Сетевая модель OSI — Википедия
[http://ru.wikipedia.org/wiki/%D0%A1%D0%B5%D1%82%D0%B5%D0%B2%D0%B0%D1%8F_%D0%BC%D0%BE%D0%B4%D0%B5%D0%BB%D1%8C_OSI#.D0.A2.D1.80.D0.B0.D0.BD.D1.81.D0.BF.D0.BE.D1.80.D1.82.D0.BD.D1.8B.D0.B9_.D1.83.D1.80.D0.BE.D0.B2.D0.B5.D0.BD.D1.8C_.28.D0.B0.D0.BD.D0.B3.D0.B] - - public:zodchy