IPv6 Flashcards
What does EUI stand for?
Extended Unique Identifier
What is the / range for IPv6 unique local address space?
FC00::/7
What do IPv6 link-local addresses start with?
FE80
What is the prefix range for link-local addresses?
FE80::/10 FE80 FE90 FEA0 FEB0
What method is used to create the link-local address for an interface?
FE80::/64 + EUI-64 interface ID
What do IPv6 multicast addressess start with?
FF
What is the IPv6 multicast range?
FF00::/8
What IPv6 multicast range is reserved for link local only?
FF02::/16
When a host wants to use DHCPv6 to get an IP, what source/destination addresses does it use?
Source = it's link-local address Destination = FF02::1:2
What does SLAAC stand for?
StateLess Address AutoConfiguration
Command to set an IPv6 dhcp relay on an interface
conf t
int gi0/0
ipv6 dhcp relay destination DHCP server addr
What are 2 uses for link-local addresses?
Communication with directly connected neighbors
Routers use their neighbors link-local addresses as next hops in routing tables
3 steps for a host to get an IPv6 address using SLAAC
- Discover the v6 prefix on the link using NDP RS/RA messages.
- Create an interface ID and append it to the prefix.
- Test that it’s not a duplicate using DAD.
What address is an RS message sent to?
All-routers
FF02::2
When using SLAAC, how does a host come up with it’s interface ID?
Either using EUI-64 or coming up with a random value.
What is the all-host IPv6 address?
FF02::1
What 5 IPv6 functions use NDP?
SLAAC DAD Router Discovery Neighbor MAC Discovery Prefix/length Discovery
What is the all-DHCP-agents multicast address?
FF02::1:2
What is the all-router IPv6 address?
FF02::2
Where would a host using SLAAC get the DNS server address?
From stateless DHCPv6
4 major types of IPv6 addresses
Global Unicast
Unique local
Multicast
Link-local
How does DAD work?
Host sends a NS message for it’s IPv6 address. If someone answers, must be a duplicate.
Who primarily sends an RS message?
Hosts
When are RA messages sent?
In response to a RS message
Or
Unsolicited, on a timer
What does NDP replace?
IPv4 ARP
If you really want to configure the link-local address, what is the syntax?
ipv6 address local IPv6 addr link-local
Command to statically configure an IPv6 address on an interface
conf t
interface int
ipv6 address address/mask
Command to have an interface use an EUI-64 address
ipv6 address prefix/64 eui-64
Command to have a router use SLAAC to dynamically get an IPv6 address
ipv6 address autoconfig
Command to have a router use DHCPv6 on an interface
ipv6 address dhcp
Command to enable a router to forward IPv6 packets
ipv6 unicast-routing
What is the scope of the solicited-node multicast address?
Link-local
In IPv6, what replaces ARP?
Neighbor discovery
What does NDP stand for?
Neighbor Discovery Protocol
What types of messages are used to find a neighbor’s MAC address in IPv6?Using what protocol?
NS and NA
NDP
What are global unicast IPv6 addresses the equivalent of?
Public IPv4 addresses
What are the versions of the IGPs that support IPv6?
RIPng
OSPFv3
EIGRPv6
What are unique local IPv6 addresses the equivalent of?
Roughly, RFC1918 addresses
What do RS and RA stand for?
Router Solicitation
Router Advertisement
Who primarily sends RA messages?
Routers
2 commands to see IPv6 interface information
show ipv6 interface brief
show ipv6 interace interface
DHCPv4 uses Discover/Offer/Request/Acknowledgement messages. What does DHCPv6 use?
Solicit - Host
Advertise - Server
Request - Host
Reply - Server
When a host uses SLAAC, what crucial data is it missing?
the DNS server’s address
When a router receives a link-local packet, what are the steps it takes to forward it out another interface?
Link local packets are not forwarded out other interfaces; they are scoped to a single link.
4 steps to creating an EUI-64 address
- Take the MAC address of the interface, and split it in half.
- Insert FF:FE into the middle of the MAC.
- Invert the 7th bit of the the result from step 2.
- Append this to the IPv6 prefix.
What are the 2 rules for shortening IPv6 addresses?
- In each quartet, remove any leading 0’s.
2. For any single sequence of quartet’s whos value is 0, collapse that sequence into ::
If an organization is allocated a /54, how many bits are available for subnets?
10
How many bits in an IPv6 address?How many bytes?
128 bits
16 bytes
What’s the size of the required section of the IPv6 header?
40 bytes
How many : delimited sections are there in an IPv6 address?
82340:1111:AAAA:0001:1234:5678:9ABC:1234
What is the 7th bit in the EUI-64 interface ID?
The universal/local bit.
Syntax to configure an IPv6 address on interface s0/0/0
conf t
int s0/0/0
ipv6 address ipv6 addr/mask
Command to set an IPv6 static default route going out gi1/0
conf t
ipv6 route ::/0 gi1/0
Command to set an IPv6 static route
conf t
ipv6 route network/mask {next hop IPv6 | exit interface}
Command to enable ipv6 globally
conf t
ipv6 unicast-routing
What does DAD stand for?
Duplicate Address Detection
When is a link local IPv6 address instantiated on a router’s interface?
When another IPv6 address is configured or aqcuired on the same interface.
How are link-local addresses configured in the router?
They are automatically and self-generated.
What is the range of globally routable IPv6 addresses, in / notation.
2000::/3
What do the 2 options for the U/L bit signify?
0 = BIA MAC is being used1 = Locally administered address, ie BIA has been overwritten
What is one difference between DHCPv4 and v6 in terms of types of information supplied to the requesting host by the DHCP server.
DHCPv6 does not supply default router info. That is discovered by the host, using RS messages.
Name 2 ways for a router to get an IPv6 address dynamically
- Stateful DHCP
2. SLAAC
What’s the most common IPv6 subnet mask for hosts or interfaces?
/64
What is the ethertype for IPv6
0x86DD