CCNA Module 7
IPv6-enabled hosts create an IPv6 link-local address even if the device has not been assigned a
global unicast IPv6 address.
Recall that the link-local address is automatically added to the interface when a _______________ is assigned.
global unicast address
Stateful DHCPv6 is similar to DHCP for IPv4. A device can automatically receive its addressing information including a _________, __________, and ___________ using the services of a stateful DHCPv6 server.
global unicast address, prefix length, and the addresses of DNS servers
The most common types of IPv6 unicast addresses are
global unicast addresses (GUA) and link-local unicast addresses.
A stateless DHCPv6 server distributes DNS server addresses and domain names. It does not allocate
global unicast addresses.
Public IPv4 addresses are addresses which are
globally routed between ISP (Internet Service Provider) routers
The IPv6 Interface ID is equivalent to the _____ portion of an IPv4 address
host
The bits within the network portion of the address must be _________ for all devices that reside in the same network
identical
The command to configure an IPv6 global unicast address on an interface is
ipv6 address ipv6-address/prefix-length
IPv6 routing is not enabled by default. To enable a router as an IPv6 router, the ________________________________ global configuration command must be used.
ipv6 unicast-routing
Link-local addresses can be configured manually using the same interface command used to create IPv6 global unicast addresses but with the additional_____________parameter
link-local
the default gateway address can be configured to match the _____________of the GigabitEthernet interface.
link-local address
However, every IPv6-enabled network interface is required to have a
link-local address.
ANDing between the address and the subnet mask yields the
network address.
Recall that an IPv4 address is a hierarchical address that is made up of a _______ portion and a _______ portion.
network, host
The global routing prefix is the prefix, or
network, portion of the address that is assigned by the provider, such as an ISP, to a customer or site.
The first rule to help reduce the notation of IPv6 addresses is to
omit any leading 0s (zeros) in any 16-bit section or hextet
With a broadcast, the packet contains a destination IPv4 address with all _______ in the host portion
ones (1s)
A global unicast address is similar to a
public IPv4 address
printers, servers, and networking devices need an IP address that does not change. For this reason, these devices are typically assigned ______ IP addresses
static
The size of the global routing prefix determines the size of the
subnet ID.
The Subnet ID is used by an organization to identify
subnets within its site.
If a link-local address is not configured manually on an interface,
the device will automatically create its own without communicating with a DHCP server.
The larger the subnet ID,
the more subnets available.
When an IPv4 address is assigned to a device, the subnet mask is used to determine
the network address where the device belongs
the prefix length is
the number of bits set to 1 in the subnet mask
Logical AND is the comparison of
two bits
The bits within the host portion of the address must be _______ to identify a specific host within a network
unique
the subnet mask does not actually contain the network or host portion of an IPv4 address, it just tells the computer
where to look for these portions in a given IPv4 address.
Typically, RIRs assign a /? global routing prefix to customers
/48
IPv4 unicast host addresses are in the address range of
0.0.0.0 to 223.255.255.255
With Stateful DHCPv6 the RA message suggests devices use:
The router's link-local address, the RA's source IPv6 address for the default gateway address. A stateful DHCPv6 server to obtain a global unicast address, DNS server address, domain name and all other information.
IPv6 addresses are _____ bits in length
128
EUI-64 process: This process uses a client's 48-bit Ethernet MAC address, and inserts another ___ bits in the middle of the 48-bit MAC address to create a 64-bit Interface ID.
16
For example, an IPv4 address of 192.168.1.10 with dotted-decimal subnet mask 255.255.255.0 is equivalent to
192.168.1.10/24.
IPv6 routers periodically send out ICMPv6 RA messages, every ______ seconds, to all IPv6-enabled devices on the network
200
The IPv4 multicast addresses _____ to _______ are reserved for multicasting on the local network only.
224.0.0.0 to 224.0.0.255
An EUI-64 Interface ID is represented in binary and is made up of three parts:
24-bit OUI from the client MAC address, but the 7th bit (the Universally/Locally (U/L) bit) is reversed. This means that if the 7th bit is a 0, it becomes a 1, and vice versa. The inserted 16-bit value FFFE (in hexadecimal) 24-bit Device Identifier from the client MAC address
Each address consists of a string of _____ bits, divided into four sections called ______
32, octets
the preferred format for writing an IPv6 address is x:x:x:x:x:x:x:x, with each "x" consisting of how many hexadecimal values?
4
Designed to support extremely large networks with more than 16 million host addresses.
Class A
The RFC divided the unicast ranges into specific classes called:
Class A, B, and C
Designed to support the needs of moderate to large size networks with up to approximately 65,000 host addresses
Class B
Designed to support small networks with a maximum of 254 hosts
Class C
CIDR
Classless Inter-Domain Routing
Identifies the local gateway (i.e. local router interface IPv4 address) to reach remote networks
Default gateway
The IETF has created various protocols and tools to help network administrators migrate their networks to IPv6. The migration techniques can be divided into three categories:
Dual Stack - dual stack allows IPv4 and IPv6 to coexist on the same network segment. Dual stack devices run both IPv4 and IPv6 protocol stacks simultaneously. Tunneling - tunneling is a method of transporting an IPv6 packet over an IPv4 network. The IPv6 packet is encapsulated inside an IPv4 packet, similar to other types of data. Translation - Network Address Translation 64 (NAT64) allows IPv6-enabled devices to communicate with IPv4-enabled devices using a translation technique similar to NAT for IPv4. An IPv6 packet is translated to an IPv4 packet and vice versa.
DHCP
Dynamic Host Configuration Protocol
By default, Cisco IOS routers use _________ to generate the Interface ID for all link-local address on IPv6 interfaces
EUI-64
The advantage of EUI-64 is the ________ can be used to determine the Interface ID.
Ethernet MAC address
Serial interfaces do not have _______________________, so Cisco IOS uses the MAC address of the ___________________
Ethernet MAC addresses, first available Ethernet interface
EUI
Extended Unique Identifier
IPv6 multicast addresses have the prefix
FF00::/8.
An easy way to identify that an address was more than likely created using EUI-64 is the ______ located in the middle of the Interface ID
FFFE
A global unicast address has three parts:
Global routing prefix Subnet ID Interface ID
Using SLAAC, devices rely on the local router's ____________ messages to obtain the necessary information.
ICMPv6 Router Advertisement (RA)
Unique IPv4 address of the host
IPv4 address
After the Interface ID is established, either through the EUI-64 process or through random generation, it can be combined with an _______ in the RA message to create a global unicast address
IPv6 prefix
When the router interface is configured with a global unicast address and is in the "up/up" state, the __________ and __________ is added to the IPv6 routing table as a connected route.
IPv6 prefix, prefix length
Stateless Address Autoconfiguration (SLAAC) is a method that allows a device to obtain its prefix, prefix length, default gateway address, and other information from an ___________ without the use of a DHCPv6 server.
IPv6 router
When the RA message is either SLAAC or SLAAC with stateless DHCPv6, the client must generate its own
Interface ID
Both IPv4 and IPv6 addresses are managed by the
Internet Assigned Numbers Authority (IANA)
The [up/up] output on the same line as the interface indicates the
Layer 1/Layer 2 interface state
More commonly known as the Automatic Private IP Addressing (APIPA) addresses, they are used by a Windows DHCP client to self-configure in the event that there are no DHCP servers available.
Link-Local addresses
More commonly identified as only 127.0.0.1, these are special addresses used by a host to direct traffic to itself.
Loopback address
The show interface command displays the __________ of the Ethernet interfaces
MAC address
___________ is used to translate between private IPv4 and public IPv4 addresses
NAT
Does IPv6 use use the dotted-decimal subnet mask notation?
NO
Does IPv6 have a broadcast address?
NOOOOO
NAT
Network Address Translation
The ICMPv6 RA message includes:
Network prefix and prefix length - Tells the device which network it belongs to. Default gateway address - This is an IPv6 link-local address, the source IPv6 address of the RA message. DNS addresses and domain name - Addresses of DNS servers and a domain name.
Will routers forward packets with a link-local source or destination address?
No
How many times can a double colon be used in an IPv6 address?
Only once
Ethernet MAC addresses are usually represented in hexadecimal and are made up of two parts:
Organizationally Unique Identifier (OUI) - The OUI is a 24-bit (6 hexadecimal digits) vendor code assigned by IEEE. Device Identifier - The device identifier is a unique 24-bit (6 hexadecimal digits) value within a common OUI.
2001:0DB8:ACAD: 0001 :0000:0000:0000:0100 /64 Part 1= Part 2= Part 3=
Part 1= Global routing prefix Part 2= Subnet ID Part 3= Interface ID
the two parts of the address are created as follows:
Prefix - Received in the RA message Interface ID - Uses the EUI-64 process or by generating a random 64-bit number
RIR
Regional Internet Registries
With the SLAAC and Stateless DHCPv6 option, the RA message suggests devices use:
SLAAC to create its own IPv6 global unicast address The router's link-local address, the RA's source IPv6 address for the default gateway address. A stateless DHCPv6 server to obtain other information such as a DNS server address and a domain name.
SLAAC
Stateless Address Autoconfiguration
There are two ways in which a device can obtain an IPv6 global unicast address automatically:
Stateless Address Autoconfiguration (SLAAC) DHCPv6
Step 1 of the EUI-64 process
Step 1: Divide the MAC address between the OUI and device identifier.
Step 2 of the EUI-64 process
Step 2: Insert the hexadecimal value FFFE, which in binary is: 1111 1111 1111 1110.
Step 3 of the EUI-64 process
Step 3: Convert the first 2 hexadecimal values of the OUI to binary and flip the U/L bit (bit 7). In this example, the 0 in bit 7 is changed to a 1.
Used to identify the network/host portion of the IPv4 address
Subnet mask
The all-0s address can also be used, but is reserved as a _______________, and should be assigned only to routers.
Subnet-Router anycast address
These addresses are set aside for teaching and learning purposes and can be used in documentation and network examples.
TEST-NET addresses
There are three types of IPv6 addresses:
Unicast - An IPv6 unicast address uniquely identifies an interface on an IPv6-enabled device. As shown in the figure, a source IPv6 address must be a unicast address. Multicast - An IPv6 multicast address is used to send a single IPv6 packet to multiple destinations. Anycast - An IPv6 anycast address is any IPv6 unicast address that can be assigned to multiple devices. A packet sent to an anycast address is routed to the nearest device having that address. Anycast addresses are beyond the scope of this course.
Recall that the prefix, or network portion, of an IPv4 address, can be identified by
a dotted-decimal subnet mask or prefix length (slash notation).
Each multicast group is represented by
a single IPv4 multicast destination address
Unique local addresses are used for local addressing within
a site or between a limited number of sites.
With IPv6, the term link refers to
a subnet.
The DHCP server provides
an IP address, subnet mask, default gateway, and other configuration information.
The second rule to help reduce the notation of IPv6 addresses is that a double colon (::) can replace
any single, contiguous string of one or more 16-bit segments (hextets) consisting of all 0s.
hosts, servers, and network devices use ________ addressing
binary
Packets with a source or destination link-local address (Can or cannot) be routed beyond the link from which the packet originated.
cannot
SLAAC is stateless, which means there is no _________________ allocating global unicast addresses and keeping a list of devices and their addresses.
central server
Link-local addresses are used to
communicate with other devices on the same local link
Within the route table, a C next to a route indicates that this is a
directly connected network
subdividing networks can improve network performance by
eliminating excessive broadcast traffic.
To convert a binary IPv4 address to its dotted decimal equivalent, divide the IPv4 address into
four 8-bit octets
