31 Days Before Your CCNA Exam

142 31 Days Before Your CCNA ExamFigure 19-2IPv6 Address Format with Interface ID and EUI-64Subnet Prefix48 Bits 16 Bits 64 BitsPrefix (ISP-assigned)SubnetInterface IDSite Prefix1st Half ofMACEUI-64 FormatFFFE2nd Half ofMACFlip 7th Bit (ReadingLeft to Right) in FirstByte to a Binary 1For example, the following two lines list a host’s MAC address and corresponding EUI-64 formatinterface ID, assuming the use of an address configuration option that uses the EUI-64 format:■■MAC Address: 0034:5678:9ABCEUI-64 Interface ID: 0234:56FF:FE78:9ABCNote To change the seventh bit (reading left to right) in the example, convert hex 00 tobinary 00000000, change the seventh bit to 1 (00000010), and then convert back to hex, forhex 02 as the first two digits.IPv6 Address ManagementTwo options exist for static IPv6 address configuration for both routers and hosts:■■Static configuration of the entire addressStatic configuration of a /64 prefix with the host calculating its EUI-64 interface ID to completethe IP address.IPv6 supports two methods of dynamic configuration of IPv6 addresses:■■DHCPv6: Works the same conceptually as DHCP in IPv4.Stateless autoconfiguration: A host dynamically learns the /64 prefix through the IPv6Neighbor Discovery Protocol (NDP) and then calculates the rest of its address by using anEUI-64 interface ID based on its network interface card (NIC) MAC address.Transitioning to IPv6The transition from IPv4 to IPv6 does not require upgrades on all nodes at the same time. Manytransition mechanisms enable smooth integration of IPv4 and IPv6. Other mechanisms that allowIPv4 nodes to communicate with IPv6 nodes are available. Different situations demand differentstrategies. Different transition mechanisms include the following: