10 - IPv6 Flashcards
What was IPv4 ARP replaced with in IPv6?
NDP (Neighbor Discovery Protocol)
What is the Prefix / prefix length in IPv6?
Number of bits that make up the prefix, which is the equivalent of a SubnetID in IPV4
What is a Global Unicast address similar to from IPv4?
Public IPv4 address
What is a Global Routing Prefix?
A reserved block of IPv6 addresses that only one company can use
What are the first hex digits for IPv6 Unique Local addresses?
FD
What are the first hex digits for IPv6 Multicast addresses?
FF
What are the first hex digits for IPv6 Link Local addresses?
FE80
What are the three parts to an IPv6 address?
- Global Routing Prefix
- Subnet
- Interface ID
How many bits is the Subnet section of an IPv6 address?
64 - Prefix Length bits
What are the two components of a Prefix/Subnet ID?
- Global Routing Prefix
- Subnet
What is the formal name for the Subnet ID in IPv6?
Prefix ID
What is another name for the IPv6 Subnet ID / Prefix ID?
Subnet Router Anycast Address
What is SLAAC?
Stateless Address Autoconfiguration
What are Unique Local unicast addresses?
Private IPv6 addresses
How many bits is the Global ID in a Unique Local Unicast address?
40 bits
What are the three components of the first 64bits of a Unique Local address?
- First 8 bits must be FD
- 40 bit Global ID
- 16 bits Subnet
What are the three components of the first 64bits of a Unique Local address?
- First 8 bits must be FD
- 40 bit Global ID
- 16 bits Subnet
True/False: You can leave a space between the address and the /prefix length when entering the command on the device
False
How do you enable IPv6 routing?
ipv6 unicast-routing
interface> ipv6 address …
What is an alternative method to static assignment for an IPv6 interface ID?
EUI-64 autoconfiguration
What are the steps EUI-64 autoconfiguration uses to build the interface ID?
- Split the 6byte MAC address of the interface into two halves
- Insert FFFE in the middle
- Invert the 7th bit of the resultant interface ID
How would you configure an interface using EUI-64?
ipv6 address 2001:DB8:1111:4::/64 eui-64
What command is used to override the burned in MAC address for an interface?
mac-address 0201.AA00.0001
True/False: You must only enter the prefix and not the full address when configuring an interface address in eui-64 mode or else the command will fail
False. IOS automatically converts the address to the matching prefix
What are two ways Cisco routers support to allow a router interface to dynamically learn an IPv6 address?
- Stateful DHCP
- SLAAC
How do you configure a router interface to use DHCP?
ip address dhcp
How do you configure a router interface to use SLAAC?
ip address autoconfig
What are IPv6 Link Local addresses used for?
Not used for normal packet flows containing application data. They are used for overhead protocols and for routing e.g. next hop IP
True/False: NDP uses link-local addresses
True
What command could you use to show the link-local address of a neighboring router?
show ipv6 route
True/False: Link-local addresses can represent more than one host
False. They are Unicast
True/False: Link-local addresses can be automatically generated
True
What is the forwarding scope for link-local addresses?
Only the link itself. Routers do not forward packets with link-local destination addresses
What do link local addresses always start with? (Including the 54 bits after the first 10)
FE80:0:0:0
What three ways can the second half (interface ID) of the link local address be created?
- Randomly generated
- EUI-64
- Manually configured
What command would you use to manually configure a link local address?
ipv6 address [address] link-local
What are the valid starting prefixes for link-local addresses?
FE8
FE9
FEA
FEB
True/False: If not manually configured IOS automatically calculate the link-local address using EUI-64 rules
True
What rules does SLAAC use when calculating the interface ID?
EUI-64
What does the ipv6 enable
command do?
Enable IPv6 processing on an interface and adds a link-local address but no other unicast IPv6 addresses