the pattern. If the next data bit is a 0, the output remains constant. This method of data encoding has the advantage that the highest frequency in the encoded signal occurs when transmitting a long sequence of data bit 1's, in which case the encoded signal repeats the {1, 0, -1, 0} pattern, which has a cycle length of 1/4 of the basic clock rate. Thus, in this worst case the primary energy component would be at 32.5 MHz when using a 125 MHz clock. For other data bit patterns, the energy would be distributed at lower frequencies.The data is 100Mbit/s Ethernet data is encoded using 4B-5B encoding before passing it to MLT-3 coder (this gives the 125 Mbit/s coding rate).The coding for fiber optic communications is somewhat simpler. The data is 100Mbit/s Ethernet data is just encoded using 4B-5B encoding before passing it to fiber (this gives the 125 Mbit/s coding rate). The 4B5B code first popularized by FDDI and then 100BASE-FX codes 4 bits of data to 5 bits of code. Of the 32 possible 5-bit code groups, 4B5B coding selects 16 combinations, plus a few control codes, that have either two or three bits set to one. With random data, the long-term average number of ones and zeros is the same; however, in the short term, you may receive an arbitrarily long string of code groups that have only two bits set to one. The dc content of such a signal is 2/5, not �, which leads to a dc-offset error in an ac-coupled receiver of 10%. This DC-offset results in a receiver noise-margin penalty of 2 dB compared to ideal system. 4B5B transmit one additional symbol for every 4 bits of useful data, amounting to an overhead of 25%.

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For the 100BASE-BX standard where NRZI coding is applied to the 4B5B are there rules applied to unbalanced code?
For example if I wanted to apply an all zero's ethernet packet which would look like:
01101 10010 01101 10010 01101 10010 01101 10010 01101 10010 01101 10010 01101 10010 01101 01101 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 10001 10100 10100 10100 10100 10100 10100 10100 10100 10100 10100 10100 01110 01101 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011
01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 01011 10011 00100 01101 01101 00100 01010 01100 11000
In an AC coupled system would you expect this to result in packet loss?