السلام عليكم ورحمة الله
الى اخواني أحبائي في الله عندي hwork لمادة شبكات وعلي تسليمه يوم الاثنين وبصراحة هو موضوع كبير وواسع ومش عارف كيف أختصر يشكل واضح ومفهوم بحيث اني أشرح عنه بحدود ربع ساعة من لدية المعرفة أتمنى أن يساعدني وجزاه الله خيرا كثيرا
الموضوع هو عندما نرسل باكت من ip add ver4 to ip ver6 تحدث عملية تسمى tunneling ما هي هذه العملية وكيف تقوم بعملية encapsulotion على الداتا المنتقلة
أفيدوني جزاكم الله خيرا

أقرأ هذا .. نقلته من موسوعة الويكي بيديا

Tunneling

In order to reach the IPv6 Internet, an isolated host or network must be able to use the existing IPv4 infrastructure to carry IPv6 packets. This is done using a technique somewhat misleadingly known as tunnelling (http://en.wikipedia.org/wiki/Tunneling_protocol) which consists in encapsulating IPv6 packets within IPv4, in effect using IPv4 as a link layer for IPv6.
IPv6 packets can be directly encapsulated within IPv4 packets using a protocol number of 41. They can also be encapsulated within UDP packets e.g. in order to cross a router or NAT device that block protocol 41 traffic. They can of course also use generic encapsulation schemes, such as AYIYA (http://en.wikipedia.org/wiki/AYIYA) or GRE (http://en.wikipedia.org/wiki/Generic_Routing_Encapsulation).

Automatic tunneling

Automatic tunneling refers to a technique where the tunnel endpoints are automatically determined by the routing infrastructure. The recommended technique for automatic tunneling is 6to4 (http://en.wikipedia.org/wiki/6to4)[3] (http://www.ietf.org/rfc/rfc3056.txt) tunneling, which uses protocol 41 encapsulation. Tunnel endpoints are determined by using a well-known IPv4 anycast address on the remote side, and embedding IPv4 address information within IPv6 addresses on the local side. 6to4 is widely deployed today.
Teredo (http://en.wikipedia.org/wiki/Teredo_tunneling) [4] (http://www.ietf.org/rfc/rfc4380.txt) is an automatic tunneling technique that uses UDP encapsulation and is claimed to be able to cross multiple NAT boxes. Teredo is not widely deployed today, but an experimental version of Teredo is installed with the Windows XP SP2 IPv6 stack and Teredo will reportedly be enabled by default in Windows Vista (http://en.wikipedia.org/wiki/Windows_Vista) [5] (http://msdn.microsoft.com/windowsvista/default.aspx?pull=/library/en-us/dnlong/html/AppComp.asp#app_topic11).
[edit (http://en.wikipedia.org/w/index.php?title=IPv6&action=edit&section=20)]

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Configured tunneling

Configured tunneling is a technique where the tunnel endpoints are configured explicitly, either by a human operator or by an automatic service known as a [U]Tunnel Broker (http://www.tkne.net/vb/)[6] (http://www.ietf.org/rfc/rfc3053.txt). Configured tunneling is usually more deterministic and easier to debug than automatic tunneling, and is therefore recommended for large, well-administered networks.
Configured tunneling typically uses either protocol 41 (recommended) or raw UDP encapsulation.




http://www.tcpipguide.com/free/t_IPv6DatagramEncapsulationandFormatting.htm

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