00321nam a2200121 a 450000500170000002000150001708200150003210000210004724500460006825000130011426000460012730000260017320251203110925.0  a8120329694  a004.6bSIN  aSingh, Brijendra  aData communications and computer networks  a2nd Edn.  aNew DelhibPrentice - Hall of Indiac2006  axivc357p.c24 cm. PB