# Ethernet Connectivity Selection Tutorial

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## Ethernet Connectivity Selection Tutorial

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Category 5, 5e or 6? 110 punchdown, or RJ to RJ? T568A or T568B? Shielded or unshielded? Will I choose the right Ethernet patch panel for my application? Will this choice work with future applications? Am I getting the best overall value? With all the choices you face as you design your network and select equipment, including available Ethernet patch panels, it’s easy to become confused and frustrated. Ultimately your choice of Ethernet panels should fit the applications you plan to run. ADC wrote this short tutorial to guide you through these decisions, to make them as painless as possible...

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## Nội dung Text: Ethernet Connectivity Selection Tutorial

2. Category 5e is currently the minimum TIA recommended category of wiring for new installations. Electrical characteristics for NEXT, FEXT, attenuation, and return loss are specified to 100 MHz. NEXT performance is slightly better than category 5. Category 6 is gaining popularity for new installations. Electrical characteristics for NEXT, FEXT, atten- uation, and return loss are specified to 250 MHz. Improvements in all electrical parameters are part of the higher TIA Category 6 standard. Category 7 cabling is a developing standard as of this writing. The International Standards Organization (ISO) is leading the standardization efforts for this new individually-shielded, overall- shielded, 4-pair cable with transmission specifications referenced to 600MHz. The cable end interface will probably be something other than the familiar RJ45 connector, mainly to differentiate the Category 7 installation from existing lower-bandwidth infrastructure. So, which should you use? There is quite a bit of misleading information in the industry on this sub- ject, the biggest myth being that Category 6 is required to run Gigabit Ethernet over copper (1000Base-T). Actually 1000Base-T was designed by the IEEE to run on Category 5. As long as the Category 5 is installed according to TIA-568-B standards and meets the testing criteria in TIA TSB 95, 1000Base-T will perform satisfactorily on Category 5. However, as of this writing, the TIA recommends Category 5e over Category 5 as the minimum cabling for new network infrastructure installations. When do I use Category 6? Does the application standard (i.e., Gigabit Ethernet, 10G, etc.) specify Category 6 as a minimal requirement? As of this writing, the TIA is making recommendations to the IEEE 802.3ae and the 10 Gigabit Ethernet Alliance, who are currently working on 10 Gigabit cabling systems, that any 10 Gigabit Ethernet designed to run on copper cabling use Category 6 because of its improvement in signal to noise. The good news is that Category 6 is backward compatible and will have no trouble running existing applications such as 10/100Base-T and 1000Base-T. Cable Type Summary The chart below summarizes the industry standard UTP cable types used in current networking instal- lations. In addition to the UTP cabling described above, you should understand the issues of cable shielding, and stranded versus solid cable. Category Test Frequency 10/100BaseT 1000BaseT Future Applications Relative Cost Cat 5 100 MHz Yes Yes No $Cat 5e 100 MHz Yes Yes Maybe$ Cat 6 250 MHz Yes Yes Yes $$Cat 7 600 MHz Yes Yes Yes$$ Shielded vs. Unshielded Twisted Pair Unshielded twisted pair (UTP) cabling provides immunity to electromagnetic interference (EMI) with the properties of the two conductors that make up a transmission pair being twisted together. When UTP cabling encounters electrical interference, the noise crossing the twisted pairs is cancelled by the twists in the cable (called “Common Mode Rejection”, a subject outside the scope of this paper). Standard Category 5, 5e and 6 cables contain four unshielded twisted pairs of conductors. For 10BASE-T and 100BASE-TX applications, only two pairs are used, one for the transmit circuit and one for receive circuit. For 1000BASE-T (Gigabit Ethernet) all four pairs are required. The term “shielded twisted pair” cabling can be misleading. There are actually two methods of shield- ing a twisted pair cable. Screened twisted pair cable (ScTP) provides an overall screen or metal foil around the four pairs of conductors, but each individual twisted pair is unshielded. Shielded Twisted 2