sudhang on 2008-02-25
How?????
This link has been bookmarked by 6 people . It was first bookmarked on 25 Feb 2008, by sudhang.
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26 Feb 08
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25 Feb 08
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packets sent to YouTube were flowing to Pakistan
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Pakistan government had just instituted a ban on the popular video sharing site
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Pakistan Telecom routed the address block that YouTube's servers are in to a "black hole" as a simple measure to filter access to the service
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escaped from Pakistan Telecom to its ISP PCCW in Hong Kong, which propagated the route to the rest of the world
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Classless Inter-Domain Routing (CIDR)
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CIDR allows address blocks to be given out in power of two blocks
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The number after the slash indicates how many of the 32 address bits are "network" bits, the remaining bits are used to number hosts.
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a particular IP address can now fall within multiple address ranges.
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So even though YouTube's routing information was still there, packets would flow towards Pakistan Telecom because of the longest match first rule.
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sudhang on 2008-02-25
Since the range specified by Pakistan Telecom was narrower, routers gave precedence to the Pakistan Telecom... So, packets intended for YouTube made their way to PT instead!!
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