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‫ﺍﳉﻤﻬﻮﺭﻳﺔ ﺍﳉﺰﺍﺋﺮﻳﺔ ﺍﻟﺪﳝﻘﺮﺍﻃﻴﺔ ﺍﻟﺸﻌﺒﻴﺔ‬
‫‪‬‬ ‫‪‬‬ ‫‪‬‬ ‫ﺗﺎﺭﻳﺦ ﺍﻟﺸﺒﻜﺎﺕ ــــــــــــــــ 50‬ ‫60‬ ‫ﺗﻌﺮﻳﻒ ﺷﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ ـــــــــــــ‬ ‫ـــــــــــ 70‬ ‫ﻓﻮﺍﺋﺪ ﻭ ﺧﺪﻣﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ــــــــــــ80‬ ‫ﺍﳊﺪ ﺍﻷﺩﱏ ﳌﻜﻮﻧﺎﺕ ﺷﺒﻜﺔ‬ ‫ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺔـــــــــــــــــ80‬ ‫ـــــــــــــــ01‬‫ﺧﺼﺎﺋﺺ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﺃﻧﻮﺍﻉ ﺍﻟﻨﻮﺍﻗﻞ ـــــــــــــــــ11‬ ‫ــــــــــــــــ11‬ ‫ﺗﺼﺎﻣﻴﻢ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺑﻌﺾ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺴﺘﺨﺪﻣﺔ ﰲ ﺍﻟﺸﺒﻜﺎﺕ ــــــ41‬ ‫ـــــــ71‬ ‫ﺟﺪﻭﻝ ﻳﻠﺨﺺ ﲨﻴﻊ ﻣﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ـــــــــــــــــ81‬ ‫2‬
‫‪‬‬ ‫‪‬‬ ‫‪‬‬ ‫____________________42‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﺪ ﻟﻠﻨﺪ‬ ‫ﺷﺒﻜﺔ ﺍﳌﺰﻭﺩ /ﺍﻟﺰﺑﻮﻥ _________________52‬ ‫_____________________62‬ ‫ﺷﺒﻜﺔ ﺇﺛﺮﻧﺖ‬ ‫ﺷﺒﻜﺔ ‪26 ________________ token ring‬‬ ‫_________62‬‫ﺷﺒﻜﺎﺕ ‪apple Talk‬ﻭ‪RCnet‬‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ __________________72‬ ‫_____________________82‬ ‫ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫____________92‬‫ﻛﻴﻔﻴﺔ ﻋﻤﻞ ﻣﺸﻐﻞ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻣﺒﺎﺩﺉ ﺍﻹﺭﺳﺎﻝ ____________________13‬ ‫____________________33‬ ‫ﻭﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ‬ ‫ﺃﻧﻮﺍﻉ ﻭ ﺧﺼﺎﺋﺺ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺔ___________33‬ ‫_____________________93‬ ‫ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﻣﺒﺎﺩﺉ ﻭ ﺃﺳﺎﻟﻴﺐ ﺍﻟﻮﺻﻮﻝ ﻟﻮﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ _____44‬ ‫________________74‬ ‫ﻣﺒﺎﺩﺉ ‪Osi‬‬ ‫ﻣﺒﺎﺩﺉ 208 ‪Project‬ــــــ74‬ ‫3‬
‫‪‬‬ ‫ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ ـــــــــــــ15‬ ‫ﻛﻴﻔﻴﺔ ﺗﺮﻛﻴﺐ‬ ‫ﻣﺮﺍﺣﻞ ﺗﺜﺒﻴﺖ ﺍﻟﺸﺒﻜﺔ ﰲ ﺍﻟﻨﻈﺎﻣــــــــــــ35‬ ‫85‬ ‫ﺷﺮﺡ ﻛﻴﻔﻴﺔ ﺑﻨﺎﺀ ﺷﺒﻜﺔ ﻣﻌﻠﻮﻣﺎﺗﻴﺔ ______________‬ ‫4‬
‫ﺗﺎﺭﻳﺦ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﺑﺪﺃﺕ ﺃﻭﱃ ﳏﺎﻭﻻﺕ ﺍﻟﺘﻮﺍﺻﻞ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ﰲ ﻋﺎﻡ 0691 ﺣﻴﺚ ﰎ ﺑﻨﺎﺀ ﺃﻭﻝ ﺷﺒﻜﺔ‬ ‫ﰲ ﺍﻟﻌﺎﱂ ﺍﲰﻬﺎ ‪ saber‬ﻭ ﺍﺳﺘﺨﺪﻣﺖ ﰲ ﳎﺎﻝ ﺣﺠﺰ ﺗﺬﺍﻛﺮ ﺍﻟﻄﲑﺍﻥ ﻭ ﰎ ﺑﻨﺎﺅﻫﺎ ﻋﻦ ﻃﺮﻳﻖ ﺍﻟﺘﻌﺎﻭﻥ ﺍﻟﺬﻱ‬ ‫ﰎ ﺑﲔ ﺷﺮﻛﺔ ‪ IBM‬ﻭ ﻣﺆﺳﺴﺔ ﺍﻟﻄﲑﺍﻥ ،‪ American Air lines‬ﰒ ﻇﻬﺮﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﰲ ﻋﺎﻡ‬ ‫4691 ﻟﺘﺴـﻬﻞ ﺗﺸﺎﺭﻙ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻭ ﺍﳋﺪﻣﺎﺕ ﻣﻊ ﺍﶈﻴﻂ ﺍﻟﻘﺮﻳﺐ ، ﻭ ﱂ ﺗﻠﺒﺚ ﺃﻥ ﺗﻮﺟﻬﺖ ﺍﻟﺘﻄﻮﺭﺍﺕ‬ ‫ﺇﱃ ﺗـﺄﻣﲔ ﺍﻟﺘﻮﺍﺻـﻞ ﺍﻟﺸـﺒﻜﻲ ﻣـﻊ ﳎﻤﻮﻋﺎﺕ ﺃﻛﱪ ، ﻓﻈﻬﺮﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻮﺍﺳﻌﺔ ‪Wide Area‬‬ ‫‪ Networks‬ﰲ ﻋﺎﻡ 6691 ، ﻭﻫﻨﺎ ﻛﺎﻧﺖ ﺑﺪﺍﻳﺔ ﻣﺮﺣﻠﺔ ﺟﺪﻳﺪﺓ ﰲ ﺛﻮﺭﺓ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﱵ ﱂ ﺗﺘﻮﻗﻒ ﻋﻨﺪ‬ ‫ﻫﺬﺍ ﺍﳊﺪ ﻓﺄﻧﺸﺌﺖ ﻭﺍﺣﺪﺓ ﰲ ﻭﺯﺍﺭﺓ ﺍﻟﺪﻓﺎﻉ ﺍﻷﻣﺮﻳﻜﻴﺔ ﰲ ﺳﻨﺔ 9691 ﺗﺴﻤﻰ ‪ ARPANET‬ﻭ ﺍﻟﱵ‬ ‫ﻛـﺎﻥ ﻣـﻦ ﺃﻋﻈﻢ ﻧﺘﺎﺋﺠﻬﺎ ﻇﻬﻮﺭ ﺍﻹﻧﺘﺮﻧﺖ ﻓﻴﻤﺎ ﺑﻌﺪ ، ﻭ ﺍﻟﱵ ﺍﺗﺴﻌﺖ ﻟﺘﺸﻤﻞ ﺃﻗﻄﺎﺏ ﻛﻮﻛﺒﻨﺎ ﺍﻟﺼﻐﲑ‬ ‫ﻓﺄﺣﺎﻟﺘﻪ ﻗﺮﻳﺔ ﺻﻐﲑﺓ ، ﻳﺮﻯ ﻭﻳﺴﻤﻊ ﻭ ﻳﺘﺒﺎﺩﻝ ﺃﻓﺮﺍﺩﻫﺎ ﻣﻌﺎﺭﻓﻬﻢ ﻭ ﻣﻌﻠﻮﻣﺎ‪‬ﻢ ﺑﺴﻬﻮﻟﺔ ﱂ ﻳﺴﺒﻖ ﳍﺎ ﻣﺜﻴﻞ .‬ ‫ﻭﻣـﻦ ﺍﳌﺆﻛﺪ ﺃﻥ ﺁﻣﺎﻝ ﺍﻟﻘﺎﺋﻤﲔ ﻋﻠﻰ ﺗﻄﻮﻳﺮﻫﺎ ، ﻟﻦ ﺗﺘﻮﻗﻒ ﻋﻨﺪ ﻫﺬﺍ ﺍﳊﺪ ﺑﻞ ﻫﻲ ﻣﺎﺿﻴﺔ ﻗﺪﻣﺎ ﻟﻼﺭﺗﻘﺎﺀ‬ ‫ﺑﺸﺒﻜﺎﺕ ﺍﳊﺎﺳﻮﺏ ﺇﱃ ﻣﺎ ﳛﺎﻛﻲ ﺍﻟﺸﺒﻜﺔ ﺍﻟﻌﺼﺒﻴﺔ ﺍﻹﻧﺴﺎﻧﻴﺔ ﻣﻦ ﺣﻴﺚ ﺍﻟﻔﺎﻋﻠﻴﺔ ﻭ ﺍﻻﺳﺘﺠﺎﺑﺔ .‬ ‫5‬
‫ﺗﻌﺮﻳﻒ ﺷﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ :‬ ‫ﺍﻟﺸـﺒﻜﺔ ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﺣﺎﺳﺒﺎﺕ ﻣﺘﻨﻮﻋﺔ ﻭ ﳐﺘﻠﻔﺔ ) ﺣﺎﺳﺒﺎﺕ ﺷﺨﺼﻴﺔ، ﳏﻄﺎﺕ‬ ‫ﻋﻤـﻞ، ﺣﺎﺳـﺒﺎﺕ ﻣﺘﻮﺳﻄﺔ ، ﺣﺎﺳﺒﺎﺕ ﻛﺒﲑﺓ ﺃﻭ ﻋﻤﻼﻗﺔ( ﻣﺮﺗﺒﻄﺔ ﺑﺒﻌﻀﻬﺎ ﺍﻟﺒﻌﺾ ﻋﻦ ﻃﺮﻳﻖ ﻭﺣﺪﺍﺕ‬ ‫ﺭﺑـﻂ )‪ (Network Cards‬ﻭﻭﺳـﺎﺋﻂ )ﻣﻦ ﺃﺳﻼﻙ ﳏﻮﺭﻳﺔ، ﺃﺳﻼﻙ ﻣﱪﻭﻣﺔ ﻭ ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ( ﻭ ﺃﺟﻬﺰﺓ‬ ‫ﻣـﻠﺤﻘﺔ )ﺟﻬـﺎﺯ ﺗﻘﻮﻳﺔ ﺃﻭ ﻣﻜﺮﺭ، ﳎﻤﻌﺎﺕ ﺗﻮﺻﻴﻞ، ﺟﺴﻮﺭ..( ﻣﻜﻮﻧﺔ ﺑﺬﻟﻚ ﺷﺒﻜﺔ ﻣﺘﻜﺎﻣﻠﺔ، ﻭ‪‬ﺬﻩ‬ ‫ﺍﻟﻄـﺮﻳﻘﺔ ﳝﻜﻦ ﻷﻱ ﺣﺎﺳﺐ ﺃﻥ ﻳﺴﺘﻔﻴﺪ ﻣﻦ ﺍﳋﺪﻣﺎﺕ )ﻣﻌﻠﻮﻣﺎﺕ ، ﺑﺮﺍﻣﺞ ، ﻣﻠﺤﻘﺎﺕ ( ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ‬ ‫ﺍﳊﺎﺳﺒﺎﺕ ﺍﻷﺧﺮﻯ ﺍﳌﺮﺗﺒﻄﺔ ﻣﻊ ﺍﻟﺸﺒﻜﺔ ﺣﻴﺚ ﺍ‪‬ﺎ ﺗﺴﻤﺢ ﺑﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﻣﻮﺍﺭﺩ ﳊﺎﺳﺐ.‬ ‫ﻛﻤﺎ ﺗﺴﻤﺢ ﻟﻠﻤﺴﺘﺨﺪﻣﲔ ﺑﺎﻟﺘﻮﺍﺻﻞ ﻣﻊ ﻳﻌﻀﻬﻢ ﺍﻟﺒﻌﺾ ﺑﺸﻜﻞ ﻓﻮﺭﻱ.‬ ‫6‬
‫ﻓﻮﺍﺋﺪ ﻭ ﺧﺪﻣﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫‪ ü‬ﺍﳌﺸﺎﺭﻛﺔ ﰲ ﺍﳌﻌﻠﻮﻣﺎﺕ : ﺍﻋﺘﻤﺎﺩﺍ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺎﺕ ﳝﻜﻦ ﺃﻥ ﻳﺘﻢ ﺗﺒﺎﺩﻝ ﺍﳌﻌﻠﻮﻣﺎﺕ‬ ‫ﻭ ﺍﳌﻠﻔﺎﺕ ) ﻧﺼﻮﺹ ، ﺻﻮﺭ ، ﺻﻮﺕ....ﺍﱁ( ﻋﻠﻰ ﺍﺧﺘﻼﻑ ﺃﻧﻮﺍﻋﻬﺎ .‬ ‫‪ ü‬ﺍﳌﺸـﺎﺭﻛﺔ ﰲ ﻣـﻮﺍﺭﺩ ﺍﻟﺸـﺒﻜﺔ : ﻣـﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ_ ﻛﺎﳌﻌﺪﺍﺕ ) ﺍﻟﻄﺎﺑﻌﺎﺕ – ﺍﳌﺎﺳﺢ‬ ‫ﺍﻟﻀـﻮﺋﻲ...ﺍﱁ (، ﻭ ﺍﻟـﱪﺍﻣﺞ)ﺍﻟﱪﺍﻣﺞ ﺍﻟﺘﻨﻔﻴﺬﻳﺔ، ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ..(، ﲝﻴﺚ ﻳﻘﻮﻡ ﺃﻛﺜﺮ ﻣﻦ‬ ‫ﻭﺍﺣﺪ ﺑﺎﺳﺘﺨﺪﺍﻣﻬﺎ.‬ ‫‪ ü‬ﺍﻟﻘﺪﺭﺓ ﻋﻠﻰ ﺍﺳﺘﺨﺪﺍﻡ ﺑﺮﳎﻴﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ : ﻣﻦ ﺃﻫﻢ ﺍﻟﱪﳎﻴﺎﺕ ﺍﳌﺴﺘﺨﺪﻣﺔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ ﺃﻧﻈﻤﺔ ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﻭ ﻣﺎ ﻳﻌﺮﻑ‬ ‫ﺑــ)‪ (group ware‬ﻭ ﻫـﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ ﳝﻜﻦ ﺃﻥ ﻳﺘﺤﺪﺛﻮﺍ ﻣﻊ‬ ‫ﺑﻌﻀﻬﻢ ﺍﻟﺒﻌﺾ ﰲ ﺃﻱ ﳎﺎﻝ ﻣﻌﲔ.‬ ‫‪ ü‬ﺇﻧﺸﺎﺀ ﳎﻤﻮﻋﺎﺕ ﻋﻤﻞ : ﺗﺴﺘﺨﺪﻡ ﺍﻟﺸﺒﻜﺔ ﰲ ﺍﻻﺗﺼﺎﻝ ﻟﺘﻘﺪﻡ ﺇﺩﺍﺭﺓ ﻣﺸﺘﺮﻛﺔ ﻟﻠﻮﺛﺎﺋﻖ‬ ‫ﻣـﻦ ﻗـﺒﻞ ﳎﻤﻮﻋـﺔ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ ﰲ ﺃﻣﺎﻛﻦ ﳐﺘﻠﻔﺔ ﰲ ﺍﻟﻮﻗﺖ ﻧﻔﺴﻪ ﳑﺎ ﻳﺴﻤﺢ‬ ‫ﺑﺎﻟـﺘﻌﺪﻳﻞ ﻋـﻠﻰ ﻣﺴﺘﻨﺪ ﻣﺎ ﻣﻦ ﻗﺒﻞ ﺃﻛﺜﺮ ﻣﻦ ﻣﺴﺘﺨﺪﻡ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ ، ﻛﻤﺎ ﺃﻥ‬ ‫ﺍﳌﺴـﺘﺨﺪﻣﲔ ﻳﺴـﺘﻄﻴﻌﻮﺍ ﺍﳌﺸﺎﺭﻛﺔ ﰲ ﺗﺸﻐﻴﻞ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻭ ﺍﻟﱪﺍﻣﺞ ﺍﳌﺨﺘﻠﻔﺔ ﻋﻠﻰ‬ ‫ﺃﺟﻬﺰﺓ ﳐﺘﻠﻔﺔ .‬ ‫‪ ü‬ﺃ.2.5. ﺍﻻﺗﺼـﺎﻝ : ﺍﻟﺸـﺒﻜﺎﺕ ﺗﺴﻬﻞ ﻋﻤﻠﻴﺔ ﺍﻻﺗﺼﺎﻝ ﲝﻴﺚ ﳝﻜﻦ ﳏﺎﻭﺭﺓ ﺃﻱ‬ ‫ﺷﺨﺺ ﰲ ﺃﻱ ﻣﻜﺎﻥ ﻣﻦ ﺍﻟﻌﺎﱂ.‬ ‫‪ ü‬ﺃ.2.6. ﺧﺪﻣﺎﺕ ﺍﻟﱪﻳﺪ : ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺧﺪﻣﺔ ﻭﺍﺳﻌﺔ ﺍﻻﻧﺘﺸﺎﺭ ، ﺇﺫ ﺃﻧﻪ ﺃﺳﺮﻉ ﻭ‬ ‫ﺃﺭﺧﺺ ﻣﻦ ﺍﻟﺮﺳﺎﺋﻞ ﺍﻟﻮﺭﻗﻴﺔ ، ﻭ ﺃﻛﺜﺮ ﺳﺮﻳﺔ ﻣﻦ ﺍﳌﻜﺎﳌﺎﺕ ﺍﳍﺎﺗﻔﻴﺔ ، ﻭ ﺃﻗﻞ ﺇﺯﻋﺎﺟﺎ ﻣﻦ‬ ‫ﺍﻟﻔﺎﻛﺲ . ﺇﺫ ﻳﻘﺪﻡ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺇﻣﻜﺎﻧﻴﺔ ﺇﺭﺳﺎﻝ ﺍﻟﻮﺛﺎﺋﻖ ‪ Documents‬ﻭ ﺍﻟﺼﻮﺭ‬ ‫‪ Images‬ﻭ ﺍﻟﺼﻮﺕ ‪ ، Audio‬ﻋﻠﻰ ﺷﻜﻞ ﻣﺮﻓﻘﺎﺕ ، ﻛﻞ ﺫﻟﻚ ﳚﺮﻱ ﰲ ﻇﺮﻑ ﺛﻮﺍﱐ ﺃﻭ‬ ‫ﺩﻗﺎﺋﻖ . ﻭ ﻳﻌﺘﻤﺪ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﰲ ﺁﻟﻴﺔ ﻋﻤﻠﻪ ﻋﻠﻰ ﺍﻟﻌﻨﺎﻭﻳﻦ ﺍﻹﻟﻜﺘﺮﻭﻧﻴﺔ ‪Electronic‬‬ ‫‪ ، Addresses‬ﺇﺫ ﺗﺮﺳﻞ ﺍﳌﺴﺘﻨﺪﺍﺕ ﺍﻹﻟﻜﺘﺮﻭﻧﻴﺔ ﺇﱃ ﻋﻨﻮﺍﻥ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺍﳋﺎﺹ‬ ‫ﺑﺎﳌﺴﺘﻠﻢ ﺍﳌﻄﻠﻮﺏ ، ﻭ ﻗﺪ ﻇﻬﺮﺕ ﺍﻛﱪ ﻓﻮﺍﺋﺪ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﰲ ﺍﻟﺸﺮﻛﺎﺕ ، ﺇﺫ ﺣﻞ ﳏﻞ‬ ‫ﺍﳌﺬﻛﺮﺍﺕ ﺍﻟﱵ ﻳﺘﻢ ﺗﺒﺎﺩﳍﺎ ﺑﲔ ﺍﳌﻜﺎﺗﺐ ، ﻭ ﺍﻹﻋﻼﻧﺎﺕ ، ﻭ ﺍﻷﺳﺌﻠﺔ ، ﻭ ﺍﻟﺘﻌﻴﻴﻨﺎﺕ ، ﺇﺿﺎﻓﺔ‬ ‫ﺇﱃ ﺍﻟﺮﺩﻭﺩ ﻋﻠﻰ ﺍﻻﺳﺘﻔﺴﺎﺭﺍﺕ ﺍﳋﺎﺻﺔ ﺑﺎﻟﻌﻤﻞ .‬ ‫7‬
‫ﺍ‬ ‫ﳊﺪ ﺍﻷﺩﻧﻰ ﳌﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ :‬ ‫‪ v‬ﺟﻬﺎﺯﻱ ﺣﺎﺳﻮﺏ ﻋﻠﻰ ﺍﻷﻗﻞ .‬ ‫‪ v‬ﺑﻄﺎﻗـﺔ ﺍﻟﺸـﺒﻜﺔ : ﺣﻴﺚ ﺗﺸﻜﻞ ﺍﻟﺒﻄﺎﻗﺔ ﺟﺴﺮ ﺍﻻﺗﺼﺎﻝ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﻭ ﻣﻜﻮﻧﺎﺕ‬ ‫ﺍﻟﺸﺒﻜﺔ.‬ ‫‪Radio‬‬ ‫‪ v‬ﻭﺳﻂ ﻧﺎﻗﻞ ﻟﻼﺗﺼﺎﻝ ﺑﲔ ﻋﻨﺎﺻﺮ ﺍﻟﺸﺒﻜﺔ ﻣﺜﻞ ﺍﻷﺳﻼﻙ ﺃﻭ ﺍﻷﻣﻮﺍﺝ ﺍﻟﻘﺼﲑﺓ‬ ‫‪waves‬‬ ‫‪ v‬ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻻﺗﺼﺎﻝ: ﲢﺪﺩ ﺧﻮﺍﺭﺯﻣﻴﺔ ﲣﺎﻃﺐ ﻣﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ ﻭ ﺍﳌﻮﺍﺻﻔﺎﺕ‬ ‫ﺍﻟﺘﻘﻨـﻴﺔ ﺍﻟﻮﺍﺟـﺐ ﺗﻮﻓﲑﻫﺎ ﻣﺜﻞ ﻋﺮﺽ ﺍﳊﺰﻣﺔ ﺍﳌﺴﺘﺨﺪﻣﺔ ‪ ، bandwidth‬ﻭ ﻃﺮﻳﻘﺔ‬ ‫ﺗﺮﺗﻴﺐ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻋﻨﺪ ﺇﺭﺳﺎﳍﺎ ‪ formats packets‬ﻭﻏﲑﻫﺎ ﻣﻦ ﺍﳌﻮﺻﻔﺎﺕ ﺍﻟﺘﻘﻨﻴﺔ .‬ ‫‪ v‬ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﻟﺸﺒﻜﺔ )‪ Network operating System (nos‬ﻳﻘﺪﻡ ﺧﺪﻣﺔ ﺗﻨﻈﻴﻢ‬ ‫ﺍﻟﺼﻼﺣﻴﺎﺕ ﻭ ﺣﻘﻮﻕ ﺍﳌﺴﺘﺨﺪﻣﲔ ﰲ ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺍﳌﻮﺍﺭﺩ ﻭ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺸﺘﺮﻛﺔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻪ: ﻣﺎﻳﻜﺮﻭﺳﻮﻓﺖ ﻭﻳﻨﺪﻭﺯ 89 ، ﻭﻳﻨﺪﻭﺯ 0002 ، ﻭﻳﻨﺪﻭﺯ ‪win‬‬ ‫‪...win xp ، nt‬‬ ‫ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﺃﺻـﺒﺢ ﺍﻟﺘﺼﻨﻴﻒ ﰲ ﻋﺼﺮﻧﺎ ﻫﺬﺍ ﻋﻠﻤﺎ ﻭﺍﺳﻌﺎ، ﻭﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﻫﻮ ﺑﻌﻴﻨﻪ ﻋﻠﻢ ﻣﺴﺘﻘﻞ‬ ‫ﺇﺫ ﻳﻮﺟﺪ ﺍﻟﻌﺪﻳﺪ ﻣﻦ ﺍﳌﻌﺎﻳﲑ ﺍﻟﱵ ﳝﻜﻦ ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀﺍ ﻋﻠﻴﻬﺎ ، ﻭ ﻣﻦ ﻫﺬﻩ ﺍﳌﻌﺎﻳﲑ :‬ ‫- ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀ ﻋﻠﻰ ﻋﻼﻗﺔ ﺍﻷﻧﻈﻤﺔ ﺑﺒﻌﻀﻬﺎ :‬ ‫‪ v‬ﺷﺒﻜﺔ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ‪ : peer to peer‬ﺷﺒﻜﺔ ﲢﺘﻮﻱ ﻋﻠﻰ ﻃﺮﻓﻴﺎﺕ‬ ‫ﻣﺘﻮﺍﺯﻧﺔ ﺍﻟﻘﺪﺭﺍﺕ ﻳﺘﻢ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ ﺗﺒﺎﺩﻝ ﺍﳌﻠﻔﺎﺕ ﻭ ﺍﻟﱪﻳﺪ ﻭ ﺗﺸﺎﺭﻙ‬ ‫ﺍﳌﻮﺍﺭﺩ) ﺍﻟﻄﺎﺑﻌﺔ ، ﺍﳌﺎﺳﺢ ، ﺍﳌﻮﺩﻡ( .‬ ‫‪ v‬ﺷـﺒﻜﺎﺕ ﺍﳋﺎﺩﻡ ﺍﳌﺴﺘﻔﻴﺪ ‪ : client/server‬ﺗﻌﺘﻤﺪ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﻋﻠﻰ ﺍﳋﺎﺩﻡ . ﻭﻳﻜﻮﻥ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺫﺍ ﻣﻮﺍﺻﻔﺎﺕ ﺧﺎﺻﺔ ﲤﻜﻨﻪ ﻣﻦ ﺗﻘﺪﱘ‬ ‫ﺃﻋﻠﻰ ﻣﺴﺘﻮﻯ ﻣﻦ ﺍﳋﺪﻣﺎﺕ‬ ‫ﻭ ﻗﺪ ﻳﻜﻮﻥ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺧﺎﺩﻣﺎ ﳋﺪﻣﺔ ﻭﺍﺣﺪﺓ ﺃﻭ ﺃﻛﺜﺮ.‬ ‫8‬
‫- ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀ ﻋﻠﻰ ﺍﻟﺘﻮﺯﻉ ﺍﳉﻐﺮﺍﰲ :‬ ‫§ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ )‪: local Area Network (LAN‬‬ ‫ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﺷﺒﻜﺎﺕ ﺗﺘﻜﻮﻥ ﻣﻦ ﻋﺪﺩ ﻗﻠﻴﻞ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ، ﰲ ﺍﻟﻌﺎﺩﺓ ﺗﻜﻮﻥ ﳏﺘﻮﺍﺓ ﺩﺍﺧﻞ‬ ‫ﻣﻜﺘـﺐ ﺃﻭ ﳎﻤﻮﻋـﺔ ﻣﻦ ﺍﳌﻜﺎﺗﺐ ﺩﺍﺧﻞ ﺑﻨﺎﻳﺔ ﻭﺍﺣﺪﺓ ، ﻭ ﺗﻘﺪﻡ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﰲ ﻭﻗﺘﻨﺎ ﺍﳊﺎﱄ ﺳﺮﻋﺔ‬ ‫ﻛـﺒﲑﺓ ﻟﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺗﺸﺎﺭﻙ ﺍﳌﻮﺍﺭﺩ ، ﳑﺎ ﳚﻌﻞ ﺍﳌﺴﺘﺨﺪﻡ ﺍﻟﺬﻱ ﻳﺴﺘﻔﻴﺪ ﻣﻦ ﺍﻟﺸﺒﻜﺔ ﻳﻈﻦ ﺃﻥ ﻫﺬﻩ‬ ‫ﺍﳌﻮﺍﺭﺩ ﻣﻮﺟﻮﺩﺓ ﻋﻠﻰ ﺟﻬﺎﺯﻩ ﺍﻟﺸﺨﺼﻲ .‬ ‫§ ﺷﺒﻜﺎﺕ ﻧﻄﺎﻕ ﺍﳌﺪﻥ )‪: Metropolitan Area Networks (MAN‬‬ ‫ﺷـﺒﻜﺎﺕ ﻧﻄـﺎﻕ ﺍﳌﺪﻥ ﺗﻘﻮﻡ ﻋﻠﻰ ﻧﻔﺲ ﻣﺒﺪﺃ ﻋﻤﻞ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ ، ﻭﻟﻜﻦ ﺗﻌﻤﻞ‬ ‫ﺑﺴﺮﻋﺎﺕ ﻓﺎﺋﻘﺔ ﻭ ﺗﺴﺘﺨﺪﻡ ﰲ ﺍﻟﻌﺎﺩﺓ ﺍﻷﻟﻴﺎﻑ ﺍﻟﻀﻮﺋﻴﺔ ﻛﻮﺳﻂ ﺍﺗﺼﺎﻝ ، ﻭ ﻫﻲ ﻋﺎﺩﺓ ﺗﻐﻄﻲ ﻣﺴﺎﺣﺎﺕ‬ ‫ﻭﺍﺳﻌﺔ ﺗﺘﺮﺍﻭﺡ ﺑﲔ 02 ﺇﱃ 001 ﻛﻴﻠﻮﻣﺘﺮ .‬ ‫§ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ )‪:Wide Area Networks (WAN‬‬ ‫ﻣﻦ ﺗﻠﺒﻴﺔ‬ ‫)‪(LAN and MAN‬‬ ‫ﰲ ﺑﺪﺍﻳـﺔ ﻇﻬـﻮﺭ ﺍﻟﺸـﺒﻜﺎﺕ ﱂ ﺗـﺘﻤﻜﻦ ﺷﺒﻜﺎﺕ ﺍﻟـ‬ ‫ﺍﺣﺘﻴﺎﺟﺎﺕ ﺍﻟﺸﺮﻛﺎﺕ ﺍﻟﻜﱪﻯ ﺍﻟﱵ ﺗﺘﻮﺯﻉ ﻣﻜﺎﺗﺒﻬﺎ ﻋﻠﻰ ﻣﺴﺘﻮﻯ ﻋﺪﺓ ﺩﻭﻝ ، ﳍﺬﺍ ﻛﺎﻥ ﻻﺑﺪ ﻣﻦ ﺗﻮﺳﻴﻊ‬ ‫ﻭﺗﻄﻮﻳﺮ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﺑﺈﺩﺧﺎﻝ ﻭﺳﺎﺋﻞ ﺟﺪﻳﺪﺓ ﻋﻠﻴﻬﺎ ﲝﻴﺚ ﲤﻜﻨﻨﺎ ﻣﻦ ﺭﺑﻂ ﻋﺪﺓ ﺷﺒﻜﺎﺕ ، ﰲ ﺩﻭﻟﺔ ﺃﻭ‬ ‫ﰲ ﻋـﺪﺓ ﺩﻭﻝ ﳐﺘﻠﻔﺔ ، ﻭ ﻳﻄﻠﻖ ﻋﻠﻰ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺘﺸﺒﻴﻚ ﺍﺳﻢ ‪ WAN‬ﺃﻭ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ‬ ‫ﻭﺑﺎﺳـﺘﺨﺪﺍﻡ ﻫـﺬﻩ ﺍﻟﺘﻘﻨﻴﺔ ﺗﺰﺍﻳﺪ ﻋﺪﺩ ﺍﳌﺴﺘﺨﺪﻣﲔ ﻟﺸﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ ﰲ ﺍﻟﺸﺮﻛﺎﺕ ﺍﻟﻜﺒﲑﺓ ﺇﱃ ﺁﻻﻑ‬ ‫ﺍﻷﺷﺨﺎﺹ ، ﻭ ﺗﻌﺪ ﺍﻹﻧﺘﺮﻧﺖ ﻣﺜﺎﻻ ﺟﻴﺪﺍ ﻋﻠﻴﻬﺎ ﻓﻬﻲ ﺃﻛﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻮﺍﺳﻌﺔ ﺣﱴ ﺍﻵﻥ.‬ ‫ﺗﻨﻘﺴﻢ ﺷﺒﻜﺎﺕ ﺍﻟـ ‪ WAN‬ﺇﱃ ﻓﺌﺘﲔ :‬ ‫1. ‪ : Network Enterprise‬ﻳﻘـﻮﻡ ﺑﺎﻟـﺮﺑﻂ ﺑـﲔ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺃﻭ ﺍﻟﻔﺮﻭﻉ ﺍﻟﺘﺎﺑﻌﺔ‬ ‫ﻟﺸﺮﻛﺔ ﺃﻭ ﻣﺆﺳﺴﺔ ﻭﺍﺣﺪﺓ ﻋﻠﻰ ﻣﺴﺘﻮﻯ ﺩﻭﻟﺔ ﻭﺍﺣﺪﺓ ﺃﻭ ﻋﺪﺓ ﺩﻭﻝ .‬ ‫: ﻳﻌﻤﻞ ﻋﻠﻰ ﺭﺑﻂ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﺘﺎﺑﻌﺔ ﻟﻌﺪﺓ ﻣﺆﺳﺴﺎﺕ ﳐﺘﻠﻔﺔ‬ ‫2. ‪Network global‬‬ ‫ﻣﻊ ﺑﻌﻀﻬﺎ ﺍﻟﺒﻌﺾ .‬ ‫9‬
‫ﺧﺼﺎﺋﺺ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ‬ ‫ﺷﺒﻜﺔ ﻧﻄﺎﻕ ﺍﳌﺪﻥ‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ‬ ‫ﺇﺳـﻢ ﻧﻮﻉ ﺍﻟﺸﺒﻜﺔ‬ ‫‪WAN‬‬ ‫‪MAN‬‬ ‫‪LAN‬‬ ‫ﺧﺼﺎﺋﺼــﻬﺎ‬ ‫ﻣﻦ ﺑﻌﺾ‬ ‫ﺍﻟﺘﻐﻄﻴﺔ ﺍﳉﻐﺮﺍﻓﻴﺔ‬ ‫ﻋﺎﳌﻴﺔ ﺍﻟﺘﻐﻄﻴﺔ‬ ‫ﺍﻟﻜﻴﻠﻮﻣﺘﺮﺍﺕ‬ ‫ﺗﺼﻞ ﺣﱴ 001 ﻣﺘﺮ‬ ‫ﺇﱃ ﺍﻵﻻﻑ‬ ‫ﺳﺮﻋﺔ ﻣﻨﺨﻔﻀﺔ ﺑﺴﺒﺐ ﻋﺪﺩ‬ ‫اﻟﺴﺮﻋﺔ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﳌﻠﺤﻘﺔ ﻭﺧﺎﺻﺔ‬ ‫ﻓﺎﺋﻘﺔ ﺟﺪﺍ ﻭ ﺗﺘﺮﺍﻭﺡ ﺑﲔ 4‬ ‫ﺃﺟﻬﺰﺓ ﺍﳌﻮﺩﻡ ﺫﺍﺕ ﺍﻟﺴﺮﻋﺔ‬ ‫ﺗﻌﺎﺩﻝ ﺗﻘﺮﻳﺒﺎ ﺳﺮﻋﺔ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﳎﺎ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ ﺇﱃ 0001‬ ‫ﺍﳌﻨﺨﻔﻀﺔ ﻭ ﺍﻟﱵ ﲢﺴﺐ‬ ‫ﺍﻟﻮﺍﺳﻌﺔ‬ ‫ﳎﺎ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ‬ ‫ﺑﺎﻟﻜﻴﻠﻮ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ‬ ‫ﺣﺴﺐ ﺍﻟﺘﻘﻨﻴﺔ ﺍﳌﺴﺘﻌﻤﻠﺔ‬ ‫)‪(Kbps‬‬ ‫ﻋﺪﺩ ﻛﺜﲑ ﺟﺪﺍ ﳛﺴﺐ‬ ‫ﻋﺪد اﻟﺤﺎﺳﺒﺎت‬ ‫ﻋﺪﺩ ﻛﺜﲑ‬ ‫ﻣﻦ 2 ﺇﱃ ﺑﻌﺾ ﺍﳌﺌﺎﺕ‬ ‫ﺑﻌﺸﺮﺍﺕ ﺍﻵﻻﻑ‬ ‫اﻟﻮﺳﺎﺋﻂ و اﻟﻤﻠﺤﻘﺎت‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﶈﻴﻄﻴﺔ، ﺃﺟﻬﺰﺓ‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ ﺍﻷﺟﻬﺰﺓ‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻣﻮﺩﻡ ﻣﺘﻌﺪﺩ‬ ‫ﺍﶈﻴﻄﻴﺔ، ﻭ ﺃﺟﻬﺰﺓ ﺍﳌﻮﺩﻡ‬ ‫)‪(Multiplexer‬‬ ‫اﻟﺘﻮاﺻﻞ‬ ‫ﻣﺘﻮﺍﺻﻞ- ‪‬‬ ‫ﻣﻨﻘﻄﻊ‬ ‫ﻣﺘﻮﺍﺻﻞ- ‪‬‬ ‫ﻣﻨﻘﻄﻊ‬ ‫ﻣﺘﻮﺍﺻﻞ 42ﺳﺎﻋﺔ/42‬ ‫01‬
‫ﺃﻧﻮﺍﻉ ﺍﻟﻨﻮﺍﻗﻞ:‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﻋﺎﺩﺓ ﻧﻮﻉ ﻭﺍﺣﺪ ﻣﻦ ﻭﺳﺎﺋﻂ ﺍﻻﺗﺼﺎﻝ ﻭ ﺃﺣﻴﺎﻧﺎ ﺃﻛﺜﺮ ﻣﻦ ﻧﻮﻉ ، ﻭﻫﺬﻩ‬ ‫ﺍﻟﻮﺳﺎﺋﻂ ﺇﻣﺎ ﺃﻥ ﺗﻜﻮﻥ ﺃﺳﻼﻙ ﻭﻫﻲ ﺛﻼﺙ ﺃﻧﻮﺍﻉ ﺇﻣﺎ ﺃﻥ ﺗﻜﻮﻥ ﻭﺳﻴﻂ ﻻﺳﻠﻜﻲ ﻭ ﺗﺘﻤﺜﻞ ﰲ:‬ ‫: ﻭ ﺗﻜﻮﻥ ﻫﺬﻩ‬ ‫)‪(Twisted pair cable‬‬ ‫‪ v‬ﺃﺳـﻼﻙ ﻣـﺰﺩﻭﺟﺔ ﻣﻠـﺘﻔﺔ‬ ‫‪( Shielded or not‬‬ ‫ﺍﻷﺳﻼﻙ ﺇﻣﺎ ﻣﻐﻄﺎﺓ ﺑﻄﺒﻘﺔ ﻭﺍﻗﻴﺔ ﺃﻭ ﻏﲑ ﻣﻐﻄﺎﺓ‬ ‫)‪shielded‬‬ ‫‪ v‬ﺃﺳـﻼﻙ ﳏﻮﺭﻳﺔ )‪ : (Coaxial cable‬ﻭﻫﻲ ﺗﻨﻘﺴﻢ ﺇﱃ ﻧﻮﻋﲔ ﺭﻗﻴﻘﺔ ﻭ‬ ‫ﻏﻠﻴﻈﺔ.‬ ‫‪ v‬ﺍﻷﻟﻴﺎﻑ ﺍﻟﺒﺼﺮﻳﺔ )‪. (Fiber Optic Cable‬‬ ‫‪ v‬ﻭﺳﻴﻂ ﺍﺗﺼﺎﻝ ﻻﺳﻠﻜﻲ )‪. (Wireless transmission media‬‬ ‫ﺗﺼﺎﻣﻴﻢ ﺍﻟﺸﺒﻜﺔ :‬ ‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﺍﻟﻨﺠﻤﺔ ) ‪: (star‬‬ ‫ﺗﻘـﻮﻡ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺫﺍﺕ ﺍﻟﺘﺼﻤﻴﻢ ﻣﻦ ﺍﻟﻨﻮﻉ ﺍﻟﻨﺠﻤﺔ )‪ ، (Star‬ﺑﺮﺑﻂ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ‬ ‫ﺑﺄﺳﻼﻙ ﻣﻮﺻﻠﺔ ﲜﻬﺎﺯ ﻣﺮﻛﺰﻱ ﻳﻄﻠﻖ ﻋﻠﻴﻪ ﺍﶈﻮﺭ ﺃﻭ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ )‪. (Hub‬‬ ‫‪ v‬ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ:‬ ‫ﺍﻹﺷﺎﺭﺍﺕ ﺗﻨﺘﻘﻞ ﻣﻦ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺼﺪﺭ ﺍﻟﺬﻱ‬ ‫‪Hub‬‬ ‫ﻳﺮﻏﺐ ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ‬ ‫ﻭﻣﻨﻪ ﺇﱃ ﺑﺎﻗﻲ ﺍﻷﺟﻬﺰﺓ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ . ﻳﻌﺘﱪ ﺗﺼﻤﻴﻢ‬ ‫ﺍﻟﻨﺠﻤﺔ ‪ Star‬ﺍﻷﻛﺜﺮ ﺇﺭﺍﺣﺔ ﻣﻦ ﺑﲔ ﺍﻟﺘﺼﺎﻣﻴﻢ‬ ‫)‪(Star‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻘﻨﻴﺔ ﳒﻤﺔ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﺣﻴﺚ ﺃﻧﻪ ﻳﺴﻤﺢ ﺑﺘﺤﺮﻳﻚ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻣﻦ ﻣﻜﺎ‪‬ﺎ ﻭ ﺇﺻﻼﺣﻬﺎ ﻭ ﺗﻐﻴﲑ ﺍﻟﺘﻮﺻﻴﻼﺕ ﺩﻭﻥ ﺃﻥ ﺗﺘﺄﺛﺮ ﺍﻟﺸﺒﻜﺔ.‬ ‫11‬
‫ﻧﻈﺎﻡ ﺍﻟﺘﻮﺻﻴﻞ ﰲ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪: Hub‬‬ ‫ﻳﻌـﺰﻝ ﻛﻞ ﺳﻠﻚ ﻣﻦ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺔ ﻋﻦ ﺍﻵﺧﺮ .ﻭ ﺑﺎﻟﺘﺎﱄ ﺇﺫﺍ ﺗﻮﻗﻒ ﺟﻬﺎﺯ ﻣﺎ ﺃﻭ ﺍﻧﻘﻄﻊ‬ ‫ﺍﻟﺴﻠﻚ ﺍﻟﺬﻱ ﻳﻮﺻﻠﻪ ﺑﺎﳌﻮﺯﻉ ﻓﻠﻦ ﻳﺘﺄﺛﺮ ﺇﻻ ﺍﻟﺬﻱ ﺗﻮﻗﻒ ﺑﻴﻨﻤﺎ ﺑﺎﻗﻲ ﺍﻷﺟﻬﺰﺓ ﺳﺘﺒﻘﻰ ﺗﻌﻤﻞ‬ ‫ﻣﻦ ﺧﻼﻝ ﺍﻟﺸﺒﻜﺔ ﺩﻭﻥ ﻣﺸﺎﻛﻞ .‬ ‫‪v‬ﻣﺸﺎﻛﻠﻬﺎ:‬ ‫• ﺗﻮﻗﻒ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ﻋﻦ ﺍﻟﻌﻤﻞ ﻳﺆﺩﻱ ﺇﱃ ﺗﻮﻗﻒ ﺍﻟﺸﺒﻜﺔ ﻛﻜﻞ ﻋﻦ ﺍﻟﻌﻤﻞ .‬ ‫• ﺗﻜﻠﻔـﺔ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺘﺼﻤﻴﻢ ﻣﺮﺗﻔﻌﺔ ﺧﺎﺻﺔ ﰲ ﺣﺎﻟﺔ ﻛﱪ ﺍﻟﺸﺒﻜﺔ ﻷ‪‬ﺎ ﺳﺘﻄﻠﺐ‬ ‫ﺃﺳﻼﻙ ﻛﺜﲑﺓ ﻭ ﺍﳌﻮﺯﻉ ﻗﺪ ﻳﻜﻮﻥ ﺳﻌﺮﻩ ﻣﺮﺗﻔﻌﺎ.‬ ‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﺣﻠﻘﺔ )‪: (RING‬‬ ‫ﰲ ﺗﺼـﻤﻴﻢ ﺍﻟﺸـﺒﻜﺎﺕ ﻣﻦ ﺍﻟﻨﻮﻉ ﺣﻠﻘﺔ ﻳﺘﻢ ﺭﺑﻂ ﺍﻷﺟﻬﺰﺓ ﲝﻠﻘﺔ ﺃﻭ ﺩﺍﺋﺮﺓ ﻣﻦ ﺍﻟﺴﻠﻚ‬ ‫ﺑﺪﻭﻥ ‪‬ﺎﻳﺎﺕ ﺗﻮﻗﻒ.‬ ‫ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ :‬ ‫ﺗﻨﺘﻘﻞ ﺍﻹﺷﺎﺭﺍﺕ ﻋﻠﻰ ﻣﺪﺍﺭ ﺍﳊﻠﻘﺔ ﰲ ﺍﲡﺎﻩ ﻭﺍﺣﺪ‬ ‫ﻭ ﲤﺮ ﻣﻦ ﺧﻼﻝ ﻛﻞ ﺟﻬﺎﺯ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺣﻴﺚ ﻳﻘﻮﻡ ﺑﺈﻧﻌﺎﺷﻬﺎ‬ ‫ﻭ ﺗﻘﻮﻳﺘﻬﺎ ﰒ ﻳﻌﻴﺪ ﺇﺭﺳﺎﳍﺎ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺇﱃ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺘﺎﱄ .‬ ‫)‪(ring‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻘﻨﻴﺔ ﺣﻠﻘﺔ‬ ‫ﻣﺸﺎﻛﻠﻬﺎ:‬ ‫1. ﻋﻨﺪ ﺗﻄﻮﻳﺮﻫﺎ ﳚﺐ ﺇﻳﻘﺎﻑ ﻋﻤﻠﻬﺎ ﺃﺛﻨﺎﺀ ﻋﻤﻠﻴﺔ ﺍﻟﺘﻄﻮﻳﺮ .‬ ‫2. ﲟـﺎ ﺃﻥ ﺍﻹﺷـﺎﺭﺓ ﲤﺮ ﻋﻠﻰ ﻛﻞ ﺟﻬﺎﺯ ﻓﺈﻥ ﻓﺸﻞ ﺃﺣﺪ ﺍﻷﺟﻬﺰﺓ ﺃﻭ ﺗﻮﻗﻔﻪ ﻋﻦ ﺍﻟﻌﻤﻞ‬ ‫ﺳﻴﺆﺩﻱ ﺇﱃ ﺗﻮﻗﻒ ﺍﻟﺸﺒﻜﺔ ﻛﻜﻞ ﻋﻦ ﺍﻟﻌﻤﻞ .‬ ‫21‬
‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﻗﺎﻃﺮﺓ )‪: (Bus‬‬ ‫ﰲ ﺗﺼـﻤﻴﻢ ﺍﻟﺸـﺒﻜﺔ ﺑﺸﻜﻞ ‪ bus‬ﻳﺘﻢ ﺗﻮﺻﻴﻞ ﺍﳊﻮﺍﺳﻴﺐ ﰲ ﺻﻒ ، ﻋﻠﻰ ﻃﻮﻝ ﺳﻠﻚ‬ ‫ﻭﺍﺣﺪ ﻭ ﺗﻌﺘﻤﺪ ﻓﻜﺮﺓ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻋﻠﻰ ﺛﻼﺛﺔ ﺃﻣﻮﺭ ﺃﺳﺎﺳﻴﺔ ﺗﺘﻤﺜﻞ ﰲ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ ﻭ ﺍﺭﺗﺪﺍﺩ ﺍﻹﺷﺎﺭﺓ‬ ‫ﻭ ﺍﻟﻨﻬﺎﺋﻲ ﺃﻭ ﺍﳌﻨﻬﻲ.‬ ‫ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ :‬ ‫‪v‬‬ ‫‪Terminal‬‬ ‫)‪connector lettre(T‬‬ ‫ﺗﺮﺳﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻋﻠﻰ ﺷﻜﻞ‬ ‫ﺇﺷﺎﺭﺍﺕ ﻛﻬﺮﺑﺎﺋﻴﺔ ﺇﱃ ﻛﻞ ﺍﳊﻮﺍﺳﻴﺐ ﺍﳌﻮﺻﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ‬ ‫ﻭ ﻳﺘﻢ ﻗﺒﻮﻝ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻣﻦ ﻗﺒﻞ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺬﻱ ﻳﺘﻮﺍﻓﻖ‬ ‫ﻋﻨﻮﺍﻧﻪ ﻣﻊ ﺍﻟﻌﻨﻮﺍﻥ ﺍﳌﺸﻔﺮ ﺩﺍﺧﻞ ﺍﻹﺷﺎﺭﺓ ﺍﻷﺻﻠﻴﺔ‬ ‫ﺑﺘﻘﻨﻴﺔ) ‪(bus‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺍﳌﺮﺳﻠﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ .‬ ‫ﻋﻨﺪﻣﺎ ﺗﺮﺳﻞ ﺇﺷﺎﺭﺓ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻓﺈ‪‬ﺎ ﺗﻨﺘﻘﻞ ﻣﻦ ﺑﺪﺍﻳﺔ ﺍﻟﺴﻠﻚ ﺇﱃ ‪‬ﺎﻳﺘﻪ ، ﻭ ﺇﺫﺍ ﱂ ﻳﺘﻢ ﻣﻘﺎﻃﻌﺔ‬ ‫ﻫـﺬﻩ ﺍﻹﺷﺎﺭﺓ ﻓﺈ‪‬ﺎ ﺳﺘﺒﻘﻰ ﺗﺮﺗﺪ ﻋﻠﻰ ﻃﻮﻝ ﺍﻟﺴﻠﻚ ، ﻭ ﺳﺘﻤﻨﻊ ﺍﳊﻮﺍﺳﺐ ﺍﻷﺧﺮﻯ ﻣﻦ ﺍﻹﺭﺳﺎﻝ ﳍﺬﺍ‬ ‫ﳚـﺐ ﺇﻳﻘـﺎﻑ ﻫﺬﻩ ﺍﻹﺷﺎﺭﺓ ﺑﻌﺪ ﻭﺻﻮﳍﺎ ﺇﱃ ﻋﻨﻮﺍ‪‬ﺎ ﺍﳌﻄﻠﻮﺏ. ﻹﻳﻘﺎﻑ ﺍﻹﺷﺎﺭﺓ ﻭﻣﻨﻌﻬﺎ ﻣﻦ ﺍﻻﺭﺗﺪﺍﺩ‬ ‫ﻳﺴـﺘﺨﺪﻡ ﻣـﻨﻬﻲ ‪ Terminator‬ﻭﻳـﺘﻢ ﻭﺿـﻌﻪ ﻋﻨﺪ ﻛﻞ ﻃﺮﻑ ﻣﻦ ﺃﻃﺮﺍﻑ ﺍﻟﺴﻠﻚ ﻭ ﻳﻮﺻﻞ ﺑﻜﻞ‬ ‫ﺣﺎﺳﻮﺏ ﻣﺘﺼﻞ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫‪ v‬ﻋﻤﻞ ‪ :Terminator‬ﻳﻘﻮﻡ ﺑﺎﻣﺘﺼﺎﺹ ﺃﻱ ﺇﺷﺎﺭﺓ ﺣﺮﺓ ﻋﻠﻰ ﺍﻟﺴﻠﻚ ﳑﺎ ﳚﻌﻠﻪ ﻣﻔﺮﻏﺎ‬ ‫ﻣﻦ ﺃﻱ ﺇﺷﺎﺭﺍﺕ ، ﳑﺎ ﳝﻜﻦ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺘﺎﱄ ﻣﻦ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﻧﺎﻗﻞ ﺍﻟﺸﺒﻜﺔ .‬ ‫‪v‬ﺍﻟﻌﻮﺍﻣﻞ ﺍﻟﱵ ﺗﺆﺛﺮ ﻋﻠﻰ ﺃﺩﺍﺀ ﺷﺒﻜﺔ ‪ Bus‬ﻫﻲ :‬ ‫• ﺍﻹﻣﻜﺎﻧﻴﺎﺕ ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ ﻣﻜﻮﻧﺎﺕ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫• ﻋﺪﺩ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫• ﻧﻮﻋﻴﺔ ﺍﻟﱪﺍﻣﺞ ﺍﳌﺸﻐﻠﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ .‬ ‫• ﺍﳌﺴﺎﻓﺔ ﺑﲔ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫31‬
‫ﻟﻜﻲ ﻳﺘﻢ ﺍﻻﺗﺼﺎﻝ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ، ﻻﺑﺪ ﻣﻦ‬ ‫ﺑﻌـﺾ ﺍﻷﺟﻬـﺰﺓ ﺍﳌﺴـﺘﺨﺪﻣﺔ ﰲ ﺍﻟﺸـﺒﻜﺎﺕ :‬ ‫ﺍﺳﺘﺨﺪﺍﻡ ﺑﻌﺾ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺴﺎﻋﺪﺓ ﻭ ﻧﺴﺘﻌﺮﺽ ﻓﻴﻤﺎ ﻳﻠﻲ ﻫﺬﻩ ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﻟﻮﻇﺎﺋﻒ ﺍﻟﱵ ﺗﻘﻮﻡ ‪‬ﺎ :‬ ‫‪ v‬ﺍﳌﻮﺩﻡ ‪: Modem‬‬ ‫ﻣﻦ ﺍﳌﻌﻠﻮﻡ ﺃﻥ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺗﺘﻌﺎﻣﻞ ﻣﻊ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ ‪ Digital signals‬ﻓﻘﻂ‬ ‫ﻭﻟﻜـﻦ ﺧﻄـﻮﻁ ﺍﳍﺎﺗﻒ ﺍﻟﻌﺎﺩﻳﺔ ﻻ ﺗﻨﻘﻞ ﺳﻮﻯ ﺍﻹﺷﺎﺭﺍﺕ‬ ‫ﺍﻟﺘﻮﺍﺻﻠﻴﺔ )ﺍﻟﺘﻤﺎﺛﻠﻴﺔ( ‪. Signals analog‬‬ ‫ﻭﳍـﺬﺍ ﻻﺑـﺪ ﻣﻦ ﺟﻬﺎﺯ )ﻣﻮﺩﻡ( ﳛﻮﻝ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ‬ ‫‪ digital‬ﺇﱃ ﺗﻮﺍﺻﻠﻴﺔ )ﺍﻟﺘﻤﺎﺛﻠﻴﺔ( ‪ analog‬ﰲ ﺍﻟﻄﺮﻑ ﺍﳌﺮﺳﻞ‬ ‫ﻋﱪ ﻋﻤﻠﻴﺔ ﺗﺪﻋﻰ ﺍﻟﺘﻌﺪﻳﻞ ‪. Modulation‬‬ ‫ﺍﻹﺷـﺎﺭﺍﺕ ﺍﻟﻨﺎﲡﺔ ﻋﱪ ﺧﻄﻮﻁ ﺍﳍﺎﺗﻒ ، ﲢﻮﻝ ﻣﻦ ﺗﻮﺍﺻﻠﻴﺔ‬ ‫)ﺍﻟﺘﻤﺎﺛﻠـﻴﺔ( ﺇﱃ ﺭﻗﻤﻴﺔ ﰲ ﺍﻟﻄﺮﻑ ﺍﳌﺴﺘﻘﺒﻞ ﻋﱪ ﻋﻤﻠﻴﺔ ﺗﺪﻋﻰ ﻓﻚ ﺍﻟﺘﻌﺪﻳﻞ ،‪ Demodulation‬ﻭ ﻣﻦ ﻫﻨﺎ‬ ‫ﻛﺎﻧـﺖ ﺃﺟﻬـﺰﺓ ﺍﳌﻮﺩﻡ ﻗﺎﺩﺭﺓ ﻋﻠﻰ ﺭﺑﻂ ﺃﺟﻬﺰﺓ ﺣﺎﺳﻮﺏ ، ﺃﻭ ﺣﱴ ﺷﺒﻜﺎﺕ ﻛﺎﻣﻠﺔ ﺑﻌﻴﺪﺓ ﻋﻦ ﺑﻌﻀﻬﺎ‬ ‫ﺑﺎﺳﺘﺨﺪﺍﻡ ﺍﳍﺎﺗﻒ .‬ ‫‪ v‬ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪: Hub‬‬ ‫ﺗﺘﺼﻞ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﰲ ﻣﻌﻈﻢ ﺃﻧﻮﺍﻉ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ‬ ‫ﲜﻬـﺎﺯ ﻳﻘـﻮﻡ ﺑـﺪﻭﺭ ﻧﻘﻄﺔ ﻭﺻﻞ ﻣﺮﻛﺰﻳﺔ ﺑﲔ ﺃﺟﻬﺰﺓ‬ ‫ﺍﻟﺸﺒﻜﺔ ، ﻭ ﻫﻮ ﻳﺪﻋﻰ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪hub‬‬ ‫ﻭ ﻭﻇﻴﻔﺘﻪ ﻫﻲ ﺭﺑﻂ ﻗﻄﻊ ﺍﻟﺸﺒﻜﺔ ﺑﺒﻌﻀﻬﺎ ، ﻭ ﻣﻦ ﺃﻧﻮﺍﻉ‬ ‫ﺍﳌﻮﺯﻋﺎﺕ :‬ ‫• ﺍﳌﻮﺯﻉ ﺍﳋﺎﻣﻞ ‪ : passive hub‬ﳝﺮﺭ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻮﺍﺭﺩﺓ‬ ‫ﻣﻦ ﺍﻟﻘﻄﻊ ﺍﳌﺨﺘﻠﻔﺔ ﻟﺸﺒﻜﺔ ، ﻭ ﺗﺴﺘﻄﻴﻊ ﲨﻴﻊ ﺍﻷﺟﻬﺰﺓ ﺍﳌﻮﺻﻮﻟﺔ ﻣﻌﻪ‬ ‫ﺍﺳﺘﻘﺒﺎﻝ ﺣﺰﻡ ‪ packets‬ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﺎﺭﺓ ﻋﱪﻩ .‬ ‫• ﺍﳌﻮﺯﻉ ﺍﻟﻨﺸﻂ ‪ : Active hub‬ﳛﻮﻱ ﻫﺬﺍ‬ ‫ﺍﳌﻮﺯﻉ ﺃﺟﺰﺍﺀ ﺇﻟﻴﻜﺘﺮﻭﻧﻴﺔ ﺗﻌﻴﺪ ﺗﻮﻟﻴﺪ ﺍﻹﺷﺎﺭﺍﺕ‬ ‫ﺍﳌﺎﺭﺓ ﰲ ﺍﻟﺸﺒﻜﺔ .‬ ‫41‬
‫‪ v‬ﺍﳌﻜﺮﺭ ‪: Repeater‬‬ ‫ﺗﺘﻌﺮﺽ ﺍﻹﺷﺎﺭﺍﺕ ﺃﺛﻨﺎﺀ ﻋﻤﻠﻴﺔ ﺍﻹﺭﺳﺎﻝ ﻟﻠﺘﺸﻮﻳﺶ ﻭ ﺍﻟﺘﺸﻮﻳﻪ‬ ‫ﻋﱪ ﺧﻄﻮﻁ ﺍﻟﻨﻘﻞ ، ﳑﺎ ﻭﻟﺪ ﺍﳊﺎﺟﺔ ﺇﱃ ﺗﺼﻤﻴﻢ ﺟﻬﺎﺯ ﻳﺪﻋﻰ‬ ‫ﺍﳌﻜـﺮﺭ ‪ Repeater‬ﻳﺴﺘﺨﺪﻡ ﻹﻧﻌﺎﺵ ﺍﻹﺷﺎﺭﺓ ﺍﳌﺮﺳﻠﺔ ﻋﱪ ﺍﻟﺸﺒﻜﺔ ﲝﻴﺚ ﺗﺒﻘﻰ ﻗﻮﻳﺔ ﻋﻨﺪ ﻭﺻﻮﳍﺎ ﺇﱃ‬ ‫ﳏﻄﺎﺕ ﺍﻟﻌﻤﻞ‬ ‫ﺍﳌﺴﺘﻘﺒﻠﺔ ﳍﺎ ﻭ ﻳﻮﺟﺪ ﻧﻮﻋﺎﻥ ﻣﻦ ﻫﺬﻩ ﺍﳌﻜﺮﺭﺍﺕ :‬ ‫• ﺗﻮﺍﺻﻠﻲ ‪ Analog‬ﻳﻀﺨﻢ ﺍﻹﺷﺎﺭﺓ ﻭ ﺣﺴﺐ .‬ ‫ﻳﻌﻴﺪ ﺑﻨﺎﺀ ﺍﻹﺷﺎﺭﺓ ﻟﺘﺼﺒﺢ ﻗﺮﻳﺒﺔ ﺟﺪﺍ ﻣﻦ ﺍﻷﺻﻠﻴﺔ.‬ ‫ﺭﻗﻤﻲ ‪Digital‬‬ ‫•‬ ‫‪ v‬ﺍﳉﺴﺮ ‪: Bridge‬‬ ‫ﻟﺘﻮﺳﻴﻊ ﺣﺠﻢ ﺍﻟﺸﺒﻜﺎﺕ ﺍﳌﻮﺟﻮﺩﺓ ﺻﻤﻢ ﺟﻬﺎﺯ ﻳﺪﻋﻰ ﺍﳉﺴﺮ‬ ‫‪ Bridge‬ﳝﻜﻨﻪ ﺭﺑﻂ ﺷﺒﻜﺘﲔ ﳏﻠﻴﺘﲔ ﺗﺴﺘﺨﺪﻣﺎﻥ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ‬ ‫ﻧﻔﺴﻪ .‬ ‫‪ v‬ﺍﶈﻮﻝ ‪: Switch‬‬ ‫ﻟﺘﺤﺪﻳﺪ ﺍﳌﺴﺎﺭ ﺍﻟﺬﻱ ﺗﻨﻘﻞ ﻋﱪﻩ ﺣﺰﻡ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺑﲔ ﺍﻟﻘﻄﻊ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﻟﻠﺸﺒﻜﺔ ﺍﶈﻠﻴﺔ ، ﻭ ﺗﺪﻋﻰ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﱵ‬ ‫ﺗﺴﺘﺨﺪﻣﻪ ‪. Switch LAN‬‬ ‫‪ v‬ﺍﳌﻮﺟﻪ ‪: Router‬‬ ‫ﻣﻊ ﺍﻻﺯﺩﻳﺎﺩ ﺍﳍﺎﺋﻞ ﰲ ﻋﺪﺩ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ، ﱂ ﻳﻜﻦ‬ ‫ﺍﳉﺴﺮ ‪ Bridge‬ﻗﺎﺩﺭﺍ ﻋﻠﻰ ﺇﺟﺮﺍﺀ ﻫﺬﺍ ﺍﻟﺮﺑﻂ، ﻓﻜﺎﻥ ﺍﳊﻞ‬ ‫ﰲ ﺟﻬﺎﺯ ﻳﺪﻋﻰ ﺍﳌﻮﺟﻪ ‪ Router‬ﻳﻘﻮﻡ ‪‬ﺬﺍ ﺍﻟﺮﺑﻂ‬ ‫ﻭ ﳝﺮﺭ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺣﺰﻡ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺑﺎﻻﻋﺘﻤﺎﺩ ﻋﻠﻰ ﻋﻨﺎﻭﻳﻦ ﻣﻨﻄﻘﻴﺔ‬ ‫ﻛﻤـﺎ ﻳﺘﺒﻊ ﺧﻮﺍﺭﺯﻣﻴﺔ ﲤﻜﻨﻪ ﻣﻦ ﺍﺧﺘﻴﺎﺭ ﺍﳌﺴﺎﺭ ﺍﻷﻓﻀﻞ ﻟﻨﻘﻞ ﺣﺰﻡ‬ ‫ﺍﳌﻌﻠﻮﻣﺎﺕ ﺇﱃ ﻫﺪﻓﻬﺎ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻷﺧﺮﻯ.‬ ‫51‬
‫ﻋﻠﻰ ﺭﺑﻂ ﺷﺒﻜﺎﺕ ﳏﻠﻴﺔ‬ ‫‪Router‬‬ ‫‪ v‬ﺍﻟﺒﻮﺍﺑﺔ ‪ : Gateway‬ﺃﺩﻯ ﻋﺪﻡ ﻣﻘﺪﺭﺓ ﺍﳌﻮﺟﻪ‬ ‫ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﻟﱪﺍﻣﺞ ﺍﻟﱵ ﺗﺮﺑﻂ ﺑﲔ ﺷﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ، ﺇﺫ ﺗﻨﻘﻞ‬ ‫ﺍﳌﻌﻠﻮﻣﺎﺕ ﻭ ﲢﻮﳍﺎ ﺇﱃ ﺻﻴﻐﺔ ﺗﺘﻮﺍﻓﻖ ﻣﻊ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺸﺒﻜﺔ ﺍﻷﺧﺮﻯ.ﺗﺴﺘﺨﺪﻡ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ﺇﱃ ﺍﺳﺘﺨﺪﺍﻡ ﻣﺎ ﻳﺪﻋﻰ ‪ Gateway‬ﻭ ﻫﻲ ﳎﻤﻮﻋﺔ ﻣﻦ‬ ‫61‬
  ‫ﻧﻈﻢ إدارة‬ ‫ﺑﺮﺗﻮﻛﻮﻻ‬ ‫ﻧﻈﻢ ﺗﺸﻐﻴﻞ‬ ‫أﺟﻬﺰة رﺑﻂ ﻣﻠﺤﻘﺔ‬ ‫ﺑﻄﺎﻗﺎت رﺑﻂ و وﺳﺎﺋﻂ‬ Computers ‫ﺣﺎﺳﺒﺎت‬ ‫اﻟﺸﺒﻜﺔ‬ ‫اﻻﺗﺼﺎل‬ ‫اﻟﺸﺒﻜﺔ‬ Devices Cards & NMS Communic NOS Communication ation Media Protocols ‫( - ﺟﻬﺎﺯ ﺗﻘﻮﻳﺔ ﺃﻭ‬coaxial ‫ﺃﺳﻼﻙ ﳏﻮﺭﻳﺔ‬ (Terminals)‫- ﻃﺮﻓﻴﺎﺕ‬ Repeater ‫ﻣﻜﺮﺭ‬ Cables) (PC) ‫- ﺣﺎﺳﺒﺎﺕ ﺷﺨﺼﻴﺔ‬ ‫ﺃﺳﻼﻙ ﻣﱪﻭﻣﺔ‬ Hub ‫- ﳎﻤﻊ‬ ‫- ﳏﻄﺎﺕ ﻋﻤﻞ‬ (Twisted Pairs) Bridge ‫- ﺟﺴﺮ‬ (Work Stations) (Optical ‫ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﻣﺘﻮﺳﻄﺔ‬ Gateway ‫- ﺑﻮﺍﺑﺔ‬ Fiber) (Mini Computers) Switch ‫- ﻣﻔﺘﺎﺡ‬ ‫ﺍﻷﻭﺳﺎﻁ ﺍﻟﻼﺳﻠﻜﻴﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﺭﺋﻴﺴﻴﺔ‬ ‫ﻣﺴﺎﺭ ﺭﺑﻂ‬ (Wireless Media) (Mainframe) Router ‫ﻛﺮﺩ ﻭﺍﺟﻬﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﻋﻤﻼﻗﺔ‬ ‫- ﻣﻮﺩﻡ‬ (NIC Card ) Modem (Super Computers) 17
‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ:‬ ‫ﺗﻌﺮﻳﻔﻬﺎ :‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻟﻘﻮﺍﻧﲔ ﻭ ﺍﻹﺟﺮﺍﺀﺍﺕ ﺍﻟﱵ ﺗﺘﺤﻜﻢ ﺑﺎﻻﺗﺼﺎﻝ‬ ‫ﻭ ﺍﻟﺘﻔﺎﻋﻞ ﺑﲔ ﺍﳊﻮﺍﺳﺐ ﺍﳌﺨﺘﻠﻔﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫ﰲ ﺍﳉﻬﺎﺯ ﺍﳌﺮﺳﻞ ﺗﻜﻮﻥ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﺴﺌﻮﻟﺔ ﻋﻦ ﺍﻟﻘﻴﺎﻡ ﺑﺎﳌﻬﺎﻡ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﻘﺴﻴﻢ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺣﺰﻡ.‬ ‫• ﺇﺿﺎﻓﺔ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻟﻌﻨﻮﻧﺔ ﺇﱃ ﺍﳊﺰﻡ.‬ ‫• ﲢﻀﲑ ﺍﳊﺰﻡ ﻟﻺﺭﺳﺎﻝ.‬ ‫ﺑﻴﻨﻤﺎ ﺗﻘﻮﻡ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﰲ ﺍﳉﻬﺎﺯ ﺍﳌﺴﺘﻘﺒﻞ ﺑﺎﻟﻌﻤﻞ ﺍﻟﺘﺎﱄ:‬ ‫• ﺍﻟﺘﻘﺎﻁ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﻭﺳﻂ ﺍﻻﺗﺼﺎﻝ.‬ ‫• ﺇﺩﺧﺎﻝ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺩﺍﺧﻞ ﺍﳊﺎﺳﻮﺏ ﻋﱪ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﲡﻤﻴﻊ ﻛﻞ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﳌﺮﺳﻠﺔ ﻭ ﻗﺮﺍﺀﺓ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻟﺘﺤﻜﻢ ﺍﳌﻀﺎﻓﺔ ﺇﱃ ﻫﺬﻩ ﺍﳊﺰﻡ.‬ ‫• ﻧﺴﺦ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﺍﳊﺰﻡ ﺇﱃ ﺫﺍﻛﺮﺓ ﻣﺆﻗﺘﺔ ﻹﻋﺎﺩﺓ ﲡﻤﻴﻌﻬﺎ.‬ ‫• ﲤﺮﻳﺮ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﳌﻌﺎﺩ ﲡﻤﻴﻌﻬﺎ ﺇﱃ ﺍﻟﱪﺍﻣﺞ ﰲ ﺻﻮﺭﺓ ﻣﻔﻬﻮﻣﺔ ﻗﺎﺑﻠﺔ ﻟﻼﺳﺘﺨﺪﺍﻡ .‬ ‫ﺗﻨﻘﺴﻢ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺑﺸﻜﻞ ﻋﺎﻡ ﺇﱃ ﻗﺴﻤﲔ:‬ ‫1.ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﳏﺪﺩﺓ ﻭﺟﻬﺔ ﺍﻻﺗﺼﺎﻝ ‪: Connection-Oriente‬‬ ‫ﻳﻘـﻮﻡ ﺍﻟـﱪﻭﺗﻮﻛﻮﻝ ﻣـﻦ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﺑﺈﻋﺪﺍﺩ ﺍﺗﺼﺎﻝ ﻣﺒﺎﺷﺮ ﻳﺴﻤﻰ ﺩﺍﺋﺮﺓ ﻇﺎﻫﺮﻳﺔ ﺃﻭ ﺍﻓﺘﺮﺍﺿﻴﺔ ﺑﲔ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﳌﺘﺼﻠﺔ ﰲ ﺍﻟﺸﺒﻜﺔ. ﻭ ﳛﻘﻖ ﻫﺬﺍ ﺍﻻﺗﺼﺎﻝ ﺍﳌﺒﺎﺷﺮ ﻣﻮﺛﻮﻗﻴﺔ ﻋﺎﻟﻴﺔ ﻟﺘﺴﻠﻴﻢ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﻟﻜﻨﻪ ﻗﺪ‬ ‫ﻳـﺆﺩﻱ ﺇﱃ ﺑﻄﺊ ﰲ ﻋﻤﻞ ﻭ ﺃﺩﺍﺀ ﺍﻟﺸﺒﻜﺔ. ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪Transmission Control Protocol‬‬ ‫)‪ (TCP‬ﻭﺍﺣﺪﺍ ﻣﻨﻬﺎ .‬ ‫81‬
‫2. ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪: Connectionless‬‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﻦ ﻫﺪﺍ ﺍﻟﻨﻮﻉ ﻻ ﺗﻮﻓﺮ ﺍﺗﺼﺎﻻ ﻣﺒﺎﺷﺮﺍ ﻣﻊ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺴﺘﻘﺒﻞ ﻗﺒﻞ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﳑـﺎ ﻳﻌﲏ ﺃﻥ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺗﻨﺘﻘﻞ ﺑﺴﺮﻋﺔ ﺃﻛﱪ ﳑﺎ ﳛﺴﻦ ﻣﻦ ﺃﺩﺍﺀ ﺍﻟﺸﺒﻜﺔ ، ﻭ ﻟﻜﻦ ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﻟﻴﺴﺖ‬ ‫ﺗﺎﻣﺔ ﺍﳌﻮﺛﻮﻗﻴﺔ ﻧﻈﺮﺍ ﻷﻧﻪ ﻻ ﺳﺒﻴﻞ ﳌﻌﺮﻓﺔ ﻓﻴﻤﺎ ﺇﺫﺍ ﺣﺪﺛﺖ ﺃﺧﻄﺎﺀ ﺃﺛﻨﺎﺀ ﺍﻹﺭﺳﺎﻝ ﺃﻡ ﱂ ﲢﺪﺙ.‬ ‫ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ )‪ Internet Protocol (IP‬ﻣﺜﺎﻻ ﻭﺍﺿﺤﺎ ﻋﻠﻰ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ .‬ ‫ﺗﻨﻘﺴﻢ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺣﺴﺐ ﻭﻇﻴﻔﺘﻬﺎ ﺇﱃ ﺛﻼﺙ ﺃﻗﺴﺎﻡ:‬ ‫1. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺗﻄﺒﻴﻘﺎﺕ ‪: Application Protocols‬‬ ‫ﺗﻌﻤـﻞ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﰲ ﺍﻟﻄﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻭ ﺗﺘﻠﺨﺺ ﻣﻬﻤﺘﻬﺎ ﰲ ﺗﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﲢﻘﻴﻖ‬ ‫ﺍﻟﺘﻔﺎﻋﻞ ﺑﲔ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻬﺎ:‬ ‫• )‪.Server Message Block (SMB‬‬ ‫• )‪. Novell’s NetWare Core Protocols (NCPs‬‬ ‫• )‪File Transfer Access and Management Protocol (FTAMP‬‬ ‫2. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻧﻘﻞ ‪: Transport Protocols‬‬ ‫ﺃﻣـﺎ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟـﻨﻘﻞ ﻓﺘﺴﺘﺨﺪﻡ ﻟﺘﻮﻓﲑ ﺟﻠﺴﺎﺕ ﺍﻻﺗﺼﺎﻝ ﺑﲔ ﺍﳊﻮﺍﺳﺐ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﻫﻲ‬ ‫ﻣﺴﺆﻭﻟﺔ ﻋﻦ ﺻﻴﺎﻧﺔ ﺟﻮﺩﺓ ﻭ ﺩﻗﺔ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﻨﻘﻮﻟﺔ ﺑﲔ ﺍﻷﺟﻬﺰﺓ ، ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻬﺎ:‬ ‫• ﺍﳉﺰﺀ ﺍﻟﻨﺎﻗﻞ ﻣﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ‪. NWLink‬‬ ‫• ﺍﳉﺰﺀ ﺍﻟﻨﺎﻗﻞ ﻣﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪. NetBEUI‬‬ ‫• )‪.Sequenced Packet Exchange(SPX‬‬ ‫• )‪.Transmission Control Protocol(TCP‬‬ ‫3. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺷﺒﻜﺔ ‪: Network Protocols‬‬ ‫ﺑﻴﻨﻤﺎ ﺗﻘﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺸﺒﻜﺔ ﺧﺪﻣﺎﺕ ﺭﺑﻂ ‪ Link Services‬ﻭ ﺗﺘﻠﺨﺺ ﻣﻬﺎﻣﻬﺎ ﰲ :‬ ‫• ﻋﻨﻮﻧﺔ ﻭ ﺗﻮﺟﻴﻪ ﺍﳌﻌﻠﻮﻣﺎﺕ.‬ ‫• ﺍﻟﺒﺤﺚ ﻋﻦ ﺃﺧﻄﺎﺀ ﰲ ﻋﻤﻠﻴﺔ ﺍﻹﺭﺳﺎﻝ.‬ ‫91‬
‫• ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻃﻠﺒﺎﺕ ﺇﻋﺎﺩﺓ ﺍﻹﺭﺳﺎﻝ.‬ ‫‪Token‬‬ ‫• ﲢﺪﻳـﺪ ﻗﻮﺍﻧـﲔ ﺍﻻﺗﺼﺎﻝ ﰲ ﺑﻴﺌﺎﺕ ﳏﺪﺩﺓ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﻣﺜﻞ ﺇﺛﺮﻧﺖ ﻭ‬ ‫‪.Ring‬‬ ‫ﻣﻦ ﺍﻷﻣﺜﻠﺔ ﻋﻠﻰ ﻫﺬﻩ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﺎ ﻳﻠﻲ:‬ ‫‪.Internet Protocol‬‬ ‫)‪(IP‬‬ ‫•‬ ‫‪. Internetwork Packet Exchange‬‬ ‫)‪(IPX‬‬ ‫•‬ ‫2. ﻭﺻﻒ ﻟﺒﺎﻗﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪: TCP/IP‬‬ ‫)‪Transmission Control Protocol/Internet Protocol(TCP/IP‬‬ ‫ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺎﻗﺔ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﱵ ﺗﺴﻤﺢ ﻟﻠﺸﺒﻜﺎﺕ ﻭ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ‬ ‫ﻣﻦ ﺍﻷﺟﻬﺰﺓ ﺑﺎﻻﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ. ﺣﻴﺚ ﻳﻮﻓﺮ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP/IP‬ﺧﺼﺎﺋﺺ ﺗﺸﺒﻴﻚ ﻭ ﺗﻮﺟﻴﻪ‬ ‫ﻭ ﻭﺻﻮﻝ ﻟﺸﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ ﻭ ﺍﻻﺳﺘﻔﺎﺩﺓ ﻣﻦ ﻣﻮﺍﺭﺩﻫﺎ. ﻭﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ﺍﻟﻘﻴﺎﺳﻲ ﺍﳌﺴﺘﺨﺪﻡ ﻟﻀﻤﺎﻥ‬ ‫ﺍﻟـﺘﻮﺍﻓﻖ ﺑﲔ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ، ﻭ ﺣﺎﻟﻴﺎ ﻓﺈﻥ ﺃﻏﻠﺐ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﻭ ﺍﻟﻮﺍﺳﻌﺔ ﺗﺪﻋﻢ‬ ‫ﻫـﺬﺍ ﺍﻟـﱪﻭﺗﻮﻛﻮﻝ. ﺗﺘﻜﻮﻥ ﺑﺎﻗﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP/IP‬ﻣﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ، ﻭﻟﻜﻦ‬ ‫ﺗﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP‬ﻭ ‪ IP‬ﻫﻲ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﶈﻮﺭﻳﺔ ﰲ ﻫﺬﻩ ﺍﻟﺒﺎﻗﺔ.‬ ‫‪ v‬ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪: TCP‬‬ ‫ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﳐﺼﺼﺎ ﻟﻠﻨﻘﻞ ‪ Transport Protocol‬ﻭﻫﻮ ﻳﻮﻓﺮ ﺍﺗﺼﺎﻻ ﻣﻮﺟﻬﺎ‬ ‫‪ Oriented -Connection‬ﻭ ﻳﺪﻋﻢ ﺍﻻﺗﺼﺎﻝ ﻣﺰﺩﻭﺝ ﺍﻻﲡﺎﻩ ‪ Full Duplex‬ﻭ ﻳﻮﻓﺮ ﲢﻜﻤﺎ ﺑﺘﺪﻓﻖ‬ ‫ﺍﻟﺒـﻴﺎﻧﺎﺕ. ﻛﻤﺎ ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﺑﻄﻴﺌﺎ ﰲ ﻋﻤﻠﻪ ﳍﺬﺍ ﻛﺎﻥ ﻻﺑﺪ ﻣﻦ ﺗﻮﻓﲑ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺁﺧﺮ‬ ‫ﺃﺳـﺮﻉ ﻳﻜﻮﻥ ﻋﻤﻠﻪ ﻣﻜﻤﻼ ﳍﺬﺍ ﰲ ﻧﻔﺲ ﻃﺒﻘﺔ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﰲ ﺣﺰﻣﺔ ‪ TCP/IP‬ﻛﻤﺎ ﳒﺪ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻ ﺁﺧﺮ ﻫﻮ ﺑﺮﻭﺗﻮﻛﻮﻝ )‪ User Datagram Protocol (UDP‬ﻭ ﻫﻮ ﻳﻮﻓﺮ ﺧﺪﻣﺔ ﺳﺮﻳﻌﺔ‬ ‫ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪ Connectionless‬ﻟﺘﻨﻔﻴﺬ ﻧﻔﺲ ﻭﻇﺎﺋﻒ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪.TCP‬‬ ‫02‬
‫ﺑﺮﻭﺗﻮﻛﻮﻝ ‪: IP‬‬ ‫ﻫـﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺷﺒﻜﺔ ‪ Network Protocol‬ﻭﻫﻮ ﻳﻮﻓﺮ ﺗﺴﻠﻴﻢ ﻟﻠﺒﻴﺎﻧﺎﺕ ﺩﻭﻥ‬ ‫ﺍﺗﺼﺎﻝ ﻣﺴﺒﻖ ‪ .Connectionless‬ﺗﺴﻠﻚ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﺴﺎﺭﺍﺕ ﳐﺘﻠﻔﺔ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺮﺳﻞ‬ ‫ﻭ ﺍﳌﺴـﺘﻘﺒﻞ ﰲ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ ﻭ ﻋﻨﺪ ﻭﺻﻮﻝ ﺍﳊﺰﻡ ﺇﱃ ﻭﺟﻬﺘﻬﺎ ﻓﺈﻥ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻫﻮ ﺍﳌﺴﺆﻭﻝ‬ ‫ﻋـﻦ ﺇﻋـﺎﺩﺓ ﺗﺮﺗﻴـﺐ ﻭ ﲡﻤـﻴﻊ ﺍﳊﺰﻡ ﻟﻠﺤﺼﻮﻝ ﻋﻠﻰ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻷﺻﻠﻴﺔ . ﻋﻠﻰ ﻧﻔﺲ ﺍﻟﻄﺒﻘﺔ ﻣﻊ‬ ‫ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﰲ ﺑﺎﻗـﺔ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP/IP‬ﻛﻤﺎ ﳒﺪ ﺃﻥ ﻫﻨﺎﻙ ﺑﺮﻭﺗﻮﻛﻮﻻ ﻣﻜﻤﻼ ﻟﻌﻤﻞ‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻭ ﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪ (ICMP) Internet Control Message Protocol‬ﻭﺣﻴﺚ‬ ‫ﻳﻮﻓـﺮ ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﺧﺪﻣﺔ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪ ، Connectionless‬ﻓﺈﺫﺍ ﺣﺼﻠﺖ ﺃﻱ ﻣﺸﺎﻛﻞ ﰲ‬ ‫ﺍﻹﺭﺳـﺎﻝ ﻓﺈﻧﻪ ﻻ ﻳﻮﺟﺪ ﺃﻱ ﻃﺮﻳﻘﺔ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻟﻠﺘﻌﺮﻑ ﻋﻠﻰ ﻫﺬﻩ ﺍﳌﺸﺎﻛﻞ ﺃﻭ ﺣﻠﻬﺎ ، ﻭ ﻫﻨﺎ‬ ‫ﻳﺄﰐ ﺩﻭﺭ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ ICMP‬ﻟﻴﻜﻮﻥ ﻣﻜﻤﻼ ﰲ ﻋﻤﻠﻪ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ ،IP‬ﻭ ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ‬ ‫ﻗﻴﺎﺳـﻲ ﻳﺆﻣﻦ ﺧﺪﻣﺔ ﺍﻟﺘﺮﺍﺳﻞ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ . IP‬ﻓﺈﺫﺍ ﺃﻋﺘﱪ ﺃﻥ ﺣﺰﻣﺔ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻗﺪ ﰎ ﻋﻨﻮﻧﺘﻬﺎ‬ ‫ﺑﺸـﻜﻞ ﺧﺎﻃﺊ ﻭ ﺃﺭﺳﻠﺖ ﻟﻮﺟﻬﺔ ﺧﺎﻃﺌﺔ ، ﻓﺈﻥ ﺩﻭﺭ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ ICMP‬ﻳﺘﻤﺜﻞ ﺑﺈﺻﺪﺍﺭ ﺗﻘﺮﻳﺮ ﻋﻦ‬ ‫ﺍﳌﺸـﻜﻠﺔ ﻭ ﺗﻮﺟﻴﻬﻬﺎ ﻟﻠﱪﻧﺎﻣﺞ ﺍﻟﺸﺒﻜﻲ ﳊﻞ ﻫﺬﻩ ﺍﳌﺸﻜﻠﺔ ، ﳍﺬﺍ ﳒﺪ ﺃﻥ ﻋﻤﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ICMP‬‬ ‫ﻳﺰﻳﺪ ﻣﻦ ﻣﻮﺛﻮﻗﻴﺔ ﻋﻤﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫ﺍﻟﻄﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻣﻦ ﺑﺎﻗﺔ ‪ TCP/IP‬ﺗﺘﻀﻤﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺘﺎﻟﻴﺔ :‬ ‫‪ : SMTP v‬ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ Simple Mail Transfer Protocol‬ﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ‬ ‫ﺍﳌﺴـﺆﻭﻝ ﻋﻦ ﺇﺭﺳﺎﻝ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﻭ ﻫﻮ ﻳﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﱄ ‪ TCP‬ﻭ ‪ IP‬ﻟﺘﺒﺎﺩﻝ‬ ‫ﺍﻟﺮﺳﺎﺋﻞ‬ ‫‪ : FTP v‬ﺑﻴـﻨﻤﺎ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ File Transfer Protocol‬ﻫﻮ ﺍﳌﺴﺆﻭﻝ ﻋﻦ ﻧﺴﺦ ﺍﳌﻠﻔﺎﺕ‬ ‫ﺑﲔ ﺟﻬﺎﺯ ﻭ ﺁﺧﺮ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﻫﻮ ﻳﺴﻤﺢ ﺑﺎﻷﻣﻮﺭ ﺍﻟﺘﺎﻟﻴﺔ :‬ ‫• ﺍﻟﺪﺧﻮﻝ ﺇﱃ ﺟﻬﺎﺯ ﺁﺧﺮ ﻋﻦ ﺑﻌﺪ .‬ ‫• ﺍﻟﺘﻨﻘﻞ ﺑﲔ ﺍ‪‬ﻠﺪﺍﺕ .‬ ‫• ﺗﻨﻔﻴﺬ ﻭ ﺗﺸﻐﻴﻞ ﺍﻷﻭﺍﻣﺮ .‬ ‫12‬
‫• ﻣﻌﺎﳉﺔ ﺍﳌﻠﻔﺎﺕ .‬ ‫‪ : SNMP v‬ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ Simple Network Management Protocol‬ﻭ ﺍﻟـﺬﻱ‬ ‫ﻃﻮﺭ‬ ‫ﻣﻦ ﻗﺒﻞ ‪ Internet Engineering Task Force‬ﻓﻬﻮ ﳐﺼﺺ ﻹﺩﺍﺭﺓ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻭ ﻳﻘـﻮﻡ ﲜﻤﻊ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻹﺩﺍﺭﺓ ﻣﻦ ﻛﻞ ﺟﻬﺎﺯ ﻣﺘﺼﻞ ﺑﺎﻟﺸﺒﻜﺔ ﻭ ﻫﻮ ﺃﻳﻀﺎ ﺍﻟﺬﻱ ﻳﺴﺘﻘﺒﻞ ﺍﻟﺘﻘﺎﺭﻳﺮ‬ ‫ﻋـﻦ ﺣـﺪﻭﺙ ﻣﺸـﺎﻛﻞ ﺃﻭ ﺃﺧﻄﺎﺀ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ، ﻭﻫﺬﺍ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ﻳﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻣﻨﻬﺎ : ) ‪(Telnet , IP, IPX , APPleTalk , DECnet‬‬ ‫‪ : Telnet v‬ﺗﻌﺘـﱪ ﻭﻇـﺎﺋﻒ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ Telnet‬ﻣﺸﺎ‪‬ﺔ ﻟﻮﻇﺎﺋﻒ ‪ FTP‬ﻓﻬﻮ ﻳﺴﻤﺢ‬ ‫ﺑﺎﻟﺪﺧﻮﻝ ﺇﱃ ﺟﻬﺎﺯ ﺁﺧﺮ ﻋﻦ ﺑﻌﺪ ﻭ ﺗﺸﻐﻴﻞ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻋﻠﻴﻪ .‬ ‫3. ﺃﻫﻢ ﳑﻴﺰﺍﺕ ﺣﺰﻣﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪: TCP/IP‬‬ ‫• ﺍﳌﻮﺛﻮﻗﻴﺔ ﻭ ﺍﻻﻧﺘﺸﺎﺭ .‬ ‫• ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ .‬ ‫• ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﺍﻧﺖ .‬ ‫• ﺩﻋﻢ ﺗﻮﺟﻴﻪ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ‪. Routing‬‬ ‫• ﺗﻮﻓﲑ ﺍﻟﻘﺎﺑﻠﻴﺔ ﻟﻼﺗﺼﺎﻝ ﻷﻧﻈﻤﺔ ﺍﻟﺘﺸﻐﻴﻞ ﻭ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺨﺘﻠﻔﺔ .‬ ‫• ﺍﻟﺪﻋﻢ ﻭ ﺍﻟﺘﻔﺎﻫﻢ ﻣﻊ ﻏﲑﻩ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ .‬ ‫22‬
‫4. ﺍﻟﻌﻴﻮﺏ ﺍﻷﺳﺎﺳﻴﺔ ﳊﺰﻣﺔ ‪: TCP/IP‬‬ ‫• ﺣﺠﻢ ﺍﳊﺰﻣﺔ ﺍﻟﻜﺒﲑ ﻭ ﺗﻌﻘﻴﺪﻫﺎ .‬ ‫ﺳـﺮﻋﺘﻪ ﺍﳌﺘﻮﺍﺿـﻌﺔ . ﺑﺎﻟﻨﺴﺒﺔ ﳍﺎﺗﲔ ﺍﳌﺸﻜﻠﺘﲔ ﻓﻘﺪ ﺃﺻﺒﺤﺘﺎ ﺃﻗﻞ ﺗﺄﺛﲑﺍ ﻣﻊ ﺍﻟﺘﻄﻮﺭ ﺍﻟﺬﻱ ﺣﺼﻞ ﰲ‬ ‫ﺃﻧﻈﻤـﺔ ﺍﻟﺘﺸـﻐﻴﻞ. ﺃﻣﺎ ﻋﻦ ﻣﻮﺿﻮﻉ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺑﺸﻜﻞ ﻋﺎﻡ، ﻫﻨﺎﻙ ﺃﻧﻮﺍﻉ ﻛﺜﲑﺓ ، ﻭ ﻗﺪ ﻋﻤﺪﻧﺎ‬ ‫ﺷﺮﺡ ﺍﻟﺸﻬﲑ ﻣﻨﻬﺎ ﻓﻘﻂ.‬ ‫32‬
‫ﺷﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ‪:Peer-to-Peer Networks‬‬ ‫1. ﺗﻌﺮﻳﻒ ﺷﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ : ﻫﻲ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻣﻜﻮﻧﺔ ﻣﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ﳍﺎ ﺣﻘﻮﻕ ﻣﺘﺴﺎﻭﻳﺔ‬ ‫ﻭ ﻻ ﲢﺘﻮﻱ ﻋﻠﻰ ﻣﺰﻭﺩ ﳐﺼﺺ ﺑﻞ ﻛﻞ ﺟﻬﺎﺯ ﰲ ﺍﻟﺸﺒﻜﺔ ﻳﻜﻮﻥ ﻣﺰﻭﺩ ﻭ ﺯﺑﻮﻧﺎ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫2. ﳑﻴﺰﺍ‪‬ﺎ:‬ ‫• ﻣﻦ ﺍﳌﻤﻴﺰﺍﺕ ﺍﻟﺮﺋﻴﺴﻴﺔ ﻟﺸﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ﻫﻮ ﺃﻥ ﺗﻜﻠﻔﺘﻬﺎ ﳏﺪﻭﺩﺓ .‬ ‫• ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﻻ ﲢﺘﺎﺝ ﺍﱃ ﺑﺮﺍﻣﺞ ﺇﺿﺎﻓﻴﺔ ﻋﻠﻰ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ .‬ ‫• ﻻ ﲢﺘﺎﺝ ﺍﱃ ﺃﺟﻬﺰﺓ ﻗﻮﻳﺔ ، ﻷﻥ ﻣﻬﺎﻡ ﺇﺩﺍﺭﺓ ﻣﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ ﻣﻮﺯﻋﺔ ﻋﻠﻰ ﻛﻞ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻭ ﻟﻴﺴﺖ ﻣﻮﻛﻠﺔ ﺍﱃ ﺟﻬﺎﺯ ﻣﺰﻭﺩ ﺑﻌﻴﻨﻪ.‬ ‫• ﺗﺜﺒﻴﺖ ﺍﻟﺸﺒﻜﺔ ﻭﺇﻋﺪﺍﺩﻫﺎ ﰲ ﻏﺎﻳﺔ ﺍﻟﺴﻬﻮﻟﺔ.‬ ‫• ﺃﻥ ﻳﻜﻮﻥ ﻋﺪﺩ ﺍﻷﺟﻬﺰﺓ ﰲ ﺍﻟﺸﺒﻜﺔ ﻻ ﻳﺘﺠﺎﻭﺯ ﺍﻟﻌﺸﺮﺓ .‬ ‫3. ﻋﻴﻮ‪‬ﺎ :‬ ‫• ﺍﻟﻌﻴﺐ ﺍﻟﺮﺋﻴﺴﻲ ﳍﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﻫﻮ ﺃ‪‬ﺎ ﻏﲑ ﻣﻨﺎﺳﺒﺔ ﻟﻠﺸﺒﻜﺎﺕ ﺍﻟﻜﺒﲑ ﺓ.‬ ‫• ﻣﻊ ﳕﻮ ﺍﻟﺸﺒﻜﺔ ﺗﺼﺒﺢ ﺍﻹﺩﺍﺭﺓ ﺍﻟﻼﻣﺮﻛﺰﻳﺔ ﺳﺒﺒﺎ ﰲ ﻫﺪﺭ ﺍﻟﻮﻗﺖ ﻭ ﺍﳉﻬﺪ.‬ ‫ﻣﻼﺣﻈﺔ :‬ ‫ﺇﺩﺍﺭﺓ ﺍﻟﺸﺒﻜﺔ ﻋﻠﻰ ﻧﻮﻋﲔ : ﻣﺮﻛﺰﻳﺔ ﻭ ﻣﻮﺯﻋﺔ .‬ ‫- ﰲ ﺣﺎﻟﺔ ﺍﻹﺩﺍﺭﺓ ﺍﳌﺮﻛﺰﻳﺔ ، ﻓﺈﻥ ﺍﻟﺸﺒﻜﺔ ﺗﻜﻮﻥ ﻣﺴﲑﺓ ﺑﻮﺍﺳﻄﺔ ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺷﺒﻜﺎﺕ ﻣﺮﻛﺰﻱ .‬ ‫- ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﻟﺸﺒﻜﺎﺕ : ﻫﻮ ﺍﻟﱪﻧﺎﻣﺞ ﺍﻟﺬﻱ ﻳﺪﻳﺮ ﻭ ﻳﺘﺤﻜﻢ ﺑﻨﺸﺎﻃﺎﺕ ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﳌﺴﺘﺨﺪﻣﲔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ .‬ ‫- ﰲ ﺣﺎﻟﺔ ﺍﻹﺩﺍﺭﺓ ﺍﳌﻮﺯﻋﺔ ، ﻓﺈﻥ ﻛﻞ ﻣﺴﺘﺨﺪﻡ ﻣﺴﺆﻭﻝ ﻋﻦ ﺇﺩﺍﺭﺓ ﺟﻬﺎﺯﻩ ﻭﲢﺪﻳﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﻭ ﺍﳌﻮﺍﺭﺩ ﺍﻟﱵ ﻳﺮﻳﺪ ﻣﺸﺎﺭﻛﺘﻬﺎ ﻣﻊ ﺍﻵﺧﺮﻳﻦ.‬ ‫4. ﺍﻧﻈﻤﺔ ﺍﻟﺘﺸﻐﻴﻞ:‬ ‫ﻳﻌﺘﱪ ﻧﻈﺎﻡ ‪ NT‬ﻭ ﻭﻳﻨﺪﻭﺯ 0002 ﺃﻓﻀﻞ ﻣﻦ ﺑﺎﻗﻲ ﺍﻷﻧﻈﻤﺔ ﻧﻈﺮﺍ ﻟﻸﺩﻭﺍﺕ ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ ﻹﺩﺍﺭﺓ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻭ ﺍﳌﺴﺘﻮﻯ ﺍﻟﻌﺎﱄ ﻣﻦ ﺍﻷﻣﺎﻥ ﺍﻟﺬﻱ ﺗﻮﻓﺮﻩ.‬ ‫42‬
‫ﺷﺒﻜﺎﺕ ﺍﻟﺰﺑﻮﻥ / ﺍﳌﺰﻭﺩ ‪: Client / Server Networks‬‬ ‫1. ﺗﻌﺮﻳﻒ ﺍﳌﺰﻭﺩ :‬ ‫ﺍﳌﺰﻭﺩ ﺟﻬﺎﺯ ﺣﺎﺳﻮﺏ ﳛﺘﻮﻱ ﻋﻠﻰ ﻣﺴﺎﺣﺔ ﲣﺰﻳﻦ ﻛﺒﲑﺓ ﻭ ﻣﻌﺎﰿ ﻗﻮﻱ ﻭﺫﺍﻛﺮﺓ ﻭﻓﲑﺓ ﻭﻗﺪ‬ ‫ﻳﻜﻮﻥ ﻣﺼﻨﻮﻋﺎ ﺧﺼﻴﺼﺎ ﻟﻴﻜﻮﻥ ﻣﺰﻭﺩ.‬ ‫2. ﳑﻴﺰﺍ‪‬ﺎ:‬ ‫• ﺍﻟﻨﺴﺦ ﺍﻹﺣﺘﻴﺎﻃﻲ ﳊﻤﺎﻳﺔ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﺍﻟﺘﻠﻒ ﻭ ﺍﻟﻀﻴﺎﻉ.‬ ‫• ﺗﺪﻋﻴﻢ ﺁﻻﻑ ﺍﳌﺴﺘﺨﺪﻣﲔ .‬ ‫• ﰲ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﺗﻜﻮﻥ ﻣﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ ﻣﺘﻤﺮﻛﺰﺓ ﰲ ﺟﻬﺎﺯ ﻭﺍﺣﺪ ﻫﻮ ﺍﳌﺰﻭﺩ.‬ ‫• ﻳﻌﺘﱪ ﺃﻣﻦ ﺍﻟﺸﺒﻜﺔ ﻣﻦ ﺃﻫﻢ ﺍﻷﺳﺒﺎﺏ ﻹﺳﺘﺨﺪﺍﻡ ﺷﺒﻜﺎﺕ ﺍﻟﺰﺑﻮﻥ / ﺍﳌﺰﻭﺩ.‬ ‫3. ﺃﻧﻮﺍﻉ ﻟﻠﻤﺰﻭﺩﺍﺕ ﻣﻦ ﺣﻴﺚ ﻋﻤﻠﻬﺎ:‬ ‫• ﻣﺰﻭﺩﺍﺕ ﻣﻠﻔﺎﺕ ‪. File Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻟﻄﺒﺎﻋﺔ ‪. Print Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ‪. Application Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻹﺗﺼﺎﻻﺕ ‪. Communication Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ ‪. Database Servers‬‬ ‫52‬
‫ﺷﺒﻜﺎﺕ ﺇﺛﲑﻧﺖ :‬ ‫ﺷﺮﻛﺔ ‪Xerox‬‬ ‫ﺗﻌﺘﱪ ‪ Ethernet‬ﺇﺣﺪﻯ ﻣﻌﻤﺎﺭﻳﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ‪ LAN‬ﺍﻟﱵ ﻃﻮﺭ‪‬ﺎ‬ ‫‪IEEE .Networking Standard‬‬ ‫ﰲ ﻣﻨﺘﺼﻒ ﺍﻟﺴﺒﻌﻴﻨﻴﺎﺕ، ﻭ ﻫﻲ ﲤﺜﻞ ﺍﻟﻘﺎﻋﺪﺓ ﳌﻌﻴﺎﺭ ﺍﻟﺘﺸﺒﻴﻚ‬ ‫ﺗﺴﺘﺨﺪﻡ ﺇﺛﺮﻧﺖ ﻃﺮﻳﻘﺔ ﺧﺎﺻﺔ ﻟﺘﺴﻤﺢ ﻷﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ ﺑﺈﺭﺳﺎﻝ ﺑﻴﺎﻧﺎ‪‬ﺎ‬ ‫3.208‬ ‫ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﺫﻟﻚ ﻟﺘﻨﻈﻴﻢ ﺣﺮﻛﺔ ﻧﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ ، ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﺗﺴﻤﻰ ﲢﺴﺲ ﺍﻟﻨﺎﻗﻞ ﻣﺘﻌﺪﺩ‬ ‫‪Carrier Sense Multiple Access with Collision‬‬ ‫ﺍﻟﻮﺻﻮﻝ ﻣﻊ ﺍﻛﺘﺸﺎﻑ ﺍﻟﺘﺼﺎﺩﻡ .‬ ‫)‪ ، Detection(CSMA/CD‬ﺑﺎﺳﺘﺨﺪﺍﻡ ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﻳﺮﺍﻗﺐ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺸﺒﻜﺔ ﻭ ﻳﻘﻮﻡ ﺑﺎﻹﺭﺳﺎﻝ‬ ‫ﻋﻨﺪﻣﺎ ﳛﺲ ﺃﻥ ﺍﻟﺴﻠﻚ ﻏﲑ ﻣﺸﻐﻮﻝ ﺑﺄﻱ ﺇﺷﺎﺭﺓ.ﺇﺫﺍ ﺣﺼﻞ ﺗﺼﺎﺩﻡ ﻧﺎﺗﺞ ﻋﻦ ﺣﺎﺳﻮﺏ ﺁﺧﺮ ﻗﺎﻡ ﺑﺈﺭﺳﺎﻝ‬ ‫ﺍﻟﺒﻴﺎﻧﺎﺕ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ ، ﻓﺈﻥ ﻛﻼ ﺍﳊﺎﺳﻮﺑﺎﻥ ﺳﻴﺘﻮﻗﻔﺎﻥ ﻋﻦ ﺍﻹﺭﺳﺎﻝ ﻭ ﺳﻴﻨﺘﻈﺮ ﻛﻞ ﻣﻨﻬﻤﺎ ﻭﻗﺖ‬ ‫ﻋﺸﻮﺍﺋﻲ ﻟﻴﻌﻴﺪ ﺇﺭﺳﺎﻝ ﺑﻴﺎﻧﺎﺗﻪ ﳑﺎ ﻳﻘﻠﻞ ﻣﻦ ﺍﺣﺘﻤﺎﻝ ﺣﺪﻭﺙ ﺗﺼﺎﺩﻡ ﺁﺧﺮ.‬ ‫ﺷﺒﻜﺎﺕ ‪:Token Ring‬‬ ‫ﻓﻜﺮﺓ ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻇﻬﺮﺕ ﺃﻭﻝ ﻣﺮﺓ ﰲ ﺃﻭﺍﺋﻞ ﺍﻟﺴﺘﻴﻨﺎﺕ ، ﻭﻟﻜﻨﻬﺎ ﱂ ﺗﻨﻔﺬ‬ ‫ﺇﻻ ﺑﻌﺪ ﺍﻹﺗﻔﺎﻕ ﻋﻠﻰ ﺍﳌﻌﻴﺎﺭ 5.208 ‪ IEEE‬ﺍﻟﺬﻱ ﻳﺼﻒ ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻣﻦ ﺧﻼﻝ ﺗﺼﻤﻴﻢ‬ ‫ﺍﳊﻠﻘﺔ ‪ Ring‬ﻭ ﻛﺎﻥ ﺫﻟﻚ ﻋﺎﻡ 5891 ﻭﻫﻲ ﲤﺜﻞ ﺍﳌﻨﺎﻓﺲ ﺍﻷﻗﻮﻯ ﻟﺸﺒﻜﺎﺕ ﺇﺛﺮﻧﺖ ﺫﺍﺕ ﺍﳌﻌﻴﺎﺭ ‪IEEE‬‬ ‫3.208 . ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻫﻲ ﺷﺒﻜﺎﺕ ﳏﻠﻴﺔ ‪ LAN‬ﻭ ﲡﻤﻊ ﺑﲔ ﺧﺎﺻﻴﺘﲔ:‬ ‫1. ﲤﺮﻳﺮ ﺍﻹﺷﺎﺭﺓ ‪. Token Passing‬‬ ‫2. ﺍﻟﺘﺼﻤﻴﻢ ﺍﳍﺠﲔ ﻟﻠﺤﻠﻘﺔ ﻭ ﺍﻟﻨﺠﻤﺔ .‬ ‫ﻗﺎﻣﺖ ﺍﻟﻠﺠﻨﺔ ﺍﳌﺴﺌﻮﻟﺔ ﻋﻦ ﺍﳌﻌﻴﺎﺭ 5.208 ‪ IEEE‬ﺑﺘﻄﻮﻳﺮ ﻭﺳﻴﻠﺔ ﻟﻠﺘﺤﻜﻢ ﺑﺎﻟﻮﺻﻮﻝ ﺍﱃ ﻭﺳﻂ‬ ‫ﺍﻹﺭﺳﺎﻝ )‪ ، Media Access Control (MAC‬ﻭ ﺗﺴﻤﻰ ﻫﺬﻩ ﺍﻟﻮﺳﻴﻠﺔ ﲤﺮﻳﺮ ﺍﻹﺷﺎﺭﺓ ‪Token‬‬ ‫‪. Passing‬‬ ‫ﺷﺒﻜﺎﺕ ‪ AppleTalk‬ﻭ ‪:ARCnet‬‬ ‫1. ﺷﺒﻜﺎﺕ ‪: AppleTalk‬‬ ‫ﰲ ﻣﻨﺘﺼﻒ ﺍﻟﺜﻤﺎﻧﻴﻨﺎﺕ ﻗﺎﻣﺖ ﺷﺮﻛﺔ ‪ Apple Computer‬ﺑﺘﻘﺪﱘ ﻣﻌﻤﺎﺭﻳﺔ ﻟﺸﺒﻜﺔ ﺧﺎﺻﺔ ﻟﺮﺑﻂ ﳎﻤﻮﻋﺔ‬ ‫ﺻﻐﲑﺓ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ. ﺗﻌﺘﱪ ﻗﺪﺭﺍﺕ ﺍﻟﺘﺸﺒﻴﻚ ﻣﺪﳎﺔ ﺩﺍﺧﻞ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺸﺨﺼﻲ ‪Apple‬‬ ‫)‪ Macintosh (Mac‬ﳑﺎ ﳚﻌﻞ ﻣﻌﻤﺎﺭﻳﺔ ﺷﺒﻜﺎﺕ ‪ Apple‬ﺃﺑﺴﻂ ﻣﻦ ﻏﲑﻫﺎ ﻣﻦ ﻣﻌﻤﺎﺭﻳﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ .‬ ‫62‬
‫1.1. ﺗﺘﻀﻤﻦ ﻋﺎﺋﻠﺔ ﺷﺒﻜﺎﺕ ‪ Apple‬ﺍﻟﺘﺎﱄ :‬ ‫• ‪. AppleTalk‬‬ ‫• ‪. LocalTalk‬‬ ‫• ‪. AppleShare‬‬ ‫• ‪. EtherTalk‬‬ ‫• ‪. TokenTalk‬‬ ‫ﺗﺴﺘﺨﺪﻡ ‪ LocalTalk‬ﻧﻈﺎﻡ ﺍﻟﻮﺻﻮﻝ ﺍﱃ ﺍﻟﻮﺳﻂ ﻣﻦ ﺍﻟﻨﻮﻉ ‪ CSMA/CA‬ﻭ ﺫﻟﻚ ﺑﻐﺾ ﺍﻟﻨﻈﺮ ﻫﻞ‬ ‫ﺍﻟﺘﺼﻤﻴﻢ ﻣﻦ ﻧﻮﻉ ﺍﻟﻨﺎﻗﻞ ﺃﻭ ﺍﻟﻨﺠﻤﺔ.‬ ‫2. ﺷﺒﻜﺔ ‪Arcnet‬‬ ‫ﺗﻌﺘﱪ ﺷﺒﻜﺔ )‪ Attached Resource Computer Network (ARCNet‬ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﺒﺴﻴﻄﺔ ﻏﲑ‬ ‫ﺍﳌﻜﻠﻔﺔ ﺍﳌﻮﺟﻬﺔ ﻟﺸﺒﻜﺎﺕ ﳎﻤﻮﻋﺎﺕ ﺍﻟﻌﻤﻞ.‬ ‫ﻭﻗﺪ ﻃﻮﺭﺕ ﺷﺒﻜﺎﺕ ‪ ARCNet‬ﻣﻦ ﻗﺒﻞ ﺷﺮﻛﺔ ‪ Datapoint Corporation‬ﻋﺎﻡ 7791.‬ ‫ﻭ ﺃﻭﻝ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ‪ ARCNet‬ﻛﺎﻧﺖ ﻣﺘﻮﻓﺮﺓ ﻋﺎﻡ 3891.‬ ‫ﺗﺴﺘﺨﺪﻡ ﺷﺒﻜﺎﺕ ‪ ARCNet‬ﻧﻈﺎﻡ ‪ Token Passing‬ﰲ ﺷﺒﻜﺎﺕ ﺍﻟﻨﺎﻗﻞ ‪ Bus‬ﺃﻭ ﺷﺒﻜﺎﺕ ‪Star‬‬ ‫‪. Bus‬‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ :‬ ‫ﺗﻮﻓﺮ ﺍﻷﺳﻼﻙ ﺧﻴﺎﺭﺍﺕ ﻓﻌﺎﻟﺔ ﻟﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﳌﻮﺍﺭﺩ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ، ﻭ ﻟﻜﻦ ﺍﻷﺳﻼﻙ‬ ‫ﻛﻮﺳﻂ ﺇﺭﺳﺎﻝ ﻻ ﳜﻠﻮ ﻣﻦ ﺍﻟﻌﻴﻮﺏ. ﳍﺬﺍ ﺑﺪﺃﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﻼﺳﻠﻜﻴﺔ ‪ Wireless LAN‬ﺗﺸﻜﻞ‬ ‫ﺧﻴﺎﺭﺍ ﻓﻌﺎﻻ ﻟﻠﺘﺸﺒﻴﻚ ﻭ ﺍﻟﺴﺒﺐ ﻳﺘﻠﺨﺺ ﻓﻤﺎﻳﻠﻲ :‬ ‫1. ﺍﻟﺘﻄﻮﺭﺍﺕ ﺍﳌﺘﻼﺣﻘﺔ ﰲ ﺍﻟﺘﻘﻨﻴﺎﺕ ﻭ ﺍﳌﻨﺘﺠﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ.‬ ‫2. ﺍﻹﳔﻔﺎﺽ ﺍﳌﺘﻮﺍﺻﻞ ﰲ ﺍﻷﺳﻌﺎﺭ.‬ ‫3. ﺍﻟﻄﻠﺐ ﺍﳌﺘﺰﺍﻳﺪ ﻋﻠﻰ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﺑﺴﺒﺐ ﺍﳊﺮﻳﺔ ﺍﻟﻜﺒﲑﺓ ﺍﻟﱵ ﺗﻮﻓﺮﻫﺎ.‬ ‫72‬
‫1. ﺗﻌﺘﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ ﻣﻔﻴﺪﺓ ﰲ ﺍﳊﺎﻻﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﻮﻓﲑ ﺇﺗﺼﺎﻻﺕ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﺰﺩﲪﺔ.‬ ‫• ﺗﻮﻓﲑ ﺇﺗﺼﺎﻻﺕ ﻟﻠﻤﺴﺘﺨﺪﻣﲔ ﻛﺜﲑﻱ ﺍﻟﺘﻨﻘﻞ.‬ ‫• ﺑﻨﺎﺀ ﺷﺒﻜﺎﺕ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻌﺰﻭﻟﺔ ﺍﻟﱵ ﻳﺼﻌﺐ ﺗﻮﺻﻴﻠﻬﺎ ﺑﺄﺳﻼﻙ.‬ ‫ﳏﻄﺔ ﺍﻟﻌﻤﻞ ﺍﻟﻼﺳﻠﻜﻴﺔ ﺗﺒﺪﻭ ﻭ ﺗﻌﻤﻞ ﺑﺸﻜﻞ ﻣﺸﺎﺑﻪ ﻟﻠﻤﺤﻄﺎﺕ ﺍﻟﺴﻠﻜﻴﺔ ﻭ ﺍﻹﺧﺘﻼﻑ ﺍﻟﻮﺣﻴﺪ‬ ‫ﻳﺘﻤﺜﻞ ﰲ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ ﺍﳌﺴﺘﺨﺪﻡ.‬ ‫ﻫﻨﺎﻙ ﺛﻼﺙ ﺗﻘﻨﻴﺎﺕ ﺃﺳﺎﺳﻴﺔ ﺗﺴﺘﺨﺪﻡ ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﰲ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ ﺍﶈﻠﻴﺔ:‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ﺃﺣﺎﺩﻳﺔ ﺍﻟﺘﺮﺩﺩ ‪. single-frequency radio‬‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺭﺍﺩﻳﻮ ﺍﻟﻄﻴﻒ ﺍﻹﻧﺘﺸﺎﺭﻱ ‪. spread-spectrum radio‬‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ ‪. infrared‬‬ ‫ﺑﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺔ ‪: Network Adapter Cards‬‬ ‫ﻟﻜﻲ ﻳﺘﻤﻜﻦ ﺟﻬﺎﺯ ﺍﳊﺎﺳﻮﺏ ﻣﻦ ﺍﻹﺗﺼﺎﻝ ﻻﺑﺪ ﻟﻪ ﻣﻦ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﻭ ﺍﻟﱵ ﺗﻌﺘﱪ ﺍﻟﻮﺍﺟﻬﺔ‬ ‫ﺍﻟﱵ ﺗﺼﻞ ﺑﲔ ﺟﻬﺎﺯ ﺍﳊﺎﺳﻮﺏ ﻭ ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ .‬ ‫1. ﺩﻭﺭ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ:‬ ‫• ﲢﻀﲑ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻟﺒﺜﻬﺎ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﺍﻟﺘﺤﻜﻢ ﺑﺘﺪﻓﻖ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﻭ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ .‬ ‫• ﺗﺮﲨﺔ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ﻣﻦ ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ ﺍﱃ ﺑﺎﻳﺘﺎﺕ ﻳﻔﻬﻤﻬﺎ ﻣﻌﺎﰿ ﺍﳊﺎﺳﻮﺏ‬ ‫ﻭ ﻋﻨﺪ ﺍﻹﺭﺳﺎﻝ ﻓﺈ‪‬ﺎ ﺗﺘﺮﺟﻢ ﺇﺷﺎﺭﺍﺕ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺮﻗﻤﻴﺔ ﺍﱃ ﻧﺒﻀﺎﺕ ﻛﻬﺮﺑﺎﺋﻴﺔ ﻳﺴﺘﻄﻴﻊ ﺳﻠﻚ‬ ‫ﺍﻟﺸﺒﻜﺔ ﲪﻠﻬﺎ.‬ ‫ﻛﻞ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﲤﺘﻠﻚ ﻋﻨﻮﺍﻥ ﺷﺒﻜﺔ ﻓﺮﻳﺪ ، ﻛﻤﺎ ﲢﺘﻮﻱ ﻋﻠﻰ ﺃﺟﺰﺍﺀ ﻣﺎﺩﻳﺔ ‪ Hardware‬ﻭ ﺃﺟﺰﺍﺀ‬ ‫ﺑﺮﳎﻴﺔ ‪) Software‬ﺍﳉﺰﺀ ﺍﻟﱪﳎﻲ ﻳﻜﻮﻥ ﳐﺰﻧﺎ ﺩﺍﺧﻞ ﺫﺍﻛﺮﺓ ‪ ROM‬ﻭ ﻳﻜﻮﻥ ﻣﺴﺆﻭﻝ ﻋﻦ ﺗﻮﺟﻴﻪ‬ ‫ﻭ ﺗﻨﻔﻴﺬ ﺍﳌﻬﺎﻡ ﺍﳌﻮﻛﻠﺔ ﺑﺎﻟﺒﻄﺎﻗﺔ(.‬ ‫82‬
‫ﺍﻟﻘﻀﺎﻳﺎ ﺍﻟﱵ ﳚﺐ ﺃﻥ ﺗﺘﻔﻖ ﻋﻠﻴﻬﺎ ﺍﻟﺒﻄﺎﻗﺎﺕ ﻟﻜﻲ ﻳﺘﻢ ﺍﻹﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ ﻫﻲ:‬ ‫1. ﺍﳊﺠﻢ ﺍﻷﻗﺼﻰ ‪‬ﻤﻮﻋﺎﺕ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺳﻴﺘﻢ ﺇﺭﺳﺎﳍﺎ.‬ ‫2. ﻣﻘﺪﺍﺭ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺳﻴﺘﻢ ﺇﺭﺳﺎﳍﺎ ﻗﺒﻞ ﺍﳊﺼﻮﻝ ﻋﻠﻰ ﺗﺄﻛﻴﺪ ﻟﻮﺻﻮﳍﺎ.‬ ‫3. ﻓﺘﺮﺓ ﺍﻟﺰﻣﻦ ﺍﻟﱵ ﺗﻔﺼﻞ ﺑﲔ ﺇﺭﺳﺎﻝ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫4. ﻓﺘﺮﺓ ﺍﻟﺰﻣﻦ ﺍﻟﱵ ﳚﺐ ﺇﻧﺘﻈﺎﺭﻫﺎ ﻗﺒﻞ ﺍﳊﺼﻮﻝ ﻋﻠﻰ ﺗﺄﻛﻴﺪ ﻭﺻﻮﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫5. ﻣﻘﺪﺍﺭ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺗﺴﺘﻄﻴﻊ ﻛﻞ ﺑﻄﺎﻗﺔ ﺍﺳﺘﻘﺒﺎﻟﻪ ﻗﺒﻞ ﺃﻥ ﺗﻔﻴﺾ ‪.Overflow‬‬ ‫6. ﺳﺮﻋﺔ ﻧﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫ﲟﺠﺮﺩ ﺍﻹﺗﻔﺎﻕ ﻋﻠﻰ ﺍﻟﻘﻀﺎﻳﺎ ﺍﻟﺴﺎﺑﻘﺔ ﺗﺒﺪﺃ ﻋﻤﻠﻴﺔ ﺗﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺑﲔ ﺍﻟﺒﻄﺎﻗﺎﺕ ﺑﺪﻭﻥ ﻣﺸﺎﻛﻞ.‬ ‫2. ﺗﻘﻮﻡ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﺑﻌﺪﺩ ﻣﻦ ﻣﻬﺎﻡ ﺍﻟﺘﺤﻜﻢ ﺗﺸﻤﻞ:‬ ‫• ﻣﺮﺍﻗﺒﺔ ﻭﺳﻂ ﺍﻹﺗﺼﺎﻝ.‬ ‫• ﻃﻠﺐ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﻟﺘﻌﺮﻑ ﻋﻠﻴﻬﺎ ﺑﺎﻟﺘﺄﻛﺪ ﻣﻦ ﺃﻥ ﻋﻨﻮﺍﻥ ﺍﻟﻮﺟﻬﺔ ﺍﳌﻮﺟﻮﺩ ﰲ ﺍﳊﺰﻣﺔ‬ ‫ﻫﻮ ﻧﻔﺴﻪ ﻋﻨﻮﺍﻥ ﺍﻟﺒﻄﺎﻗﺔ ﺍﻟﱵ ﺳﺘﺘﺴﻠﻢ ﺍﳊﺰﻣﺔ.‬ ‫• ﺍﻛﺘﺸﺎﻑ ﺍﻷﺧﻄﺎﺀ ﻭ ﺣﻠﻬﺎ.‬ ‫ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ‪: Network Drivers‬‬ ‫1. ﺗﻌﺮﻳﻒ :‬ ‫ﻣﺸﻐﻞ ﺍﳉﻬﺎﺯ ‪ Device Driver‬ﻫﻮ ﺍﻟﱪﻧﺎﻣﺞ ﺍﻟﺬﻱ ﻳﺴﻤﺢ ﻟﻨﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﳊﺎﺳﻮﺏ ﺑﺎﻟﻌﻤﻞ‬ ‫ﻭ ﺍﻟﺘﺨﺎﻃﺐ ﻣﻊ ﺟﻬﺎﺯ ﻣﻌﲔ.‬ ‫2. ﻛﻴﻔﻴﺔ ﻋﻤﻞ ﻣﺸﻐﻞ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ:‬ ‫ﺍﻥ ﺑﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ ﻳﺘﻢ ﺗﺼﻨﻴﻌﻬﺎ ﻣﻦ ﻗﺒﻞ ﺷﺮﻛﺎﺕ ﳐﺘﻠﻔﺔ ، ﻭ ﺑﺎﻟﺘﺎﱄ ﻓﻬﻨﺎﻙ ﺍﺣﺘﻤﺎﻝ‬ ‫ﺃﻥ ﻳﻜﻮﻥ ﻟﻜﻞ ﺑﻄﺎﻗﺔ ﺧﻮﺍﺹ ﳐﺘﻠﻔﺔ ﻭ ﺳﻴﻜﻮﻥ ﻣﻦ ﺍﳌﺴﺘﺤﻴﻞ ﻋﻤﻠﻴﺎ ﺗﺰﻭﻳﺪ ﲨﻴﻊ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ‬ ‫ﺑﺎﻟﱪﺍﻣﺞ ﺍﻟﻼﺯﻣﺔ ﻟﻠﻌﻤﻞ ﻣﻊ ﻛﻞ ﻧﻮﻉ ﻣﻦ ﺃﻧﻮﺍﻉ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ، ﻭ ﺑﺪﻻ ﻣﻦ ﺫﻟﻚ ﻓﺈﻥ ﻛﻞ ﻣﺼﻨﻊ‬ ‫ﻳﺰﻭﺩ ﺑﻄﺎﻗﺘﻪ ﺑﱪﻧﺎﻣﺞ ﻟﻠﺘﺸﻐﻴﻞ ﳐﺰﻥ ﻋﻠﻰ ﻗﺮﺹ ﻣﺮﻥ . ﻭ ﺃﺣﻴﺎﻧﺎ ﳛﺘﻮﻱ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﻋﻠﻰ ﻫﺬﻩ‬ ‫ﺍﳌﺸﻐﻼﺕ. ﺗﻘﻮﻡ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻮﻓﲑ ﺇﺗﺼﺎﻝ ﺑﲔ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻭ ﺑﲔ ﻣﻮﺟﻪ ﺑﺮﳎﻲ ﰲ ﺍﳊﺎﺳﻮﺏ‬ ‫ﻳﺴﻤﻰ ‪ Redirector Network‬ﻭ ﻫﻮ ﺟﺰﺀ ﻣﻦ ﺑﺮﻧﺎﻣﺞ ﺍﻟﺘﺸﺒﻴﻚ ﻭ ﻣﻬﻤﺘﻪ ﺍﺳﺘﻘﺒﺎﻝ ﻃﻠﺒﺎﺕ‬ ‫)‪ Input/Output (I/O‬ﻟﻠﻤﻠﻔﺎﺕ ﻋﻠﻰ ﺟﻬﺎﺯ ﺁﺧﺮ ﻭ ﲢﻮﻳﻠﻬﺎ ﻟﻠﺠﻬﺎﺯ ﺍﳌﻄﻠﻮﺏ. ﻳﺘﻢ ﺗﻨﺼﻴﺐ ﻣﺸﻐﻞ‬ ‫92‬
‫ﺍﻟﺒﻄﺎﻗﺔ ﻣﻦ ﺧﻼﻝ ﺑﺮﻧﺎﻣﺞ ﺍﻹﻋﺪﺍﺩ ﺍﳌﺘﻮﻓﺮ ﻋﻠﻰ ﺍﻟﻘﺮﺹ ﺍﳌﺮﻥ ﻭ ﻳﺘﻢ ﲣﺰﻳﻦ ﻫﺬﺍ ﺍﳌﺸﻐﻞ ﻋﻠﻰ ﺍﻟﻘﺮﺹ‬ ‫ﺍﻟﺼﻠﺐ ﻟﻠﺠﻬﺎﺯ.‬ ‫ﺗﻌﻤﻞ ﻣﺸﻐﻼﺕ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻣﻦ ﺧﻼﻝ ﺍﻟﻄﺒﻘﺔ ﺍﻟﻔﺮﻋﻴﺔ ‪ MAC‬ﻟﻄﺒﻘﺔ ‪ Data-Link‬ﰲ ‪OSI‬‬ ‫ﻋﻠﻰ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺃﻥ ﺗﻜﻮﻥ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ﺃﺣﺪ ﻣﻌﺎﻳﲑ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫1. )‪.Network Driver Interface Specification (NDIS‬‬ ‫2. )‪. Open Data-Link Interface (ODI‬‬ ‫‪Novell NetWare‬‬ ‫ﺑﺮﻧﺎﻣﺞ ﺗﺸﺒﻴﻚ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ﻣﺘﻮﺍﻓﻖ ﻣﻊ ‪ NDIS‬ﺑﻴﻨﻤﺎ ﺃﻧﻈﻤﺔ‬ ‫ﻓﻬﻲ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ‪. ODI‬ﺗﻘﻮﻡ ﻫﺬﻩ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺑﻌﺰﻝ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻋﻦ ﺗﻔﺎﺻﻴﻞ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﺍﳌﺴﺘﺨﺪﻣﺔ ﻭﻋﺰﻝ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﻦ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ ﻟﺒﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ. ﻣﻊ ﻫﺬﻩ‬ ‫ﺍﻟﻮﺍﺟﻬﺎﺕ ﺃﺻﺒﺢ ﻻ ﺩﺍﻋﻲ ﻟﻜﺘﺎﺑﺔ ﻣﺸﻐﻼﺕ ﺧﺎﺻﺔ ﻟﻜﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺃﻭ ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺑﻞ ﺃﺻﺒﺢ ﻳﻜﻔﻲ‬ ‫ﻛﺘﺎﺑﺔ ﻣﺸﻐﻼﺕ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ﺃﺣﺪ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺁﻧﻔﺔ ﺍﻟﺬﻛﺮ ﲝﻴﺚ ﺃﺻﺒﺢ ﺍﳌﺴﺘﺨﺪﻣﻮﻥ ﻗﺎﺩﺭﻭﻥ ﻋﻠﻰ‬ ‫ﺍﻹﺗﺼﺎﻝ ﻋﱪ ﺷﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ﺑﺎﺳﺘﺨﺪﺍﻡ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﻭﺣﻴﺪﺓ ﻭ ﻣﺸﻐﻞ ﺷﺒﻜﺔ‬ ‫ﻭﺣﻴﺪ ﻣﺘﻮﺍﻓﻖ ﻣﻊ ﻭﺍﺟﻬﺔ ‪ NDIS‬ﺃﻭ ‪ ODI‬ﻭ ﻣﻦ ﺍﳌﻤﻜﻦ ﻋﻨﺪ ﺍﻟﻀﺮﻭﺭﺓ ﲢﻤﻴﻞ ﻛﻼ ﺍﻟﻮﺍﺟﻬﺘﲔ ﻋﻠﻰ‬ ‫ﻧﻔﺲ ﺍﳉﻬﺎﺯ.‬ ‫ﺗﺘﻤﺘﻊ ﻭﺍﺟﻬﺔ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺍﻟﱵ ﺗﻌﺘﻤﺪﻫﺎ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ﻭ ﻫﻲ ‪ NDIS‬ﺑﺎﳌﻤﻴﺰﺍﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﺪﻋﻢ ﺇﺳﺘﺨﺪﺍﻡ ﺃﻛﺜﺮ ﻣﻦ ﻣﻌﺎﰿ ﻋﻠﻰ ﻧﻔﺲ ﺍﳉﻬﺎﺯ.‬ ‫• ﺗﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ ﺍﺗﺼﺎﻻﺕ ﺃﻭ ﺭﻭﺍﺑﻂ ﺷﺒﻜﻴﺔ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫• ﺗﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻧﻘﻞ ﳏﻤﻠﺔ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫ﻛﻞ ﻣﺸﻐﻞ ‪ NDIS‬ﻳﻜﻮﻥ ﻣﺴﺌﻮﻻ ﻋﻦ ﺍﳌﻬﺎﻡ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺇﺭﺳﺎﻝ ﻭ ﺍﺳﺘﻘﺒﺎﻝ ﺍﳊﺰﻡ ﻋﱪ ﺍﻹﺗﺼﺎﻝ ﺍﻟﺸﺒﻜﻲ.‬ ‫• ﺍﻹﺩﺍﺭﺓ ﺍﻟﻔﻌﻠﻴﺔ ﻟﺒﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﲟﺎ ﻳﺘﻨﺎﺳﺐ ﻣﻊ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ.‬ ‫• ﺗﺸﻐﻴﻞ ﻧﻈﺎﻡ ‪ Input/Output‬ﰲ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻭ ﺗﻠﻘﻲ ﻃﻠﺒﺎﺕ ﺍﳌﻘﺎﻃﻌﺔ ﻣﻨﻬﺎ.‬ ‫• ﺇﻋﻼﻡ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﺑﺎﺳﺘﻘﺒﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺃﻭ ﺍﻹﻧﺘﻬﺎﺀ ﻣﻦ ﺇﺭﺳﺎﳍﺎ.‬ ‫03‬
‫• ﻋﺰﻝ ﻣﻌﻠﻮﻣﺎﺕ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﺃﻭ ﻣﻜﻮﻧﺎﺕ ﺍﳉﻬﺎﺯ ﻋﻦ ﻣﺸﻐﻼﺕ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﰲ ﺣﺎﻟﺔ‬ ‫ﻋﺪﻡ ﺣﺎﺟﺔ ﻫﺬﻩ ﺍﳌﺸﻐﻼﺕ ﳍﺬﻩ ﺍﳌﻌﻠﻮﻣﺎﺕ.‬ ‫ﻣﺒﺎﺩﺉ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ :‬ ‫ﻗﺒﻞ ﺃﻥ ﻳﺘﻤﻜﻦ ﺣﺎﺳﻮﺑﲔ ﻣﻦ ﺍﻹﺗﺼﺎﻝ ﻣﻌﺎ ﻻﺑﺪ ﻣﻦ ﺗﻮﻓﺮ ﺷﺮﻃﲔ :‬ ‫1. ﺃﻥ ﺗﺘﻢ ﺗﺮﲨﺔ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﱃ ﺇﺷﺎﺭﺍﺕ ﳝﻜﻦ ﻧﻘﻠﻬﺎ ﺑﻴﻨﻬﻤﺎ.‬ ‫2. ﺃﻥ ﺗﺘﻮﻓﺮ ﻗﻨﺎﺓ ﻳﺴﺘﻄﻴﻌﺎﻥ ﻣﻦ ﺧﻼﳍﺎ ﺇﺭﺳﺎﻝ ﻭ ﺇﺳﺘﻘﺒﺎﻝ ﺍﻹﺷﺎﺭﺍﺕ.‬ ‫ﺗﺴﺘﻄﻴﻊ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﺳﺘﺨﺪﺍﻡ ﺍﻷﻧﻮﺍﻉ ﺍﻟﺘﺎﻟﻴﺔ ﻣﻦ ﺍﻹﺷﺎﺭﺍﺕ ﻟﻺﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ:‬ ‫‪.pulses‬‬ ‫ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ‪electrical‬‬ ‫• ﺍﻟﻨﺒﻀﺎﺕ‬ ‫• ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ‪. waves radio‬‬ ‫• ﻣﻮﺟﺎﺕ ﺍﳌﻴﻜﺮﻭ ﻭﻳﻒ ‪. microwaves‬‬ ‫‪.light‬‬ ‫‪infrared‬‬ ‫• ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ‬ ‫ﺍﳋﺎﺻﻴﺔ ﺍﻟﱵ ﲡﻤﻌﻬﺎ :‬ ‫ﻫﻨﺎﻙ ﺧﺎﺻﻴﺔ ﻭﺍﺣﺪﺓ ﲡﻤﻊ ﺑﲔ ﻫﺬﻩ ﺍﻹﺷﺎﺭﺍﺕ ﺍﳌﺨﺘﻠﻔﺔ ﻭ ﻫﻲ ﺃ‪‬ﺎ ﻛﻠﻬﺎ ﺗﻌﺘﱪ ﻣﻮﺟﺎﺕ‬ ‫ﻛﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ.‬ ‫13‬
‫ﺗﻌﺮﻳﻔﺎﺕ :‬ ‫1. ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺘﻤﺎﺛﻠﻴﺔ : ﻫﻲ ﺇﺷﺎﺭﺍﺕ ﻣﺴﺘﻤﺮﺓ ﺗﺘﻤﺜﻞ ﻓﻴﻬﺎ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻛﻤﻘﺎﺩﻳﺮ ﻓﻴﺰﻳﺎﺋﻴﺔ‬ ‫ﻣﻦ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ﻭ ﻣﺜﺎﻝ ﻋﻠﻴﻬﺎ ﺍﻟﺘﻴﺎﺭ ﺍﻟﻜﻬﺮﺑﺎﺋﻲ ﻭ ﺍﳌﻮﺟﺎﺕ ﺍﻟﺼﻮﺗﻴﺔ.‬ ‫2. ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ : ﻫﻲ ﺇﺷﺎﺭﺍﺕ ﻣﻨﻔﺼﻠﺔ ‪ disecrete‬ﻭ ﺗﺴﺘﺨﺪﻡ ﻗﻴﻤﺘﲔ ﻓﻘﻂ‬ ‫ﻫﻲ ﺻﻔﺮ ﺃﻭ ﻭﺍﺣﺪ ﻟﺘﻤﺜﻴﻞ ﺍﻹﺷﺎﺭﺓ ﺍﻷﺻﻠﻴﺔ.‬ ‫3. ﺍﳌﻮﺟﺎﺕ ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ : ﺗﻀﻢ ﺃﻧﻮﺍﻉ ﻋﺪﻳﺪﺓ ﻣﻦ ﺍﳌﻮﺟﺎﺕ ﺗﺘﺮﺍﻭﺡ ﺑﲔ ﺃﺷﻌﺔ‬ ‫ﺟﺎﻣﺎ ﻭﺑﲔ ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ﺍﻟﻄﻮﻳﻠﺔ. ﻫﺬﺍ ﺍﳌﺪﻯ ﺍﻟﻜﺒﲑ ﻣﻦ ﺍﳌﻮﺟﺎﺕ‬ ‫ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ ﻳﻄﻠﻖ ﻋﻠﻴﻪ ﺍﺳﻢ ﺍﻟﻄﻴﻒ ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻲ . ﺟﺰﺀ ﳏﺪﻭﺩ ﻓﻘﻂ‬ ‫ﻣﻦ ﻫﺬﺍ ﺍﻟﻄﻴﻒ ﻳﺴﺘﺨﺪﻡ ﻟﻨﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫23‬
‫ﻭﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ:‬ ‫1. ﻭﺳﺎﺋﻂ ﺳﻠﻜﻴﺔ: ﺍﻟﻮﺳﺎﺋﻂ ﺍﻟﺴﻠﻜﻴﺔ ﺗﻜﻮﻥ ﺇﻣﺎ ﺃﺳﻼﻙ ﻣﻌﺪﻧﻴﺔ ﺃﻭ ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ ﻭﺗﻮﺻﻞ ﺍﻟﻜﻬﺮﺑﺎﺀ‬ ‫ﻭ ﺍﻟﻀﻮﺀ ﻋﻠﻰ ﺍﻟﺘﻮﺍﱄ.‬ ‫2. ﻭﺳﺎﺋﻂ ﻻﺳﻠﻜﻴﺔ: ﺍﻹﺭﺳﺎﻝ ﺍﻟﻼﺳﻠﻜﻲ ﻳﺴﺘﺨﺪﻡ ﺍﻟﻐﻼﻑ ﺍﳉﻮﻱ ﻛﻮﺳﻂ ﺇﺭﺳﺎﻝ ﻟﻨﻘﻞ ﺍﻹﺷﺎﺭﺓ.‬ ‫2.2. ﺗﺘﻀﻤﻦ ﺍﻟﻮﺳﺎﺋﻂ ﺍﻟﻼﺳﻠﻜﻴﺔ :‬ ‫• ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ.‬ ‫• ﻣﻮﺟﺎﺕ ﺍﳌﻴﻜﺮﻭ ﻭﻳﻒ.‬ ‫• ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ.‬ ‫ﻗﺒﻞ ﲢﺪﻳﺪ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ ﺍﻷﻧﺴﺐ ﻟﺸﺒﻜﺔ ﻣﺎ ﳚﺐ ﺍﻹﺟﺎﺑﺔ ﻋﻠﻰ ﻫﺬﻩ ﺍﻷﺳﺌﻠﺔ:‬ ‫1. ﻣﺎ ﻫﻮ ﻣﻘﺪﺍﺭ ﺛﻘﻞ ﺃﻭ ﺍﺯﺩﺣﺎﻡ ﺣﺮﻛﺔ ﻧﻘﻞ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﺘﻮﻗﻊ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ؟‬ ‫2. ﻣﺎ ﻫﻲ ﺍﳌﺴﺎﻓﺔ ﺍﻟﱵ ﻋﻠﻰ ﻭﺳﻂ ﺍﻹﺗﺼﺎﻝ ﺗﻐﻄﻴﺘﻬﺎ ﺃﻭ ﺍﻟﻮﺻﻮﻝ ﺇﻟﻴﻬﺎ ؟‬ ‫3. ﻣﺎ ﻫﻲ ﺍﻹﺣﺘﻴﺎﺟﺎﺕ ﺍﻷﻣﻨﻴﺔ ﻟﻠﺸﺒﻜﺔ ؟‬ ‫4. ﻣﺎ ﻫﻲ ﺍﳌﻴﺰﺍﻧﻴﺔ ﺍﳌﺨﺼﺼﺔ ﻟﻮﺳﻂ ﺍﻹﺗﺼﺎﻝ ؟‬ ‫ﺃﻧﻮﺍﻉ ﻭﺧﺼﺎﺋﺺ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﻫﻨﺎﻙ ﺛﻼﺙ ﺃﻧﻮﺍﻉ ﺭﺋﻴﺴﻴﺔ ﻣﻦ ﺍﻷﺳﻼﻙ ﻫﻲ:‬ ‫‪ v‬ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ‪. Coaxial Cable‬‬ ‫‪ v‬ﺍﻷﺳﻼﻙ ﺍﳌﻠﺘﻮﻳﺔ ‪. Twisted Pair‬‬ ‫‪ v‬ﺍﻷﻟﻴﺎﻑ ﺍﻟﺒﺼﺮﻳﺔ ‪. Fiber Optic‬‬ ‫ﻫﻨﺎﻙ ﻃﺮﻳﻘﺘﺎﻥ ﻹﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ ﻋﱪ ﺍﻟﺴﻠﻚ ﳘﺎ:‬ ‫1. ﺃﻧﻈﻤﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻷﺳﺎﺳﻲ ‪:Baseband‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻹﺭﺳﺎﻝ ﺍﻟﺮﻗﻤﻲ ﻟﻺﺷﺎﺭﺓ ﺑﻮﺍﺳﻄﺔ ﺗﺮﺩﺩ ﻭﺍﺣﺪ ﻓﻘﻂ ، ﺣﻴﺚ ﺃﻥ ﺍﻹﺷﺎﺭﺓ ﺍﻟﺮﻗﻤﻴﺔ‬ ‫ﺗﺴﺘﺨﺪﻡ ﻛﺎﻣﻞ ﺳﻌﺔ ﻧﻄﺎﻕ ﺍﻟﺒﺚ ‪. Bandwidth‬‬ ‫33‬
‫ﺑﺎﺳﺘﺨﺪﺍﻡ ﻫﺬﻩ ﺍﻟﺘﻘﻨﻴﺔ ﰲ ﺍﻟﺒﺚ ﻳﺴﺘﻄﻴﻊ ﺃﻱ ﺟﻬﺎﺯ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺍﺕ ﰲ ﺍﲡﺎﻫﲔ ﻭﺑﻌﺾ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺗﺴﺘﻄﻴﻊ ﺇﺭﺳﺎﻝ ﻭ ﺍﺳﺘﻘﺒﺎﻝ ﺍﻹﺷﺎﺭﺓ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫2. ﺃﻧﻈﻤﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ ‪: Broadband‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻹﺭﺳﺎﻝ ﺍﻟﺘﻤﺎﺛﻠﻲ ﻟﻺﺷﺎﺭﺓ ‪ Analog‬ﻣﻊ ﻣﺪﻯ ﺃﻭﺳﻊ ﻣﻦ ﺍﻟﺘﺮﺩﺩﺍﺕ ، ﳑﺎ ﻳﺴﻤﺢ ﻷﻛﺜﺮ‬ ‫ﻣﻦ ﺇﺷﺎﺭﺓ ﺃﻥ ﺗﺴﺘﺨﺪﻡ ﻧﻔﺲ ﺍﻟﺴﻠﻚ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫ﻛﻤﺎ ﺃﻥ ﺗﺪﻓﻖ ﺍﻹﺷﺎﺭﺍﺕ ﰲ ﺃﻧﻈﻤﺔ ‪ Broadband‬ﻳﺘﻢ ﰲ ﺍﲡﺎﻩ ﻭﺍﺣﺪ ﻓﻘﻂ ﳊﻞ ﻫﺬﻩ ﺍﳌﺸﻜﻠﺔ ﺗﺴﺘﺨﺪﻡ‬ ‫ﺍﻟﻄﺮﻳﻘﺘﲔ ﺍﻟﺘﺎﻟﻴﺘﲔ :‬ ‫- ﺍﺳـﺘﺨﺪﺍﻡ ﺳـﻠﻚ ﺛـﻨﺎﺋﻲ ﻓـﻴﻜﻮﻥ ﻛﻞ ﺟﻬﺎﺯ ﻣﻮﺻﻞ ﺑﺴﻠﻜﲔ ﻭﺍﺣﺪ ﻟﻺﺭﺳﺎﻝ ﻭﺍﻵﺧﺮ‬ ‫ﻟﻺﺳﺘﻘﺒﺎﻝ.‬ ‫- ﺍﺳﺘﺨﺪﺍﻡ ﺳﻠﻚ ﻭﺍﺣﺪ ﻣﻊ ﺗﻘﺴﻴﻢ ﺳﻌﺔ ﺍﻟﻨﻄﺎﻕ ﺍﱃ ﻗﺴﻤﲔ ، ﲝﻴﺚ ﻳﺘﻮﻓﺮ ﻗﻨﺎﺗﲔ‬ ‫ﻭ ﻛﻞ ﻗﻨﺎﺓ ﺗﺴﺘﺨﺪﻡ ﺗﺮﺩﺩ ﳐﺘﻠﻒ ، ﻭﺗﻜﻮﻥ ﻭﺍﺣﺪﺓ ﻟﻺﺭﺳﺎﻝ ﻭ ﺍﻷﺧﺮﻯ ﻟﻺﺳﺘﻘﺒﺎﻝ.‬ ‫ﺗﺴﺘﺨﺪﻡ ﺃﻧﻈﻤﺔ ‪ Broadband‬ﺃﺟﻬﺰﺓ ﺧﺎﺻﺔ ﻟﺘﻘﻮﻳﺔ ﺍﻹﺷﺎﺭﺓ ﺍﻟﺘﻤﺎﺛﻠﻴﺔ .‬ ‫ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ:‬ ‫‪v‬‬ ‫ﻣﺎﺩﺓ ﻋﺎﺯﻟﺔ‬ ‫ﻏﻄﺎﺀ ﺧﺎﺭﺟﻲ ﻣﺼﻨﻮﻍ ﻣﻦ ﺍﻟﺒﻼﺳﺘﻴﻚ‬ ‫ﺿﻔﺎﺋﺮ ﻣﻌﺪﻧﻴﺔ ﻟﻠﺤﻤﺎﻳﺔ‬ ‫ﳏﻮﺭ ﻣﻦ ﺍﻟﻨﺤﺎﺱ ﺍﻟﺼﻠﺐ‬ ‫1. ﺃﻧﻮﺍﻉ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ:‬ ‫1.1. ﺍﻟﺴﻠﻚ ﺍﶈﻮﺭﻱ ﺍﻟﺮﻗﻴﻖ ‪ : Thin‬ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺳﻠﻚ ﻣﺮﻥ ﺭﻗﻴﻖ ﻳﺴﺘﺨﺪﻡ‬ ‫ﻋﺎﺩﺓ ﰲ ﺷﺒﻜﺎﺕ 2‪ 10Base‬ﻭ ﻳﻮﺻﻞ ﻣﺒﺎﺷﺮﺓ ﺍﱃ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ.‬ ‫43‬
‫: ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺳﻠﻚ ﺛﺨﲔ ﻣﺘﺼﻠﺐ ﻭ‬ ‫‪Thick‬‬ ‫1.2. ﺍﻟﺴﻠﻚ ﺍﶈﻮﺭﻱ ﺍﻟﺜﺨﲔ‬ ‫ﻏﲑ ﻣﺮﻥ ﻳﺴﺘﺨﺪﻡ ﻋﺎﺩﺓ ﰲ ﺷﺒﻜﺎﺕ 5‪ 10Base‬ﻭ ﻷﻧﻪ ﺃﺛﺨﻦ ﻣﻦ ﺍﻟﻨﻮﻉ‬ ‫ﺍﻷﻭﻝ ﻓﺈﻧﻪ ﻳﺴﺘﻄﻴﻊ ﺍﻟﻮﺻﻮﻝ ﺍﱃ ﻣﺴﺎﻓﺎﺕ ﺃﺑﻌﺪ ﺩﻭﻥ ﺗﻮﻫﲔ ﻟﻺﺷﺎﺭﺓ .‬ ‫2. ﺍﳌﻮﺍﺻﻔﺎﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ:‬ ‫11-‪RG‬‬ ‫ﻭ‬ ‫8-‪RG‬‬ ‫1. 05 ﺃﻭﻡ )ﺃﻭﻡ ﻫﻲ ﻭﺣﺪﺓ ﻗﻴﺎﺱ ﻣﻘﺎﻭﻣﺔ ﺍﻟﺴﻠﻚ ﻟﻠﺘﻴﺎﺭ ﺍﳌﺘﺮﺩﺩ(‬ ‫)ﻟﻠﺴﻠﻚ ﺍﻟﺜﺨﲔ(.‬ ‫2. 05 ﺃﻭﻡ 85-‪ RG‬ﻟﻠﺴﻠﻚ ﺍﻟﺮﻗﻴﻖ.‬ ‫3. 57 ﺃﻭﻡ 95-‪ RG‬ﻭ ﻳﺴﺘﺨﺪﻡ ﻟﺴﻠﻚ ﺍﻟﺘﻠﻔﺎﺯ.‬ ‫4. 39 ﺃﻭﻡ 26-‪ RG‬ﻭ ﺗﺴﺘﺨﺪﻡ ﳌﻮﺍﺻﻔﺎﺕ ﺷﺒﻜﺎﺕ ‪. ARCnet‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ﻣﺸﺎﺑﻚ ﺃﻭ ﻭﺻﻼﺕ ﺧﺎﺻﺔ ﻟﻮﺻﻞ ﺍﻷﺳﻼﻙ ﻣﻌﺎ ﻭﺷﺒﻚ ﺍﻷﺟﻬﺰﺓ ﺗﺴﻤﻰ‬ ‫ﻫﺬﻩ ﺍﳌﺸﺎﺑﻚ )‪. BNC (British Naval Connectors‬‬ ‫ﺗﺘﻀﻤﻦ ﻋﺎﺋﻠﺔ ﻣﺸﺎﺑﻚ ‪ BNC‬ﺍﳌﻜﻮﻧﺎﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫1. ‪. BNC cable connector‬‬ ‫2. ‪. BNC T connector‬‬ ‫3. ‪. BNC barrel connector‬‬ ‫4. ‪. BNC terminator‬‬ ‫3. ﺍﺻﻨﺎﻓﻬﺎ:‬ ‫ﺗﺼﻨﻒ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ﺍﱃ ﺻﻨﻔﲔ ﻭﻓﻘﺎ ﻟﺘﺮﻛﻴﺐ ﻏﻼﻓﻬﺎ ﺍﳋﺎﺭﺟﻲ ﻭ ﻃﺒﻴﻌﺔ ﺍﳌﻜﺎﻥ ﺍﻟﺬﻱ ﺳﺘﺮﻛﺐ‬ ‫ﻓﻴﻪ ﻭ ﻫﺬﺍﻥ ﺍﻟﺼﻨﻔﺎﻥ ﳘﺎ:‬ ‫ﺍﻟﺼﻨﻒ ﺍﻷﻭﻝ )‪ : polyvinyl chloride (PVC‬ﻣﺮﻥ ﻭ ﳑﻜﻦ ﺍﺳﺘﺨﺪﺍﻣﻪ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻔﺘﻮﺣﺔ‬ ‫ﺃﻭ ﺍﳌﻌﺮﺿﺔ ﻟﺘﻬﻮﻳﺔ ﺟﻴﺪﺓ ﻭﻟﻜﻦ ﻧﻈﺮﺍ ﻷﻧﻪ ﻗﺪ ﺗﻨﺒﻌﺚ ﻣﻨﻪ ﺭﻭﺍﺋﺢ ﺳﺎﻣﺔ ﰲ ﺣﺎﻟﺔ ﺣﺪﻭﺙ ﺣﺮﻳﻖ ﻓﺈﻥ‬ ‫ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﻏﲑ ﺍﶈﺒﺬ ﺍﺳﺘﺨﺪﺍﻣﻪ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻐﻠﻘﺔ ﺃﻭ ﺳﻴﺌﺔ ﺍﻟﺘﻬﻮﻳﺔ.‬ ‫53‬
Networks
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Networks

  • 2. ‫‪‬‬ ‫‪‬‬ ‫‪‬‬ ‫ﺗﺎﺭﻳﺦ ﺍﻟﺸﺒﻜﺎﺕ ــــــــــــــــ 50‬ ‫60‬ ‫ﺗﻌﺮﻳﻒ ﺷﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ ـــــــــــــ‬ ‫ـــــــــــ 70‬ ‫ﻓﻮﺍﺋﺪ ﻭ ﺧﺪﻣﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ــــــــــــ80‬ ‫ﺍﳊﺪ ﺍﻷﺩﱏ ﳌﻜﻮﻧﺎﺕ ﺷﺒﻜﺔ‬ ‫ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺔـــــــــــــــــ80‬ ‫ـــــــــــــــ01‬‫ﺧﺼﺎﺋﺺ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﺃﻧﻮﺍﻉ ﺍﻟﻨﻮﺍﻗﻞ ـــــــــــــــــ11‬ ‫ــــــــــــــــ11‬ ‫ﺗﺼﺎﻣﻴﻢ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺑﻌﺾ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺴﺘﺨﺪﻣﺔ ﰲ ﺍﻟﺸﺒﻜﺎﺕ ــــــ41‬ ‫ـــــــ71‬ ‫ﺟﺪﻭﻝ ﻳﻠﺨﺺ ﲨﻴﻊ ﻣﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ـــــــــــــــــ81‬ ‫2‬
  • 3. ‫‪‬‬ ‫‪‬‬ ‫‪‬‬ ‫____________________42‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﺪ ﻟﻠﻨﺪ‬ ‫ﺷﺒﻜﺔ ﺍﳌﺰﻭﺩ /ﺍﻟﺰﺑﻮﻥ _________________52‬ ‫_____________________62‬ ‫ﺷﺒﻜﺔ ﺇﺛﺮﻧﺖ‬ ‫ﺷﺒﻜﺔ ‪26 ________________ token ring‬‬ ‫_________62‬‫ﺷﺒﻜﺎﺕ ‪apple Talk‬ﻭ‪RCnet‬‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ __________________72‬ ‫_____________________82‬ ‫ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫____________92‬‫ﻛﻴﻔﻴﺔ ﻋﻤﻞ ﻣﺸﻐﻞ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻣﺒﺎﺩﺉ ﺍﻹﺭﺳﺎﻝ ____________________13‬ ‫____________________33‬ ‫ﻭﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ‬ ‫ﺃﻧﻮﺍﻉ ﻭ ﺧﺼﺎﺋﺺ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺔ___________33‬ ‫_____________________93‬ ‫ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﻣﺒﺎﺩﺉ ﻭ ﺃﺳﺎﻟﻴﺐ ﺍﻟﻮﺻﻮﻝ ﻟﻮﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ _____44‬ ‫________________74‬ ‫ﻣﺒﺎﺩﺉ ‪Osi‬‬ ‫ﻣﺒﺎﺩﺉ 208 ‪Project‬ــــــ74‬ ‫3‬
  • 4. ‫‪‬‬ ‫ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ ـــــــــــــ15‬ ‫ﻛﻴﻔﻴﺔ ﺗﺮﻛﻴﺐ‬ ‫ﻣﺮﺍﺣﻞ ﺗﺜﺒﻴﺖ ﺍﻟﺸﺒﻜﺔ ﰲ ﺍﻟﻨﻈﺎﻣــــــــــــ35‬ ‫85‬ ‫ﺷﺮﺡ ﻛﻴﻔﻴﺔ ﺑﻨﺎﺀ ﺷﺒﻜﺔ ﻣﻌﻠﻮﻣﺎﺗﻴﺔ ______________‬ ‫4‬
  • 5. ‫ﺗﺎﺭﻳﺦ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﺑﺪﺃﺕ ﺃﻭﱃ ﳏﺎﻭﻻﺕ ﺍﻟﺘﻮﺍﺻﻞ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ﰲ ﻋﺎﻡ 0691 ﺣﻴﺚ ﰎ ﺑﻨﺎﺀ ﺃﻭﻝ ﺷﺒﻜﺔ‬ ‫ﰲ ﺍﻟﻌﺎﱂ ﺍﲰﻬﺎ ‪ saber‬ﻭ ﺍﺳﺘﺨﺪﻣﺖ ﰲ ﳎﺎﻝ ﺣﺠﺰ ﺗﺬﺍﻛﺮ ﺍﻟﻄﲑﺍﻥ ﻭ ﰎ ﺑﻨﺎﺅﻫﺎ ﻋﻦ ﻃﺮﻳﻖ ﺍﻟﺘﻌﺎﻭﻥ ﺍﻟﺬﻱ‬ ‫ﰎ ﺑﲔ ﺷﺮﻛﺔ ‪ IBM‬ﻭ ﻣﺆﺳﺴﺔ ﺍﻟﻄﲑﺍﻥ ،‪ American Air lines‬ﰒ ﻇﻬﺮﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﰲ ﻋﺎﻡ‬ ‫4691 ﻟﺘﺴـﻬﻞ ﺗﺸﺎﺭﻙ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻭ ﺍﳋﺪﻣﺎﺕ ﻣﻊ ﺍﶈﻴﻂ ﺍﻟﻘﺮﻳﺐ ، ﻭ ﱂ ﺗﻠﺒﺚ ﺃﻥ ﺗﻮﺟﻬﺖ ﺍﻟﺘﻄﻮﺭﺍﺕ‬ ‫ﺇﱃ ﺗـﺄﻣﲔ ﺍﻟﺘﻮﺍﺻـﻞ ﺍﻟﺸـﺒﻜﻲ ﻣـﻊ ﳎﻤﻮﻋﺎﺕ ﺃﻛﱪ ، ﻓﻈﻬﺮﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻮﺍﺳﻌﺔ ‪Wide Area‬‬ ‫‪ Networks‬ﰲ ﻋﺎﻡ 6691 ، ﻭﻫﻨﺎ ﻛﺎﻧﺖ ﺑﺪﺍﻳﺔ ﻣﺮﺣﻠﺔ ﺟﺪﻳﺪﺓ ﰲ ﺛﻮﺭﺓ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﱵ ﱂ ﺗﺘﻮﻗﻒ ﻋﻨﺪ‬ ‫ﻫﺬﺍ ﺍﳊﺪ ﻓﺄﻧﺸﺌﺖ ﻭﺍﺣﺪﺓ ﰲ ﻭﺯﺍﺭﺓ ﺍﻟﺪﻓﺎﻉ ﺍﻷﻣﺮﻳﻜﻴﺔ ﰲ ﺳﻨﺔ 9691 ﺗﺴﻤﻰ ‪ ARPANET‬ﻭ ﺍﻟﱵ‬ ‫ﻛـﺎﻥ ﻣـﻦ ﺃﻋﻈﻢ ﻧﺘﺎﺋﺠﻬﺎ ﻇﻬﻮﺭ ﺍﻹﻧﺘﺮﻧﺖ ﻓﻴﻤﺎ ﺑﻌﺪ ، ﻭ ﺍﻟﱵ ﺍﺗﺴﻌﺖ ﻟﺘﺸﻤﻞ ﺃﻗﻄﺎﺏ ﻛﻮﻛﺒﻨﺎ ﺍﻟﺼﻐﲑ‬ ‫ﻓﺄﺣﺎﻟﺘﻪ ﻗﺮﻳﺔ ﺻﻐﲑﺓ ، ﻳﺮﻯ ﻭﻳﺴﻤﻊ ﻭ ﻳﺘﺒﺎﺩﻝ ﺃﻓﺮﺍﺩﻫﺎ ﻣﻌﺎﺭﻓﻬﻢ ﻭ ﻣﻌﻠﻮﻣﺎ‪‬ﻢ ﺑﺴﻬﻮﻟﺔ ﱂ ﻳﺴﺒﻖ ﳍﺎ ﻣﺜﻴﻞ .‬ ‫ﻭﻣـﻦ ﺍﳌﺆﻛﺪ ﺃﻥ ﺁﻣﺎﻝ ﺍﻟﻘﺎﺋﻤﲔ ﻋﻠﻰ ﺗﻄﻮﻳﺮﻫﺎ ، ﻟﻦ ﺗﺘﻮﻗﻒ ﻋﻨﺪ ﻫﺬﺍ ﺍﳊﺪ ﺑﻞ ﻫﻲ ﻣﺎﺿﻴﺔ ﻗﺪﻣﺎ ﻟﻼﺭﺗﻘﺎﺀ‬ ‫ﺑﺸﺒﻜﺎﺕ ﺍﳊﺎﺳﻮﺏ ﺇﱃ ﻣﺎ ﳛﺎﻛﻲ ﺍﻟﺸﺒﻜﺔ ﺍﻟﻌﺼﺒﻴﺔ ﺍﻹﻧﺴﺎﻧﻴﺔ ﻣﻦ ﺣﻴﺚ ﺍﻟﻔﺎﻋﻠﻴﺔ ﻭ ﺍﻻﺳﺘﺠﺎﺑﺔ .‬ ‫5‬
  • 6. ‫ﺗﻌﺮﻳﻒ ﺷﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ :‬ ‫ﺍﻟﺸـﺒﻜﺔ ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﺣﺎﺳﺒﺎﺕ ﻣﺘﻨﻮﻋﺔ ﻭ ﳐﺘﻠﻔﺔ ) ﺣﺎﺳﺒﺎﺕ ﺷﺨﺼﻴﺔ، ﳏﻄﺎﺕ‬ ‫ﻋﻤـﻞ، ﺣﺎﺳـﺒﺎﺕ ﻣﺘﻮﺳﻄﺔ ، ﺣﺎﺳﺒﺎﺕ ﻛﺒﲑﺓ ﺃﻭ ﻋﻤﻼﻗﺔ( ﻣﺮﺗﺒﻄﺔ ﺑﺒﻌﻀﻬﺎ ﺍﻟﺒﻌﺾ ﻋﻦ ﻃﺮﻳﻖ ﻭﺣﺪﺍﺕ‬ ‫ﺭﺑـﻂ )‪ (Network Cards‬ﻭﻭﺳـﺎﺋﻂ )ﻣﻦ ﺃﺳﻼﻙ ﳏﻮﺭﻳﺔ، ﺃﺳﻼﻙ ﻣﱪﻭﻣﺔ ﻭ ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ( ﻭ ﺃﺟﻬﺰﺓ‬ ‫ﻣـﻠﺤﻘﺔ )ﺟﻬـﺎﺯ ﺗﻘﻮﻳﺔ ﺃﻭ ﻣﻜﺮﺭ، ﳎﻤﻌﺎﺕ ﺗﻮﺻﻴﻞ، ﺟﺴﻮﺭ..( ﻣﻜﻮﻧﺔ ﺑﺬﻟﻚ ﺷﺒﻜﺔ ﻣﺘﻜﺎﻣﻠﺔ، ﻭ‪‬ﺬﻩ‬ ‫ﺍﻟﻄـﺮﻳﻘﺔ ﳝﻜﻦ ﻷﻱ ﺣﺎﺳﺐ ﺃﻥ ﻳﺴﺘﻔﻴﺪ ﻣﻦ ﺍﳋﺪﻣﺎﺕ )ﻣﻌﻠﻮﻣﺎﺕ ، ﺑﺮﺍﻣﺞ ، ﻣﻠﺤﻘﺎﺕ ( ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ‬ ‫ﺍﳊﺎﺳﺒﺎﺕ ﺍﻷﺧﺮﻯ ﺍﳌﺮﺗﺒﻄﺔ ﻣﻊ ﺍﻟﺸﺒﻜﺔ ﺣﻴﺚ ﺍ‪‬ﺎ ﺗﺴﻤﺢ ﺑﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﻣﻮﺍﺭﺩ ﳊﺎﺳﺐ.‬ ‫ﻛﻤﺎ ﺗﺴﻤﺢ ﻟﻠﻤﺴﺘﺨﺪﻣﲔ ﺑﺎﻟﺘﻮﺍﺻﻞ ﻣﻊ ﻳﻌﻀﻬﻢ ﺍﻟﺒﻌﺾ ﺑﺸﻜﻞ ﻓﻮﺭﻱ.‬ ‫6‬
  • 7. ‫ﻓﻮﺍﺋﺪ ﻭ ﺧﺪﻣﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫‪ ü‬ﺍﳌﺸﺎﺭﻛﺔ ﰲ ﺍﳌﻌﻠﻮﻣﺎﺕ : ﺍﻋﺘﻤﺎﺩﺍ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺎﺕ ﳝﻜﻦ ﺃﻥ ﻳﺘﻢ ﺗﺒﺎﺩﻝ ﺍﳌﻌﻠﻮﻣﺎﺕ‬ ‫ﻭ ﺍﳌﻠﻔﺎﺕ ) ﻧﺼﻮﺹ ، ﺻﻮﺭ ، ﺻﻮﺕ....ﺍﱁ( ﻋﻠﻰ ﺍﺧﺘﻼﻑ ﺃﻧﻮﺍﻋﻬﺎ .‬ ‫‪ ü‬ﺍﳌﺸـﺎﺭﻛﺔ ﰲ ﻣـﻮﺍﺭﺩ ﺍﻟﺸـﺒﻜﺔ : ﻣـﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ_ ﻛﺎﳌﻌﺪﺍﺕ ) ﺍﻟﻄﺎﺑﻌﺎﺕ – ﺍﳌﺎﺳﺢ‬ ‫ﺍﻟﻀـﻮﺋﻲ...ﺍﱁ (، ﻭ ﺍﻟـﱪﺍﻣﺞ)ﺍﻟﱪﺍﻣﺞ ﺍﻟﺘﻨﻔﻴﺬﻳﺔ، ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ..(، ﲝﻴﺚ ﻳﻘﻮﻡ ﺃﻛﺜﺮ ﻣﻦ‬ ‫ﻭﺍﺣﺪ ﺑﺎﺳﺘﺨﺪﺍﻣﻬﺎ.‬ ‫‪ ü‬ﺍﻟﻘﺪﺭﺓ ﻋﻠﻰ ﺍﺳﺘﺨﺪﺍﻡ ﺑﺮﳎﻴﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ : ﻣﻦ ﺃﻫﻢ ﺍﻟﱪﳎﻴﺎﺕ ﺍﳌﺴﺘﺨﺪﻣﺔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ ﺃﻧﻈﻤﺔ ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﻭ ﻣﺎ ﻳﻌﺮﻑ‬ ‫ﺑــ)‪ (group ware‬ﻭ ﻫـﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ ﳝﻜﻦ ﺃﻥ ﻳﺘﺤﺪﺛﻮﺍ ﻣﻊ‬ ‫ﺑﻌﻀﻬﻢ ﺍﻟﺒﻌﺾ ﰲ ﺃﻱ ﳎﺎﻝ ﻣﻌﲔ.‬ ‫‪ ü‬ﺇﻧﺸﺎﺀ ﳎﻤﻮﻋﺎﺕ ﻋﻤﻞ : ﺗﺴﺘﺨﺪﻡ ﺍﻟﺸﺒﻜﺔ ﰲ ﺍﻻﺗﺼﺎﻝ ﻟﺘﻘﺪﻡ ﺇﺩﺍﺭﺓ ﻣﺸﺘﺮﻛﺔ ﻟﻠﻮﺛﺎﺋﻖ‬ ‫ﻣـﻦ ﻗـﺒﻞ ﳎﻤﻮﻋـﺔ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ ﰲ ﺃﻣﺎﻛﻦ ﳐﺘﻠﻔﺔ ﰲ ﺍﻟﻮﻗﺖ ﻧﻔﺴﻪ ﳑﺎ ﻳﺴﻤﺢ‬ ‫ﺑﺎﻟـﺘﻌﺪﻳﻞ ﻋـﻠﻰ ﻣﺴﺘﻨﺪ ﻣﺎ ﻣﻦ ﻗﺒﻞ ﺃﻛﺜﺮ ﻣﻦ ﻣﺴﺘﺨﺪﻡ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ ، ﻛﻤﺎ ﺃﻥ‬ ‫ﺍﳌﺴـﺘﺨﺪﻣﲔ ﻳﺴـﺘﻄﻴﻌﻮﺍ ﺍﳌﺸﺎﺭﻛﺔ ﰲ ﺗﺸﻐﻴﻞ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻭ ﺍﻟﱪﺍﻣﺞ ﺍﳌﺨﺘﻠﻔﺔ ﻋﻠﻰ‬ ‫ﺃﺟﻬﺰﺓ ﳐﺘﻠﻔﺔ .‬ ‫‪ ü‬ﺃ.2.5. ﺍﻻﺗﺼـﺎﻝ : ﺍﻟﺸـﺒﻜﺎﺕ ﺗﺴﻬﻞ ﻋﻤﻠﻴﺔ ﺍﻻﺗﺼﺎﻝ ﲝﻴﺚ ﳝﻜﻦ ﳏﺎﻭﺭﺓ ﺃﻱ‬ ‫ﺷﺨﺺ ﰲ ﺃﻱ ﻣﻜﺎﻥ ﻣﻦ ﺍﻟﻌﺎﱂ.‬ ‫‪ ü‬ﺃ.2.6. ﺧﺪﻣﺎﺕ ﺍﻟﱪﻳﺪ : ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺧﺪﻣﺔ ﻭﺍﺳﻌﺔ ﺍﻻﻧﺘﺸﺎﺭ ، ﺇﺫ ﺃﻧﻪ ﺃﺳﺮﻉ ﻭ‬ ‫ﺃﺭﺧﺺ ﻣﻦ ﺍﻟﺮﺳﺎﺋﻞ ﺍﻟﻮﺭﻗﻴﺔ ، ﻭ ﺃﻛﺜﺮ ﺳﺮﻳﺔ ﻣﻦ ﺍﳌﻜﺎﳌﺎﺕ ﺍﳍﺎﺗﻔﻴﺔ ، ﻭ ﺃﻗﻞ ﺇﺯﻋﺎﺟﺎ ﻣﻦ‬ ‫ﺍﻟﻔﺎﻛﺲ . ﺇﺫ ﻳﻘﺪﻡ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺇﻣﻜﺎﻧﻴﺔ ﺇﺭﺳﺎﻝ ﺍﻟﻮﺛﺎﺋﻖ ‪ Documents‬ﻭ ﺍﻟﺼﻮﺭ‬ ‫‪ Images‬ﻭ ﺍﻟﺼﻮﺕ ‪ ، Audio‬ﻋﻠﻰ ﺷﻜﻞ ﻣﺮﻓﻘﺎﺕ ، ﻛﻞ ﺫﻟﻚ ﳚﺮﻱ ﰲ ﻇﺮﻑ ﺛﻮﺍﱐ ﺃﻭ‬ ‫ﺩﻗﺎﺋﻖ . ﻭ ﻳﻌﺘﻤﺪ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﰲ ﺁﻟﻴﺔ ﻋﻤﻠﻪ ﻋﻠﻰ ﺍﻟﻌﻨﺎﻭﻳﻦ ﺍﻹﻟﻜﺘﺮﻭﻧﻴﺔ ‪Electronic‬‬ ‫‪ ، Addresses‬ﺇﺫ ﺗﺮﺳﻞ ﺍﳌﺴﺘﻨﺪﺍﺕ ﺍﻹﻟﻜﺘﺮﻭﻧﻴﺔ ﺇﱃ ﻋﻨﻮﺍﻥ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﺍﳋﺎﺹ‬ ‫ﺑﺎﳌﺴﺘﻠﻢ ﺍﳌﻄﻠﻮﺏ ، ﻭ ﻗﺪ ﻇﻬﺮﺕ ﺍﻛﱪ ﻓﻮﺍﺋﺪ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﰲ ﺍﻟﺸﺮﻛﺎﺕ ، ﺇﺫ ﺣﻞ ﳏﻞ‬ ‫ﺍﳌﺬﻛﺮﺍﺕ ﺍﻟﱵ ﻳﺘﻢ ﺗﺒﺎﺩﳍﺎ ﺑﲔ ﺍﳌﻜﺎﺗﺐ ، ﻭ ﺍﻹﻋﻼﻧﺎﺕ ، ﻭ ﺍﻷﺳﺌﻠﺔ ، ﻭ ﺍﻟﺘﻌﻴﻴﻨﺎﺕ ، ﺇﺿﺎﻓﺔ‬ ‫ﺇﱃ ﺍﻟﺮﺩﻭﺩ ﻋﻠﻰ ﺍﻻﺳﺘﻔﺴﺎﺭﺍﺕ ﺍﳋﺎﺻﺔ ﺑﺎﻟﻌﻤﻞ .‬ ‫7‬
  • 8. ‫ﺍ‬ ‫ﳊﺪ ﺍﻷﺩﻧﻰ ﳌﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ :‬ ‫‪ v‬ﺟﻬﺎﺯﻱ ﺣﺎﺳﻮﺏ ﻋﻠﻰ ﺍﻷﻗﻞ .‬ ‫‪ v‬ﺑﻄﺎﻗـﺔ ﺍﻟﺸـﺒﻜﺔ : ﺣﻴﺚ ﺗﺸﻜﻞ ﺍﻟﺒﻄﺎﻗﺔ ﺟﺴﺮ ﺍﻻﺗﺼﺎﻝ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﻭ ﻣﻜﻮﻧﺎﺕ‬ ‫ﺍﻟﺸﺒﻜﺔ.‬ ‫‪Radio‬‬ ‫‪ v‬ﻭﺳﻂ ﻧﺎﻗﻞ ﻟﻼﺗﺼﺎﻝ ﺑﲔ ﻋﻨﺎﺻﺮ ﺍﻟﺸﺒﻜﺔ ﻣﺜﻞ ﺍﻷﺳﻼﻙ ﺃﻭ ﺍﻷﻣﻮﺍﺝ ﺍﻟﻘﺼﲑﺓ‬ ‫‪waves‬‬ ‫‪ v‬ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻻﺗﺼﺎﻝ: ﲢﺪﺩ ﺧﻮﺍﺭﺯﻣﻴﺔ ﲣﺎﻃﺐ ﻣﻜﻮﻧﺎﺕ ﺍﻟﺸﺒﻜﺔ ﻭ ﺍﳌﻮﺍﺻﻔﺎﺕ‬ ‫ﺍﻟﺘﻘﻨـﻴﺔ ﺍﻟﻮﺍﺟـﺐ ﺗﻮﻓﲑﻫﺎ ﻣﺜﻞ ﻋﺮﺽ ﺍﳊﺰﻣﺔ ﺍﳌﺴﺘﺨﺪﻣﺔ ‪ ، bandwidth‬ﻭ ﻃﺮﻳﻘﺔ‬ ‫ﺗﺮﺗﻴﺐ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻋﻨﺪ ﺇﺭﺳﺎﳍﺎ ‪ formats packets‬ﻭﻏﲑﻫﺎ ﻣﻦ ﺍﳌﻮﺻﻔﺎﺕ ﺍﻟﺘﻘﻨﻴﺔ .‬ ‫‪ v‬ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﻟﺸﺒﻜﺔ )‪ Network operating System (nos‬ﻳﻘﺪﻡ ﺧﺪﻣﺔ ﺗﻨﻈﻴﻢ‬ ‫ﺍﻟﺼﻼﺣﻴﺎﺕ ﻭ ﺣﻘﻮﻕ ﺍﳌﺴﺘﺨﺪﻣﲔ ﰲ ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺍﳌﻮﺍﺭﺩ ﻭ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺸﺘﺮﻛﺔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻪ: ﻣﺎﻳﻜﺮﻭﺳﻮﻓﺖ ﻭﻳﻨﺪﻭﺯ 89 ، ﻭﻳﻨﺪﻭﺯ 0002 ، ﻭﻳﻨﺪﻭﺯ ‪win‬‬ ‫‪...win xp ، nt‬‬ ‫ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﺃﺻـﺒﺢ ﺍﻟﺘﺼﻨﻴﻒ ﰲ ﻋﺼﺮﻧﺎ ﻫﺬﺍ ﻋﻠﻤﺎ ﻭﺍﺳﻌﺎ، ﻭﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﻫﻮ ﺑﻌﻴﻨﻪ ﻋﻠﻢ ﻣﺴﺘﻘﻞ‬ ‫ﺇﺫ ﻳﻮﺟﺪ ﺍﻟﻌﺪﻳﺪ ﻣﻦ ﺍﳌﻌﺎﻳﲑ ﺍﻟﱵ ﳝﻜﻦ ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀﺍ ﻋﻠﻴﻬﺎ ، ﻭ ﻣﻦ ﻫﺬﻩ ﺍﳌﻌﺎﻳﲑ :‬ ‫- ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀ ﻋﻠﻰ ﻋﻼﻗﺔ ﺍﻷﻧﻈﻤﺔ ﺑﺒﻌﻀﻬﺎ :‬ ‫‪ v‬ﺷﺒﻜﺔ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ‪ : peer to peer‬ﺷﺒﻜﺔ ﲢﺘﻮﻱ ﻋﻠﻰ ﻃﺮﻓﻴﺎﺕ‬ ‫ﻣﺘﻮﺍﺯﻧﺔ ﺍﻟﻘﺪﺭﺍﺕ ﻳﺘﻢ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ ﺗﺒﺎﺩﻝ ﺍﳌﻠﻔﺎﺕ ﻭ ﺍﻟﱪﻳﺪ ﻭ ﺗﺸﺎﺭﻙ‬ ‫ﺍﳌﻮﺍﺭﺩ) ﺍﻟﻄﺎﺑﻌﺔ ، ﺍﳌﺎﺳﺢ ، ﺍﳌﻮﺩﻡ( .‬ ‫‪ v‬ﺷـﺒﻜﺎﺕ ﺍﳋﺎﺩﻡ ﺍﳌﺴﺘﻔﻴﺪ ‪ : client/server‬ﺗﻌﺘﻤﺪ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﻋﻠﻰ ﺍﳋﺎﺩﻡ . ﻭﻳﻜﻮﻥ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺫﺍ ﻣﻮﺍﺻﻔﺎﺕ ﺧﺎﺻﺔ ﲤﻜﻨﻪ ﻣﻦ ﺗﻘﺪﱘ‬ ‫ﺃﻋﻠﻰ ﻣﺴﺘﻮﻯ ﻣﻦ ﺍﳋﺪﻣﺎﺕ‬ ‫ﻭ ﻗﺪ ﻳﻜﻮﻥ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺧﺎﺩﻣﺎ ﳋﺪﻣﺔ ﻭﺍﺣﺪﺓ ﺃﻭ ﺃﻛﺜﺮ.‬ ‫8‬
  • 9. ‫- ﺗﺼﻨﻴﻒ ﺍﻟﺸﺒﻜﺎﺕ ﺑﻨﺎﺀ ﻋﻠﻰ ﺍﻟﺘﻮﺯﻉ ﺍﳉﻐﺮﺍﰲ :‬ ‫§ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ )‪: local Area Network (LAN‬‬ ‫ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﺷﺒﻜﺎﺕ ﺗﺘﻜﻮﻥ ﻣﻦ ﻋﺪﺩ ﻗﻠﻴﻞ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ، ﰲ ﺍﻟﻌﺎﺩﺓ ﺗﻜﻮﻥ ﳏﺘﻮﺍﺓ ﺩﺍﺧﻞ‬ ‫ﻣﻜﺘـﺐ ﺃﻭ ﳎﻤﻮﻋـﺔ ﻣﻦ ﺍﳌﻜﺎﺗﺐ ﺩﺍﺧﻞ ﺑﻨﺎﻳﺔ ﻭﺍﺣﺪﺓ ، ﻭ ﺗﻘﺪﻡ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﰲ ﻭﻗﺘﻨﺎ ﺍﳊﺎﱄ ﺳﺮﻋﺔ‬ ‫ﻛـﺒﲑﺓ ﻟﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺗﺸﺎﺭﻙ ﺍﳌﻮﺍﺭﺩ ، ﳑﺎ ﳚﻌﻞ ﺍﳌﺴﺘﺨﺪﻡ ﺍﻟﺬﻱ ﻳﺴﺘﻔﻴﺪ ﻣﻦ ﺍﻟﺸﺒﻜﺔ ﻳﻈﻦ ﺃﻥ ﻫﺬﻩ‬ ‫ﺍﳌﻮﺍﺭﺩ ﻣﻮﺟﻮﺩﺓ ﻋﻠﻰ ﺟﻬﺎﺯﻩ ﺍﻟﺸﺨﺼﻲ .‬ ‫§ ﺷﺒﻜﺎﺕ ﻧﻄﺎﻕ ﺍﳌﺪﻥ )‪: Metropolitan Area Networks (MAN‬‬ ‫ﺷـﺒﻜﺎﺕ ﻧﻄـﺎﻕ ﺍﳌﺪﻥ ﺗﻘﻮﻡ ﻋﻠﻰ ﻧﻔﺲ ﻣﺒﺪﺃ ﻋﻤﻞ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ ، ﻭﻟﻜﻦ ﺗﻌﻤﻞ‬ ‫ﺑﺴﺮﻋﺎﺕ ﻓﺎﺋﻘﺔ ﻭ ﺗﺴﺘﺨﺪﻡ ﰲ ﺍﻟﻌﺎﺩﺓ ﺍﻷﻟﻴﺎﻑ ﺍﻟﻀﻮﺋﻴﺔ ﻛﻮﺳﻂ ﺍﺗﺼﺎﻝ ، ﻭ ﻫﻲ ﻋﺎﺩﺓ ﺗﻐﻄﻲ ﻣﺴﺎﺣﺎﺕ‬ ‫ﻭﺍﺳﻌﺔ ﺗﺘﺮﺍﻭﺡ ﺑﲔ 02 ﺇﱃ 001 ﻛﻴﻠﻮﻣﺘﺮ .‬ ‫§ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ )‪:Wide Area Networks (WAN‬‬ ‫ﻣﻦ ﺗﻠﺒﻴﺔ‬ ‫)‪(LAN and MAN‬‬ ‫ﰲ ﺑﺪﺍﻳـﺔ ﻇﻬـﻮﺭ ﺍﻟﺸـﺒﻜﺎﺕ ﱂ ﺗـﺘﻤﻜﻦ ﺷﺒﻜﺎﺕ ﺍﻟـ‬ ‫ﺍﺣﺘﻴﺎﺟﺎﺕ ﺍﻟﺸﺮﻛﺎﺕ ﺍﻟﻜﱪﻯ ﺍﻟﱵ ﺗﺘﻮﺯﻉ ﻣﻜﺎﺗﺒﻬﺎ ﻋﻠﻰ ﻣﺴﺘﻮﻯ ﻋﺪﺓ ﺩﻭﻝ ، ﳍﺬﺍ ﻛﺎﻥ ﻻﺑﺪ ﻣﻦ ﺗﻮﺳﻴﻊ‬ ‫ﻭﺗﻄﻮﻳﺮ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﺑﺈﺩﺧﺎﻝ ﻭﺳﺎﺋﻞ ﺟﺪﻳﺪﺓ ﻋﻠﻴﻬﺎ ﲝﻴﺚ ﲤﻜﻨﻨﺎ ﻣﻦ ﺭﺑﻂ ﻋﺪﺓ ﺷﺒﻜﺎﺕ ، ﰲ ﺩﻭﻟﺔ ﺃﻭ‬ ‫ﰲ ﻋـﺪﺓ ﺩﻭﻝ ﳐﺘﻠﻔﺔ ، ﻭ ﻳﻄﻠﻖ ﻋﻠﻰ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺘﺸﺒﻴﻚ ﺍﺳﻢ ‪ WAN‬ﺃﻭ ﺷﺒﻜﺎﺕ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ‬ ‫ﻭﺑﺎﺳـﺘﺨﺪﺍﻡ ﻫـﺬﻩ ﺍﻟﺘﻘﻨﻴﺔ ﺗﺰﺍﻳﺪ ﻋﺪﺩ ﺍﳌﺴﺘﺨﺪﻣﲔ ﻟﺸﺒﻜﺔ ﺍﳊﺎﺳﻮﺏ ﰲ ﺍﻟﺸﺮﻛﺎﺕ ﺍﻟﻜﺒﲑﺓ ﺇﱃ ﺁﻻﻑ‬ ‫ﺍﻷﺷﺨﺎﺹ ، ﻭ ﺗﻌﺪ ﺍﻹﻧﺘﺮﻧﺖ ﻣﺜﺎﻻ ﺟﻴﺪﺍ ﻋﻠﻴﻬﺎ ﻓﻬﻲ ﺃﻛﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻮﺍﺳﻌﺔ ﺣﱴ ﺍﻵﻥ.‬ ‫ﺗﻨﻘﺴﻢ ﺷﺒﻜﺎﺕ ﺍﻟـ ‪ WAN‬ﺇﱃ ﻓﺌﺘﲔ :‬ ‫1. ‪ : Network Enterprise‬ﻳﻘـﻮﻡ ﺑﺎﻟـﺮﺑﻂ ﺑـﲔ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺃﻭ ﺍﻟﻔﺮﻭﻉ ﺍﻟﺘﺎﺑﻌﺔ‬ ‫ﻟﺸﺮﻛﺔ ﺃﻭ ﻣﺆﺳﺴﺔ ﻭﺍﺣﺪﺓ ﻋﻠﻰ ﻣﺴﺘﻮﻯ ﺩﻭﻟﺔ ﻭﺍﺣﺪﺓ ﺃﻭ ﻋﺪﺓ ﺩﻭﻝ .‬ ‫: ﻳﻌﻤﻞ ﻋﻠﻰ ﺭﺑﻂ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﺘﺎﺑﻌﺔ ﻟﻌﺪﺓ ﻣﺆﺳﺴﺎﺕ ﳐﺘﻠﻔﺔ‬ ‫2. ‪Network global‬‬ ‫ﻣﻊ ﺑﻌﻀﻬﺎ ﺍﻟﺒﻌﺾ .‬ ‫9‬
  • 10. ‫ﺧﺼﺎﺋﺺ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ‬ ‫ﺷﺒﻜﺔ ﻧﻄﺎﻕ ﺍﳌﺪﻥ‬ ‫ﺷﺒﻜﺔ ﺍﻟﻨﻄﺎﻕ ﺍﶈﻠﻲ‬ ‫ﺇﺳـﻢ ﻧﻮﻉ ﺍﻟﺸﺒﻜﺔ‬ ‫‪WAN‬‬ ‫‪MAN‬‬ ‫‪LAN‬‬ ‫ﺧﺼﺎﺋﺼــﻬﺎ‬ ‫ﻣﻦ ﺑﻌﺾ‬ ‫ﺍﻟﺘﻐﻄﻴﺔ ﺍﳉﻐﺮﺍﻓﻴﺔ‬ ‫ﻋﺎﳌﻴﺔ ﺍﻟﺘﻐﻄﻴﺔ‬ ‫ﺍﻟﻜﻴﻠﻮﻣﺘﺮﺍﺕ‬ ‫ﺗﺼﻞ ﺣﱴ 001 ﻣﺘﺮ‬ ‫ﺇﱃ ﺍﻵﻻﻑ‬ ‫ﺳﺮﻋﺔ ﻣﻨﺨﻔﻀﺔ ﺑﺴﺒﺐ ﻋﺪﺩ‬ ‫اﻟﺴﺮﻋﺔ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﳌﻠﺤﻘﺔ ﻭﺧﺎﺻﺔ‬ ‫ﻓﺎﺋﻘﺔ ﺟﺪﺍ ﻭ ﺗﺘﺮﺍﻭﺡ ﺑﲔ 4‬ ‫ﺃﺟﻬﺰﺓ ﺍﳌﻮﺩﻡ ﺫﺍﺕ ﺍﻟﺴﺮﻋﺔ‬ ‫ﺗﻌﺎﺩﻝ ﺗﻘﺮﻳﺒﺎ ﺳﺮﻋﺔ ﺍﻟﺸﺒﻜﺎﺕ‬ ‫ﳎﺎ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ ﺇﱃ 0001‬ ‫ﺍﳌﻨﺨﻔﻀﺔ ﻭ ﺍﻟﱵ ﲢﺴﺐ‬ ‫ﺍﻟﻮﺍﺳﻌﺔ‬ ‫ﳎﺎ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ‬ ‫ﺑﺎﻟﻜﻴﻠﻮ ﺑﺖ ﰲ ﺍﻟﺜﺎﻧﻴﺔ‬ ‫ﺣﺴﺐ ﺍﻟﺘﻘﻨﻴﺔ ﺍﳌﺴﺘﻌﻤﻠﺔ‬ ‫)‪(Kbps‬‬ ‫ﻋﺪﺩ ﻛﺜﲑ ﺟﺪﺍ ﳛﺴﺐ‬ ‫ﻋﺪد اﻟﺤﺎﺳﺒﺎت‬ ‫ﻋﺪﺩ ﻛﺜﲑ‬ ‫ﻣﻦ 2 ﺇﱃ ﺑﻌﺾ ﺍﳌﺌﺎﺕ‬ ‫ﺑﻌﺸﺮﺍﺕ ﺍﻵﻻﻑ‬ ‫اﻟﻮﺳﺎﺋﻂ و اﻟﻤﻠﺤﻘﺎت‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﶈﻴﻄﻴﺔ، ﺃﺟﻬﺰﺓ‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ ﺍﻷﺟﻬﺰﺓ‬ ‫ﲨﻴﻊ ﺃﻧﻮﺍﻉ ﺍﻟﻮﺳﺎﺋﻂ ﻭ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻣﻮﺩﻡ ﻣﺘﻌﺪﺩ‬ ‫ﺍﶈﻴﻄﻴﺔ، ﻭ ﺃﺟﻬﺰﺓ ﺍﳌﻮﺩﻡ‬ ‫)‪(Multiplexer‬‬ ‫اﻟﺘﻮاﺻﻞ‬ ‫ﻣﺘﻮﺍﺻﻞ- ‪‬‬ ‫ﻣﻨﻘﻄﻊ‬ ‫ﻣﺘﻮﺍﺻﻞ- ‪‬‬ ‫ﻣﻨﻘﻄﻊ‬ ‫ﻣﺘﻮﺍﺻﻞ 42ﺳﺎﻋﺔ/42‬ ‫01‬
  • 11. ‫ﺃﻧﻮﺍﻉ ﺍﻟﻨﻮﺍﻗﻞ:‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﻋﺎﺩﺓ ﻧﻮﻉ ﻭﺍﺣﺪ ﻣﻦ ﻭﺳﺎﺋﻂ ﺍﻻﺗﺼﺎﻝ ﻭ ﺃﺣﻴﺎﻧﺎ ﺃﻛﺜﺮ ﻣﻦ ﻧﻮﻉ ، ﻭﻫﺬﻩ‬ ‫ﺍﻟﻮﺳﺎﺋﻂ ﺇﻣﺎ ﺃﻥ ﺗﻜﻮﻥ ﺃﺳﻼﻙ ﻭﻫﻲ ﺛﻼﺙ ﺃﻧﻮﺍﻉ ﺇﻣﺎ ﺃﻥ ﺗﻜﻮﻥ ﻭﺳﻴﻂ ﻻﺳﻠﻜﻲ ﻭ ﺗﺘﻤﺜﻞ ﰲ:‬ ‫: ﻭ ﺗﻜﻮﻥ ﻫﺬﻩ‬ ‫)‪(Twisted pair cable‬‬ ‫‪ v‬ﺃﺳـﻼﻙ ﻣـﺰﺩﻭﺟﺔ ﻣﻠـﺘﻔﺔ‬ ‫‪( Shielded or not‬‬ ‫ﺍﻷﺳﻼﻙ ﺇﻣﺎ ﻣﻐﻄﺎﺓ ﺑﻄﺒﻘﺔ ﻭﺍﻗﻴﺔ ﺃﻭ ﻏﲑ ﻣﻐﻄﺎﺓ‬ ‫)‪shielded‬‬ ‫‪ v‬ﺃﺳـﻼﻙ ﳏﻮﺭﻳﺔ )‪ : (Coaxial cable‬ﻭﻫﻲ ﺗﻨﻘﺴﻢ ﺇﱃ ﻧﻮﻋﲔ ﺭﻗﻴﻘﺔ ﻭ‬ ‫ﻏﻠﻴﻈﺔ.‬ ‫‪ v‬ﺍﻷﻟﻴﺎﻑ ﺍﻟﺒﺼﺮﻳﺔ )‪. (Fiber Optic Cable‬‬ ‫‪ v‬ﻭﺳﻴﻂ ﺍﺗﺼﺎﻝ ﻻﺳﻠﻜﻲ )‪. (Wireless transmission media‬‬ ‫ﺗﺼﺎﻣﻴﻢ ﺍﻟﺸﺒﻜﺔ :‬ ‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﺍﻟﻨﺠﻤﺔ ) ‪: (star‬‬ ‫ﺗﻘـﻮﻡ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺫﺍﺕ ﺍﻟﺘﺼﻤﻴﻢ ﻣﻦ ﺍﻟﻨﻮﻉ ﺍﻟﻨﺠﻤﺔ )‪ ، (Star‬ﺑﺮﺑﻂ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ‬ ‫ﺑﺄﺳﻼﻙ ﻣﻮﺻﻠﺔ ﲜﻬﺎﺯ ﻣﺮﻛﺰﻱ ﻳﻄﻠﻖ ﻋﻠﻴﻪ ﺍﶈﻮﺭ ﺃﻭ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ )‪. (Hub‬‬ ‫‪ v‬ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ:‬ ‫ﺍﻹﺷﺎﺭﺍﺕ ﺗﻨﺘﻘﻞ ﻣﻦ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺼﺪﺭ ﺍﻟﺬﻱ‬ ‫‪Hub‬‬ ‫ﻳﺮﻏﺐ ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ‬ ‫ﻭﻣﻨﻪ ﺇﱃ ﺑﺎﻗﻲ ﺍﻷﺟﻬﺰﺓ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ . ﻳﻌﺘﱪ ﺗﺼﻤﻴﻢ‬ ‫ﺍﻟﻨﺠﻤﺔ ‪ Star‬ﺍﻷﻛﺜﺮ ﺇﺭﺍﺣﺔ ﻣﻦ ﺑﲔ ﺍﻟﺘﺼﺎﻣﻴﻢ‬ ‫)‪(Star‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻘﻨﻴﺔ ﳒﻤﺔ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﺣﻴﺚ ﺃﻧﻪ ﻳﺴﻤﺢ ﺑﺘﺤﺮﻳﻚ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻣﻦ ﻣﻜﺎ‪‬ﺎ ﻭ ﺇﺻﻼﺣﻬﺎ ﻭ ﺗﻐﻴﲑ ﺍﻟﺘﻮﺻﻴﻼﺕ ﺩﻭﻥ ﺃﻥ ﺗﺘﺄﺛﺮ ﺍﻟﺸﺒﻜﺔ.‬ ‫11‬
  • 12. ‫ﻧﻈﺎﻡ ﺍﻟﺘﻮﺻﻴﻞ ﰲ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪: Hub‬‬ ‫ﻳﻌـﺰﻝ ﻛﻞ ﺳﻠﻚ ﻣﻦ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺔ ﻋﻦ ﺍﻵﺧﺮ .ﻭ ﺑﺎﻟﺘﺎﱄ ﺇﺫﺍ ﺗﻮﻗﻒ ﺟﻬﺎﺯ ﻣﺎ ﺃﻭ ﺍﻧﻘﻄﻊ‬ ‫ﺍﻟﺴﻠﻚ ﺍﻟﺬﻱ ﻳﻮﺻﻠﻪ ﺑﺎﳌﻮﺯﻉ ﻓﻠﻦ ﻳﺘﺄﺛﺮ ﺇﻻ ﺍﻟﺬﻱ ﺗﻮﻗﻒ ﺑﻴﻨﻤﺎ ﺑﺎﻗﻲ ﺍﻷﺟﻬﺰﺓ ﺳﺘﺒﻘﻰ ﺗﻌﻤﻞ‬ ‫ﻣﻦ ﺧﻼﻝ ﺍﻟﺸﺒﻜﺔ ﺩﻭﻥ ﻣﺸﺎﻛﻞ .‬ ‫‪v‬ﻣﺸﺎﻛﻠﻬﺎ:‬ ‫• ﺗﻮﻗﻒ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ﻋﻦ ﺍﻟﻌﻤﻞ ﻳﺆﺩﻱ ﺇﱃ ﺗﻮﻗﻒ ﺍﻟﺸﺒﻜﺔ ﻛﻜﻞ ﻋﻦ ﺍﻟﻌﻤﻞ .‬ ‫• ﺗﻜﻠﻔـﺔ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺘﺼﻤﻴﻢ ﻣﺮﺗﻔﻌﺔ ﺧﺎﺻﺔ ﰲ ﺣﺎﻟﺔ ﻛﱪ ﺍﻟﺸﺒﻜﺔ ﻷ‪‬ﺎ ﺳﺘﻄﻠﺐ‬ ‫ﺃﺳﻼﻙ ﻛﺜﲑﺓ ﻭ ﺍﳌﻮﺯﻉ ﻗﺪ ﻳﻜﻮﻥ ﺳﻌﺮﻩ ﻣﺮﺗﻔﻌﺎ.‬ ‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﺣﻠﻘﺔ )‪: (RING‬‬ ‫ﰲ ﺗﺼـﻤﻴﻢ ﺍﻟﺸـﺒﻜﺎﺕ ﻣﻦ ﺍﻟﻨﻮﻉ ﺣﻠﻘﺔ ﻳﺘﻢ ﺭﺑﻂ ﺍﻷﺟﻬﺰﺓ ﲝﻠﻘﺔ ﺃﻭ ﺩﺍﺋﺮﺓ ﻣﻦ ﺍﻟﺴﻠﻚ‬ ‫ﺑﺪﻭﻥ ‪‬ﺎﻳﺎﺕ ﺗﻮﻗﻒ.‬ ‫ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ :‬ ‫ﺗﻨﺘﻘﻞ ﺍﻹﺷﺎﺭﺍﺕ ﻋﻠﻰ ﻣﺪﺍﺭ ﺍﳊﻠﻘﺔ ﰲ ﺍﲡﺎﻩ ﻭﺍﺣﺪ‬ ‫ﻭ ﲤﺮ ﻣﻦ ﺧﻼﻝ ﻛﻞ ﺟﻬﺎﺯ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺣﻴﺚ ﻳﻘﻮﻡ ﺑﺈﻧﻌﺎﺷﻬﺎ‬ ‫ﻭ ﺗﻘﻮﻳﺘﻬﺎ ﰒ ﻳﻌﻴﺪ ﺇﺭﺳﺎﳍﺎ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺇﱃ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺘﺎﱄ .‬ ‫)‪(ring‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻘﻨﻴﺔ ﺣﻠﻘﺔ‬ ‫ﻣﺸﺎﻛﻠﻬﺎ:‬ ‫1. ﻋﻨﺪ ﺗﻄﻮﻳﺮﻫﺎ ﳚﺐ ﺇﻳﻘﺎﻑ ﻋﻤﻠﻬﺎ ﺃﺛﻨﺎﺀ ﻋﻤﻠﻴﺔ ﺍﻟﺘﻄﻮﻳﺮ .‬ ‫2. ﲟـﺎ ﺃﻥ ﺍﻹﺷـﺎﺭﺓ ﲤﺮ ﻋﻠﻰ ﻛﻞ ﺟﻬﺎﺯ ﻓﺈﻥ ﻓﺸﻞ ﺃﺣﺪ ﺍﻷﺟﻬﺰﺓ ﺃﻭ ﺗﻮﻗﻔﻪ ﻋﻦ ﺍﻟﻌﻤﻞ‬ ‫ﺳﻴﺆﺩﻱ ﺇﱃ ﺗﻮﻗﻒ ﺍﻟﺸﺒﻜﺔ ﻛﻜﻞ ﻋﻦ ﺍﻟﻌﻤﻞ .‬ ‫21‬
  • 13. ‫ﺗﺼﻤﻴﻢ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻋﻠﻰ ﺷﻜﻞ ﻗﺎﻃﺮﺓ )‪: (Bus‬‬ ‫ﰲ ﺗﺼـﻤﻴﻢ ﺍﻟﺸـﺒﻜﺔ ﺑﺸﻜﻞ ‪ bus‬ﻳﺘﻢ ﺗﻮﺻﻴﻞ ﺍﳊﻮﺍﺳﻴﺐ ﰲ ﺻﻒ ، ﻋﻠﻰ ﻃﻮﻝ ﺳﻠﻚ‬ ‫ﻭﺍﺣﺪ ﻭ ﺗﻌﺘﻤﺪ ﻓﻜﺮﺓ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻋﻠﻰ ﺛﻼﺛﺔ ﺃﻣﻮﺭ ﺃﺳﺎﺳﻴﺔ ﺗﺘﻤﺜﻞ ﰲ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ ﻭ ﺍﺭﺗﺪﺍﺩ ﺍﻹﺷﺎﺭﺓ‬ ‫ﻭ ﺍﻟﻨﻬﺎﺋﻲ ﺃﻭ ﺍﳌﻨﻬﻲ.‬ ‫ﻛﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ :‬ ‫‪v‬‬ ‫‪Terminal‬‬ ‫)‪connector lettre(T‬‬ ‫ﺗﺮﺳﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻋﻠﻰ ﺷﻜﻞ‬ ‫ﺇﺷﺎﺭﺍﺕ ﻛﻬﺮﺑﺎﺋﻴﺔ ﺇﱃ ﻛﻞ ﺍﳊﻮﺍﺳﻴﺐ ﺍﳌﻮﺻﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ‬ ‫ﻭ ﻳﺘﻢ ﻗﺒﻮﻝ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻣﻦ ﻗﺒﻞ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺬﻱ ﻳﺘﻮﺍﻓﻖ‬ ‫ﻋﻨﻮﺍﻧﻪ ﻣﻊ ﺍﻟﻌﻨﻮﺍﻥ ﺍﳌﺸﻔﺮ ﺩﺍﺧﻞ ﺍﻹﺷﺎﺭﺓ ﺍﻷﺻﻠﻴﺔ‬ ‫ﺑﺘﻘﻨﻴﺔ) ‪(bus‬‬ ‫ﺑﻨﻴﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫ﺍﳌﺮﺳﻠﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ .‬ ‫ﻋﻨﺪﻣﺎ ﺗﺮﺳﻞ ﺇﺷﺎﺭﺓ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻓﺈ‪‬ﺎ ﺗﻨﺘﻘﻞ ﻣﻦ ﺑﺪﺍﻳﺔ ﺍﻟﺴﻠﻚ ﺇﱃ ‪‬ﺎﻳﺘﻪ ، ﻭ ﺇﺫﺍ ﱂ ﻳﺘﻢ ﻣﻘﺎﻃﻌﺔ‬ ‫ﻫـﺬﻩ ﺍﻹﺷﺎﺭﺓ ﻓﺈ‪‬ﺎ ﺳﺘﺒﻘﻰ ﺗﺮﺗﺪ ﻋﻠﻰ ﻃﻮﻝ ﺍﻟﺴﻠﻚ ، ﻭ ﺳﺘﻤﻨﻊ ﺍﳊﻮﺍﺳﺐ ﺍﻷﺧﺮﻯ ﻣﻦ ﺍﻹﺭﺳﺎﻝ ﳍﺬﺍ‬ ‫ﳚـﺐ ﺇﻳﻘـﺎﻑ ﻫﺬﻩ ﺍﻹﺷﺎﺭﺓ ﺑﻌﺪ ﻭﺻﻮﳍﺎ ﺇﱃ ﻋﻨﻮﺍ‪‬ﺎ ﺍﳌﻄﻠﻮﺏ. ﻹﻳﻘﺎﻑ ﺍﻹﺷﺎﺭﺓ ﻭﻣﻨﻌﻬﺎ ﻣﻦ ﺍﻻﺭﺗﺪﺍﺩ‬ ‫ﻳﺴـﺘﺨﺪﻡ ﻣـﻨﻬﻲ ‪ Terminator‬ﻭﻳـﺘﻢ ﻭﺿـﻌﻪ ﻋﻨﺪ ﻛﻞ ﻃﺮﻑ ﻣﻦ ﺃﻃﺮﺍﻑ ﺍﻟﺴﻠﻚ ﻭ ﻳﻮﺻﻞ ﺑﻜﻞ‬ ‫ﺣﺎﺳﻮﺏ ﻣﺘﺼﻞ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫‪ v‬ﻋﻤﻞ ‪ :Terminator‬ﻳﻘﻮﻡ ﺑﺎﻣﺘﺼﺎﺹ ﺃﻱ ﺇﺷﺎﺭﺓ ﺣﺮﺓ ﻋﻠﻰ ﺍﻟﺴﻠﻚ ﳑﺎ ﳚﻌﻠﻪ ﻣﻔﺮﻏﺎ‬ ‫ﻣﻦ ﺃﻱ ﺇﺷﺎﺭﺍﺕ ، ﳑﺎ ﳝﻜﻦ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺘﺎﱄ ﻣﻦ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﻧﺎﻗﻞ ﺍﻟﺸﺒﻜﺔ .‬ ‫‪v‬ﺍﻟﻌﻮﺍﻣﻞ ﺍﻟﱵ ﺗﺆﺛﺮ ﻋﻠﻰ ﺃﺩﺍﺀ ﺷﺒﻜﺔ ‪ Bus‬ﻫﻲ :‬ ‫• ﺍﻹﻣﻜﺎﻧﻴﺎﺕ ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ ﻣﻜﻮﻧﺎﺕ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫• ﻋﺪﺩ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫• ﻧﻮﻋﻴﺔ ﺍﻟﱪﺍﻣﺞ ﺍﳌﺸﻐﻠﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ .‬ ‫• ﺍﳌﺴﺎﻓﺔ ﺑﲔ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ .‬ ‫31‬
  • 14. ‫ﻟﻜﻲ ﻳﺘﻢ ﺍﻻﺗﺼﺎﻝ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ، ﻻﺑﺪ ﻣﻦ‬ ‫ﺑﻌـﺾ ﺍﻷﺟﻬـﺰﺓ ﺍﳌﺴـﺘﺨﺪﻣﺔ ﰲ ﺍﻟﺸـﺒﻜﺎﺕ :‬ ‫ﺍﺳﺘﺨﺪﺍﻡ ﺑﻌﺾ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺴﺎﻋﺪﺓ ﻭ ﻧﺴﺘﻌﺮﺽ ﻓﻴﻤﺎ ﻳﻠﻲ ﻫﺬﻩ ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﻟﻮﻇﺎﺋﻒ ﺍﻟﱵ ﺗﻘﻮﻡ ‪‬ﺎ :‬ ‫‪ v‬ﺍﳌﻮﺩﻡ ‪: Modem‬‬ ‫ﻣﻦ ﺍﳌﻌﻠﻮﻡ ﺃﻥ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺗﺘﻌﺎﻣﻞ ﻣﻊ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ ‪ Digital signals‬ﻓﻘﻂ‬ ‫ﻭﻟﻜـﻦ ﺧﻄـﻮﻁ ﺍﳍﺎﺗﻒ ﺍﻟﻌﺎﺩﻳﺔ ﻻ ﺗﻨﻘﻞ ﺳﻮﻯ ﺍﻹﺷﺎﺭﺍﺕ‬ ‫ﺍﻟﺘﻮﺍﺻﻠﻴﺔ )ﺍﻟﺘﻤﺎﺛﻠﻴﺔ( ‪. Signals analog‬‬ ‫ﻭﳍـﺬﺍ ﻻﺑـﺪ ﻣﻦ ﺟﻬﺎﺯ )ﻣﻮﺩﻡ( ﳛﻮﻝ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ‬ ‫‪ digital‬ﺇﱃ ﺗﻮﺍﺻﻠﻴﺔ )ﺍﻟﺘﻤﺎﺛﻠﻴﺔ( ‪ analog‬ﰲ ﺍﻟﻄﺮﻑ ﺍﳌﺮﺳﻞ‬ ‫ﻋﱪ ﻋﻤﻠﻴﺔ ﺗﺪﻋﻰ ﺍﻟﺘﻌﺪﻳﻞ ‪. Modulation‬‬ ‫ﺍﻹﺷـﺎﺭﺍﺕ ﺍﻟﻨﺎﲡﺔ ﻋﱪ ﺧﻄﻮﻁ ﺍﳍﺎﺗﻒ ، ﲢﻮﻝ ﻣﻦ ﺗﻮﺍﺻﻠﻴﺔ‬ ‫)ﺍﻟﺘﻤﺎﺛﻠـﻴﺔ( ﺇﱃ ﺭﻗﻤﻴﺔ ﰲ ﺍﻟﻄﺮﻑ ﺍﳌﺴﺘﻘﺒﻞ ﻋﱪ ﻋﻤﻠﻴﺔ ﺗﺪﻋﻰ ﻓﻚ ﺍﻟﺘﻌﺪﻳﻞ ،‪ Demodulation‬ﻭ ﻣﻦ ﻫﻨﺎ‬ ‫ﻛﺎﻧـﺖ ﺃﺟﻬـﺰﺓ ﺍﳌﻮﺩﻡ ﻗﺎﺩﺭﺓ ﻋﻠﻰ ﺭﺑﻂ ﺃﺟﻬﺰﺓ ﺣﺎﺳﻮﺏ ، ﺃﻭ ﺣﱴ ﺷﺒﻜﺎﺕ ﻛﺎﻣﻠﺔ ﺑﻌﻴﺪﺓ ﻋﻦ ﺑﻌﻀﻬﺎ‬ ‫ﺑﺎﺳﺘﺨﺪﺍﻡ ﺍﳍﺎﺗﻒ .‬ ‫‪ v‬ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪: Hub‬‬ ‫ﺗﺘﺼﻞ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﰲ ﻣﻌﻈﻢ ﺃﻧﻮﺍﻉ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ‬ ‫ﲜﻬـﺎﺯ ﻳﻘـﻮﻡ ﺑـﺪﻭﺭ ﻧﻘﻄﺔ ﻭﺻﻞ ﻣﺮﻛﺰﻳﺔ ﺑﲔ ﺃﺟﻬﺰﺓ‬ ‫ﺍﻟﺸﺒﻜﺔ ، ﻭ ﻫﻮ ﻳﺪﻋﻰ ﺍﳌﻮﺯﻉ ﺍﻟﺸﺒﻜﻲ ‪hub‬‬ ‫ﻭ ﻭﻇﻴﻔﺘﻪ ﻫﻲ ﺭﺑﻂ ﻗﻄﻊ ﺍﻟﺸﺒﻜﺔ ﺑﺒﻌﻀﻬﺎ ، ﻭ ﻣﻦ ﺃﻧﻮﺍﻉ‬ ‫ﺍﳌﻮﺯﻋﺎﺕ :‬ ‫• ﺍﳌﻮﺯﻉ ﺍﳋﺎﻣﻞ ‪ : passive hub‬ﳝﺮﺭ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻮﺍﺭﺩﺓ‬ ‫ﻣﻦ ﺍﻟﻘﻄﻊ ﺍﳌﺨﺘﻠﻔﺔ ﻟﺸﺒﻜﺔ ، ﻭ ﺗﺴﺘﻄﻴﻊ ﲨﻴﻊ ﺍﻷﺟﻬﺰﺓ ﺍﳌﻮﺻﻮﻟﺔ ﻣﻌﻪ‬ ‫ﺍﺳﺘﻘﺒﺎﻝ ﺣﺰﻡ ‪ packets‬ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﺎﺭﺓ ﻋﱪﻩ .‬ ‫• ﺍﳌﻮﺯﻉ ﺍﻟﻨﺸﻂ ‪ : Active hub‬ﳛﻮﻱ ﻫﺬﺍ‬ ‫ﺍﳌﻮﺯﻉ ﺃﺟﺰﺍﺀ ﺇﻟﻴﻜﺘﺮﻭﻧﻴﺔ ﺗﻌﻴﺪ ﺗﻮﻟﻴﺪ ﺍﻹﺷﺎﺭﺍﺕ‬ ‫ﺍﳌﺎﺭﺓ ﰲ ﺍﻟﺸﺒﻜﺔ .‬ ‫41‬
  • 15. ‫‪ v‬ﺍﳌﻜﺮﺭ ‪: Repeater‬‬ ‫ﺗﺘﻌﺮﺽ ﺍﻹﺷﺎﺭﺍﺕ ﺃﺛﻨﺎﺀ ﻋﻤﻠﻴﺔ ﺍﻹﺭﺳﺎﻝ ﻟﻠﺘﺸﻮﻳﺶ ﻭ ﺍﻟﺘﺸﻮﻳﻪ‬ ‫ﻋﱪ ﺧﻄﻮﻁ ﺍﻟﻨﻘﻞ ، ﳑﺎ ﻭﻟﺪ ﺍﳊﺎﺟﺔ ﺇﱃ ﺗﺼﻤﻴﻢ ﺟﻬﺎﺯ ﻳﺪﻋﻰ‬ ‫ﺍﳌﻜـﺮﺭ ‪ Repeater‬ﻳﺴﺘﺨﺪﻡ ﻹﻧﻌﺎﺵ ﺍﻹﺷﺎﺭﺓ ﺍﳌﺮﺳﻠﺔ ﻋﱪ ﺍﻟﺸﺒﻜﺔ ﲝﻴﺚ ﺗﺒﻘﻰ ﻗﻮﻳﺔ ﻋﻨﺪ ﻭﺻﻮﳍﺎ ﺇﱃ‬ ‫ﳏﻄﺎﺕ ﺍﻟﻌﻤﻞ‬ ‫ﺍﳌﺴﺘﻘﺒﻠﺔ ﳍﺎ ﻭ ﻳﻮﺟﺪ ﻧﻮﻋﺎﻥ ﻣﻦ ﻫﺬﻩ ﺍﳌﻜﺮﺭﺍﺕ :‬ ‫• ﺗﻮﺍﺻﻠﻲ ‪ Analog‬ﻳﻀﺨﻢ ﺍﻹﺷﺎﺭﺓ ﻭ ﺣﺴﺐ .‬ ‫ﻳﻌﻴﺪ ﺑﻨﺎﺀ ﺍﻹﺷﺎﺭﺓ ﻟﺘﺼﺒﺢ ﻗﺮﻳﺒﺔ ﺟﺪﺍ ﻣﻦ ﺍﻷﺻﻠﻴﺔ.‬ ‫ﺭﻗﻤﻲ ‪Digital‬‬ ‫•‬ ‫‪ v‬ﺍﳉﺴﺮ ‪: Bridge‬‬ ‫ﻟﺘﻮﺳﻴﻊ ﺣﺠﻢ ﺍﻟﺸﺒﻜﺎﺕ ﺍﳌﻮﺟﻮﺩﺓ ﺻﻤﻢ ﺟﻬﺎﺯ ﻳﺪﻋﻰ ﺍﳉﺴﺮ‬ ‫‪ Bridge‬ﳝﻜﻨﻪ ﺭﺑﻂ ﺷﺒﻜﺘﲔ ﳏﻠﻴﺘﲔ ﺗﺴﺘﺨﺪﻣﺎﻥ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ‬ ‫ﻧﻔﺴﻪ .‬ ‫‪ v‬ﺍﶈﻮﻝ ‪: Switch‬‬ ‫ﻟﺘﺤﺪﻳﺪ ﺍﳌﺴﺎﺭ ﺍﻟﺬﻱ ﺗﻨﻘﻞ ﻋﱪﻩ ﺣﺰﻡ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺑﲔ ﺍﻟﻘﻄﻊ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﻟﻠﺸﺒﻜﺔ ﺍﶈﻠﻴﺔ ، ﻭ ﺗﺪﻋﻰ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﱵ‬ ‫ﺗﺴﺘﺨﺪﻣﻪ ‪. Switch LAN‬‬ ‫‪ v‬ﺍﳌﻮﺟﻪ ‪: Router‬‬ ‫ﻣﻊ ﺍﻻﺯﺩﻳﺎﺩ ﺍﳍﺎﺋﻞ ﰲ ﻋﺪﺩ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ، ﱂ ﻳﻜﻦ‬ ‫ﺍﳉﺴﺮ ‪ Bridge‬ﻗﺎﺩﺭﺍ ﻋﻠﻰ ﺇﺟﺮﺍﺀ ﻫﺬﺍ ﺍﻟﺮﺑﻂ، ﻓﻜﺎﻥ ﺍﳊﻞ‬ ‫ﰲ ﺟﻬﺎﺯ ﻳﺪﻋﻰ ﺍﳌﻮﺟﻪ ‪ Router‬ﻳﻘﻮﻡ ‪‬ﺬﺍ ﺍﻟﺮﺑﻂ‬ ‫ﻭ ﳝﺮﺭ ﻫﺬﺍ ﺍﳉﻬﺎﺯ ﺣﺰﻡ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺑﺎﻻﻋﺘﻤﺎﺩ ﻋﻠﻰ ﻋﻨﺎﻭﻳﻦ ﻣﻨﻄﻘﻴﺔ‬ ‫ﻛﻤـﺎ ﻳﺘﺒﻊ ﺧﻮﺍﺭﺯﻣﻴﺔ ﲤﻜﻨﻪ ﻣﻦ ﺍﺧﺘﻴﺎﺭ ﺍﳌﺴﺎﺭ ﺍﻷﻓﻀﻞ ﻟﻨﻘﻞ ﺣﺰﻡ‬ ‫ﺍﳌﻌﻠﻮﻣﺎﺕ ﺇﱃ ﻫﺪﻓﻬﺎ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻷﺧﺮﻯ.‬ ‫51‬
  • 16. ‫ﻋﻠﻰ ﺭﺑﻂ ﺷﺒﻜﺎﺕ ﳏﻠﻴﺔ‬ ‫‪Router‬‬ ‫‪ v‬ﺍﻟﺒﻮﺍﺑﺔ ‪ : Gateway‬ﺃﺩﻯ ﻋﺪﻡ ﻣﻘﺪﺭﺓ ﺍﳌﻮﺟﻪ‬ ‫ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﻟﱪﺍﻣﺞ ﺍﻟﱵ ﺗﺮﺑﻂ ﺑﲔ ﺷﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ، ﺇﺫ ﺗﻨﻘﻞ‬ ‫ﺍﳌﻌﻠﻮﻣﺎﺕ ﻭ ﲢﻮﳍﺎ ﺇﱃ ﺻﻴﻐﺔ ﺗﺘﻮﺍﻓﻖ ﻣﻊ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺸﺒﻜﺔ ﺍﻷﺧﺮﻯ.ﺗﺴﺘﺨﺪﻡ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ﺇﱃ ﺍﺳﺘﺨﺪﺍﻡ ﻣﺎ ﻳﺪﻋﻰ ‪ Gateway‬ﻭ ﻫﻲ ﳎﻤﻮﻋﺔ ﻣﻦ‬ ‫61‬
  • 17.   ‫ﻧﻈﻢ إدارة‬ ‫ﺑﺮﺗﻮﻛﻮﻻ‬ ‫ﻧﻈﻢ ﺗﺸﻐﻴﻞ‬ ‫أﺟﻬﺰة رﺑﻂ ﻣﻠﺤﻘﺔ‬ ‫ﺑﻄﺎﻗﺎت رﺑﻂ و وﺳﺎﺋﻂ‬ Computers ‫ﺣﺎﺳﺒﺎت‬ ‫اﻟﺸﺒﻜﺔ‬ ‫اﻻﺗﺼﺎل‬ ‫اﻟﺸﺒﻜﺔ‬ Devices Cards & NMS Communic NOS Communication ation Media Protocols ‫( - ﺟﻬﺎﺯ ﺗﻘﻮﻳﺔ ﺃﻭ‬coaxial ‫ﺃﺳﻼﻙ ﳏﻮﺭﻳﺔ‬ (Terminals)‫- ﻃﺮﻓﻴﺎﺕ‬ Repeater ‫ﻣﻜﺮﺭ‬ Cables) (PC) ‫- ﺣﺎﺳﺒﺎﺕ ﺷﺨﺼﻴﺔ‬ ‫ﺃﺳﻼﻙ ﻣﱪﻭﻣﺔ‬ Hub ‫- ﳎﻤﻊ‬ ‫- ﳏﻄﺎﺕ ﻋﻤﻞ‬ (Twisted Pairs) Bridge ‫- ﺟﺴﺮ‬ (Work Stations) (Optical ‫ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﻣﺘﻮﺳﻄﺔ‬ Gateway ‫- ﺑﻮﺍﺑﺔ‬ Fiber) (Mini Computers) Switch ‫- ﻣﻔﺘﺎﺡ‬ ‫ﺍﻷﻭﺳﺎﻁ ﺍﻟﻼﺳﻠﻜﻴﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﺭﺋﻴﺴﻴﺔ‬ ‫ﻣﺴﺎﺭ ﺭﺑﻂ‬ (Wireless Media) (Mainframe) Router ‫ﻛﺮﺩ ﻭﺍﺟﻬﺔ ﺍﻟﺸﺒﻜﺔ‬ ‫- ﺣﺎﺳﺒﺎﺕ ﻋﻤﻼﻗﺔ‬ ‫- ﻣﻮﺩﻡ‬ (NIC Card ) Modem (Super Computers) 17
  • 18. ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ:‬ ‫ﺗﻌﺮﻳﻔﻬﺎ :‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻟﻘﻮﺍﻧﲔ ﻭ ﺍﻹﺟﺮﺍﺀﺍﺕ ﺍﻟﱵ ﺗﺘﺤﻜﻢ ﺑﺎﻻﺗﺼﺎﻝ‬ ‫ﻭ ﺍﻟﺘﻔﺎﻋﻞ ﺑﲔ ﺍﳊﻮﺍﺳﺐ ﺍﳌﺨﺘﻠﻔﺔ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫ﰲ ﺍﳉﻬﺎﺯ ﺍﳌﺮﺳﻞ ﺗﻜﻮﻥ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﺴﺌﻮﻟﺔ ﻋﻦ ﺍﻟﻘﻴﺎﻡ ﺑﺎﳌﻬﺎﻡ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﻘﺴﻴﻢ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺣﺰﻡ.‬ ‫• ﺇﺿﺎﻓﺔ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻟﻌﻨﻮﻧﺔ ﺇﱃ ﺍﳊﺰﻡ.‬ ‫• ﲢﻀﲑ ﺍﳊﺰﻡ ﻟﻺﺭﺳﺎﻝ.‬ ‫ﺑﻴﻨﻤﺎ ﺗﻘﻮﻡ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﰲ ﺍﳉﻬﺎﺯ ﺍﳌﺴﺘﻘﺒﻞ ﺑﺎﻟﻌﻤﻞ ﺍﻟﺘﺎﱄ:‬ ‫• ﺍﻟﺘﻘﺎﻁ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﻭﺳﻂ ﺍﻻﺗﺼﺎﻝ.‬ ‫• ﺇﺩﺧﺎﻝ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺇﱃ ﺩﺍﺧﻞ ﺍﳊﺎﺳﻮﺏ ﻋﱪ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﲡﻤﻴﻊ ﻛﻞ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﳌﺮﺳﻠﺔ ﻭ ﻗﺮﺍﺀﺓ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻟﺘﺤﻜﻢ ﺍﳌﻀﺎﻓﺔ ﺇﱃ ﻫﺬﻩ ﺍﳊﺰﻡ.‬ ‫• ﻧﺴﺦ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﺍﳊﺰﻡ ﺇﱃ ﺫﺍﻛﺮﺓ ﻣﺆﻗﺘﺔ ﻹﻋﺎﺩﺓ ﲡﻤﻴﻌﻬﺎ.‬ ‫• ﲤﺮﻳﺮ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﳌﻌﺎﺩ ﲡﻤﻴﻌﻬﺎ ﺇﱃ ﺍﻟﱪﺍﻣﺞ ﰲ ﺻﻮﺭﺓ ﻣﻔﻬﻮﻣﺔ ﻗﺎﺑﻠﺔ ﻟﻼﺳﺘﺨﺪﺍﻡ .‬ ‫ﺗﻨﻘﺴﻢ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺑﺸﻜﻞ ﻋﺎﻡ ﺇﱃ ﻗﺴﻤﲔ:‬ ‫1.ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﳏﺪﺩﺓ ﻭﺟﻬﺔ ﺍﻻﺗﺼﺎﻝ ‪: Connection-Oriente‬‬ ‫ﻳﻘـﻮﻡ ﺍﻟـﱪﻭﺗﻮﻛﻮﻝ ﻣـﻦ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﺑﺈﻋﺪﺍﺩ ﺍﺗﺼﺎﻝ ﻣﺒﺎﺷﺮ ﻳﺴﻤﻰ ﺩﺍﺋﺮﺓ ﻇﺎﻫﺮﻳﺔ ﺃﻭ ﺍﻓﺘﺮﺍﺿﻴﺔ ﺑﲔ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺍﳌﺘﺼﻠﺔ ﰲ ﺍﻟﺸﺒﻜﺔ. ﻭ ﳛﻘﻖ ﻫﺬﺍ ﺍﻻﺗﺼﺎﻝ ﺍﳌﺒﺎﺷﺮ ﻣﻮﺛﻮﻗﻴﺔ ﻋﺎﻟﻴﺔ ﻟﺘﺴﻠﻴﻢ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﻟﻜﻨﻪ ﻗﺪ‬ ‫ﻳـﺆﺩﻱ ﺇﱃ ﺑﻄﺊ ﰲ ﻋﻤﻞ ﻭ ﺃﺩﺍﺀ ﺍﻟﺸﺒﻜﺔ. ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪Transmission Control Protocol‬‬ ‫)‪ (TCP‬ﻭﺍﺣﺪﺍ ﻣﻨﻬﺎ .‬ ‫81‬
  • 19. ‫2. ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪: Connectionless‬‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﻦ ﻫﺪﺍ ﺍﻟﻨﻮﻉ ﻻ ﺗﻮﻓﺮ ﺍﺗﺼﺎﻻ ﻣﺒﺎﺷﺮﺍ ﻣﻊ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺴﺘﻘﺒﻞ ﻗﺒﻞ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﳑـﺎ ﻳﻌﲏ ﺃﻥ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺗﻨﺘﻘﻞ ﺑﺴﺮﻋﺔ ﺃﻛﱪ ﳑﺎ ﳛﺴﻦ ﻣﻦ ﺃﺩﺍﺀ ﺍﻟﺸﺒﻜﺔ ، ﻭ ﻟﻜﻦ ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﻟﻴﺴﺖ‬ ‫ﺗﺎﻣﺔ ﺍﳌﻮﺛﻮﻗﻴﺔ ﻧﻈﺮﺍ ﻷﻧﻪ ﻻ ﺳﺒﻴﻞ ﳌﻌﺮﻓﺔ ﻓﻴﻤﺎ ﺇﺫﺍ ﺣﺪﺛﺖ ﺃﺧﻄﺎﺀ ﺃﺛﻨﺎﺀ ﺍﻹﺭﺳﺎﻝ ﺃﻡ ﱂ ﲢﺪﺙ.‬ ‫ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ )‪ Internet Protocol (IP‬ﻣﺜﺎﻻ ﻭﺍﺿﺤﺎ ﻋﻠﻰ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ .‬ ‫ﺗﻨﻘﺴﻢ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺣﺴﺐ ﻭﻇﻴﻔﺘﻬﺎ ﺇﱃ ﺛﻼﺙ ﺃﻗﺴﺎﻡ:‬ ‫1. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺗﻄﺒﻴﻘﺎﺕ ‪: Application Protocols‬‬ ‫ﺗﻌﻤـﻞ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﰲ ﺍﻟﻄﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻭ ﺗﺘﻠﺨﺺ ﻣﻬﻤﺘﻬﺎ ﰲ ﺗﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﲢﻘﻴﻖ‬ ‫ﺍﻟﺘﻔﺎﻋﻞ ﺑﲔ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻬﺎ:‬ ‫• )‪.Server Message Block (SMB‬‬ ‫• )‪. Novell’s NetWare Core Protocols (NCPs‬‬ ‫• )‪File Transfer Access and Management Protocol (FTAMP‬‬ ‫2. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻧﻘﻞ ‪: Transport Protocols‬‬ ‫ﺃﻣـﺎ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟـﻨﻘﻞ ﻓﺘﺴﺘﺨﺪﻡ ﻟﺘﻮﻓﲑ ﺟﻠﺴﺎﺕ ﺍﻻﺗﺼﺎﻝ ﺑﲔ ﺍﳊﻮﺍﺳﺐ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﻫﻲ‬ ‫ﻣﺴﺆﻭﻟﺔ ﻋﻦ ﺻﻴﺎﻧﺔ ﺟﻮﺩﺓ ﻭ ﺩﻗﺔ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﻨﻘﻮﻟﺔ ﺑﲔ ﺍﻷﺟﻬﺰﺓ ، ﻭ ﻣﻦ ﺃﻣﺜﻠﺘﻬﺎ:‬ ‫• ﺍﳉﺰﺀ ﺍﻟﻨﺎﻗﻞ ﻣﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ‪. NWLink‬‬ ‫• ﺍﳉﺰﺀ ﺍﻟﻨﺎﻗﻞ ﻣﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪. NetBEUI‬‬ ‫• )‪.Sequenced Packet Exchange(SPX‬‬ ‫• )‪.Transmission Control Protocol(TCP‬‬ ‫3. ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺷﺒﻜﺔ ‪: Network Protocols‬‬ ‫ﺑﻴﻨﻤﺎ ﺗﻘﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺸﺒﻜﺔ ﺧﺪﻣﺎﺕ ﺭﺑﻂ ‪ Link Services‬ﻭ ﺗﺘﻠﺨﺺ ﻣﻬﺎﻣﻬﺎ ﰲ :‬ ‫• ﻋﻨﻮﻧﺔ ﻭ ﺗﻮﺟﻴﻪ ﺍﳌﻌﻠﻮﻣﺎﺕ.‬ ‫• ﺍﻟﺒﺤﺚ ﻋﻦ ﺃﺧﻄﺎﺀ ﰲ ﻋﻤﻠﻴﺔ ﺍﻹﺭﺳﺎﻝ.‬ ‫91‬
  • 20. ‫• ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻃﻠﺒﺎﺕ ﺇﻋﺎﺩﺓ ﺍﻹﺭﺳﺎﻝ.‬ ‫‪Token‬‬ ‫• ﲢﺪﻳـﺪ ﻗﻮﺍﻧـﲔ ﺍﻻﺗﺼﺎﻝ ﰲ ﺑﻴﺌﺎﺕ ﳏﺪﺩﺓ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﻣﺜﻞ ﺇﺛﺮﻧﺖ ﻭ‬ ‫‪.Ring‬‬ ‫ﻣﻦ ﺍﻷﻣﺜﻠﺔ ﻋﻠﻰ ﻫﺬﻩ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻣﺎ ﻳﻠﻲ:‬ ‫‪.Internet Protocol‬‬ ‫)‪(IP‬‬ ‫•‬ ‫‪. Internetwork Packet Exchange‬‬ ‫)‪(IPX‬‬ ‫•‬ ‫2. ﻭﺻﻒ ﻟﺒﺎﻗﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪: TCP/IP‬‬ ‫)‪Transmission Control Protocol/Internet Protocol(TCP/IP‬‬ ‫ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺎﻗﺔ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﱵ ﺗﺴﻤﺢ ﻟﻠﺸﺒﻜﺎﺕ ﻭ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ‬ ‫ﻣﻦ ﺍﻷﺟﻬﺰﺓ ﺑﺎﻻﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ. ﺣﻴﺚ ﻳﻮﻓﺮ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP/IP‬ﺧﺼﺎﺋﺺ ﺗﺸﺒﻴﻚ ﻭ ﺗﻮﺟﻴﻪ‬ ‫ﻭ ﻭﺻﻮﻝ ﻟﺸﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ ﻭ ﺍﻻﺳﺘﻔﺎﺩﺓ ﻣﻦ ﻣﻮﺍﺭﺩﻫﺎ. ﻭﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ﺍﻟﻘﻴﺎﺳﻲ ﺍﳌﺴﺘﺨﺪﻡ ﻟﻀﻤﺎﻥ‬ ‫ﺍﻟـﺘﻮﺍﻓﻖ ﺑﲔ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ، ﻭ ﺣﺎﻟﻴﺎ ﻓﺈﻥ ﺃﻏﻠﺐ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﻭ ﺍﻟﻮﺍﺳﻌﺔ ﺗﺪﻋﻢ‬ ‫ﻫـﺬﺍ ﺍﻟـﱪﻭﺗﻮﻛﻮﻝ. ﺗﺘﻜﻮﻥ ﺑﺎﻗﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP/IP‬ﻣﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ، ﻭﻟﻜﻦ‬ ‫ﺗﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP‬ﻭ ‪ IP‬ﻫﻲ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﶈﻮﺭﻳﺔ ﰲ ﻫﺬﻩ ﺍﻟﺒﺎﻗﺔ.‬ ‫‪ v‬ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪: TCP‬‬ ‫ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﳐﺼﺼﺎ ﻟﻠﻨﻘﻞ ‪ Transport Protocol‬ﻭﻫﻮ ﻳﻮﻓﺮ ﺍﺗﺼﺎﻻ ﻣﻮﺟﻬﺎ‬ ‫‪ Oriented -Connection‬ﻭ ﻳﺪﻋﻢ ﺍﻻﺗﺼﺎﻝ ﻣﺰﺩﻭﺝ ﺍﻻﲡﺎﻩ ‪ Full Duplex‬ﻭ ﻳﻮﻓﺮ ﲢﻜﻤﺎ ﺑﺘﺪﻓﻖ‬ ‫ﺍﻟﺒـﻴﺎﻧﺎﺕ. ﻛﻤﺎ ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﺑﻄﻴﺌﺎ ﰲ ﻋﻤﻠﻪ ﳍﺬﺍ ﻛﺎﻥ ﻻﺑﺪ ﻣﻦ ﺗﻮﻓﲑ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺁﺧﺮ‬ ‫ﺃﺳـﺮﻉ ﻳﻜﻮﻥ ﻋﻤﻠﻪ ﻣﻜﻤﻼ ﳍﺬﺍ ﰲ ﻧﻔﺲ ﻃﺒﻘﺔ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ TCP‬ﰲ ﺣﺰﻣﺔ ‪ TCP/IP‬ﻛﻤﺎ ﳒﺪ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻ ﺁﺧﺮ ﻫﻮ ﺑﺮﻭﺗﻮﻛﻮﻝ )‪ User Datagram Protocol (UDP‬ﻭ ﻫﻮ ﻳﻮﻓﺮ ﺧﺪﻣﺔ ﺳﺮﻳﻌﺔ‬ ‫ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪ Connectionless‬ﻟﺘﻨﻔﻴﺬ ﻧﻔﺲ ﻭﻇﺎﺋﻒ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪.TCP‬‬ ‫02‬
  • 21. ‫ﺑﺮﻭﺗﻮﻛﻮﻝ ‪: IP‬‬ ‫ﻫـﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺷﺒﻜﺔ ‪ Network Protocol‬ﻭﻫﻮ ﻳﻮﻓﺮ ﺗﺴﻠﻴﻢ ﻟﻠﺒﻴﺎﻧﺎﺕ ﺩﻭﻥ‬ ‫ﺍﺗﺼﺎﻝ ﻣﺴﺒﻖ ‪ .Connectionless‬ﺗﺴﻠﻚ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﺴﺎﺭﺍﺕ ﳐﺘﻠﻔﺔ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺮﺳﻞ‬ ‫ﻭ ﺍﳌﺴـﺘﻘﺒﻞ ﰲ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ ﻭ ﻋﻨﺪ ﻭﺻﻮﻝ ﺍﳊﺰﻡ ﺇﱃ ﻭﺟﻬﺘﻬﺎ ﻓﺈﻥ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻫﻮ ﺍﳌﺴﺆﻭﻝ‬ ‫ﻋـﻦ ﺇﻋـﺎﺩﺓ ﺗﺮﺗﻴـﺐ ﻭ ﲡﻤـﻴﻊ ﺍﳊﺰﻡ ﻟﻠﺤﺼﻮﻝ ﻋﻠﻰ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻷﺻﻠﻴﺔ . ﻋﻠﻰ ﻧﻔﺲ ﺍﻟﻄﺒﻘﺔ ﻣﻊ‬ ‫ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﰲ ﺑﺎﻗـﺔ ﺑـﺮﻭﺗﻮﻛﻮﻻﺕ ‪ TCP/IP‬ﻛﻤﺎ ﳒﺪ ﺃﻥ ﻫﻨﺎﻙ ﺑﺮﻭﺗﻮﻛﻮﻻ ﻣﻜﻤﻼ ﻟﻌﻤﻞ‬ ‫ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻭ ﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ‪ (ICMP) Internet Control Message Protocol‬ﻭﺣﻴﺚ‬ ‫ﻳﻮﻓـﺮ ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﺧﺪﻣﺔ ﻋﺪﳝﺔ ﺍﻻﺗﺼﺎﻝ ‪ ، Connectionless‬ﻓﺈﺫﺍ ﺣﺼﻠﺖ ﺃﻱ ﻣﺸﺎﻛﻞ ﰲ‬ ‫ﺍﻹﺭﺳـﺎﻝ ﻓﺈﻧﻪ ﻻ ﻳﻮﺟﺪ ﺃﻱ ﻃﺮﻳﻘﺔ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻟﻠﺘﻌﺮﻑ ﻋﻠﻰ ﻫﺬﻩ ﺍﳌﺸﺎﻛﻞ ﺃﻭ ﺣﻠﻬﺎ ، ﻭ ﻫﻨﺎ‬ ‫ﻳﺄﰐ ﺩﻭﺭ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ ICMP‬ﻟﻴﻜﻮﻥ ﻣﻜﻤﻼ ﰲ ﻋﻤﻠﻪ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ ،IP‬ﻭ ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺑﺮﻭﺗﻮﻛﻮﻝ‬ ‫ﻗﻴﺎﺳـﻲ ﻳﺆﻣﻦ ﺧﺪﻣﺔ ﺍﻟﺘﺮﺍﺳﻞ ﻟﱪﻭﺗﻮﻛﻮﻝ ‪ . IP‬ﻓﺈﺫﺍ ﺃﻋﺘﱪ ﺃﻥ ﺣﺰﻣﺔ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﻗﺪ ﰎ ﻋﻨﻮﻧﺘﻬﺎ‬ ‫ﺑﺸـﻜﻞ ﺧﺎﻃﺊ ﻭ ﺃﺭﺳﻠﺖ ﻟﻮﺟﻬﺔ ﺧﺎﻃﺌﺔ ، ﻓﺈﻥ ﺩﻭﺭ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ ICMP‬ﻳﺘﻤﺜﻞ ﺑﺈﺻﺪﺍﺭ ﺗﻘﺮﻳﺮ ﻋﻦ‬ ‫ﺍﳌﺸـﻜﻠﺔ ﻭ ﺗﻮﺟﻴﻬﻬﺎ ﻟﻠﱪﻧﺎﻣﺞ ﺍﻟﺸﺒﻜﻲ ﳊﻞ ﻫﺬﻩ ﺍﳌﺸﻜﻠﺔ ، ﳍﺬﺍ ﳒﺪ ﺃﻥ ﻋﻤﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ICMP‬‬ ‫ﻳﺰﻳﺪ ﻣﻦ ﻣﻮﺛﻮﻗﻴﺔ ﻋﻤﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ IP‬ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫ﺍﻟﻄﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻣﻦ ﺑﺎﻗﺔ ‪ TCP/IP‬ﺗﺘﻀﻤﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺍﻟﺘﺎﻟﻴﺔ :‬ ‫‪ : SMTP v‬ﻳﻌﺘﱪ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ Simple Mail Transfer Protocol‬ﻫﻮ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ‬ ‫ﺍﳌﺴـﺆﻭﻝ ﻋﻦ ﺇﺭﺳﺎﻝ ﺍﻟﱪﻳﺪ ﺍﻹﻟﻜﺘﺮﻭﱐ ﻭ ﻫﻮ ﻳﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﱄ ‪ TCP‬ﻭ ‪ IP‬ﻟﺘﺒﺎﺩﻝ‬ ‫ﺍﻟﺮﺳﺎﺋﻞ‬ ‫‪ : FTP v‬ﺑﻴـﻨﻤﺎ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ File Transfer Protocol‬ﻫﻮ ﺍﳌﺴﺆﻭﻝ ﻋﻦ ﻧﺴﺦ ﺍﳌﻠﻔﺎﺕ‬ ‫ﺑﲔ ﺟﻬﺎﺯ ﻭ ﺁﺧﺮ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﻫﻮ ﻳﺴﻤﺢ ﺑﺎﻷﻣﻮﺭ ﺍﻟﺘﺎﻟﻴﺔ :‬ ‫• ﺍﻟﺪﺧﻮﻝ ﺇﱃ ﺟﻬﺎﺯ ﺁﺧﺮ ﻋﻦ ﺑﻌﺪ .‬ ‫• ﺍﻟﺘﻨﻘﻞ ﺑﲔ ﺍ‪‬ﻠﺪﺍﺕ .‬ ‫• ﺗﻨﻔﻴﺬ ﻭ ﺗﺸﻐﻴﻞ ﺍﻷﻭﺍﻣﺮ .‬ ‫12‬
  • 22. ‫• ﻣﻌﺎﳉﺔ ﺍﳌﻠﻔﺎﺕ .‬ ‫‪ : SNMP v‬ﺑـﺮﻭﺗﻮﻛﻮﻝ ‪ Simple Network Management Protocol‬ﻭ ﺍﻟـﺬﻱ‬ ‫ﻃﻮﺭ‬ ‫ﻣﻦ ﻗﺒﻞ ‪ Internet Engineering Task Force‬ﻓﻬﻮ ﳐﺼﺺ ﻹﺩﺍﺭﺓ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻭ ﻳﻘـﻮﻡ ﲜﻤﻊ ﻣﻌﻠﻮﻣﺎﺕ ﺍﻹﺩﺍﺭﺓ ﻣﻦ ﻛﻞ ﺟﻬﺎﺯ ﻣﺘﺼﻞ ﺑﺎﻟﺸﺒﻜﺔ ﻭ ﻫﻮ ﺃﻳﻀﺎ ﺍﻟﺬﻱ ﻳﺴﺘﻘﺒﻞ ﺍﻟﺘﻘﺎﺭﻳﺮ‬ ‫ﻋـﻦ ﺣـﺪﻭﺙ ﻣﺸـﺎﻛﻞ ﺃﻭ ﺃﺧﻄﺎﺀ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ، ﻭﻫﺬﺍ ﺍﻟﱪﻭﺗﻮﻛﻮﻝ ﻳﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ‬ ‫ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻣﻨﻬﺎ : ) ‪(Telnet , IP, IPX , APPleTalk , DECnet‬‬ ‫‪ : Telnet v‬ﺗﻌﺘـﱪ ﻭﻇـﺎﺋﻒ ﺑﺮﻭﺗﻮﻛﻮﻝ ‪ Telnet‬ﻣﺸﺎ‪‬ﺔ ﻟﻮﻇﺎﺋﻒ ‪ FTP‬ﻓﻬﻮ ﻳﺴﻤﺢ‬ ‫ﺑﺎﻟﺪﺧﻮﻝ ﺇﱃ ﺟﻬﺎﺯ ﺁﺧﺮ ﻋﻦ ﺑﻌﺪ ﻭ ﺗﺸﻐﻴﻞ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ﻋﻠﻴﻪ .‬ ‫3. ﺃﻫﻢ ﳑﻴﺰﺍﺕ ﺣﺰﻣﺔ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ‪: TCP/IP‬‬ ‫• ﺍﳌﻮﺛﻮﻗﻴﺔ ﻭ ﺍﻻﻧﺘﺸﺎﺭ .‬ ‫• ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﻧﺖ .‬ ‫• ﺍﻟﻮﺻﻮﻝ ﺇﱃ ﺷﺒﻜﺔ ﺍﻹﻧﺘﺮﺍﻧﺖ .‬ ‫• ﺩﻋﻢ ﺗﻮﺟﻴﻪ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ‪. Routing‬‬ ‫• ﺗﻮﻓﲑ ﺍﻟﻘﺎﺑﻠﻴﺔ ﻟﻼﺗﺼﺎﻝ ﻷﻧﻈﻤﺔ ﺍﻟﺘﺸﻐﻴﻞ ﻭ ﺍﻷﺟﻬﺰﺓ ﺍﳌﺨﺘﻠﻔﺔ .‬ ‫• ﺍﻟﺪﻋﻢ ﻭ ﺍﻟﺘﻔﺎﻫﻢ ﻣﻊ ﻏﲑﻩ ﻣﻦ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ .‬ ‫22‬
  • 23. ‫4. ﺍﻟﻌﻴﻮﺏ ﺍﻷﺳﺎﺳﻴﺔ ﳊﺰﻣﺔ ‪: TCP/IP‬‬ ‫• ﺣﺠﻢ ﺍﳊﺰﻣﺔ ﺍﻟﻜﺒﲑ ﻭ ﺗﻌﻘﻴﺪﻫﺎ .‬ ‫ﺳـﺮﻋﺘﻪ ﺍﳌﺘﻮﺍﺿـﻌﺔ . ﺑﺎﻟﻨﺴﺒﺔ ﳍﺎﺗﲔ ﺍﳌﺸﻜﻠﺘﲔ ﻓﻘﺪ ﺃﺻﺒﺤﺘﺎ ﺃﻗﻞ ﺗﺄﺛﲑﺍ ﻣﻊ ﺍﻟﺘﻄﻮﺭ ﺍﻟﺬﻱ ﺣﺼﻞ ﰲ‬ ‫ﺃﻧﻈﻤـﺔ ﺍﻟﺘﺸـﻐﻴﻞ. ﺃﻣﺎ ﻋﻦ ﻣﻮﺿﻮﻉ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﺑﺸﻜﻞ ﻋﺎﻡ، ﻫﻨﺎﻙ ﺃﻧﻮﺍﻉ ﻛﺜﲑﺓ ، ﻭ ﻗﺪ ﻋﻤﺪﻧﺎ‬ ‫ﺷﺮﺡ ﺍﻟﺸﻬﲑ ﻣﻨﻬﺎ ﻓﻘﻂ.‬ ‫32‬
  • 24. ‫ﺷﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ‪:Peer-to-Peer Networks‬‬ ‫1. ﺗﻌﺮﻳﻒ ﺷﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ : ﻫﻲ ﺷﺒﻜﺔ ﳏﻠﻴﺔ ﻣﻜﻮﻧﺔ ﻣﻦ ﳎﻤﻮﻋﺔ ﻣﻦ ﺍﻷﺟﻬﺰﺓ ﳍﺎ ﺣﻘﻮﻕ ﻣﺘﺴﺎﻭﻳﺔ‬ ‫ﻭ ﻻ ﲢﺘﻮﻱ ﻋﻠﻰ ﻣﺰﻭﺩ ﳐﺼﺺ ﺑﻞ ﻛﻞ ﺟﻬﺎﺯ ﰲ ﺍﻟﺸﺒﻜﺔ ﻳﻜﻮﻥ ﻣﺰﻭﺩ ﻭ ﺯﺑﻮﻧﺎ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫2. ﳑﻴﺰﺍ‪‬ﺎ:‬ ‫• ﻣﻦ ﺍﳌﻤﻴﺰﺍﺕ ﺍﻟﺮﺋﻴﺴﻴﺔ ﻟﺸﺒﻜﺎﺕ ﺍﻟﻨﺪ ﻟﻠﻨﺪ ﻫﻮ ﺃﻥ ﺗﻜﻠﻔﺘﻬﺎ ﳏﺪﻭﺩﺓ .‬ ‫• ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﻻ ﲢﺘﺎﺝ ﺍﱃ ﺑﺮﺍﻣﺞ ﺇﺿﺎﻓﻴﺔ ﻋﻠﻰ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ .‬ ‫• ﻻ ﲢﺘﺎﺝ ﺍﱃ ﺃﺟﻬﺰﺓ ﻗﻮﻳﺔ ، ﻷﻥ ﻣﻬﺎﻡ ﺇﺩﺍﺭﺓ ﻣﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ ﻣﻮﺯﻋﺔ ﻋﻠﻰ ﻛﻞ ﺍﻷﺟﻬﺰﺓ‬ ‫ﻭ ﻟﻴﺴﺖ ﻣﻮﻛﻠﺔ ﺍﱃ ﺟﻬﺎﺯ ﻣﺰﻭﺩ ﺑﻌﻴﻨﻪ.‬ ‫• ﺗﺜﺒﻴﺖ ﺍﻟﺸﺒﻜﺔ ﻭﺇﻋﺪﺍﺩﻫﺎ ﰲ ﻏﺎﻳﺔ ﺍﻟﺴﻬﻮﻟﺔ.‬ ‫• ﺃﻥ ﻳﻜﻮﻥ ﻋﺪﺩ ﺍﻷﺟﻬﺰﺓ ﰲ ﺍﻟﺸﺒﻜﺔ ﻻ ﻳﺘﺠﺎﻭﺯ ﺍﻟﻌﺸﺮﺓ .‬ ‫3. ﻋﻴﻮ‪‬ﺎ :‬ ‫• ﺍﻟﻌﻴﺐ ﺍﻟﺮﺋﻴﺴﻲ ﳍﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﻫﻮ ﺃ‪‬ﺎ ﻏﲑ ﻣﻨﺎﺳﺒﺔ ﻟﻠﺸﺒﻜﺎﺕ ﺍﻟﻜﺒﲑ ﺓ.‬ ‫• ﻣﻊ ﳕﻮ ﺍﻟﺸﺒﻜﺔ ﺗﺼﺒﺢ ﺍﻹﺩﺍﺭﺓ ﺍﻟﻼﻣﺮﻛﺰﻳﺔ ﺳﺒﺒﺎ ﰲ ﻫﺪﺭ ﺍﻟﻮﻗﺖ ﻭ ﺍﳉﻬﺪ.‬ ‫ﻣﻼﺣﻈﺔ :‬ ‫ﺇﺩﺍﺭﺓ ﺍﻟﺸﺒﻜﺔ ﻋﻠﻰ ﻧﻮﻋﲔ : ﻣﺮﻛﺰﻳﺔ ﻭ ﻣﻮﺯﻋﺔ .‬ ‫- ﰲ ﺣﺎﻟﺔ ﺍﻹﺩﺍﺭﺓ ﺍﳌﺮﻛﺰﻳﺔ ، ﻓﺈﻥ ﺍﻟﺸﺒﻜﺔ ﺗﻜﻮﻥ ﻣﺴﲑﺓ ﺑﻮﺍﺳﻄﺔ ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺷﺒﻜﺎﺕ ﻣﺮﻛﺰﻱ .‬ ‫- ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﻟﺸﺒﻜﺎﺕ : ﻫﻮ ﺍﻟﱪﻧﺎﻣﺞ ﺍﻟﺬﻱ ﻳﺪﻳﺮ ﻭ ﻳﺘﺤﻜﻢ ﺑﻨﺸﺎﻃﺎﺕ ﺍﻷﺟﻬﺰﺓ ﻭ ﺍﳌﺴﺘﺨﺪﻣﲔ ﻋﻠﻰ‬ ‫ﺍﻟﺸﺒﻜﺔ .‬ ‫- ﰲ ﺣﺎﻟﺔ ﺍﻹﺩﺍﺭﺓ ﺍﳌﻮﺯﻋﺔ ، ﻓﺈﻥ ﻛﻞ ﻣﺴﺘﺨﺪﻡ ﻣﺴﺆﻭﻝ ﻋﻦ ﺇﺩﺍﺭﺓ ﺟﻬﺎﺯﻩ ﻭﲢﺪﻳﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ‬ ‫ﻭ ﺍﳌﻮﺍﺭﺩ ﺍﻟﱵ ﻳﺮﻳﺪ ﻣﺸﺎﺭﻛﺘﻬﺎ ﻣﻊ ﺍﻵﺧﺮﻳﻦ.‬ ‫4. ﺍﻧﻈﻤﺔ ﺍﻟﺘﺸﻐﻴﻞ:‬ ‫ﻳﻌﺘﱪ ﻧﻈﺎﻡ ‪ NT‬ﻭ ﻭﻳﻨﺪﻭﺯ 0002 ﺃﻓﻀﻞ ﻣﻦ ﺑﺎﻗﻲ ﺍﻷﻧﻈﻤﺔ ﻧﻈﺮﺍ ﻟﻸﺩﻭﺍﺕ ﺍﻟﱵ ﺗﻘﺪﻣﻬﺎ ﻹﺩﺍﺭﺓ ﺍﻟﺸﺒﻜﺔ‬ ‫ﻭ ﺍﳌﺴﺘﻮﻯ ﺍﻟﻌﺎﱄ ﻣﻦ ﺍﻷﻣﺎﻥ ﺍﻟﺬﻱ ﺗﻮﻓﺮﻩ.‬ ‫42‬
  • 25. ‫ﺷﺒﻜﺎﺕ ﺍﻟﺰﺑﻮﻥ / ﺍﳌﺰﻭﺩ ‪: Client / Server Networks‬‬ ‫1. ﺗﻌﺮﻳﻒ ﺍﳌﺰﻭﺩ :‬ ‫ﺍﳌﺰﻭﺩ ﺟﻬﺎﺯ ﺣﺎﺳﻮﺏ ﳛﺘﻮﻱ ﻋﻠﻰ ﻣﺴﺎﺣﺔ ﲣﺰﻳﻦ ﻛﺒﲑﺓ ﻭ ﻣﻌﺎﰿ ﻗﻮﻱ ﻭﺫﺍﻛﺮﺓ ﻭﻓﲑﺓ ﻭﻗﺪ‬ ‫ﻳﻜﻮﻥ ﻣﺼﻨﻮﻋﺎ ﺧﺼﻴﺼﺎ ﻟﻴﻜﻮﻥ ﻣﺰﻭﺩ.‬ ‫2. ﳑﻴﺰﺍ‪‬ﺎ:‬ ‫• ﺍﻟﻨﺴﺦ ﺍﻹﺣﺘﻴﺎﻃﻲ ﳊﻤﺎﻳﺔ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻣﻦ ﺍﻟﺘﻠﻒ ﻭ ﺍﻟﻀﻴﺎﻉ.‬ ‫• ﺗﺪﻋﻴﻢ ﺁﻻﻑ ﺍﳌﺴﺘﺨﺪﻣﲔ .‬ ‫• ﰲ ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﺗﻜﻮﻥ ﻣﻮﺍﺭﺩ ﺍﻟﺸﺒﻜﺔ ﻣﺘﻤﺮﻛﺰﺓ ﰲ ﺟﻬﺎﺯ ﻭﺍﺣﺪ ﻫﻮ ﺍﳌﺰﻭﺩ.‬ ‫• ﻳﻌﺘﱪ ﺃﻣﻦ ﺍﻟﺸﺒﻜﺔ ﻣﻦ ﺃﻫﻢ ﺍﻷﺳﺒﺎﺏ ﻹﺳﺘﺨﺪﺍﻡ ﺷﺒﻜﺎﺕ ﺍﻟﺰﺑﻮﻥ / ﺍﳌﺰﻭﺩ.‬ ‫3. ﺃﻧﻮﺍﻉ ﻟﻠﻤﺰﻭﺩﺍﺕ ﻣﻦ ﺣﻴﺚ ﻋﻤﻠﻬﺎ:‬ ‫• ﻣﺰﻭﺩﺍﺕ ﻣﻠﻔﺎﺕ ‪. File Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻟﻄﺒﺎﻋﺔ ‪. Print Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻟﺘﻄﺒﻴﻘﺎﺕ ‪. Application Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﺍﻹﺗﺼﺎﻻﺕ ‪. Communication Servers‬‬ ‫• ﻣﺰﻭﺩﺍﺕ ﻗﻮﺍﻋﺪ ﺍﻟﺒﻴﺎﻧﺎﺕ ‪. Database Servers‬‬ ‫52‬
  • 26. ‫ﺷﺒﻜﺎﺕ ﺇﺛﲑﻧﺖ :‬ ‫ﺷﺮﻛﺔ ‪Xerox‬‬ ‫ﺗﻌﺘﱪ ‪ Ethernet‬ﺇﺣﺪﻯ ﻣﻌﻤﺎﺭﻳﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ‪ LAN‬ﺍﻟﱵ ﻃﻮﺭ‪‬ﺎ‬ ‫‪IEEE .Networking Standard‬‬ ‫ﰲ ﻣﻨﺘﺼﻒ ﺍﻟﺴﺒﻌﻴﻨﻴﺎﺕ، ﻭ ﻫﻲ ﲤﺜﻞ ﺍﻟﻘﺎﻋﺪﺓ ﳌﻌﻴﺎﺭ ﺍﻟﺘﺸﺒﻴﻚ‬ ‫ﺗﺴﺘﺨﺪﻡ ﺇﺛﺮﻧﺖ ﻃﺮﻳﻘﺔ ﺧﺎﺻﺔ ﻟﺘﺴﻤﺢ ﻷﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﳌﺘﺼﻠﺔ ﺑﺎﻟﺸﺒﻜﺔ ﺑﺈﺭﺳﺎﻝ ﺑﻴﺎﻧﺎ‪‬ﺎ‬ ‫3.208‬ ‫ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﻭ ﺫﻟﻚ ﻟﺘﻨﻈﻴﻢ ﺣﺮﻛﺔ ﻧﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ ، ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﺗﺴﻤﻰ ﲢﺴﺲ ﺍﻟﻨﺎﻗﻞ ﻣﺘﻌﺪﺩ‬ ‫‪Carrier Sense Multiple Access with Collision‬‬ ‫ﺍﻟﻮﺻﻮﻝ ﻣﻊ ﺍﻛﺘﺸﺎﻑ ﺍﻟﺘﺼﺎﺩﻡ .‬ ‫)‪ ، Detection(CSMA/CD‬ﺑﺎﺳﺘﺨﺪﺍﻡ ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﻳﺮﺍﻗﺐ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺸﺒﻜﺔ ﻭ ﻳﻘﻮﻡ ﺑﺎﻹﺭﺳﺎﻝ‬ ‫ﻋﻨﺪﻣﺎ ﳛﺲ ﺃﻥ ﺍﻟﺴﻠﻚ ﻏﲑ ﻣﺸﻐﻮﻝ ﺑﺄﻱ ﺇﺷﺎﺭﺓ.ﺇﺫﺍ ﺣﺼﻞ ﺗﺼﺎﺩﻡ ﻧﺎﺗﺞ ﻋﻦ ﺣﺎﺳﻮﺏ ﺁﺧﺮ ﻗﺎﻡ ﺑﺈﺭﺳﺎﻝ‬ ‫ﺍﻟﺒﻴﺎﻧﺎﺕ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ ، ﻓﺈﻥ ﻛﻼ ﺍﳊﺎﺳﻮﺑﺎﻥ ﺳﻴﺘﻮﻗﻔﺎﻥ ﻋﻦ ﺍﻹﺭﺳﺎﻝ ﻭ ﺳﻴﻨﺘﻈﺮ ﻛﻞ ﻣﻨﻬﻤﺎ ﻭﻗﺖ‬ ‫ﻋﺸﻮﺍﺋﻲ ﻟﻴﻌﻴﺪ ﺇﺭﺳﺎﻝ ﺑﻴﺎﻧﺎﺗﻪ ﳑﺎ ﻳﻘﻠﻞ ﻣﻦ ﺍﺣﺘﻤﺎﻝ ﺣﺪﻭﺙ ﺗﺼﺎﺩﻡ ﺁﺧﺮ.‬ ‫ﺷﺒﻜﺎﺕ ‪:Token Ring‬‬ ‫ﻓﻜﺮﺓ ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻇﻬﺮﺕ ﺃﻭﻝ ﻣﺮﺓ ﰲ ﺃﻭﺍﺋﻞ ﺍﻟﺴﺘﻴﻨﺎﺕ ، ﻭﻟﻜﻨﻬﺎ ﱂ ﺗﻨﻔﺬ‬ ‫ﺇﻻ ﺑﻌﺪ ﺍﻹﺗﻔﺎﻕ ﻋﻠﻰ ﺍﳌﻌﻴﺎﺭ 5.208 ‪ IEEE‬ﺍﻟﺬﻱ ﻳﺼﻒ ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻣﻦ ﺧﻼﻝ ﺗﺼﻤﻴﻢ‬ ‫ﺍﳊﻠﻘﺔ ‪ Ring‬ﻭ ﻛﺎﻥ ﺫﻟﻚ ﻋﺎﻡ 5891 ﻭﻫﻲ ﲤﺜﻞ ﺍﳌﻨﺎﻓﺲ ﺍﻷﻗﻮﻯ ﻟﺸﺒﻜﺎﺕ ﺇﺛﺮﻧﺖ ﺫﺍﺕ ﺍﳌﻌﻴﺎﺭ ‪IEEE‬‬ ‫3.208 . ﺷﺒﻜﺎﺕ ‪ Token Ring‬ﻫﻲ ﺷﺒﻜﺎﺕ ﳏﻠﻴﺔ ‪ LAN‬ﻭ ﲡﻤﻊ ﺑﲔ ﺧﺎﺻﻴﺘﲔ:‬ ‫1. ﲤﺮﻳﺮ ﺍﻹﺷﺎﺭﺓ ‪. Token Passing‬‬ ‫2. ﺍﻟﺘﺼﻤﻴﻢ ﺍﳍﺠﲔ ﻟﻠﺤﻠﻘﺔ ﻭ ﺍﻟﻨﺠﻤﺔ .‬ ‫ﻗﺎﻣﺖ ﺍﻟﻠﺠﻨﺔ ﺍﳌﺴﺌﻮﻟﺔ ﻋﻦ ﺍﳌﻌﻴﺎﺭ 5.208 ‪ IEEE‬ﺑﺘﻄﻮﻳﺮ ﻭﺳﻴﻠﺔ ﻟﻠﺘﺤﻜﻢ ﺑﺎﻟﻮﺻﻮﻝ ﺍﱃ ﻭﺳﻂ‬ ‫ﺍﻹﺭﺳﺎﻝ )‪ ، Media Access Control (MAC‬ﻭ ﺗﺴﻤﻰ ﻫﺬﻩ ﺍﻟﻮﺳﻴﻠﺔ ﲤﺮﻳﺮ ﺍﻹﺷﺎﺭﺓ ‪Token‬‬ ‫‪. Passing‬‬ ‫ﺷﺒﻜﺎﺕ ‪ AppleTalk‬ﻭ ‪:ARCnet‬‬ ‫1. ﺷﺒﻜﺎﺕ ‪: AppleTalk‬‬ ‫ﰲ ﻣﻨﺘﺼﻒ ﺍﻟﺜﻤﺎﻧﻴﻨﺎﺕ ﻗﺎﻣﺖ ﺷﺮﻛﺔ ‪ Apple Computer‬ﺑﺘﻘﺪﱘ ﻣﻌﻤﺎﺭﻳﺔ ﻟﺸﺒﻜﺔ ﺧﺎﺻﺔ ﻟﺮﺑﻂ ﳎﻤﻮﻋﺔ‬ ‫ﺻﻐﲑﺓ ﻣﻦ ﺍﳌﺴﺘﺨﺪﻣﲔ. ﺗﻌﺘﱪ ﻗﺪﺭﺍﺕ ﺍﻟﺘﺸﺒﻴﻚ ﻣﺪﳎﺔ ﺩﺍﺧﻞ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺸﺨﺼﻲ ‪Apple‬‬ ‫)‪ Macintosh (Mac‬ﳑﺎ ﳚﻌﻞ ﻣﻌﻤﺎﺭﻳﺔ ﺷﺒﻜﺎﺕ ‪ Apple‬ﺃﺑﺴﻂ ﻣﻦ ﻏﲑﻫﺎ ﻣﻦ ﻣﻌﻤﺎﺭﻳﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ .‬ ‫62‬
  • 27. ‫1.1. ﺗﺘﻀﻤﻦ ﻋﺎﺋﻠﺔ ﺷﺒﻜﺎﺕ ‪ Apple‬ﺍﻟﺘﺎﱄ :‬ ‫• ‪. AppleTalk‬‬ ‫• ‪. LocalTalk‬‬ ‫• ‪. AppleShare‬‬ ‫• ‪. EtherTalk‬‬ ‫• ‪. TokenTalk‬‬ ‫ﺗﺴﺘﺨﺪﻡ ‪ LocalTalk‬ﻧﻈﺎﻡ ﺍﻟﻮﺻﻮﻝ ﺍﱃ ﺍﻟﻮﺳﻂ ﻣﻦ ﺍﻟﻨﻮﻉ ‪ CSMA/CA‬ﻭ ﺫﻟﻚ ﺑﻐﺾ ﺍﻟﻨﻈﺮ ﻫﻞ‬ ‫ﺍﻟﺘﺼﻤﻴﻢ ﻣﻦ ﻧﻮﻉ ﺍﻟﻨﺎﻗﻞ ﺃﻭ ﺍﻟﻨﺠﻤﺔ.‬ ‫2. ﺷﺒﻜﺔ ‪Arcnet‬‬ ‫ﺗﻌﺘﱪ ﺷﺒﻜﺔ )‪ Attached Resource Computer Network (ARCNet‬ﻣﻦ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﺒﺴﻴﻄﺔ ﻏﲑ‬ ‫ﺍﳌﻜﻠﻔﺔ ﺍﳌﻮﺟﻬﺔ ﻟﺸﺒﻜﺎﺕ ﳎﻤﻮﻋﺎﺕ ﺍﻟﻌﻤﻞ.‬ ‫ﻭﻗﺪ ﻃﻮﺭﺕ ﺷﺒﻜﺎﺕ ‪ ARCNet‬ﻣﻦ ﻗﺒﻞ ﺷﺮﻛﺔ ‪ Datapoint Corporation‬ﻋﺎﻡ 7791.‬ ‫ﻭ ﺃﻭﻝ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ‪ ARCNet‬ﻛﺎﻧﺖ ﻣﺘﻮﻓﺮﺓ ﻋﺎﻡ 3891.‬ ‫ﺗﺴﺘﺨﺪﻡ ﺷﺒﻜﺎﺕ ‪ ARCNet‬ﻧﻈﺎﻡ ‪ Token Passing‬ﰲ ﺷﺒﻜﺎﺕ ﺍﻟﻨﺎﻗﻞ ‪ Bus‬ﺃﻭ ﺷﺒﻜﺎﺕ ‪Star‬‬ ‫‪. Bus‬‬ ‫ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ :‬ ‫ﺗﻮﻓﺮ ﺍﻷﺳﻼﻙ ﺧﻴﺎﺭﺍﺕ ﻓﻌﺎﻟﺔ ﻟﺘﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﳌﻮﺍﺭﺩ ﻋﱪ ﺍﻟﺸﺒﻜﺎﺕ ، ﻭ ﻟﻜﻦ ﺍﻷﺳﻼﻙ‬ ‫ﻛﻮﺳﻂ ﺇﺭﺳﺎﻝ ﻻ ﳜﻠﻮ ﻣﻦ ﺍﻟﻌﻴﻮﺏ. ﳍﺬﺍ ﺑﺪﺃﺕ ﺍﻟﺸﺒﻜﺎﺕ ﺍﶈﻠﻴﺔ ﺍﻟﻼﺳﻠﻜﻴﺔ ‪ Wireless LAN‬ﺗﺸﻜﻞ‬ ‫ﺧﻴﺎﺭﺍ ﻓﻌﺎﻻ ﻟﻠﺘﺸﺒﻴﻚ ﻭ ﺍﻟﺴﺒﺐ ﻳﺘﻠﺨﺺ ﻓﻤﺎﻳﻠﻲ :‬ ‫1. ﺍﻟﺘﻄﻮﺭﺍﺕ ﺍﳌﺘﻼﺣﻘﺔ ﰲ ﺍﻟﺘﻘﻨﻴﺎﺕ ﻭ ﺍﳌﻨﺘﺠﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ.‬ ‫2. ﺍﻹﳔﻔﺎﺽ ﺍﳌﺘﻮﺍﺻﻞ ﰲ ﺍﻷﺳﻌﺎﺭ.‬ ‫3. ﺍﻟﻄﻠﺐ ﺍﳌﺘﺰﺍﻳﺪ ﻋﻠﻰ ﻫﺬﻩ ﺍﻟﺸﺒﻜﺎﺕ ﺑﺴﺒﺐ ﺍﳊﺮﻳﺔ ﺍﻟﻜﺒﲑﺓ ﺍﻟﱵ ﺗﻮﻓﺮﻫﺎ.‬ ‫72‬
  • 28. ‫1. ﺗﻌﺘﱪ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ ﻣﻔﻴﺪﺓ ﰲ ﺍﳊﺎﻻﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﻮﻓﲑ ﺇﺗﺼﺎﻻﺕ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﺰﺩﲪﺔ.‬ ‫• ﺗﻮﻓﲑ ﺇﺗﺼﺎﻻﺕ ﻟﻠﻤﺴﺘﺨﺪﻣﲔ ﻛﺜﲑﻱ ﺍﻟﺘﻨﻘﻞ.‬ ‫• ﺑﻨﺎﺀ ﺷﺒﻜﺎﺕ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻌﺰﻭﻟﺔ ﺍﻟﱵ ﻳﺼﻌﺐ ﺗﻮﺻﻴﻠﻬﺎ ﺑﺄﺳﻼﻙ.‬ ‫ﳏﻄﺔ ﺍﻟﻌﻤﻞ ﺍﻟﻼﺳﻠﻜﻴﺔ ﺗﺒﺪﻭ ﻭ ﺗﻌﻤﻞ ﺑﺸﻜﻞ ﻣﺸﺎﺑﻪ ﻟﻠﻤﺤﻄﺎﺕ ﺍﻟﺴﻠﻜﻴﺔ ﻭ ﺍﻹﺧﺘﻼﻑ ﺍﻟﻮﺣﻴﺪ‬ ‫ﻳﺘﻤﺜﻞ ﰲ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ ﺍﳌﺴﺘﺨﺪﻡ.‬ ‫ﻫﻨﺎﻙ ﺛﻼﺙ ﺗﻘﻨﻴﺎﺕ ﺃﺳﺎﺳﻴﺔ ﺗﺴﺘﺨﺪﻡ ﰲ ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﰲ ﺍﻟﺸﺒﻜﺎﺕ ﺍﻟﻼﺳﻠﻜﻴﺔ ﺍﶈﻠﻴﺔ:‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ﺃﺣﺎﺩﻳﺔ ﺍﻟﺘﺮﺩﺩ ‪. single-frequency radio‬‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺭﺍﺩﻳﻮ ﺍﻟﻄﻴﻒ ﺍﻹﻧﺘﺸﺎﺭﻱ ‪. spread-spectrum radio‬‬ ‫‪ v‬ﻣﻮﺟﺎﺕ ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ ‪. infrared‬‬ ‫ﺑﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺔ ‪: Network Adapter Cards‬‬ ‫ﻟﻜﻲ ﻳﺘﻤﻜﻦ ﺟﻬﺎﺯ ﺍﳊﺎﺳﻮﺏ ﻣﻦ ﺍﻹﺗﺼﺎﻝ ﻻﺑﺪ ﻟﻪ ﻣﻦ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﻭ ﺍﻟﱵ ﺗﻌﺘﱪ ﺍﻟﻮﺍﺟﻬﺔ‬ ‫ﺍﻟﱵ ﺗﺼﻞ ﺑﲔ ﺟﻬﺎﺯ ﺍﳊﺎﺳﻮﺏ ﻭ ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ .‬ ‫1. ﺩﻭﺭ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ:‬ ‫• ﲢﻀﲑ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻟﺒﺜﻬﺎ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﺇﺭﺳﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ.‬ ‫• ﺍﻟﺘﺤﻜﻢ ﺑﺘﺪﻓﻖ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺑﲔ ﺍﳊﺎﺳﻮﺏ ﻭ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ .‬ ‫• ﺗﺮﲨﺔ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ﻣﻦ ﺳﻠﻚ ﺍﻟﺸﺒﻜﺔ ﺍﱃ ﺑﺎﻳﺘﺎﺕ ﻳﻔﻬﻤﻬﺎ ﻣﻌﺎﰿ ﺍﳊﺎﺳﻮﺏ‬ ‫ﻭ ﻋﻨﺪ ﺍﻹﺭﺳﺎﻝ ﻓﺈ‪‬ﺎ ﺗﺘﺮﺟﻢ ﺇﺷﺎﺭﺍﺕ ﺍﳊﺎﺳﻮﺏ ﺍﻟﺮﻗﻤﻴﺔ ﺍﱃ ﻧﺒﻀﺎﺕ ﻛﻬﺮﺑﺎﺋﻴﺔ ﻳﺴﺘﻄﻴﻊ ﺳﻠﻚ‬ ‫ﺍﻟﺸﺒﻜﺔ ﲪﻠﻬﺎ.‬ ‫ﻛﻞ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﲤﺘﻠﻚ ﻋﻨﻮﺍﻥ ﺷﺒﻜﺔ ﻓﺮﻳﺪ ، ﻛﻤﺎ ﲢﺘﻮﻱ ﻋﻠﻰ ﺃﺟﺰﺍﺀ ﻣﺎﺩﻳﺔ ‪ Hardware‬ﻭ ﺃﺟﺰﺍﺀ‬ ‫ﺑﺮﳎﻴﺔ ‪) Software‬ﺍﳉﺰﺀ ﺍﻟﱪﳎﻲ ﻳﻜﻮﻥ ﳐﺰﻧﺎ ﺩﺍﺧﻞ ﺫﺍﻛﺮﺓ ‪ ROM‬ﻭ ﻳﻜﻮﻥ ﻣﺴﺆﻭﻝ ﻋﻦ ﺗﻮﺟﻴﻪ‬ ‫ﻭ ﺗﻨﻔﻴﺬ ﺍﳌﻬﺎﻡ ﺍﳌﻮﻛﻠﺔ ﺑﺎﻟﺒﻄﺎﻗﺔ(.‬ ‫82‬
  • 29. ‫ﺍﻟﻘﻀﺎﻳﺎ ﺍﻟﱵ ﳚﺐ ﺃﻥ ﺗﺘﻔﻖ ﻋﻠﻴﻬﺎ ﺍﻟﺒﻄﺎﻗﺎﺕ ﻟﻜﻲ ﻳﺘﻢ ﺍﻹﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ ﻫﻲ:‬ ‫1. ﺍﳊﺠﻢ ﺍﻷﻗﺼﻰ ‪‬ﻤﻮﻋﺎﺕ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺳﻴﺘﻢ ﺇﺭﺳﺎﳍﺎ.‬ ‫2. ﻣﻘﺪﺍﺭ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺳﻴﺘﻢ ﺇﺭﺳﺎﳍﺎ ﻗﺒﻞ ﺍﳊﺼﻮﻝ ﻋﻠﻰ ﺗﺄﻛﻴﺪ ﻟﻮﺻﻮﳍﺎ.‬ ‫3. ﻓﺘﺮﺓ ﺍﻟﺰﻣﻦ ﺍﻟﱵ ﺗﻔﺼﻞ ﺑﲔ ﺇﺭﺳﺎﻝ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫4. ﻓﺘﺮﺓ ﺍﻟﺰﻣﻦ ﺍﻟﱵ ﳚﺐ ﺇﻧﺘﻈﺎﺭﻫﺎ ﻗﺒﻞ ﺍﳊﺼﻮﻝ ﻋﻠﻰ ﺗﺄﻛﻴﺪ ﻭﺻﻮﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫5. ﻣﻘﺪﺍﺭ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﻟﱵ ﺗﺴﺘﻄﻴﻊ ﻛﻞ ﺑﻄﺎﻗﺔ ﺍﺳﺘﻘﺒﺎﻟﻪ ﻗﺒﻞ ﺃﻥ ﺗﻔﻴﺾ ‪.Overflow‬‬ ‫6. ﺳﺮﻋﺔ ﻧﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫ﲟﺠﺮﺩ ﺍﻹﺗﻔﺎﻕ ﻋﻠﻰ ﺍﻟﻘﻀﺎﻳﺎ ﺍﻟﺴﺎﺑﻘﺔ ﺗﺒﺪﺃ ﻋﻤﻠﻴﺔ ﺗﺒﺎﺩﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺑﲔ ﺍﻟﺒﻄﺎﻗﺎﺕ ﺑﺪﻭﻥ ﻣﺸﺎﻛﻞ.‬ ‫2. ﺗﻘﻮﻡ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﺑﻌﺪﺩ ﻣﻦ ﻣﻬﺎﻡ ﺍﻟﺘﺤﻜﻢ ﺗﺸﻤﻞ:‬ ‫• ﻣﺮﺍﻗﺒﺔ ﻭﺳﻂ ﺍﻹﺗﺼﺎﻝ.‬ ‫• ﻃﻠﺐ ﺣﺰﻡ ﺍﻟﺒﻴﺎﻧﺎﺕ ﻭ ﺍﻟﺘﻌﺮﻑ ﻋﻠﻴﻬﺎ ﺑﺎﻟﺘﺄﻛﺪ ﻣﻦ ﺃﻥ ﻋﻨﻮﺍﻥ ﺍﻟﻮﺟﻬﺔ ﺍﳌﻮﺟﻮﺩ ﰲ ﺍﳊﺰﻣﺔ‬ ‫ﻫﻮ ﻧﻔﺴﻪ ﻋﻨﻮﺍﻥ ﺍﻟﺒﻄﺎﻗﺔ ﺍﻟﱵ ﺳﺘﺘﺴﻠﻢ ﺍﳊﺰﻣﺔ.‬ ‫• ﺍﻛﺘﺸﺎﻑ ﺍﻷﺧﻄﺎﺀ ﻭ ﺣﻠﻬﺎ.‬ ‫ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ‪: Network Drivers‬‬ ‫1. ﺗﻌﺮﻳﻒ :‬ ‫ﻣﺸﻐﻞ ﺍﳉﻬﺎﺯ ‪ Device Driver‬ﻫﻮ ﺍﻟﱪﻧﺎﻣﺞ ﺍﻟﺬﻱ ﻳﺴﻤﺢ ﻟﻨﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺍﳊﺎﺳﻮﺏ ﺑﺎﻟﻌﻤﻞ‬ ‫ﻭ ﺍﻟﺘﺨﺎﻃﺐ ﻣﻊ ﺟﻬﺎﺯ ﻣﻌﲔ.‬ ‫2. ﻛﻴﻔﻴﺔ ﻋﻤﻞ ﻣﺸﻐﻞ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ:‬ ‫ﺍﻥ ﺑﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ ﻳﺘﻢ ﺗﺼﻨﻴﻌﻬﺎ ﻣﻦ ﻗﺒﻞ ﺷﺮﻛﺎﺕ ﳐﺘﻠﻔﺔ ، ﻭ ﺑﺎﻟﺘﺎﱄ ﻓﻬﻨﺎﻙ ﺍﺣﺘﻤﺎﻝ‬ ‫ﺃﻥ ﻳﻜﻮﻥ ﻟﻜﻞ ﺑﻄﺎﻗﺔ ﺧﻮﺍﺹ ﳐﺘﻠﻔﺔ ﻭ ﺳﻴﻜﻮﻥ ﻣﻦ ﺍﳌﺴﺘﺤﻴﻞ ﻋﻤﻠﻴﺎ ﺗﺰﻭﻳﺪ ﲨﻴﻊ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ‬ ‫ﺑﺎﻟﱪﺍﻣﺞ ﺍﻟﻼﺯﻣﺔ ﻟﻠﻌﻤﻞ ﻣﻊ ﻛﻞ ﻧﻮﻉ ﻣﻦ ﺃﻧﻮﺍﻉ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ، ﻭ ﺑﺪﻻ ﻣﻦ ﺫﻟﻚ ﻓﺈﻥ ﻛﻞ ﻣﺼﻨﻊ‬ ‫ﻳﺰﻭﺩ ﺑﻄﺎﻗﺘﻪ ﺑﱪﻧﺎﻣﺞ ﻟﻠﺘﺸﻐﻴﻞ ﳐﺰﻥ ﻋﻠﻰ ﻗﺮﺹ ﻣﺮﻥ . ﻭ ﺃﺣﻴﺎﻧﺎ ﳛﺘﻮﻱ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﻋﻠﻰ ﻫﺬﻩ‬ ‫ﺍﳌﺸﻐﻼﺕ. ﺗﻘﻮﻡ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺑﺘﻮﻓﲑ ﺇﺗﺼﺎﻝ ﺑﲔ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻭ ﺑﲔ ﻣﻮﺟﻪ ﺑﺮﳎﻲ ﰲ ﺍﳊﺎﺳﻮﺏ‬ ‫ﻳﺴﻤﻰ ‪ Redirector Network‬ﻭ ﻫﻮ ﺟﺰﺀ ﻣﻦ ﺑﺮﻧﺎﻣﺞ ﺍﻟﺘﺸﺒﻴﻚ ﻭ ﻣﻬﻤﺘﻪ ﺍﺳﺘﻘﺒﺎﻝ ﻃﻠﺒﺎﺕ‬ ‫)‪ Input/Output (I/O‬ﻟﻠﻤﻠﻔﺎﺕ ﻋﻠﻰ ﺟﻬﺎﺯ ﺁﺧﺮ ﻭ ﲢﻮﻳﻠﻬﺎ ﻟﻠﺠﻬﺎﺯ ﺍﳌﻄﻠﻮﺏ. ﻳﺘﻢ ﺗﻨﺼﻴﺐ ﻣﺸﻐﻞ‬ ‫92‬
  • 30. ‫ﺍﻟﺒﻄﺎﻗﺔ ﻣﻦ ﺧﻼﻝ ﺑﺮﻧﺎﻣﺞ ﺍﻹﻋﺪﺍﺩ ﺍﳌﺘﻮﻓﺮ ﻋﻠﻰ ﺍﻟﻘﺮﺹ ﺍﳌﺮﻥ ﻭ ﻳﺘﻢ ﲣﺰﻳﻦ ﻫﺬﺍ ﺍﳌﺸﻐﻞ ﻋﻠﻰ ﺍﻟﻘﺮﺹ‬ ‫ﺍﻟﺼﻠﺐ ﻟﻠﺠﻬﺎﺯ.‬ ‫ﺗﻌﻤﻞ ﻣﺸﻐﻼﺕ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻣﻦ ﺧﻼﻝ ﺍﻟﻄﺒﻘﺔ ﺍﻟﻔﺮﻋﻴﺔ ‪ MAC‬ﻟﻄﺒﻘﺔ ‪ Data-Link‬ﰲ ‪OSI‬‬ ‫ﻋﻠﻰ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺃﻥ ﺗﻜﻮﻥ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ﺃﺣﺪ ﻣﻌﺎﻳﲑ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫1. )‪.Network Driver Interface Specification (NDIS‬‬ ‫2. )‪. Open Data-Link Interface (ODI‬‬ ‫‪Novell NetWare‬‬ ‫ﺑﺮﻧﺎﻣﺞ ﺗﺸﺒﻴﻚ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ﻣﺘﻮﺍﻓﻖ ﻣﻊ ‪ NDIS‬ﺑﻴﻨﻤﺎ ﺃﻧﻈﻤﺔ‬ ‫ﻓﻬﻲ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ‪. ODI‬ﺗﻘﻮﻡ ﻫﺬﻩ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺑﻌﺰﻝ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻋﻦ ﺗﻔﺎﺻﻴﻞ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ‬ ‫ﺍﳌﺨﺘﻠﻔﺔ ﺍﳌﺴﺘﺨﺪﻣﺔ ﻭﻋﺰﻝ ﺍﻟﱪﻭﺗﻮﻛﻮﻻﺕ ﻋﻦ ﺍﻷﻧﻮﺍﻉ ﺍﳌﺨﺘﻠﻔﺔ ﻟﺒﻄﺎﻗﺎﺕ ﺍﻟﺸﺒﻜﺎﺕ. ﻣﻊ ﻫﺬﻩ‬ ‫ﺍﻟﻮﺍﺟﻬﺎﺕ ﺃﺻﺒﺢ ﻻ ﺩﺍﻋﻲ ﻟﻜﺘﺎﺑﺔ ﻣﺸﻐﻼﺕ ﺧﺎﺻﺔ ﻟﻜﻞ ﺑﺮﻭﺗﻮﻛﻮﻝ ﺃﻭ ﻧﻈﺎﻡ ﺗﺸﻐﻴﻞ ﺑﻞ ﺃﺻﺒﺢ ﻳﻜﻔﻲ‬ ‫ﻛﺘﺎﺑﺔ ﻣﺸﻐﻼﺕ ﻣﺘﻮﺍﻓﻘﺔ ﻣﻊ ﺃﺣﺪ ﺍﻟﻮﺍﺟﻬﺎﺕ ﺁﻧﻔﺔ ﺍﻟﺬﻛﺮ ﲝﻴﺚ ﺃﺻﺒﺢ ﺍﳌﺴﺘﺨﺪﻣﻮﻥ ﻗﺎﺩﺭﻭﻥ ﻋﻠﻰ‬ ‫ﺍﻹﺗﺼﺎﻝ ﻋﱪ ﺷﺒﻜﺎﺕ ﺗﺴﺘﺨﺪﻡ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﳐﺘﻠﻔﺔ ﺑﺎﺳﺘﺨﺪﺍﻡ ﺑﻄﺎﻗﺔ ﺷﺒﻜﺔ ﻭﺣﻴﺪﺓ ﻭ ﻣﺸﻐﻞ ﺷﺒﻜﺔ‬ ‫ﻭﺣﻴﺪ ﻣﺘﻮﺍﻓﻖ ﻣﻊ ﻭﺍﺟﻬﺔ ‪ NDIS‬ﺃﻭ ‪ ODI‬ﻭ ﻣﻦ ﺍﳌﻤﻜﻦ ﻋﻨﺪ ﺍﻟﻀﺮﻭﺭﺓ ﲢﻤﻴﻞ ﻛﻼ ﺍﻟﻮﺍﺟﻬﺘﲔ ﻋﻠﻰ‬ ‫ﻧﻔﺲ ﺍﳉﻬﺎﺯ.‬ ‫ﺗﺘﻤﺘﻊ ﻭﺍﺟﻬﺔ ﻣﺸﻐﻼﺕ ﺍﻟﺸﺒﻜﺔ ﺍﻟﱵ ﺗﻌﺘﻤﺪﻫﺎ ﻣﻴﻜﺮﻭﺳﻮﻓﺖ ﻭ ﻫﻲ ‪ NDIS‬ﺑﺎﳌﻤﻴﺰﺍﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺗﺪﻋﻢ ﺇﺳﺘﺨﺪﺍﻡ ﺃﻛﺜﺮ ﻣﻦ ﻣﻌﺎﰿ ﻋﻠﻰ ﻧﻔﺲ ﺍﳉﻬﺎﺯ.‬ ‫• ﺗﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ ﺍﺗﺼﺎﻻﺕ ﺃﻭ ﺭﻭﺍﺑﻂ ﺷﺒﻜﻴﺔ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫• ﺗﺴﺘﻄﻴﻊ ﺍﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻋﺪﺓ ﺑﺮﻭﺗﻮﻛﻮﻻﺕ ﻧﻘﻞ ﳏﻤﻠﺔ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫ﻛﻞ ﻣﺸﻐﻞ ‪ NDIS‬ﻳﻜﻮﻥ ﻣﺴﺌﻮﻻ ﻋﻦ ﺍﳌﻬﺎﻡ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫• ﺇﺭﺳﺎﻝ ﻭ ﺍﺳﺘﻘﺒﺎﻝ ﺍﳊﺰﻡ ﻋﱪ ﺍﻹﺗﺼﺎﻝ ﺍﻟﺸﺒﻜﻲ.‬ ‫• ﺍﻹﺩﺍﺭﺓ ﺍﻟﻔﻌﻠﻴﺔ ﻟﺒﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﲟﺎ ﻳﺘﻨﺎﺳﺐ ﻣﻊ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ.‬ ‫• ﺗﺸﻐﻴﻞ ﻧﻈﺎﻡ ‪ Input/Output‬ﰲ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﻭ ﺗﻠﻘﻲ ﻃﻠﺒﺎﺕ ﺍﳌﻘﺎﻃﻌﺔ ﻣﻨﻬﺎ.‬ ‫• ﺇﻋﻼﻡ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﺑﺎﺳﺘﻘﺒﺎﻝ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺃﻭ ﺍﻹﻧﺘﻬﺎﺀ ﻣﻦ ﺇﺭﺳﺎﳍﺎ.‬ ‫03‬
  • 31. ‫• ﻋﺰﻝ ﻣﻌﻠﻮﻣﺎﺕ ﻧﻈﺎﻡ ﺍﻟﺘﺸﻐﻴﻞ ﺃﻭ ﻣﻜﻮﻧﺎﺕ ﺍﳉﻬﺎﺯ ﻋﻦ ﻣﺸﻐﻼﺕ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ ﰲ ﺣﺎﻟﺔ‬ ‫ﻋﺪﻡ ﺣﺎﺟﺔ ﻫﺬﻩ ﺍﳌﺸﻐﻼﺕ ﳍﺬﻩ ﺍﳌﻌﻠﻮﻣﺎﺕ.‬ ‫ﻣﺒﺎﺩﺉ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ :‬ ‫ﻗﺒﻞ ﺃﻥ ﻳﺘﻤﻜﻦ ﺣﺎﺳﻮﺑﲔ ﻣﻦ ﺍﻹﺗﺼﺎﻝ ﻣﻌﺎ ﻻﺑﺪ ﻣﻦ ﺗﻮﻓﺮ ﺷﺮﻃﲔ :‬ ‫1. ﺃﻥ ﺗﺘﻢ ﺗﺮﲨﺔ ﺍﻟﺒﻴﺎﻧﺎﺕ ﺍﱃ ﺇﺷﺎﺭﺍﺕ ﳝﻜﻦ ﻧﻘﻠﻬﺎ ﺑﻴﻨﻬﻤﺎ.‬ ‫2. ﺃﻥ ﺗﺘﻮﻓﺮ ﻗﻨﺎﺓ ﻳﺴﺘﻄﻴﻌﺎﻥ ﻣﻦ ﺧﻼﳍﺎ ﺇﺭﺳﺎﻝ ﻭ ﺇﺳﺘﻘﺒﺎﻝ ﺍﻹﺷﺎﺭﺍﺕ.‬ ‫ﺗﺴﺘﻄﻴﻊ ﺃﺟﻬﺰﺓ ﺍﳊﺎﺳﻮﺏ ﺍﺳﺘﺨﺪﺍﻡ ﺍﻷﻧﻮﺍﻉ ﺍﻟﺘﺎﻟﻴﺔ ﻣﻦ ﺍﻹﺷﺎﺭﺍﺕ ﻟﻺﺗﺼﺎﻝ ﻓﻴﻤﺎ ﺑﻴﻨﻬﺎ:‬ ‫‪.pulses‬‬ ‫ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ‪electrical‬‬ ‫• ﺍﻟﻨﺒﻀﺎﺕ‬ ‫• ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ‪. waves radio‬‬ ‫• ﻣﻮﺟﺎﺕ ﺍﳌﻴﻜﺮﻭ ﻭﻳﻒ ‪. microwaves‬‬ ‫‪.light‬‬ ‫‪infrared‬‬ ‫• ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ‬ ‫ﺍﳋﺎﺻﻴﺔ ﺍﻟﱵ ﲡﻤﻌﻬﺎ :‬ ‫ﻫﻨﺎﻙ ﺧﺎﺻﻴﺔ ﻭﺍﺣﺪﺓ ﲡﻤﻊ ﺑﲔ ﻫﺬﻩ ﺍﻹﺷﺎﺭﺍﺕ ﺍﳌﺨﺘﻠﻔﺔ ﻭ ﻫﻲ ﺃ‪‬ﺎ ﻛﻠﻬﺎ ﺗﻌﺘﱪ ﻣﻮﺟﺎﺕ‬ ‫ﻛﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ.‬ ‫13‬
  • 32. ‫ﺗﻌﺮﻳﻔﺎﺕ :‬ ‫1. ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺘﻤﺎﺛﻠﻴﺔ : ﻫﻲ ﺇﺷﺎﺭﺍﺕ ﻣﺴﺘﻤﺮﺓ ﺗﺘﻤﺜﻞ ﻓﻴﻬﺎ ﺍﳌﻌﻠﻮﻣﺎﺕ ﻛﻤﻘﺎﺩﻳﺮ ﻓﻴﺰﻳﺎﺋﻴﺔ‬ ‫ﻣﻦ ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ ﻭ ﻣﺜﺎﻝ ﻋﻠﻴﻬﺎ ﺍﻟﺘﻴﺎﺭ ﺍﻟﻜﻬﺮﺑﺎﺋﻲ ﻭ ﺍﳌﻮﺟﺎﺕ ﺍﻟﺼﻮﺗﻴﺔ.‬ ‫2. ﺍﻹﺷﺎﺭﺍﺕ ﺍﻟﺮﻗﻤﻴﺔ : ﻫﻲ ﺇﺷﺎﺭﺍﺕ ﻣﻨﻔﺼﻠﺔ ‪ disecrete‬ﻭ ﺗﺴﺘﺨﺪﻡ ﻗﻴﻤﺘﲔ ﻓﻘﻂ‬ ‫ﻫﻲ ﺻﻔﺮ ﺃﻭ ﻭﺍﺣﺪ ﻟﺘﻤﺜﻴﻞ ﺍﻹﺷﺎﺭﺓ ﺍﻷﺻﻠﻴﺔ.‬ ‫3. ﺍﳌﻮﺟﺎﺕ ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ : ﺗﻀﻢ ﺃﻧﻮﺍﻉ ﻋﺪﻳﺪﺓ ﻣﻦ ﺍﳌﻮﺟﺎﺕ ﺗﺘﺮﺍﻭﺡ ﺑﲔ ﺃﺷﻌﺔ‬ ‫ﺟﺎﻣﺎ ﻭﺑﲔ ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ ﺍﻟﻄﻮﻳﻠﺔ. ﻫﺬﺍ ﺍﳌﺪﻯ ﺍﻟﻜﺒﲑ ﻣﻦ ﺍﳌﻮﺟﺎﺕ‬ ‫ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻴﺔ ﻳﻄﻠﻖ ﻋﻠﻴﻪ ﺍﺳﻢ ﺍﻟﻄﻴﻒ ﺍﻟﻜﻬﺮﻭﻣﻐﻨﺎﻃﻴﺴﻲ . ﺟﺰﺀ ﳏﺪﻭﺩ ﻓﻘﻂ‬ ‫ﻣﻦ ﻫﺬﺍ ﺍﻟﻄﻴﻒ ﻳﺴﺘﺨﺪﻡ ﻟﻨﻘﻞ ﺍﻟﺒﻴﺎﻧﺎﺕ.‬ ‫23‬
  • 33. ‫ﻭﺳﺎﺋﻂ ﺍﻹﺭﺳﺎﻝ:‬ ‫1. ﻭﺳﺎﺋﻂ ﺳﻠﻜﻴﺔ: ﺍﻟﻮﺳﺎﺋﻂ ﺍﻟﺴﻠﻜﻴﺔ ﺗﻜﻮﻥ ﺇﻣﺎ ﺃﺳﻼﻙ ﻣﻌﺪﻧﻴﺔ ﺃﻭ ﺃﻟﻴﺎﻑ ﺿﻮﺋﻴﺔ ﻭﺗﻮﺻﻞ ﺍﻟﻜﻬﺮﺑﺎﺀ‬ ‫ﻭ ﺍﻟﻀﻮﺀ ﻋﻠﻰ ﺍﻟﺘﻮﺍﱄ.‬ ‫2. ﻭﺳﺎﺋﻂ ﻻﺳﻠﻜﻴﺔ: ﺍﻹﺭﺳﺎﻝ ﺍﻟﻼﺳﻠﻜﻲ ﻳﺴﺘﺨﺪﻡ ﺍﻟﻐﻼﻑ ﺍﳉﻮﻱ ﻛﻮﺳﻂ ﺇﺭﺳﺎﻝ ﻟﻨﻘﻞ ﺍﻹﺷﺎﺭﺓ.‬ ‫2.2. ﺗﺘﻀﻤﻦ ﺍﻟﻮﺳﺎﺋﻂ ﺍﻟﻼﺳﻠﻜﻴﺔ :‬ ‫• ﻣﻮﺟﺎﺕ ﺍﻟﺮﺍﺩﻳﻮ.‬ ‫• ﻣﻮﺟﺎﺕ ﺍﳌﻴﻜﺮﻭ ﻭﻳﻒ.‬ ‫• ﺍﻷﺷﻌﺔ ﲢﺖ ﺍﳊﻤﺮﺍﺀ.‬ ‫ﻗﺒﻞ ﲢﺪﻳﺪ ﻭﺳﻂ ﺍﻹﺭﺳﺎﻝ ﺍﻷﻧﺴﺐ ﻟﺸﺒﻜﺔ ﻣﺎ ﳚﺐ ﺍﻹﺟﺎﺑﺔ ﻋﻠﻰ ﻫﺬﻩ ﺍﻷﺳﺌﻠﺔ:‬ ‫1. ﻣﺎ ﻫﻮ ﻣﻘﺪﺍﺭ ﺛﻘﻞ ﺃﻭ ﺍﺯﺩﺣﺎﻡ ﺣﺮﻛﺔ ﻧﻘﻞ ﺍﳌﻌﻠﻮﻣﺎﺕ ﺍﳌﺘﻮﻗﻊ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ؟‬ ‫2. ﻣﺎ ﻫﻲ ﺍﳌﺴﺎﻓﺔ ﺍﻟﱵ ﻋﻠﻰ ﻭﺳﻂ ﺍﻹﺗﺼﺎﻝ ﺗﻐﻄﻴﺘﻬﺎ ﺃﻭ ﺍﻟﻮﺻﻮﻝ ﺇﻟﻴﻬﺎ ؟‬ ‫3. ﻣﺎ ﻫﻲ ﺍﻹﺣﺘﻴﺎﺟﺎﺕ ﺍﻷﻣﻨﻴﺔ ﻟﻠﺸﺒﻜﺔ ؟‬ ‫4. ﻣﺎ ﻫﻲ ﺍﳌﻴﺰﺍﻧﻴﺔ ﺍﳌﺨﺼﺼﺔ ﻟﻮﺳﻂ ﺍﻹﺗﺼﺎﻝ ؟‬ ‫ﺃﻧﻮﺍﻉ ﻭﺧﺼﺎﺋﺺ ﺃﺳﻼﻙ ﺍﻟﺸﺒﻜﺎﺕ :‬ ‫ﻫﻨﺎﻙ ﺛﻼﺙ ﺃﻧﻮﺍﻉ ﺭﺋﻴﺴﻴﺔ ﻣﻦ ﺍﻷﺳﻼﻙ ﻫﻲ:‬ ‫‪ v‬ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ‪. Coaxial Cable‬‬ ‫‪ v‬ﺍﻷﺳﻼﻙ ﺍﳌﻠﺘﻮﻳﺔ ‪. Twisted Pair‬‬ ‫‪ v‬ﺍﻷﻟﻴﺎﻑ ﺍﻟﺒﺼﺮﻳﺔ ‪. Fiber Optic‬‬ ‫ﻫﻨﺎﻙ ﻃﺮﻳﻘﺘﺎﻥ ﻹﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺓ ﻋﱪ ﺍﻟﺴﻠﻚ ﳘﺎ:‬ ‫1. ﺃﻧﻈﻤﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻷﺳﺎﺳﻲ ‪:Baseband‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻹﺭﺳﺎﻝ ﺍﻟﺮﻗﻤﻲ ﻟﻺﺷﺎﺭﺓ ﺑﻮﺍﺳﻄﺔ ﺗﺮﺩﺩ ﻭﺍﺣﺪ ﻓﻘﻂ ، ﺣﻴﺚ ﺃﻥ ﺍﻹﺷﺎﺭﺓ ﺍﻟﺮﻗﻤﻴﺔ‬ ‫ﺗﺴﺘﺨﺪﻡ ﻛﺎﻣﻞ ﺳﻌﺔ ﻧﻄﺎﻕ ﺍﻟﺒﺚ ‪. Bandwidth‬‬ ‫33‬
  • 34. ‫ﺑﺎﺳﺘﺨﺪﺍﻡ ﻫﺬﻩ ﺍﻟﺘﻘﻨﻴﺔ ﰲ ﺍﻟﺒﺚ ﻳﺴﺘﻄﻴﻊ ﺃﻱ ﺟﻬﺎﺯ ﻋﻠﻰ ﺍﻟﺸﺒﻜﺔ ﺇﺭﺳﺎﻝ ﺍﻹﺷﺎﺭﺍﺕ ﰲ ﺍﲡﺎﻫﲔ ﻭﺑﻌﺾ‬ ‫ﺍﻷﺟﻬﺰﺓ ﺗﺴﺘﻄﻴﻊ ﺇﺭﺳﺎﻝ ﻭ ﺍﺳﺘﻘﺒﺎﻝ ﺍﻹﺷﺎﺭﺓ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫2. ﺃﻧﻈﻤﺔ ﺍﻟﻨﻄﺎﻕ ﺍﻟﻮﺍﺳﻊ ‪: Broadband‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻹﺭﺳﺎﻝ ﺍﻟﺘﻤﺎﺛﻠﻲ ﻟﻺﺷﺎﺭﺓ ‪ Analog‬ﻣﻊ ﻣﺪﻯ ﺃﻭﺳﻊ ﻣﻦ ﺍﻟﺘﺮﺩﺩﺍﺕ ، ﳑﺎ ﻳﺴﻤﺢ ﻷﻛﺜﺮ‬ ‫ﻣﻦ ﺇﺷﺎﺭﺓ ﺃﻥ ﺗﺴﺘﺨﺪﻡ ﻧﻔﺲ ﺍﻟﺴﻠﻚ ﰲ ﻧﻔﺲ ﺍﻟﻮﻗﺖ.‬ ‫ﻛﻤﺎ ﺃﻥ ﺗﺪﻓﻖ ﺍﻹﺷﺎﺭﺍﺕ ﰲ ﺃﻧﻈﻤﺔ ‪ Broadband‬ﻳﺘﻢ ﰲ ﺍﲡﺎﻩ ﻭﺍﺣﺪ ﻓﻘﻂ ﳊﻞ ﻫﺬﻩ ﺍﳌﺸﻜﻠﺔ ﺗﺴﺘﺨﺪﻡ‬ ‫ﺍﻟﻄﺮﻳﻘﺘﲔ ﺍﻟﺘﺎﻟﻴﺘﲔ :‬ ‫- ﺍﺳـﺘﺨﺪﺍﻡ ﺳـﻠﻚ ﺛـﻨﺎﺋﻲ ﻓـﻴﻜﻮﻥ ﻛﻞ ﺟﻬﺎﺯ ﻣﻮﺻﻞ ﺑﺴﻠﻜﲔ ﻭﺍﺣﺪ ﻟﻺﺭﺳﺎﻝ ﻭﺍﻵﺧﺮ‬ ‫ﻟﻺﺳﺘﻘﺒﺎﻝ.‬ ‫- ﺍﺳﺘﺨﺪﺍﻡ ﺳﻠﻚ ﻭﺍﺣﺪ ﻣﻊ ﺗﻘﺴﻴﻢ ﺳﻌﺔ ﺍﻟﻨﻄﺎﻕ ﺍﱃ ﻗﺴﻤﲔ ، ﲝﻴﺚ ﻳﺘﻮﻓﺮ ﻗﻨﺎﺗﲔ‬ ‫ﻭ ﻛﻞ ﻗﻨﺎﺓ ﺗﺴﺘﺨﺪﻡ ﺗﺮﺩﺩ ﳐﺘﻠﻒ ، ﻭﺗﻜﻮﻥ ﻭﺍﺣﺪﺓ ﻟﻺﺭﺳﺎﻝ ﻭ ﺍﻷﺧﺮﻯ ﻟﻺﺳﺘﻘﺒﺎﻝ.‬ ‫ﺗﺴﺘﺨﺪﻡ ﺃﻧﻈﻤﺔ ‪ Broadband‬ﺃﺟﻬﺰﺓ ﺧﺎﺻﺔ ﻟﺘﻘﻮﻳﺔ ﺍﻹﺷﺎﺭﺓ ﺍﻟﺘﻤﺎﺛﻠﻴﺔ .‬ ‫ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ:‬ ‫‪v‬‬ ‫ﻣﺎﺩﺓ ﻋﺎﺯﻟﺔ‬ ‫ﻏﻄﺎﺀ ﺧﺎﺭﺟﻲ ﻣﺼﻨﻮﻍ ﻣﻦ ﺍﻟﺒﻼﺳﺘﻴﻚ‬ ‫ﺿﻔﺎﺋﺮ ﻣﻌﺪﻧﻴﺔ ﻟﻠﺤﻤﺎﻳﺔ‬ ‫ﳏﻮﺭ ﻣﻦ ﺍﻟﻨﺤﺎﺱ ﺍﻟﺼﻠﺐ‬ ‫1. ﺃﻧﻮﺍﻉ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ:‬ ‫1.1. ﺍﻟﺴﻠﻚ ﺍﶈﻮﺭﻱ ﺍﻟﺮﻗﻴﻖ ‪ : Thin‬ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺳﻠﻚ ﻣﺮﻥ ﺭﻗﻴﻖ ﻳﺴﺘﺨﺪﻡ‬ ‫ﻋﺎﺩﺓ ﰲ ﺷﺒﻜﺎﺕ 2‪ 10Base‬ﻭ ﻳﻮﺻﻞ ﻣﺒﺎﺷﺮﺓ ﺍﱃ ﺑﻄﺎﻗﺔ ﺍﻟﺸﺒﻜﺔ.‬ ‫43‬
  • 35. ‫: ﻫﻮ ﻋﺒﺎﺭﺓ ﻋﻦ ﺳﻠﻚ ﺛﺨﲔ ﻣﺘﺼﻠﺐ ﻭ‬ ‫‪Thick‬‬ ‫1.2. ﺍﻟﺴﻠﻚ ﺍﶈﻮﺭﻱ ﺍﻟﺜﺨﲔ‬ ‫ﻏﲑ ﻣﺮﻥ ﻳﺴﺘﺨﺪﻡ ﻋﺎﺩﺓ ﰲ ﺷﺒﻜﺎﺕ 5‪ 10Base‬ﻭ ﻷﻧﻪ ﺃﺛﺨﻦ ﻣﻦ ﺍﻟﻨﻮﻉ‬ ‫ﺍﻷﻭﻝ ﻓﺈﻧﻪ ﻳﺴﺘﻄﻴﻊ ﺍﻟﻮﺻﻮﻝ ﺍﱃ ﻣﺴﺎﻓﺎﺕ ﺃﺑﻌﺪ ﺩﻭﻥ ﺗﻮﻫﲔ ﻟﻺﺷﺎﺭﺓ .‬ ‫2. ﺍﳌﻮﺍﺻﻔﺎﺕ ﺍﻟﻜﻬﺮﺑﺎﺋﻴﺔ:‬ ‫11-‪RG‬‬ ‫ﻭ‬ ‫8-‪RG‬‬ ‫1. 05 ﺃﻭﻡ )ﺃﻭﻡ ﻫﻲ ﻭﺣﺪﺓ ﻗﻴﺎﺱ ﻣﻘﺎﻭﻣﺔ ﺍﻟﺴﻠﻚ ﻟﻠﺘﻴﺎﺭ ﺍﳌﺘﺮﺩﺩ(‬ ‫)ﻟﻠﺴﻠﻚ ﺍﻟﺜﺨﲔ(.‬ ‫2. 05 ﺃﻭﻡ 85-‪ RG‬ﻟﻠﺴﻠﻚ ﺍﻟﺮﻗﻴﻖ.‬ ‫3. 57 ﺃﻭﻡ 95-‪ RG‬ﻭ ﻳﺴﺘﺨﺪﻡ ﻟﺴﻠﻚ ﺍﻟﺘﻠﻔﺎﺯ.‬ ‫4. 39 ﺃﻭﻡ 26-‪ RG‬ﻭ ﺗﺴﺘﺨﺪﻡ ﳌﻮﺍﺻﻔﺎﺕ ﺷﺒﻜﺎﺕ ‪. ARCnet‬‬ ‫ﺗﺴﺘﺨﺪﻡ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ﻣﺸﺎﺑﻚ ﺃﻭ ﻭﺻﻼﺕ ﺧﺎﺻﺔ ﻟﻮﺻﻞ ﺍﻷﺳﻼﻙ ﻣﻌﺎ ﻭﺷﺒﻚ ﺍﻷﺟﻬﺰﺓ ﺗﺴﻤﻰ‬ ‫ﻫﺬﻩ ﺍﳌﺸﺎﺑﻚ )‪. BNC (British Naval Connectors‬‬ ‫ﺗﺘﻀﻤﻦ ﻋﺎﺋﻠﺔ ﻣﺸﺎﺑﻚ ‪ BNC‬ﺍﳌﻜﻮﻧﺎﺕ ﺍﻟﺘﺎﻟﻴﺔ:‬ ‫1. ‪. BNC cable connector‬‬ ‫2. ‪. BNC T connector‬‬ ‫3. ‪. BNC barrel connector‬‬ ‫4. ‪. BNC terminator‬‬ ‫3. ﺍﺻﻨﺎﻓﻬﺎ:‬ ‫ﺗﺼﻨﻒ ﺍﻷﺳﻼﻙ ﺍﶈﻮﺭﻳﺔ ﺍﱃ ﺻﻨﻔﲔ ﻭﻓﻘﺎ ﻟﺘﺮﻛﻴﺐ ﻏﻼﻓﻬﺎ ﺍﳋﺎﺭﺟﻲ ﻭ ﻃﺒﻴﻌﺔ ﺍﳌﻜﺎﻥ ﺍﻟﺬﻱ ﺳﺘﺮﻛﺐ‬ ‫ﻓﻴﻪ ﻭ ﻫﺬﺍﻥ ﺍﻟﺼﻨﻔﺎﻥ ﳘﺎ:‬ ‫ﺍﻟﺼﻨﻒ ﺍﻷﻭﻝ )‪ : polyvinyl chloride (PVC‬ﻣﺮﻥ ﻭ ﳑﻜﻦ ﺍﺳﺘﺨﺪﺍﻣﻪ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻔﺘﻮﺣﺔ‬ ‫ﺃﻭ ﺍﳌﻌﺮﺿﺔ ﻟﺘﻬﻮﻳﺔ ﺟﻴﺪﺓ ﻭﻟﻜﻦ ﻧﻈﺮﺍ ﻷﻧﻪ ﻗﺪ ﺗﻨﺒﻌﺚ ﻣﻨﻪ ﺭﻭﺍﺋﺢ ﺳﺎﻣﺔ ﰲ ﺣﺎﻟﺔ ﺣﺪﻭﺙ ﺣﺮﻳﻖ ﻓﺈﻥ‬ ‫ﻫﺬﺍ ﺍﻟﻨﻮﻉ ﻣﻦ ﻏﲑ ﺍﶈﺒﺬ ﺍﺳﺘﺨﺪﺍﻣﻪ ﰲ ﺍﻷﻣﺎﻛﻦ ﺍﳌﻐﻠﻘﺔ ﺃﻭ ﺳﻴﺌﺔ ﺍﻟﺘﻬﻮﻳﺔ.‬ ‫53‬