在两个路由器间建立ipv6 over ipv4 tunnel，并且运行RIP

//router a

conf t

  ipv6 unicast-routing

  ipv6 router rip xxx   // xxx用来标识这个进程

int e0/0

  ipv6 address 2068:10:10:11::1/64

  ipv6 rip xxx enable

int tunnel 0

  ipv6 unnumbered e0/0

  tunnel source lo0

  tunnel destination 10.10.4.4

  tunnel mode ipv6ip   //  ipv6ip  IPv6 over IP encapsulation

  ipv6 rip xxx enable

//router b

conf t

  ipv6 unicast-routing

  ipv6 router rip xxx

int e0/0

  ipv6 address 2068:10:10:44::4/64

  ipv6 rip xxx enable

int tunnel 0

  ipv6 unnumbered e0/0

  tunnel source lo0

  tunnel destination 10.10.1.1

  tunnel mode ipv6ip

  ipv6 rip xxx enable