Routing

Routing in Ipv6 is almost identical to IPv4 except for the address increase from the original 32-bits to 128-bits addresses.  All IPv4 routing algorithms can be used for IPv6.  IPv6 also have simple routing extensions to support powerful new routing functionalities:

-Provide Selection (based on policy, performance, cost, etc)
-Host Mobility (route to current location)
-Auto-Readdressing (route to new address)

The new routing functionality is obtained by creating sequences of IPng addresses using the IPng Routing option. The routing option is used by a IPng source to list one or more intermediate nodes (or topological group) to be "visited" on the way to a packet's destination. This function is very similar in function to IPv4's Loose Source and Record Route option.  In order to make address sequences a general function, IPv6 hosts are required to reverse routes in a packet it receives, containing header and address sequences.  The functionality of implementing and supporting the reversal of source routes allows them to work with hosts that implement features such as provider selection or extended addresses.