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èŠã§ããããã®äžã§ãç¹ã«éèŠãªåœ¹å²ãæããã®ããBGPïŒBorder Gateway ProtocolïŒãã§ããð
1. BGPãšã¯ïŒ
BGPã¯ãã€ã³ã¿ãŒãããäžã®ç¬ç«ããã·ã¹ãã ïŒAutonomous Systems, ASïŒå士ãã€ãªããããã®ã«ãŒãã£ã³ã°ãããã³ã«ã§ããç°¡åã«èšãã°ãã€ã³ã¿ãŒãããã®åãããã¯ãŒã¯éã§ãæé©ãªéãéžã¶ãããã®éæ¡å 圹ã§ããBGPã¯ãCIDRã¢ãã¬ãã·ã³ã°æ¹åŒããµããŒãããŠãããããã«ããå©çšå¯èœãªIPã¢ãã¬ã¹ã®æ°ãå¢ãããŠããŸãããŸããBGPã¯ããšããšã®ãšã¯ã¹ããªã¢ã²ãŒããŠã§ã€ãããã³ã«ïŒEGPïŒã眮ãæããããã«èšèšãããŠãããçµè·¯éžæã«ç¹åãããããã³ã«ã§ããããŸãã
2. BGPãµãŒããŒã«ãŒã ãšã¯ïŒ
BGPãµãŒããŒã«ãŒã ãšã¯ãBGPãããã³ã«ãå©çšããŠè€æ°ã®åç·ïŒãã¥ã¢ã«ã©ã€ã³ããã«ãã©ã€ã³ïŒãäžã€ã®IPã¢ãã¬ã¹ã§å¹ççã«ç®¡çããé«éãã€å®å®ãããããã¯ãŒã¯æ¥ç¶ãå®çŸãããµãŒããŒã«ãŒã ã®ããšã§ããããã«ããããŠãŒã¶ãŒãç°ãªããããã¯ãŒã¯ãªãã¬ãŒã¿ãŒãå©çšããŠããŠããé«éã§å®å®ããã¢ã¯ã»ã¹ãå¯èœãšãªããŸãã
3. BGPãµãŒããŒã«ãŒã ã®3ã€ã®ã¡ãªãã
BGPãµãŒããŒã«ãŒã ãå©çšããããšã§åŸãããäž»ãªã¡ãªããã¯ä»¥äžã®3ã€ã§ãã
a. æé©ãªã«ãŒãéžæ
BGPãµãŒããŒã«ãŒã ã§ã¯ããµãŒããŒèªäœã«èšå®ããIPã¢ãã¬ã¹ã¯äžã€ã ãã§åé¡ãããŸãããBGPãããã³ã«ã«ãã£ãŠããããã¯ãŒã¯äžã®ã«ãŒã¿ãŒãæé©ãªã«ãŒããèªåçã«éžæããŸããããã«ããããŠãŒã¶ãŒã¯åžžã«æéã®ã«ãŒãã§ã¢ã¯ã»ã¹ã§ãããããå¿«é©ãªãããã¯ãŒã¯äœéšãå¯èœã§ãã
b. èªåããã¯ã¢ãã
BGPãããã³ã«ã«ã¯ãåé·ããã¯ã¢ãããšã«ãŒãé€å»ã®æ©èœãåãã£ãŠããŸããããã«ãããè€æ°ã®BGPæ¥ç¶ã©ã€ã³ãããå Žåãããã©ã€ã³ã«é害ãçºçããéã«ã¯ãèªåçã«ä»ã®ã©ã€ã³ã«åãæ¿ããããšãã§ããŸããããã«ããããµãŒãã¹ã®å®å®æ§ãåäžãããŠãŒã¶ãŒãžã®åœ±é¿ãæå°éã«æããããšãã§ããŸããð
c. ã¹ã±ãŒã©ãã«ãªæ¥ç¶
BGPãããã³ã«ãå©çšããããšã§ãä»ã®ãªãã¬ãŒã¿ãŒã®ãããã¯ãŒã¯ãšã容æã«é£æºããããšãã§ããŸããäžã€ã®IPã¢ãã¬ã¹ã§è€æ°ã®ã©ã€ã³ã䜿çšããããšãã§ããç°ãªããªãã¬ãŒã¿ãŒã®ãŠãŒã¶ãŒãããé«éã§ã¢ã¯ã»ã¹ãå¯èœã«ãªããŸããããã¯ããã¥ã¢ã«IPãã¥ã¢ã«ã©ã€ã³ã®æ§æã§ã¯å®çŸã§ããªãã倧ããªã¡ãªããã§ããð
4. BGPãµãŒããŒã«ãŒã ã®æè¡æŠèŠ
BGPã¯èªåŸã·ã¹ãã éã®ã«ãŒãã£ã³ã°ãããã³ã«ã§ããããã®äž»ãªæ©èœã¯ä»ã®BGPã¹ããŒã«ãŒãšã®éã§ãããã¯ãŒã¯å°éæ§æ å ±ã亀æããããšã§ããBGPã¯TCPïŒããŒã179ïŒããã©ã³ã¹ããŒããããã³ã«ãšããŠäœ¿çšããä¿¡é Œæ§ã®é«ãããŒã¿è»¢éãæäŸããŸãã
BGPã«ãŒã¿ãŒã¯ãçžæã®ã«ãŒã¿ãŒãšæ¥ç¶ã確ç«ããåŸãæ¥ç¶ãã©ã¡ãŒã¿ã亀æããBGPã«ãŒãã£ã³ã°ããŒãã«ãå ±æããŸãããã®ããŒãã«ã«ã¯ãåãããã¯ãŒã¯ãžã®å°éå¯èœæ§æ å ±ïŒNLRIïŒãšçµè·¯å±æ§ãå«ãŸããŸããçµè·¯å±æ§ã«ã¯ãçµè·¯ã®åºæïŒORIGINïŒãåªå 床ãªã©ã®æ å ±ãå«ãŸããŸãã
BGPã®ç¹åŸŽãšããŠãã«ãŒãã£ã³ã°æ å ±ã®å¢åæŽæ°ãæããããŸããã«ãŒãæ å ±ã«å€æŽãçããå Žåã®ã¿ãé£æ¥ããã«ãŒã¿ãŒéã§æŽæ°æ å ±ãäŒããããŸããããã«ããããããã¯ãŒã¯ã®ãã©ãã£ãã¯ãå¹ççã«ç®¡çã§ããŸãã
5. BGPãµãŒããŒã«ãŒã ã®åœ¹å²ãšå¹æ
BGPãµãŒããŒã«ãŒã ã¯ãç°ãªããããã¯ãŒã¯éã®çžäºæ¥ç¶ãæé©åãããŠãŒã¶ãŒã«å¯ŸããŠæé«ã®ãªã³ã©ã€ã³äœéšãæäŸããŸããããšãã°ãã€ã³ã¿ãŒãããã®ãåååé¡ãïŒç°ãªãå°åããããã€ãéã§ã®éä¿¡é 延ãæ¥ç¶åé¡ïŒãç·©åããåäžã®IPã¢ãã¬ã¹ã§ãã¥ã¢ã«ã©ã€ã³ã®å¹æãå®çŸããŸããããã«ããããŠãŒã¶ãŒã¯ã©ã®ãããã¯ãŒã¯ãªãã¬ãŒã¿ãŒãå©çšããŠããŠããåžžã«æé©ãªã«ãŒãã§é«éã«ã¢ã¯ã»ã¹ããããšãã§ããŸãã
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BGPãµãŒããŒã«ãŒã ã¯ãã€ã³ã¿ãŒãããäžã®ç°ãªããããã¯ãŒã¯ãå¹æçã«é£æºãããé«éã§å®å®ããæ¥ç¶ãå®çŸããããã®éèŠãªæè¡ã§ããããã«ããããŠãŒã¶ãŒã«æé«ã®ãããã¯ãŒã¯äœéšãæäŸããç°ãªããªãã¬ãŒã¿ãŒéã®çžäºæ¥ç¶ãæé©åããŸãã次åãµãŒããŒã«ãŒã ããããã¯ãŒã¯ã®è©±é¡ãåºããšãã«ã¯ããã²BGPãµãŒããŒã«ãŒã ã®ä»çµã¿ãšãã®ã¡ãªãããæãåºããŠã¿ãŠãã ããïŒðð»
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