network fundamentals ch 12
Method 2: SLAAC with a stateless DHCPv6 server
"Here is my information but you need to get other information such as DNS addresses from a stateless DHCPv6 server."
A stateless DHCPv6 server distributes DNS server addresses and domain names.
It does not allocate GUAs.
What is the purpose of the command ping ::1?
it test the internal configuration of an IPv6 host
A /64 subnet or prefix (Global Routing Prefix + Subnet ID)
leaves 64 bits for the interface ID.
At a minimum, which address is required on IPv6-enabled interfaces?
link local
What type of address is automatically assigned to an interface when IPv6 is enabled on that interface?
link local
Preferred format
means that you write IPv6 address using all 32 hexadecimal digits. It does not necessarily mean that it is the ideal method for representing the IPv6 address.
Which dynamic addressing method for GUAs is the one where devices rely solely on the contents of the RA message for their addressing information?
method 1: SLAAC
Which dynamic addressing method for GUAs is the one where devices get their IPv6 configuration in a RA message and request DNS information from a DHCPv6 server?
method 2: SLAAC and stateless DHCPv6
Which field in an IPv6 GUA is used for subnetting?
subnet ID
Method 3: Stateful DHCPv6 (no SLAAC)
"I can give you your default gateway address. You need to ask a stateful DHCPv6 server for all your other information."
Method 1: SLAAC
"I have everything you need including the prefix, prefix length, and default gateway address."
What is the recommended prefix length for most IPv6 subnets?
/64
our examples of ways to omit leading zeros:
01ab can be represented as 1ab 09f0 can be represented as 9f0 0a00 can be represented as a00 00ab can be represented as ab
16-bit subnet ID
Creates up to 65,536 subnets.
IPv6 addresses typically have two unicast addresses:
Global Unicast Address (GUA) Link-local Address (LLA)
two types of IPv6 multicast addresses:
Well-known multicast addresses Solicited node multicast addresses
IPv6 global unicast addresses (GUAs)
are globally unique and routable on the IPv6 internet. These addresses are equivalent to public IPv4 addresses.
GUA has three parts
global routing prefix subnet ID interface ID
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
SLAAC
is a method that allows a device to create its own GUA without the services of DHCPv6. Using SLAAC, devices rely on the ICMPv6 RA messages of the local router to obtain the necessary information.
IPv6 subnetting
is also easier to implement than IPv4, because there is no conversion to binary required. To determine the next available subnet, just count up in hexadecimal.
The benefit of a 128-bit address
is that it can support more than enough subnets and hosts per subnet, for each network.
Given a /48 Global Routing Prefix and a /64 prefix, what is the subnet portion of the following address: 2001:db8:cafe:1111:2222:3333:4444:5555
1111
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.
Given a /32 Global Routing Prefix and a /64 prefix, how many bits would be allocated for the Subnet ID?
32
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.
Multicast
An IPv6 multicast address is used to send a single IPv6 packet to multiple destinations.
Unicast
An IPv6 unicast address uniquely identifies an interface on an IPv6-enabled device.
What are the two methods a device can use to generate its own IPv6 interface ID?
EUI-64 randomly generated
What is indicated by a successful ping to the ::1 IPv6 address?
IP is properly installed on the host
What type of IPv6 address begins with fe80?
LLA
Which type of IPv6 unicast address is not routable between networks?
LLA
three methods for RA messages:
Method 1: SLAAC Method 2: SLAAC with a stateless DHCPv6 server Method 3: Stateful DHCPv6 (no SLAAC)
The ICMPv6 RA message includes the following:
Network prefix and prefix length Default gateway address DNS addresses and domain name
Ethernet MAC addresses are usually represented in hexadecimal and are made up of two parts:
Organizationally Unique Identifier (OUI) Device Identifier
SLAAC two parts of the address are created as follows:
Prefix Interface ID
ICMPv6 RS and RA Messages
RS messages are sent to all IPv6 routers by host requesting addressing information RA messages are sent to all IPv6 nodes, if method 1 (SLAAConly) is used the RA includes network prefix, prefix length and default gateway information
RA message suggests devices use the following:
SLAAC to create its own IPv6 GUA The router LLA, which is the RA source IPv6 address, as the default gateway address A stateless DHCPv6 server to obtain other information such as a DNS server address and a domain name
There are two ways in which a device can obtain an IPv6 GUA automatically:
Stateless Address Autoconfiguration (SLAAC) Stateful DHCPv6
There are two ways that a device can obtain an LLA:
Statically Dynamically
64-bit interface ID
Supports up to 18 quintillion host IPv6 addresses per subnet (i.e., 18,000,000,000,000,000,000).
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
the RA message suggests devices use the following:
The router LLA, which is the RA source IPv6 address, for the default gateway address. A stateful DHCPv6 server to obtain a GUA, DNS server address, domain name and other necessary information.
Rule 2- Double Colon
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 hextets consisting of all zeros.
DNS addresses and domain name
These are the addresses of DNS servers and a domain name.
ff02::2 All-routers multicast group
This is a multicast group that all IPv6 routers join. A router becomes a member of this group when it is enabled as an IPv6 router with the ipv6 unicast-routing global configuration command. A packet sent to this group is received and processed by all IPv6 routers on the link or network.
ff02::1 All-nodes multicast group
This is a multicast group that all IPv6-enabled devices join. A packet sent to this group is received and processed by all IPv6 interfaces on the link or network. This has the same effect as a broadcast address in IPv4. The figure shows an example of communication using the all-nodes multicast address. An IPv6 router sends ICMPv6 RA messages to the all-node multicast group.
Prefix
This is advertised in the RA message.
Default gateway address
This is an IPv6 LLA, the source IPv6 address of the RA message.
Statically
This means the device has been manually configured
three broad categories of IPv6 addresses:
Unicast Multicast Anycast
IPv6 unique local addresses have some similarity to RFC 1918 private addresses for IPv4, but there are significant differences:
Unique local addresses are used for local addressing within a site or between a limited number of sites. Unique local addresses can be used for devices that will never need to access another network. Unique local addresses are not globally routed or translated to a global IPv6 address.
L indicates
a Local route, the specific IPv6 address assigned to the interface. This is not an LLA. LLAs are not included in the routing table of the router because they are not routable addresses.
Dual stack
allows IPv4 and IPv6 to coexist on the same network segment. ... devices run both IPv4 and IPv6 protocol stacks simultaneously. Known as native IPv6, this means the customer network has an IPv6 connection to their ISP and is able to access content found on the internet over IPv6.
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 an IPv4 packet is translated to an IPv6 packet.
Statically configured LLAs
are used to make them more easily recognizable as belonging to router R1.
show ipv6 route command
can be used to verify that IPv6 networks and specific IPv6 interface addresses have been installed in the IPv6 routing table. will only display IPv6 networks, not IPv4 networks.
prefix length
can range from 0 to 128
LLAs can be
configured manually using the ipv6 address ipv6-link-local-address link-local command.
What is the most important motivating factor for moving to IPv6?
depletion of IPv4 addresses
show ipv6 interface brief command
displays the MAC address of the Ethernet interfaces abbreviated output for each of the interfaces
IPv6 link-local address (LLA)
enables a device to communicate with other IPv6-enabled devices on the same link and only on that link (subnet). Packets with a source or destination LLA cannot be routed beyond the link from which the packet originated. every IPv6-enabled network interface must have an LLA.
The IPv6 interface ID is
equivalent to the host portion of an IPv4 address.
True or False. RA messages are sent to all IPv6 routers by hosts requesting addressing information.
false
True or False: The Subnet ID field in an GUA must borrow bits from the interface ID.
false
Which dynamic addressing method for GUAs is the one where devices rely solely on a DHCPv6 server for their addressing information?
method 3: stateful DHCPv6
default gateway address can
only be obtained dynamically from the RA message. The stateless or stateful DHCPv6 server does not provide the default gateway address.
C next to a route indicates
that this is a directly connected network.
IEEE defined
the Extended Unique Identifier (EUI) or modified EUI-64 process. This process uses the 48-bit Ethernet MAC address of a client, and inserts another 16 bits in the middle of the 48-bit MAC address to create a 64-bit interface ID.
DHCPv6 or SLAAC is used
the LLA of the router will automatically be specified as the default gateway address.
IPv6 it is only called
the prefix length. does not use the dotted-decimal subnet mask notation.
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.will usually vary depending on the policies of the ISP.
Dynamically Creating an Interface ID
the router sends an RA messages the PC uses the prefix in the RA message and uses either EUI-64 or a random 64 - bit number to generate an interface ID
What is the minimum configuration for a router interface that is enabled for IPv6?
to have a link local IPv6 address
router interface can be configured
to send an RA using stateful DHCPv6 only
octet refers
to the eight bits of an IPv4 address.
True or False: 4 out of 5 RIRs no longer have enough IPv4 addresses to allocate to customers on a regular basis.
true
True or False? IPv6 was designed with subnetting in mind.
true
IPv6 unicast address
uniquely identifies an interface on an IPv6-enabled device. A packet sent to a unicast address is received by the interface which is assigned that address. Si
SLAAC is stateless
which means there is no central server (for example, a stateful DHCPv6 server) allocating GUAs and keeping a list of devices and their addresses. With SLAAC, the client device uses the information in the RA message to create its own GUA.
strongly recommended to use a 64-bit Interface ID for most networks.
This is because stateless address autoconfiguration (SLAAC) uses 64 bits for the Interface ID. It also makes subnetting easier to create and manage.
Link-local Address (LLA)
This is required for every IPv6-enabled device. LLAs are used to communicate with other devices on the same local link. With IPv6, the term link refers to a subnet. LLAs are confined to a single link. Their uniqueness must only be confirmed on that link because they are not routable beyond the link. In other words, routers will not forward packets with a link-local source or destination address.
Global Unicast Address (GUA)
This is similar to a public IPv4 address. These are globally unique, internet-routable addresses. GUAs can be configured statically or assigned dynamically.
Dynamically
This means the device creates its own interface ID by using randomly generated values or using the Extended Unique Identifier (EUI) method, which uses the client MAC address along with additional bits
Network prefix and prefix length
This tells the device which network it belongs to.
IPv6 addresses
are 128 bits in length and written as a string of hexadecimal values. Every four bits is represented by a single hexadecimal digit; for a total of 32 hexadecimal values,
Tunneling and translation
are for transitioning to native IPv6 and should only be used where needed. The goal should be native IPv6 communications from source to destination.
Unique local addresses (range fc00::/7 to fdff::/7)
are not yet commonly implemented. Therefore, this module only covers GUA and LLA configuration. However, unique local addresses may eventually be used to address devices that should not be accessible from the outside, such as internal servers and printers.
Which address type is not supported in IPv6?
broadcast
prefix, or network portion, of an IPv4 address
can be identified by a dotted-decimal subnet mask or prefix length (slash notation). 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.
Which of the following techniques use native IPv6 connectivity?
dual stack
two common IPv6 assigned multicast groups:
ff02::1 All-nodes multicast group ff02::2 All-routers multicast group
ping command
for IPv6 is identical to the command used with IPv4, except that an IPv6 address is used.
Which part of a GUA is assigned by the ISP?
global routing prefix
solicited-node multicast address
is similar to the all-nodes multicast address. The advantage of a solicited-node multicast address is that it is mapped to a special Ethernet multicast address. This allows the Ethernet NIC to filter the frame by examining the destination MAC address without sending it to the IPv6 process to see if the device is the intended target of the IPv6 packet.
Subnet ID field
is the area between the Global Routing Prefix and the Interface ID. Unlike IPv4 where you must borrow bits from the host portion to create subnets, IPv6 was designed with subnetting in mind.
Interface ID
is used because a single host may have multiple interfaces, each having one or more IPv6 addresses.This uses the EUI-64 process or by generating a random 64-bit number, depending on the device operating system.
Subnet ID
is used by an organization to identify subnets within its site. The larger the subnet ID, the more subnets available.
