are there various varieties?
Yes,such as  10BASE-T, 100BASE-TX, and 1000BASE-T
Ethernet
The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three use twisted pair cables and 8P8C modular connectors. They run at , , and , respectively.
where does the pfe reside on an mx960 router UNANSWERABLE what is juniper mx-series? It is a family of ethernet routers and switches what is the meaning of the initial word? Ethernet is a family of computer networking technologies commonly used in local area networks (LAN),  and wide area networks (WAN) when was it standardized? In February 1980 when was it introduced ? Ethernet was developed between 1973 and 1974 who developed it? It was inspired by ALOHAnet what is its frame structure? The "frame" begins after the start frame delimiter with a frame header featuring source and destination MAC addresses and the EtherType field giving either the protocol type for the payload protocol or the length of the payload
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Ethernet [SEP] Varieties
The Ethernet physical layer evolved over a considerable time span and encompasses coaxial, twisted pair and fiber-optic physical media interfaces, with speeds from to , with 400 Gbit/s expected by 2018. The first introduction of twisted-pair CSMA/CD was StarLAN, standardized as 802.3 1BASE5. While 1BASE5 had little market penetration, it defined the physical apparatus (wire, plug/jack, pin-out, and wiring plan) that would be carried over to 10BASE-T. The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three use twisted pair cables and 8P8C modular connectors. They run at , , and , respectively. Fiber optic variants of Ethernet (that use SFP) are also very common in larger networks, offering high performance, better electrical isolation and longer distance (tens of kilometers with some versions).