the Interface ID is established, either through the EUI-64 process or through random generation, it can be combined with an IPv6 prefix in the RA message to create a global unicast address, as shown in Figure 4. Note: To ensure the uniqueness of any IPv6 unicast address, the client may use a process known as Duplicate Address Detection (DAD). This is similar to an ARP request for its own address. If there isn’t a reply, then the address is unique. Dynamic Link-Local Addresses All IPv6 devices must have an IPv6 link-local address. A link-local address can be established dynamically or configured manually as a static link-local address. Figure 1 shows the link-local address is dynamically created using the FE80::/10 prefix and the Interface ID using the EUI-64 process or a randomly generated 64-bit number. Operating systems will typically use the same method for both a SLAAC created global unicast address and a dynamically assigned link-local address, as shown in Figure 2. Cisco routers automatically create an IPv6 link-local address whenever a global unicast address is assigned to the interface. By default, Cisco IOS routers use EUI-64 to generate the Interface ID for all link-local address on IPv6 interfaces. For serial interfaces, the router will use the MAC address of an Ethernet interface. Recall that a link-local address must be unique only on that link or network. However, a drawback to using the dynamically assigned link-local address is its length, which makes it challenging to identify and remember assigned addresses. Figure 3 displays the MAC address on router R1’s GigabitEthernet 0/0 interface. This address is used to dynamically create the link-local address on the same interface. To make it easier to recognize and remember these addresses on routers, it is common to statically configure IPv6 link-local addresses on routers. Please log into before accessing this course. Static Link-Local Addresses Configuring the link-local address manually provides the ability to create an address that is recognizable and easier to remember.
the Interface ID is established, either through the EUI-64 process or through random generation, it can be combined with an IPv6 prefix in the RA message to create a global unicast address, as shown in Figure 4. Note: To ensure the uniqueness of any IPv6 unicast address, the client may use a process known as Duplicate Address Detection (DAD). This is similar to an ARP request for its own address. If there isn’t a reply, then the address is unique. Dynamic Link-Local Addresses All IPv6 devices must have an IPv6 link-local address. A link-local address can be established dynamically or configured manually as a static link-local address. Figure 1 shows the link-local address is dynamically created using the FE80::/10 prefix and the Interface ID using the EUI-64 process or a randomly generated 64-bit number. Operating systems will typically use the same method for both a SLAAC created global unicast address and a dynamically assigned link-local address, as shown in Figure 2. Cisco routers automatically create an IPv6 link-local address whenever a global unicast address is assigned to the interface. By default, Cisco IOS routers use EUI-64 to generate the Interface ID for all link-local address on IPv6 interfaces. For serial interfaces, the router will use the MAC address of an Ethernet interface. Recall that a link-local address must be unique only on that link or network. However, a drawback to using the dynamically assigned link-local address is its length, which makes it challenging to identify and remember assigned addresses. Figure 3 displays the MAC address on router R1’s GigabitEthernet 0/0 interface. This address is used to dynamically create the link-local address on the same interface. To make it easier to recognize and remember these addresses on routers, it is common to statically configure IPv6 link-local addresses on routers. Please log into before accessing this course. Static Link-Local Addresses Configuring the link-local address manually provides the ability to create an address that is recognizable and easier to remember.