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Ñîîáùåíèå ìîæåò áûòü äîñòàâëåíî ñêîëü óãîäíîïîçäíî ïîñëå ñâîåãî îòïðàâëåíèÿ, à ìîæåò è âîîáùå ïîòåðÿòüñÿâ ñåòè.Äëÿ ïåðåäà÷è è ïðèåìà ñîîáùåíèé èñïîëüçóþòñÿ ïðîöåäóðûóïðàâëåíèÿ ñåòüþ (NCP), ïðè ïîìîùè êîòîðûõ ïðîöåññû a è bïîëó÷àþò äîñòóï ê ñåòè. Ïðîöåññ a íà÷èíàåò óñòàíàâëèâàòüñîåäèíåíèå, ïåðåäàâ îäíó åäèíèöó èíôîðìàöèè m ïðîöåäóðå A. Âçàèìîäåéñòâèå ìåæäó ïðîöåäóðàìè óïðàâëåíèÿ ñåòüþ ÷åðåçñåòü ïåðåäà÷è äàííûõ DN äîëæíî áûòü îðãàíèçîâàíî òàê,÷òîáû èíôîðìàöèÿ m áûëà äîñòàâëåíà ïðîöåññó b (ïðèïîñðåäíè÷åñòâå NCP B ), è ïîñëå ýòîãî ïðîöåññ a äîëæåí áûòüîïîâåùåí îá ýòîé äîñòàâêå (ïðè ïîñðåäíè÷åñòâå NCP A ).Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññNCPAaÏðîöåññNCPÑåòü ïåðåäà÷è äàííûõ (DN)BbÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòü?NCPANCPÑåòü ïåðåäà÷è äàííûõ (DN)BbÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòü?NCPA?NCPÑåòü ïåðåäà÷è äàííûõ (DN)BbÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòü?NCPA?NCPÑåòü ïåðåäà÷è äàííûõ (DN)B6bÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòüb6Äîñòàâèòü?NCPA?NCPÑåòü ïåðåäà÷è äàííûõ (DN)B6Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòüb6Äîñòàâèòü?NCPANCP??Ñåòü ïåðåäà÷è äàííûõ (DN)B6Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññaÏðîöåññÎòïðàâèòüb6Äîñòàâèòü?NCPANCP??6Ñåòü ïåðåäà÷è äàííûõ (DN)B6Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÏðîöåññÎòïðàâèòüaÏðîöåññ6Ïîäòâåðäèòüb6Äîñòàâèòü?NCPANCP??6B6Ñåòü ïåðåäà÷è äàííûõ (DN)Ðèñ.: Óïðîùåííàÿ àðõèòåêòóðà ñåòè.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Ïðàâèëà äèàëîãà.INCP ñîõðàíÿþò èíôîðìàöèþ î ñîñòîÿíèè äèàëîãà, íîïîñëå çàâåðøåíèÿ îáìåíà ñîîáùåíèÿìè âñÿ èíôîðìàöèÿ îñîñòîÿíèè äèàëîãà ñòèðàåòñÿ.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Ïðàâèëà äèàëîãà.IINCP ñîõðàíÿþò èíôîðìàöèþ î ñîñòîÿíèè äèàëîãà, íîïîñëå çàâåðøåíèÿ îáìåíà ñîîáùåíèÿìè âñÿ èíôîðìàöèÿ îñîñòîÿíèè äèàëîãà ñòèðàåòñÿ.Èíèöèàëèçàöèÿ èíôîðìàöèè î ñîñòîÿíèè äèàëîãàíàçûâàåòñÿ îòêðûòèåì äèàëîãà.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Ïðàâèëà äèàëîãà.IIINCP ñîõðàíÿþò èíôîðìàöèþ î ñîñòîÿíèè äèàëîãà, íîïîñëå çàâåðøåíèÿ îáìåíà ñîîáùåíèÿìè âñÿ èíôîðìàöèÿ îñîñòîÿíèè äèàëîãà ñòèðàåòñÿ.Èíèöèàëèçàöèÿ èíôîðìàöèè î ñîñòîÿíèè äèàëîãàíàçûâàåòñÿ îòêðûòèåì äèàëîãà.Ñáðîñ ñîñòîÿíèÿ íàçûâàåòñÿ çàêðûòèåì äèàëîãà.

Ïîñëåçàêðûòèÿ äèàëîãà NCP ïåðåéäåò â òî ñîñòîÿíèå, â êîòîðîìîíà ïðåáûâàëà ïåðåä îòêðûòèåì ýòîãî äèàëîãà (çàêðûòîåñîñòîÿíèå ).Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Ïðàâèëà äèàëîãà.IIIINCP ñîõðàíÿþò èíôîðìàöèþ î ñîñòîÿíèè äèàëîãà, íîïîñëå çàâåðøåíèÿ îáìåíà ñîîáùåíèÿìè âñÿ èíôîðìàöèÿ îñîñòîÿíèè äèàëîãà ñòèðàåòñÿ.Èíèöèàëèçàöèÿ èíôîðìàöèè î ñîñòîÿíèè äèàëîãàíàçûâàåòñÿ îòêðûòèåì äèàëîãà.Ñáðîñ ñîñòîÿíèÿ íàçûâàåòñÿ çàêðûòèåì äèàëîãà. Ïîñëåçàêðûòèÿ äèàëîãà NCP ïåðåéäåò â òî ñîñòîÿíèå, â êîòîðîìîíà ïðåáûâàëà ïåðåä îòêðûòèåì ýòîãî äèàëîãà (çàêðûòîåñîñòîÿíèå ).Èíôîðìàöèÿ m áûëà ïîòåðÿíà , åñëè ïðîöåññ a áûëîïîâåùåí î ïðèåìå ýòîé èíôîðìàöèè ïðîöåññîì b , íîñàìà èíôîðìàöèÿ íå áûëà äîñòàâëåíà ïðîöåññó b .Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍåíàäåæíîñòü ñåòè âûíóæäàåò NCP A è B âñòóïèòü â äèàëîã.Ïðàâèëà äèàëîãà.IIIIINCP ñîõðàíÿþò èíôîðìàöèþ î ñîñòîÿíèè äèàëîãà, íîïîñëå çàâåðøåíèÿ îáìåíà ñîîáùåíèÿìè âñÿ èíôîðìàöèÿ îñîñòîÿíèè äèàëîãà ñòèðàåòñÿ.Èíèöèàëèçàöèÿ èíôîðìàöèè î ñîñòîÿíèè äèàëîãàíàçûâàåòñÿ îòêðûòèåì äèàëîãà.Ñáðîñ ñîñòîÿíèÿ íàçûâàåòñÿ çàêðûòèåì äèàëîãà.

Ïîñëåçàêðûòèÿ äèàëîãà NCP ïåðåéäåò â òî ñîñòîÿíèå, â êîòîðîìîíà ïðåáûâàëà ïåðåä îòêðûòèåì ýòîãî äèàëîãà (çàêðûòîåñîñòîÿíèå ).Èíôîðìàöèÿ m áûëà ïîòåðÿíà , åñëè ïðîöåññ a áûëîïîâåùåí î ïðèåìå ýòîé èíôîðìàöèè ïðîöåññîì b , íîñàìà èíôîðìàöèÿ íå áûëà äîñòàâëåíà ïðîöåññó b .Èíôîðìàöèÿ m áûëà äóáëèðîâàíà , åñëè îíà áûëàäîñòàâëåíà äâàæäû.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍàäåæíàÿ ñâÿçü íåâîçìîæíà.BÄîïóñòèì NCP âûõîäèò èç ñòðîÿ è ïåðåçàïóñêàåòñÿ âçàêðûòîì ñîñòîÿíèè ïîñëå òîãî, êàê NCP A óæå îòïðàâèëàñîîáùåíèå m . Òîãäà íè NCP A , íè NCP B íå ìîãóò ñêàçàòü,áûëà ëè èíôîðìàöèÿ m óæå äîñòàâëåíà â ìîìåíò ïîëîìêèNCP B .Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍàäåæíàÿ ñâÿçü íåâîçìîæíà.BÄîïóñòèì NCP âûõîäèò èç ñòðîÿ è ïåðåçàïóñêàåòñÿ âçàêðûòîì ñîñòîÿíèè ïîñëå òîãî, êàê NCP A óæå îòïðàâèëàñîîáùåíèå m .

Òîãäà íè NCP A , íè NCP B íå ìîãóò ñêàçàòü,áûëà ëè èíôîðìàöèÿ m óæå äîñòàâëåíà â ìîìåíò ïîëîìêèNCP B .Ïðîöåäóðà A íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà íå ìîæåòñóäèòü î òîì, êàêèå ñîáûòèÿ ïðîèçîøëè â NCP B (èç-çàîòñóòñòâèÿ ñâåäåíèé î ãëîáàëüíîì ñîñòîÿíèè)Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍàäåæíàÿ ñâÿçü íåâîçìîæíà.BÄîïóñòèì NCP âûõîäèò èç ñòðîÿ è ïåðåçàïóñêàåòñÿ âçàêðûòîì ñîñòîÿíèè ïîñëå òîãî, êàê NCP A óæå îòïðàâèëàñîîáùåíèå m . Òîãäà íè NCP A , íè NCP B íå ìîãóò ñêàçàòü,áûëà ëè èíôîðìàöèÿ m óæå äîñòàâëåíà â ìîìåíò ïîëîìêèNCP B .Ïðîöåäóðà A íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà íå ìîæåòñóäèòü î òîì, êàêèå ñîáûòèÿ ïðîèçîøëè â NCP B (èç-çàîòñóòñòâèÿ ñâåäåíèé î ãëîáàëüíîì ñîñòîÿíèè)Ïðîöåäóðà B íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà âûøëà èçñòðîÿ è áûëà ïåðåçàïóùåíà â çàêðûòîì ñîñòîÿíèè.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍàäåæíàÿ ñâÿçü íåâîçìîæíà.BÄîïóñòèì NCP âûõîäèò èç ñòðîÿ è ïåðåçàïóñêàåòñÿ âçàêðûòîì ñîñòîÿíèè ïîñëå òîãî, êàê NCP A óæå îòïðàâèëàñîîáùåíèå m .

Òîãäà íè NCP A , íè NCP B íå ìîãóò ñêàçàòü,áûëà ëè èíôîðìàöèÿ m óæå äîñòàâëåíà â ìîìåíò ïîëîìêèNCP B .Ïðîöåäóðà A íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà íå ìîæåòñóäèòü î òîì, êàêèå ñîáûòèÿ ïðîèçîøëè â NCP B (èç-çàîòñóòñòâèÿ ñâåäåíèé î ãëîáàëüíîì ñîñòîÿíèè)Ïðîöåäóðà B íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà âûøëà èçñòðîÿ è áûëà ïåðåçàïóùåíà â çàêðûòîì ñîñòîÿíèè.Åñëè NCP A âíîâü îòïðàâèò ñîîáùåíèå NCP B , è NCP Bäîñòàâèò ýòî ñîîáùåíèå, òî ïðîèçîéäåò äóáëèðîâàíèåèíôîðìàöèè.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÍàäåæíàÿ ñâÿçü íåâîçìîæíà.BÄîïóñòèì NCP âûõîäèò èç ñòðîÿ è ïåðåçàïóñêàåòñÿ âçàêðûòîì ñîñòîÿíèè ïîñëå òîãî, êàê NCP A óæå îòïðàâèëàñîîáùåíèå m .

Òîãäà íè NCP A , íè NCP B íå ìîãóò ñêàçàòü,áûëà ëè èíôîðìàöèÿ m óæå äîñòàâëåíà â ìîìåíò ïîëîìêèNCP B .Ïðîöåäóðà A íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà íå ìîæåòñóäèòü î òîì, êàêèå ñîáûòèÿ ïðîèçîøëè â NCP B (èç-çàîòñóòñòâèÿ ñâåäåíèé î ãëîáàëüíîì ñîñòîÿíèè)Ïðîöåäóðà B íå ìîæåò ýòîãî ñäåëàòü, ïîòîìó ÷òî îíà âûøëà èçñòðîÿ è áûëà ïåðåçàïóùåíà â çàêðûòîì ñîñòîÿíèè.Åñëè NCP A âíîâü îòïðàâèò ñîîáùåíèå NCP B , è NCP Bäîñòàâèò ýòî ñîîáùåíèå, òî ïðîèçîéäåò äóáëèðîâàíèåèíôîðìàöèè.Åñëè ïîäòâåðæäåíèå a áóäåò îòïðàâëåíî, òîãäà êàê äîñòàâêàèíôîðìàöèè m íå ñîñòîÿëàñü, òî ñëó÷èòñÿ ïîòåðÿ èíôîðìàöèè.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP ANCP BÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?( )send mNCP BÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPP?sAPPPPPPPqÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPPPPPPP?PPq( )receive m?sAÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPPPPPPP?PPq( )deliver(m )?w crashreceive m?sAÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPPPPPPP?PPq( )deliver(m )?w crashw recoveringreceive m?sA?initBÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP ANCP BÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?( )send mNCP BÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPP?sAPPPPPPPqÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPP?sAPPP?wPPPPqcrashÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéNCP A?NCP B( )send mPPP?sAPPP?wPPPPqwcrashrecovering?initBÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ îäíèì ñîîáùåíèåì.1.NCP2.NCPABhdata, mihdata, mi,:send:receivedeliverm,closeÏîòåðÿ ñîîáùåíèÿ ïðîèñõîäèò âñÿêèé ðàç, êîãäà ñåòüîòêàçûâàåòñÿ äîñòàâèòü ñîîáùåíèå ïî íàçíà÷åíèþ, îäíàêî,çäåñü íåò íèêàêîé âîçìîæíîñòè äëÿ äóáëèðîâàíèÿ ñîîáùåíèÿ.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.1.2.3.hdata, mihdata, mi, deliver m,receive hacki, notify, closeNCP:sendNCP:receiveABNCP A:sendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCPA:sendhdata, miÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCPAB::hdata, mireceive hdata, mi,senddeliverm,sendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCP3.ABDN::hdata, mireceive hdata, mi, deliver m,hacki ïîòåðÿíî â ñåòèsendsendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCP3.4.AB::DNNCPA:hdata, mireceive hdata, mi, deliver m,hacki ïîòåðÿíî â ñåòètimeout, send hdata, misendsendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCP3.AB::DN4.NCP5.NCPAB::hdata, mireceive hdata, mi, deliver m,hacki ïîòåðÿíî â ñåòètimeout, send hdata, mireceive hdata, mi, deliver m,sendsendhacki,closesendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: ïðè çàäåðæêåïîäòâåðæäåíèÿ âîçìîæíî äóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCP3.::DN4.NCP5.NCP6.ABABNCP A:::hdata, mireceive hdata, mi, deliver m,hacki ïîòåðÿíî â ñåòètimeout, send hdata, mireceive hdata, mi, deliver m,receive hacki, notify, closesendsendhacki,closesendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.NCPA:sendhdata, m1 iÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.NCP2.NCPABhdata, m1 ihdata, m1 i,:send:receivedeliverm1 ,sendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.NCP:2.NCP:3.ABNCP A:hdata, m1 ihdata, m1 i, deliver m1 ,timeout, send hdata, m1 isendreceivesendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.NCP:NCP:ABNCP ANCP B::hdata, m1 ihdata, m1 i, deliver m1 ,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 ,sendreceivesendhacki,closesendhacki,closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.NCP:NCP:ABNCP ANCP BNCP A:::hdata, m1 ihdata, m1 i, deliver m1 , send hacki,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 , send hacki,receive hacki (øàã 1), notify, closesendreceiveclosecloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.NCP:NCP:ABNCP ANCP BNCP ANCP A::::hdata, m1 ihdata, m1 i, deliver m1 , send hacki,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 , send hacki,receive hacki (øàã 1), notify, closesend hdata, m2 isendreceiveclosecloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.7.NCP:NCP:ABNCP ANCP BNCP ANCP ADN::::hdata, m1 ihdata, m1 i, deliver m1 , send hacki,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 , send hacki,receive hacki (øàã 1), notify, closesend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòèsendreceiveclosecloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.7.8.NCP:NCP:ABNCP ANCP BNCP ANCP A::::DNNCPA:hdata, m1 ihdata, m1 i, deliver m1 , send hacki,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 , send hacki,receive hacki (øàã 1), notify, closesend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòèreceive hacki (øàã 2), notify, closesendreceiveclosecloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ äâóìÿ ñîîáùåíèÿìè.Êðîìå òîãî, ïðè ïåðåäà÷å íåñêîëüêèõ ñîîáùåíèé âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.7.8.NCP:NCP:ABNCP ANCP BNCP ANCP A::::DNNCPA:hdata, m1 ihdata, m1 i, deliver m1 , send hacki,timeout, send hdata, m1 ireceive hdata, m1 i, deliver m1 , send hacki,receive hacki (øàã 1), notify, closesend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòèreceive hacki (øàã 2), notify, closesendreceiveÇàìåäëåíèå ïåðåäà÷è ñîîáùåíèÿ îáíàðóæèòü íåâîçìîæíî,ââèäó îòñóòñòâèÿ ãëîáàëüíîé øêàëû âðåìåíè.closecloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.1.2.3.4.hdata, mihdata, mi, deliver m, send hackireceive hacki, notify, send hclosei, closereceive hclosei, closeNCP:sendNCP:receiveABNCP ANCP B::Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.1.2.3.4.hdata, mihdata, mi, deliver m, send hackireceive hacki, notify, send hclosei, closereceive hclosei, closeNCP:sendNCP:receiveABNCP ANCP B:: ýòîì ñëó÷àå ïðåæíèå ñöåíàðèè, ïðèâîäÿùèå ê îøèáêàì, óæåíåâîçìîæíû.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.Çàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.NCPA:sendhdata, m1 iÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.NCP2.NCPAB::hdata, m1 ireceive hdata, m1 i,senddeliverm1 ,sendhackiÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.NCPANCP BNCP A:::hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closesendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.NCPANCP BNCP ADN:::hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.NCPANCP BNCP A:::DNNCPA:hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsend hdata, m2 isendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.NCPANCP BNCP A:::DNNCPADN:hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòèsendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.7.NCPANCP BNCP A:::DNNCPA:DNNCPB:hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòètimeout, retransmit hacki (äëÿ øàãà 2)sendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.NCPANCP BNCP A:::DNNCPA:DN7.NCP8.NCPBA::hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòètimeout, retransmit hacki (äëÿ øàãà 2)receive hacki, notify, send hclosei, closesendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè.Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíàïîòåðÿ ñîîáùåíèÿ.1.2.3.4.5.6.NCPANCP BNCP A:::DNNCPA:DN7.NCP8.NCP9.NCPBAB:::hdata, m1 ireceive hdata, m1 i, deliver m1 , send hackireceive hacki, notify, send hclosei, closehclosei ïîòåðÿíî â ñåòèsend hdata, m2 ihdata, m2 i ïîòåðÿíî â ñåòètimeout, retransmit hacki (äëÿ øàãà 2)receive hacki, notify, send hclosei, closereceive hclosei, closesendÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).1.2.3.4.NCPANCP BNCP ANCP B::::hdata, m, xireceive hdata, m, xi, send hack, x, y ireceive hack, x, y i, notify, send hclose, x, y i,receive hclose, x, y i, deliver m, closesendcloseÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.NCPA:sendhdata, m, xiÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCPAAhdata, m, xi:send:timeout, retransmithdata, m, xiÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.NCP2.NCP3.NCPAABhdata, m, xi:send:timeout, retransmithdata, m, xi:receive(íà øàãå 2), sendhdata, m, xihack, x, y1 iÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.2.3.4.hdata, m, xiNCP:sendNCP:timeout, retransmitAANCP BNCP A:receive:receivehdata, m, xihdata, m, xi (íà øàãå 2), send hack, x, y1 ihack, x, y1 i, notify, send hclose, x, y1 i, closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.2.3.4.5.hdata, m, xiNCP:sendNCP:timeout, retransmitAANCP BNCP ANCP B:receive:receive:receivehdata, m, xihdata, m, xi (íà øàãå 2), send hack, x, y1 ihack, x, y1 i, notify, send hclose, x, y1 i, closehclose, x, y1 i, deliver m, closeÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.2.3.4.5.6.hdata, m, xiNCP:sendNCP:timeout, retransmitAANCP BNCP ANCP BNCP B:receive:receive:receive:receivehdata, m, xihdata, m, xi (íà øàãå 2), send hack, x, y1 ihack, x, y1 i, notify, send hclose, x, y1 i, closehclose, x, y1 i, deliver m, closehdata, m, xi (íà øàãå 1), send hack, x, y2 iÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.2.3.4.5.6.7.hdata, m, xiNCP:sendNCP:timeout, retransmitAANCP BNCP ANCP BNCP BNCP A:receive:receive:receive:receive:receivehdata, m, xihdata, m, xi (íà øàãå 2), send hack, x, y1 ihack, x, y1 i, notify, send hclose, x, y1 i, closehclose, x, y1 i, deliver m, closehdata, m, xi (íà øàãå 1), send hack, x, y2 ihack, x, y2 i, reply hnocon, x, y2 iÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ òðåìÿ ñîîáùåíèÿìè (èñïðàâëåííûéâàðèàíò).Îäíàêî è ýòîò ïðîòîêîë íå ÿâëÿåòñÿ íàäåæíûì: âîçìîæíîäóáëèðîâàíèå ñîîáùåíèÿ.1.2.3.4.5.6.7.8.hdata, m, xiNCP:sendNCP:timeout, retransmitAANCP BNCP ANCP BNCP BNCP ANCP B::::::hdata, m, xihdata, m, xi (íà øàãå 2), send hack, x, y1 ihack, x, y1 i, notify, send hclose, x, y1 i, closereceive hclose, x, y1 i, deliver m, closereceive hdata, m, xi (íà øàãå 1), send hack, x, y2 ireceive hack, x, y2 i, reply hnocon, x, y2 ireceive hnocon, x, y2 i â îòâåò íà hack, x, y2 i,deliver m, closereceivereceiveÇàäà÷à íàäåæíîãî îáìåíà èíôîðìàöèåéÄèàëîã ñ ÷åòûðüìÿ ñîîáùåíèÿìè.1.2.3.4.5.NCP A :NCP B :NCP A :NCP B :NCP A :send hdata, m, xireceive hdata, m, xi, send hopen, m, x, y ireceive hopen, m, x, y i, send hagree, m, x, y ireceive hagree, m, x, y i, deliver m, send hack, x, y i, closereceive hack, x, y i, notify, closeÇàäà÷è äëÿ ñàìîñòîÿòåëüíîãî ðåøåíèÿÇàäà÷à 1.Ïîêàæèòå, ÷òî â ïðîòîêîëå ñ 4 ñîîáùåíèÿìè âîçìîæíîäóáëèðîâàíèå èëè ïîòåðÿ ñîîáùåíèé ââèäó òîãî, ÷òî NCP Aâûíóæäåíà ñ÷èòàòüñÿ ñ âîçìîæíîñòüþ âûõîäà èç ñòðîÿ NCP B . ýòîì ñëó÷àå äóáëèðîâàíèå èëè ïîòåðÿ ñîîáùåíèé âîçíèêàåòäàæå â òîì ñëó÷àå, åñëè NCP B â äåéñòâèòåëüíîñòè èç ñòðîÿ íåâûõîäèò.Çàäà÷è äëÿ ñàìîñòîÿòåëüíîãî ðåøåíèÿÇàäà÷à 2.Ïîñòðîéòå ïðîòîêîë ñ äâóìÿ ñîîáùåíèÿìè, êîòîðûé íèêîãäà íåäîïóñêàåò ïîòåðè ñîîáùåíèé (õîòÿ ìîæåò äóáëèðîâàòüñîîáùåíèÿ).Çàäà÷è äëÿ ñàìîñòîÿòåëüíîãî ðåøåíèÿÇàäà÷à 2.Ïîñòðîéòå ïðîòîêîë ñ äâóìÿ ñîîáùåíèÿìè, êîòîðûé íèêîãäà íåäîïóñêàåò ïîòåðè ñîîáùåíèé (õîòÿ ìîæåò äóáëèðîâàòüñîîáùåíèÿ).Ïîäñêàçêà: âîñïîëüçóéòåñü èäåíòèôèêàöèîííûìè íîìåðàìèñîîáùåíèé, êîòîðûå áûëè ââåäåíû â èñïðàâëåííîé âåðñèèäèàëîãà ñ òðåìÿ ñîîáùåíèÿìè.Çàäà÷è äëÿ ñàìîñòîÿòåëüíîãî ðåøåíèÿÇàäà÷à 2.Ïîñòðîéòå ïðîòîêîë ñ äâóìÿ ñîîáùåíèÿìè, êîòîðûé íèêîãäà íåäîïóñêàåò ïîòåðè ñîîáùåíèé (õîòÿ ìîæåò äóáëèðîâàòüñîîáùåíèÿ).Ïîäñêàçêà: âîñïîëüçóéòåñü èäåíòèôèêàöèîííûìè íîìåðàìèñîîáùåíèé, êîòîðûå áûëè ââåäåíû â èñïðàâëåííîé âåðñèèäèàëîãà ñ òðåìÿ ñîîáùåíèÿìè.ÄÎÊÀÆÈÒÅ, ÷òî ïîñòðîåííûé ïðîòîêîë äåéñòâèòåëüíî íåòåðÿåò íè îäíîãî ñîîáùåíèÿ.Çàäà÷è äëÿ ñàìîñòîÿòåëüíîãî ðåøåíèÿÇàäà÷à 3.Ïîñòðîéòå ïðîòîêîë ñ ïÿòüþ ñîîáùåíèÿìè, êîòîðûéïðåäîòâðàùàåò ïîòåðþ èíôîðìàöèè è äîïóñêàåò äóáëèðîâàíèåòîëüêî òîãäà, êîãäà îäíà èç NCP äåéñòâèòåëüíî âûõîäèò èçñòðîÿ.ÊÎÍÅÖ ËÅÊÖÈÈ 1..

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