Network Fundamentals - IPv6 Configuration Flashcards
The command for configuring an IPv6 address on a router interface
“ipv6 address” + address/prefix length
Note: Both the abbreviated and full versions of the address can be used with this command.
The process for how EUI-64 generates the Interface ID portion of an IPv6 host address
- Split the 6-byte (12-hex-digit) MAC address in two halves
- Insert FFFE in between the two, making the interface ID now have a total of 16 hex digits (64 bits)
- Invert the seventh bit of the interface ID
Note: See Figure 30-4 on pg. 711 and Example 30-5 on pg. 712 of the ICND1 Study Guide for an example.
The command used to configure an IPv6 address on a router interface, using EUI-64 rules
“ipv6 address” + address prefix/prefix length “eui-64”
A process that generates the interface ID portion of an IPv6 address, using an interface’s MAC address
EUI-64 (extended unique identifier)
Note: If an interface does not have a MAC address, the router chooses the MAC of the lowest-numbered router interface that does have a MAC
The two ways that a router can dynamically learn an IPv6 address
- Stateful DHCP
2. Stateless Address Autoconfiguration (SLAAC)
The steps that a router goes through after an IPv6 address is configured on an interface
The router:
- Gives the interface a unicast IPv6 address
- Enables the routing of IPv6 packets in/out that
interface - Defines the IPv6 prefix (subnet) that exists off that
interface - Tells the router to add a connected IPv6 route for that
prefix, to the IPv6 routing table, when that interface is
up/up
A type of IPv6 address that is not used for normal IPv6 packet flow; used for some overhead protocols and for routing
link-local address
Note: IOS creates a link-local address for any interface that has configured at least one other unicast address using the “ipv6 address” command.
The properties of link-local addresses
These addresses are:
- Unicast (not multicast)
- Forwarding scope is the local link (subnet) only
- Usually generated automatically
- First half is always FE80:0000:0000:0000
- Second half is generated using EUI-64
Note: Can also be statically configured on
Some common uses for link-local addresses
- Used by some overhead protocols that stay local to one subnet
- Used as the next-hop address for IPv6 routes
The two types of IPv6 multicast addresses
- Link-local multicast addresses
- Solicited-node multicast addresses
Properties of a link-local multicast address
- Link-local scope: Routers do not forward packets sent to this address
- Used for communicating over a single link
- Have preset values; each address corresponds to a different type/group of noes on a link (subnet)
• Example: FF02::2 is the address for all routers on the link
• See Table 30-3 on pg. 720 for a table showing common
local-scope addresses
Properties of a solicited-node multicast address
- Link-local scope: Routers do not forward packets sent to this address. Each host on the link has a different address.
- Calculated: Address is calculated based on the last 6 hex digits of the host’s unicast IPv6 address
• Hosts with the same last 6 digits of their unicast address
will have the same address. - Operation: Each host interface must listen for packets sent to its address
- Overlap: Some hosts might have the same multicast address
The prefix for all solicited-node multicast addresses
Note: See Figure 30-11 for an example of the format for these addresses.
FF02::1:FF/104
An address that is assigned to multiple routers; packets sent to this address are routed to the nearest router configured with the address. Generally used to support some kind of service that works best when offered by multiple routers.
Anycast address
Note: See pg. 722 of the ICND1 Study Guide for more information.
The IPv6 loopback address
::1/128
