All network engineers who are working with the interdomain routing protocol used on the Interned named BGP know that BGP is not 100% secure and that misconfigurations or attacks could cause problems on the Internet. The key problem is that BGP does not have mechanisms to verify the validity of a received route advertisement. From time to time, misconfigurations happen and are discussed on operators mailing lists such as nanog. Yesterday, youtube was affected by such a misconfiguration. Some routers in Pakistan were incorrectly configured to advertise one /24 prefix belonging to youtube's /22 network. Since BGP relies on longest match, all BGP routers on the Internet redirected packets towards this /24 prefix to Pakistan where they were dropped. Unfortunately, this /24 prefix contained all DNS servers maintained by youtube... The result was that it became impossible to resolve names in the youtube.com and most youtube content was unreachable for some time. Additional details may be found in the NANOG mailing list.

This is not a new problem on the Internet, AS7007 did much worse in 1997 by configuring a black hole that attracted all Internet packets :
http://www.merit.edu/mail.archives/nanog/1997-04/msg00444.html

The research community has proposed several solutions to solve this problem, e.g. S-BGP, SoBGP, ... Unfortunately, deploying such protocols is difficult and nobody has tried until now.

The only deployed solutions are to collect BGP updates and warn network operators when a problem occurs :

• http://cs.unm.edu/~karlinjf/IAR/prefix.php?filter=most
• http://www.ris.ripe.net/myasn.html

RIPE wrote a detailed analysis of the youtube hijack, see : http://www.ripe.net/news/study-youtube-hijacking.html