CS计算机代考程序代写 scheme dns IOS DHCP ITE PC v4.0 Chapter 1

ITE PC v4.0 Chapter 1

Week 9:
IP Addressing- IPv6
Introduction to Networks

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Cisco Networking Academy program
Introduction to Networks
Chapter 8: IP Addressing

Outlines
IPv6 address representation
IPv6 address types
IPv6 global and link-local unicast addresses
Design considerations for IPv6
Summary

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Chapter 8 Sections

Week 8: Objectives
Upon completion of this chapter, you will be able to:
Explain the need for IPv6 addressing.
Describe the representation of an IPv6 address.
Describe types of IPv6 network addresses.
Configure global unicast addresses.
Describe multicast addresses.

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3. Chapter 8 Objectives
IP Addressing
Introduction
Addressing is a key function of network layer protocols that enables data communication between hosts, regardless of whether the hosts are on the same network or on different networks. Both Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) provide hierarchical addressing for packets that carry data.
Designing, implementing and managing an effective IP addressing plan ensures that networks can operate effectively and efficiently.
This chapter examines in detail the structure of IP addresses and their application to the construction and testing of IP networks and subnetworks.

8.2 IPv6 Network Addresses

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8.2 IPv6 Network Addresses

IPv4 Issues
The Need for IPv6
IPv6 is designed to be the successor to IPv4.
Depletion of IPv4 address space has been the motivating factor for moving to IPv6.
Projections show that all five RIRs will run out of IPv4 addresses between 2015 and 2020.
With an increasing Internet population, a limited IPv4 address space, issues with NAT and an Internet of things, the time has come to begin the transition to IPv6!
IPv4 has a theoretical maximum of 4.3 billion addresses, plus private addresses in combination with NAT.
IPv6 larger 128-bit address space provides for 340 undecillion addresses.
IPv6 fixes the limitations of IPv4 and includes additional enhancements, such as ICMPv6.

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33/ 8.2.1.1 The Need for IPv6
IPv6 Network Addresses
IPv4 issues
IPv6 is designed to be the successor to IPv4. IPv6 has a larger 128-bit address space, providing for 340 undecillion addresses. (That is the number 340, followed by 36 zeroes.) However, IPv6 is much more than just larger addresses. When the IETF began its development of a successor to IPv4, it used this opportunity to fix the limitations of IPv4 and include additional enhancements. One example is Internet Control Message Protocol version 6 (ICMPv6), which includes address resolution and address auto-configuration not found in ICMP for IPv4 (ICMPv4). ICMPv4 and ICMPv6 will be discussed later in this chapter.
Need for IPv6
The depletion of IPv4 address space has been the motivating factor for moving to IPv6. As Africa, Asia and other areas of the world become more connected to the Internet, there are not enough IPv4 addresses to accommodate this growth. On Monday, January 31, 2011, IANA allocated the last two /8 IPv4 address blocks to the Regional Internet Registries (RIRs). Various projections show that all five RIRs will have run out of IPv4 addresses between 2015 and 2020. At that point, the remaining IPv4 addresses will have been allocated to ISPs.
IPv4 has theoretical maximum of 4.3 billion addresses. RFC 1918 private addresses in combination with Network Address Translation (NAT) have been instrumental in slowing the depletion of IPv4 address space. NAT has limitations that severely impede peer-to-peer communications.
Internet of Things
The Internet of today is significantly different than the Internet of past decades. The Internet of today is more than email, web pages and file transfer between computers. The evolving Internet is becoming an Internet of things. No longer will the only devices accessing the Internet be computers, tablets and smart phones. The sensor-equipped, Internet-ready devices of tomorrow will include everything from automobiles and biomedical devices, to household appliances and natural ecosystems. Imagine a meeting at a customer site that is automatically scheduled on your calendar application, to begin an hour before you normally start work. This could be a significant problem, especially if you forget to check the calendar or adjust the alarm clock accordingly. Now imagine that the calendar application communicates this information directly to your alarm clock for you and to your automobile. Your car automatically warms up to melt the ice on the windshield before you enter the car and reroutes you to your meeting.
With an increasing Internet population, a limited IPv4 address space, issues with NAT and an Internet of things, the time has come to begin the transition to IPv6.

IPv4 Issues
IPv4 and IPv6 Coexistence
The migration techniques can be divided into three categories:
Dual-stack, Tunnelling, and Translation.

Dual-stack: Allows IPv4 and IPv6 to coexist on the same network. Devices run both IPv4 and IPv6 protocol stacks simultaneously.
Dual-stack

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34/ 8.2.1.2 IPv4 and IPv6 Coexistence
IPv6 Network Addresses
IPv4 issues
There is not a single date to move to IPv6. For the foreseeable future, both IPv4 and IPv6 will coexist. The transition is expected to take years. 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 – As shown in Figure 1, dual stack allows IPv4 and IPv6 to coexist on the same network. Dual stack devices run both IPv4 and IPv6 protocol stacks simultaneously.
Tunneling – As shown in Figure 2, 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 – As shown in Figure 3, 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.

IPv4 Issues
IPv4 and IPv6 Coexistence (cont.)
Tunnelling: A method of transporting an IPv6 packet over an IPv4 network. The IPv6 packet is encapsulated inside an IPv4 packet.

Tunnelling

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Tunneling – As shown in Figure 2, 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.

IPv4 Issues
IPv4 and IPv6 Coexistence (cont.)
Translation: The 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.

Translation

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36/ 8.2.1.2 IPv4 and IPV6 Coexistence (cont.)
Translation – As shown in Figure 3, 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.

IPv6 Addressing
Hexadecimal Number System
Hexadecimal is a base sixteen system.
Base 16 numbering system uses the numbers 0 to 9 and the letters A to F.
Four bits (half of a byte) can be represented with a single hexadecimal value.

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37/ 8.2.2.1 Hexadecimal Number System – PART 1 of animated slide
IPv6 Network Addresses
IPv6 Addressing
Unlike IPv4 addresses that are expressed in dotted decimal notation, IPv6 addresses are represented using hexadecimal values. You have seen hexadecimal used in the Packets Byte pane of Wireshark. In Wireshark, hexadecimal is used to represent the binary values within frames and packets. Hexadecimal is also used to represent Ethernet Media Access Control (MAC) addresses.
Hexadecimal Numbering
Hexadecimal (“Hex”) is a convenient way to represent binary values. Just as decimal is a base ten numbering system and binary is base two, hexadecimal is a base sixteen system.
The base 16 numbering system uses the numbers 0 to 9 and the letters A to F. Figure 1 shows the equivalent decimal, binary, and hexadecimal values. There are 16 unique combinations of four bits, from 0000 to 1111. The 16 digit Hexadecimal is the perfect number system to use, because any four bits can be represented with a single hexadecimal value.
Understanding Bytes
Given that 8 bits (a byte) is a common binary grouping, binary 00000000 to 11111111 can be represented in hexadecimal as the range 00 to FF. Leading zeroes can be displayed to complete the 8-bit representation. For example, the binary value 0000 1010 is shown in hexadecimal as 0A.
Representing Hexadecimal Values
Note: It is important to distinguish hexadecimal values from decimal values regarding the characters 0 to 9.
Hexadecimal is usually represented in text by the value preceded by 0x (for example 0x73) or a subscript 16. Less commonly, it may be followed by an H, for example 73H. However, because subscript text is not recognized in command line or programming environments, the technical representation of hexadecimal is preceded with “0x” (zero X). Therefore, the examples above would be shown as 0x0A and 0x73 respectively.
Hexadecimal Conversions
Number conversions between decimal and hexadecimal values are straightforward, but quickly dividing or multiplying by 16 is not always convenient.
With practice, it is possible to recognize the binary bit patterns that match the decimal and hexadecimal values. Figure 2 shows these patterns for selected 8-bit values.

IPv6 Addressing
Hexadecimal Number System (cont.)
Look at the binary bit patterns that match the decimal and hexadecimal values

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38/ 8.2.2.1 Hexadecimal Number System (cont.) Part 2 of animated slide

IPv6 Addressing
IPv6 Address Representation
128 bits in length and written as a string of hexadecimal values
In IPv6, 4 bits represents a single hexadecimal digit, 32 hexadecimal value = IPv6 address

2001:0DB8:0000:1111:0000:0000:0000:0200
FE80:0000:0000:0000:0123:4567:89AB:CDEF

Hextet used to refer to a segment of 16 bits or four hexadecimals
Can be written in either lowercase or uppercase

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39/ 8.2.2.2 IPv6 Address Representation Part 1 of 2 part slide – Preferred format examples
IPv6 Network Addresses
IPv6 Addressing
IPv6 addresses are 128 bits in length and written as a string of hexadecimal values. Every 4 bits is represented by a single hexadecimal digit; for a total of 32 hexadecimal values. IPv6 addresses are not case sensitive and can be written in either lowercase or uppercase.
Preferred Format
As shown in Figure 1, the preferred format for writing an IPv6 address is x:x:x:x:x:x:x:x, with each “x” consisting of four hexadecimal values. When referring to 8 bits of an IPv4 address we use the term octet. In IPv6, a hextet is the unofficial term used to refer to a segment of 16 bits or four hexadecimal values. Each “x” is a single hextet, 16 bits or four hexadecimal digits.
Preferred format means the IPv6 address is written using all 32 hexadecimal digits. It does not necessarily mean it is the ideal method for representing the IPv6 address. In the following pages, we will see two rules to help reduce the number of digits needed to represent an IPv6 address.
Figure 2 has examples of IPv6 addresses in the preferred format.

IPv6 Addressing
IPv6 Address Representation (cont.)

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40/ 8.2.2.2 IPv6 Address Representation (cont.) Part 2 of 2 part slide – Hextets

IPv6 Addressing
Rule 1- Omitting Leading 0s
The first rule to help reduce the notation of IPv6 addresses is any leading 0s (zeros) in any 16-bit section or hextet can be omitted.
01AB can be represented as 1AB.
09F0 can be represented as 9F0.
0A00 can be represented as A00.
00AB can be represented as AB.

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41/ 8.2.2.3 Rule 1 – Omitting Leading 0s
IPv6 Network Addresses
IPv6 Addressing
The first rule to help reduce the notation of IPv6 addresses is any leading 0s (zeros) in any 16-bit section or hextet can be omitted. For example:
01AB can be represented as 1AB
09F0 can be represented as 9F0
0A00 can be represented as A00
00AB can be represented as AB
This rule only applies to leading 0s, NOT to trailing 0s, otherwise the address would be ambiguous. For example, the hextet “ABC” could be either “0ABC” or “ABC0”.
The Figures 1 to 8 show several examples of how omitting leading 0s can be used to reduce the size of an IPv6 address. For each example the preferred format is shown. Notice how omitting the leading 0s in most examples results in a smaller address representation.

IPv6 Addressing
Rule 2 – Omitting All 0 Segments
A double colon (::) can replace any single, contiguous string of one or more 16-bit segments (hextets) consisting of all 0’s.
Double colon (::) can only be used once within an address otherwise the address will be ambiguous.
Known as the compressed format.
Incorrect address – 2001:0DB8::ABCD::1234.

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42/ 8.2.2.4 Rule 2 – Omitting All 0 Segments
IPv6 Network Addresses
IPv6 Addressing
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.
The double colon (::) can only be used once within an address, otherwise there would be more than one possible resulting address. When used with the omitting leading 0s technique, the notation of IPv6 address can often be greatly reduced. This is commonly known as the compressed format.
Incorrect address:
2001:0DB8::ABCD::1234
Possible expansions of ambiguous compressed addresses:
2001:0DB8::ABCD:0000:0000:1234
2001:0DB8::ABCD:0000:0000:0000:1234
2001:0DB8:0000:ABCD::1234
2001:0DB8:0000:0000:ABCD::1234
The Figures 1 to 7 show several examples of the how using the double colon (::) and omitting leading 0s can reduce the size of an IPv6 address.

IPv6 Addressing
Rule 2 – Omitting All 0 Segments (cont.)

Example #1

Example #2

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43/ 8.2.2.4 Rule 2 – Omitting All 0 Segments (cont.) Slide 2 of 2 slides – more examples

Types of IPv6 Addresses
IPv6 Address Types
There are three types of IPv6 addresses:
Unicast
Multicast
Anycast.

Note: IPv6 does not have broadcast addresses.

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44/ 8.2.3.1 IPv6 Address Types (out of Netacad order)

IPv6 Network Addresses
Types of IPv6 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.
Unlike IPv4, IPv6 does not have a broadcast address. However, there is an IPv6 all-nodes multicast address that essentially gives the same result.

Types of IPv6 Addresses
IPv6 Prefix Length
IPv6 does not use the dotted-decimal subnet mask notation
Prefix length indicates the network portion of an IPv6 address using the following format:
IPv6 address/prefix length
Prefix length can range from 0 to 128
Typical prefix length is /64

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45/ 8.2.3.2 IPv6 Prefix Length
IPv6 Network Addresses
Types of IPv6 Addresses
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). For example, an IP address of 192.168.1.10 with dotted-decimal subnet mask 255.255.255.0 is equivalent to 192.168.1.10/24.
IPv6 uses the prefix length to represent the prefix portion of the address. IPv6 does not use the dotted-decimal subnet mask notation. The prefix length is used to indicate the network portion of an IPv6 address using the IPv6 address/prefix length.
The prefix length can range from 0 to 128. A typical IPv6 prefix length for LANs and most other types of networks is /64. This means the prefix or network portion of the address is 64 bits in length, leaving another 64 bits for the interface ID (host portion) of the address.

Types of IPv6 Addresses
IPv6 Unicast Addresses
Unicast
Uniquely identifies an interface on an IPv6-enabled device.
A packet sent to a unicast address is received by the interface that is assigned that address.

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46/ 8.2.3.1/8.2.3.3 IPv6 Unicast Addresses
IPv6 Network Addresses
Types of IPv6 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.
Unlike IPv4, IPv6 does not have a broadcast address. However, there is an IPv6 all-nodes multicast address that essentially gives the same result.

IPv6 Network Addresses
Types of IPv6 Addresses
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). For example, an IP address of 192.168.1.10 with dotted-decimal subnet mask 255.255.255.0 is equivalent to 192.168.1.10/24.
IPv6 uses the prefix length to represent the prefix portion of the address. IPv6 does not use the dotted-decimal subnet mask notation. The prefix length is used to indicate the network portion of an IPv6 address using the IPv6 address/prefix length.
The prefix length can range from 0 to 128. A typical IPv6 prefix length for LANs and most other types of networks is /64. This means the prefix or network portion of the address is 64 bits in length, leaving another 64 bits for the interface ID (host portion) of the address.

Types of IPv6 Addresses
IPv6 Unicast Addresses (cont.)

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47/ 8.2.3.3 IPv6 Unicast Addresses (cont.)
IPv6 Network Addresses
Types of IPv6 Addresses
An IPv6 unicast address uniquely identifies an interface on an IPv6-enabled device. A packet sent to a unicast address is received by the interface that is assigned that address. Similar to IPv4, a source IPv6 address must be a unicast address. The destination IPv6 address can be either a unicast or a multicast address.
There are six types of IPv6 unicast addresses.
Global unicast
A global unicast address is similar to a public IPv4 address. These are globally unique, Internet routable addresses. Global unicast addresses can be configured statically or assigned dynamically. There are some important differences in how a device receives its IPv6 address dynamically compared to DHCP for IPv4.
Link-local
Link-local addresses are used to communicate with other devices on the same local link. With IPv6, the term link refers to a subnet. Link-local addresses 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.
Loopback
The loopback address is used by a host to send a packet to itself and cannot be assigned to a physical interface. Similar to an IPv4 loopback address, you can ping an IPv6 loopback address to test the configuration of TCP/IP on the local host. The IPv6 loopback address is all-0s except for the last bit, represented as ::1/128 or just ::1 in the compressed format.
Unspecified address
An unspecified address is an all-0s address represented in the compressed format as ::/128 or just :: in the compressed format. It cannot be assigned to an interface and is only used as a source address in an IPv6 packet. An unspecified address is used as a source address when the device does not yet have a permanent IPv6 address or when the source of the packet is irrelevant to the destination.
Unique local
[an enterprise needs to determine which hosts do not need to have network layer connectivity outside the enterprise in the foreseeable future and thus could be classified as private]
IPv6 unique local addresses have some similarity to RFC 1918 private addresses for IPv4, but there are significant differences as well. Unique local addresses are used for local addressing within a site or between a limited number of sites. These addresses should not be routable in the global IPv6. Unique local addresses are in the range of FC00::/7 to FDFF::/7.
With IPv4, private addresses are combined with NAT/PAT to provide a many-to-one translation of private-to-public addresses. This is done because of the limited availability of IPv4 address space. Many sites also use the private nature of RFC 1918 addresses to help secure or hide their network from potential security risks. However, this was never the intended use of these technologies and the IETF has always recommended that sites take the proper security precautions on their Internet facing router. Although, IPv6 does provide for site specific addressing, it is not intended to be used to help hide internal IPv6-enabled devices from the IPv6 Internet. IETF recommends that limiting access to devices should be accomplished using proper, best-practice security measures.
Note: The original IPv6 specification defined site-local addresses for a similar purpose, using the prefix range FEC0::/10. There were several ambiguities in the specification and site-local addresses were deprecated by the IETF in favor of unique local addresses.
IPv4 embedded
The last type of unicast address type is the IPv4 embedded address. These addresses are used to help transition from IPv4 to IPv6. IPv4 embedded addresses are beyond the scope of this course.

Loopback
The loopback address is used by a host to send a packet to itself and cannot be assigned to a physical interface. Similar to an IPv4 loopback address, you can ping an IPv6 loopback address to test the configuration of TCP/IP on the local host. The IPv6 loopback address is all-0s except for the last bit, represented as ::1/128 or just ::1 in the compressed format.

Types of IPv6 Addresses
IPv6 Unicast Addresses (cont.)
Global Unicast
Similar to a public IPv4 address
Globally unique
Internet routable addresses
Can be configured statically or assigned dynamically
Link-local
Used to communicate with other devices on the same local link
Confined to a single link; not routable beyond the link

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48/ 8.2.3.3 IPv6 Unicast Addresses (cont.)
IPv6 Network Addresses
Types of IPv6 Addresses
An IPv6 unicast address uniquely identifies an interface on an IPv6-enabled device. A packet sent to a unicast address is received by the interface that is assigned that address. Similar to IPv4, a source IPv6 address must be a unicast address. The destination IPv6 address can be either a unicast or a multicast address.
There are six types of IPv6 unicast addresses.
Global unicast
A global unicast address is similar to a public IPv4 address. These are globally unique, Internet routable addresses. Global unicast addresses can be configured statically or assigned dynamically. There are some important differences in how a device receives its IPv6 address dynamically compared to DHCP for IPv4.
Link-local
Link-local addresses are used to communicate with other devices on the same local link. With IPv6, the term link refers to a subnet. Link-local addresses 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.

Types of IPv6 Addresses
IPv6 Unicast Addresses (cont.)
Loopback
Used by a host to send a packet to itself and cannot be assigned to a physical interface.
Ping an IPv6 loopback address to test the configuration of TCP/IP on the local host.
All-0s except for the last bit, represented as ::1/128 or just ::1.
Unspecified Address
All-0’s address represented as ::/128 or just ::
Cannot be assigned to an interface and is only used as a source address.
An unspecified address is used as a source address when the device does not yet have a permanent IPv6 address or when the source of the packet is irrelevant to the destination.

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49/ 8.2.3.3 IPv6 Unicast Addresses (cont.)
IPv6 Network Addresses
Types of IPv6 Addresses
An IPv6 link-local address 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 link-local address cannot be routed beyond the link from where the packet originated.
Unlike IPv4 link-local addresses, IPv6 link-local addresses have a significant role in various aspects of the network. The global unicast address is not a requirement; however, every IPv6-enabled network interface is required to have a link-local address.
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. IPv6-enabled hosts create an IPv6 link-local address even if the device has not been assigned a global unicast IPv6 address. This allows IPv6-enabled devices to communicate with other IPv6-enabled devices on the same subnet. This includes communication with the default gateway (router).
IPv6 link-local addresses are in the FE80::/10 range. The /10 indicates that the first 10 bits are 1111 1110 10xx xxxx. The first hextet has a range of 1111 1110 1000 0000 (FE80) to 1111 1110 1011 1111 (FEBF).
Figure 1 shows an example of communication using IPv6 link-local addresses.
Figure 2 shows the format of an IPv6 link-local address.
IPv6 link-local addresses are also used by IPv6 routing protocols to exchange messages and as the next-hop address in the IPv6 routing table. Link-local addresses are discussed in more detail in a later course.
Note: Typically, it is the link-local address of the router and not the global unicast address that is used as the default gateway for other devices on the link.

Unspecified address
An unspecified address is an all-0s address represented in the compressed format as ::/128 or just :: in the compressed format. It cannot be assigned to an interface and is only used as a source address in an IPv6 packet. An unspecified address is used as a source address when the device does not yet have a permanent IPv6 address or when the source of the packet is irrelevant to the destination.
Unique local
IPv6 unique local addresses have some similarity to RFC 1918 private addresses for IPv4, but there are significant differences as well. Unique local addresses are used for local addressing within a site or between a limited number of sites. These addresses should not be routable in the global IPv6. Unique local addresses are in the range of FC00::/7 to FDFF::/7.
With IPv4, private addresses are combined with NAT/PAT to provide a many-to-one translation of private-to-public addresses. This is done because of the limited availability of IPv4 address space. Many sites also use the private nature of RFC 1918 addresses to help secure or hide their network from potential security risks. However, this was never the intended use of these technologies and the IETF has always recommended that sites take the proper security precautions on their Internet facing router. Although, IPv6 does provide for site specific addressing, it is not intended to be used to help hide internal IPv6-enabled devices from the IPv6 Internet. IETF recommends that limiting access to devices should be accomplished using proper, best-practice security measures.
Note: The original IPv6 specification defined site-local addresses for a similar purpose, using the prefix range FEC0::/10. There were several ambiguities in the specification and site-local addresses were deprecated by the IETF in favor of unique local addresses.
IPv4 embedded
The last type of unicast address type is the IPv4 embedded address. These addresses are used to help transition from IPv4 to IPv6. IPv4 embedded addresses are beyond the scope of this course.

Types of IPv6 Addresses
IPv6 Unicast Addresses (cont.)
Unique Local
Similar to private addresses for IPv4.
Used for local addressing within a site or between a limited number of sites.
In the range of FC00::/7 to FDFF::/7.
IPv4 Embedded (not covered in this course)
Used to help transition from IPv4 to IPv6.

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50/ 8.2.3.3 IPv6 Unicast Addresses (cont.)

Types of IPv6 Addresses
IPv6 Link-Local Unicast Addresses
Every IPv6-enabled network interface is REQUIRED to have a link-local address
Enables a device to communicate with other IPv6-enabled devices on the same link and only on that link (subnet)
FE80::/10 range, first 10 bits are 1111 1110 10xx xxxx
1111 1110 1000 0000 (FE80) – 1111 1110 1011 1111 (FEBF)
Add a header

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51/ 8.2.3.4 IPv6 Link-Local Unicast Addresses
IPv6 Network Addresses
Types of IPv6 Addresses
An IPv6 link-local address 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 link-local address cannot be routed beyond the link from where the packet originated.
Unlike IPv4 link-local addresses, IPv6 link-local addresses have a significant role in various aspects of the network. The global unicast address is not a requirement; however, every IPv6-enabled network interface is required to have a link-local address.
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. IPv6-enabled hosts create an IPv6 link-local address even if the device has not been assigned a global unicast IPv6 address. This allows IPv6-enabled devices to communicate with other IPv6-enabled devices on the same subnet. This includes communication with the default gateway (router).
IPv6 link-local addresses are in the FE80::/10 range. The /10 indicates that the first 10 bits are 1111 1110 10xx xxxx. The first hextet has a range of 1111 1110 1000 0000 (FE80) to 1111 1110 1011 1111 (FEBF).
Figure 1 shows an example of communication using IPv6 link-local addresses.
Figure 2 shows the format of an IPv6 link-local address.
IPv6 link-local addresses are also used by IPv6 routing protocols to exchange messages and as the next-hop address in the IPv6 routing table. Link-local addresses are discussed in more detail in a later course.
Note: Typically, it is the link-local address of the router and not the global unicast address that is used as the default gateway for other devices on the link.

Types of IPv6 Addresses
IPv6 Link-Local Unicast Addresses (cont.)
Packets with a source or destination link-local address cannot be routed beyond the link from where the packet originated.

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8.2.3.4 IPv6 Link-Local Unicast Addresses

IPv6 Unicast Addresses
Structure of an IPv6 Global Unicast Address
IPv6 global unicast addresses are globally unique and routable on the IPv6 Internet
Equivalent to public IPv4 addresses
ICANN allocates IPv6 address blocks to the five RIRs

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53/ 8.2.4.1 Structure of an IPv6 Global Unicast Address
IPv6 Network Addresses
IPv6 Unicast Addresses
IPv6 global unicast addresses are globally unique and routable on the IPv6 Internet. These addresses are equivalent to public IPv4 addresses. The Internet Committee for Assigned Names and Numbers (ICANN), the operator for Internet Assigned Numbers Authority (IANA), allocates IPv6 address blocks to the five RIRs. Currently, only global unicast addresses with the first three bits of 001 or 2000::/3 are being assigned. This is only 1/8th of the total available IPv6 address space, excluding only a very small portion for other types of unicast and multicast addresses.
Note: The 2001:0DB8::/32 address has been reserved for documentation purposes, including use in examples.

IPv6 Unicast Addresses
Structure of an IPv6 Global Unicast Address (cont.)
Currently, only global unicast addresses with the first three bits of 001 or 2000::/3 are being assigned

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54/ 8.2.4.1 Structure of an IPv6 Global Unicast Address (cont.)
Figure 1 shows the structure and range of a global unicast address.
A global unicast address has three parts:
Global routing prefix
Subnet ID
Interface ID
Global Routing Prefix
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. Currently, RIRs assign a /48 global routing prefix to customers. This includes everyone from enterprise business networks to individual households. This is more than enough address space for most customers.
Figure 2 shows the structure of a global unicast address using a /48 global routing prefix. /48 prefixes are the most common global routing prefixes assigned and will be used in most of the examples throughout this course.
For example, the IPv6 address 2001:0DB8:ACAD::/48 has a prefix that indicates that the first 48 bits (3 hextets) (2001:0DB8:ACAD) is the prefix or network portion of the address. The double colon (::) prior to the /48 prefix length means the rest of the address contains all 0s.
Subnet ID
The Subnet ID is used by an organization to identify subnets within its site.
Interface ID
The IPv6 Interface ID is equivalent to the host portion of an IPv4 address. The term Interface ID is used because a single host may have multiple interfaces, each having one or more IPv6 addresses.
Note: Unlike IPv4, in IPv6, the all-0s and all-1s host addresses can be assigned to a device. The all-1s address can be used due to the fact that broadcast addresses are not used within IPv6. The all-0s address can also be used but is reserved as a Subnet-Router anycast address, and should be assigned only to routers.
An easy way to read most IPv6 addresses is to count the number of hextets. As shown in Figure 3, in a /64 global unicast address the first four hextets are for the network portion of the address, with the fourth hextet indicating the Subnet ID. The remaining four hextets are for the Interface ID.

IPv6 Unicast Addresses
Structure of an IPv6 Global Unicast Address (cont.)
A global unicast address has three parts: Global Routing Prefix, Subnet ID, and Interface ID.

Global Routing Prefix is the prefix or network portion of the address assigned by the provider, such as an ISP, to a customer or site, currently, RIR’s assign a /48 global routing prefix to customers.
2001:0DB8:ACAD::/48 has a prefix that indicates that the first 48 bits (2001:0DB8:ACAD) is the prefix or network portion.

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55/ 8.2.4.1 Structure of an IPv6 Global Unicast Address (cont.)

IPv6 Unicast Addresses
Structure of an IPv6 Global Unicast Address (cont.)
Subnet ID is used by an organization to identify subnets within its site
Interface ID
Equivalent to the host portion of an IPv4 address.
Used because a single host may have multiple interfaces, each having one or more IPv6 addresses.

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56/ 8.2.4.1 Structure of an IPv6 Global Unicast Address

IPv6 Unicast Addresses
Static Configuration of a Global Unicast Address

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57/ 8.2.4.2 Static Configuration of a Global Unicast Address
IPv6 Network Addresses
IPv6 Unicast Addresses
Router Configuration
Most IPv6 configuration and verification commands in the Cisco IOS are similar to their IPv4 counterparts. In many cases the only difference is the use of ipv6 in place of ip within the commands.
The command to configure an IPv6 global unicast address on an interface is ipv6 address ipv6-address/prefix-length.
Notice that there is not a space between ipv6-address and prefix-length.
The example configuration will use the topology shown in Figure 1 and these IPv6 subnets:
2001:0DB8:ACAD:0001:/64 (or 2001:DB8:ACAD:1::/64)
2001:0DB8:ACAD:0002:/64 (or 2001:DB8:ACAD:2::/64)
2001:0DB8:ACAD:0003:/64 (or 2001:DB8:ACAD:3::/64)
As shown in Figure 2, the commands required to configure the IPv6 global unicast address on the GigabitEthernet 0/0 interface of R1 would be:
Router(config)#interface GigabitEthernet 0/0
Router(config-if)#ipv6 address 2001:db8:acad:1::1/64
Router(config-if)#no shutdown
Host Configuration
Manually configuring the IPv6 address on a host is similar to configuring an IPv4 address.
As shown in Figure 3, the default gateway address configured for PC1 is 2001:DB8:ACAD:1::1. This is the global unicast address of the R1 GigabitEthernet interface on the same network. Alternatively, the default gateway address can be configured to match the link-local address of the GigabitEthernet interface. Either configuration will work.
Note: When DHCPv6 or SLAAC is used, the link-local address will automatically be specified as the default gateway address.
Use the Syntax Checker in Figure 4 to configure the IPv6 global unicast address.
Just as with IPv4, configuring static addresses on clients does not scale to larger environments. For this reason, most network administrators in an IPv6 network will enable dynamic assignment of IPv6 addresses.
There are two ways in which a device can obtain an IPv6 global unicast address automatically:
Stateless Address Autoconfiguration (SLAAC)
DHCPv6

IPv6 Unicast Addresses
Static Configuration of an IPv6 Global Unicast Address (cont.)

Windows IPv6 Setup

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58/ 8.2.4.2 Static Configuration of an IPv6 Global Unicast Address (cont.)

IPv6 Unicast Addresses
Dynamic Configuration of a Global Unicast Address using SLAAC
Stateless Address Autoconfiguraton (SLAAC)
A method that allows a device to obtain its prefix, prefix length and default gateway from an IPv6 router
No DHCPv6 server needed
Rely on ICMPv6 Router Advertisement (RA) messages

IPv6 routers
Forwards IPv6 packets between networks
Can be configured with static routes or a dynamic IPv6 routing protocol
Sends ICMPv6 RA messages

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59/ 8.2.4.3 Dynamic Configuration of a Global Unicast Address using SLAAC
IPv6 Network Addresses
IPv6 Unicast Addresses
Stateless Address Autoconfiguration (SLAAC)
Stateless Address Autoconfiguration (SLAAC) is a method that allows a device to obtain its prefix, prefix length, and default gateway address information from an IPv6 router without the use of a DHCPv6 server. Using SLAAC, devices rely on the local router’s ICMPv6 Router Advertisement (RA) messages to obtain the necessary information.
IPv6 routers periodically send out ICMPv6 Router Advertisement (RA) messages to all IPv6-enabled devices on the network. By default, Cisco routers send out RA messages every 200 seconds to the IPv6 all-nodes multicast group address. An IPv6 device on the network does not have to wait for these periodic RA messages. A device can send a Router Solicitation (RS) message to the router, using the IPv6 all-routers multicast group address. When an IPv6 router receives an RS message it will immediately respond with a router advertisement.
Even though an interface on a Cisco router can be configured with an IPv6 address, this does not make it an “IPv6 router”. An IPv6 router is a router that:
Forwards IPv6 packets between networks
Can be configured with static IPv6 routes or a dynamic IPv6 routing protocol
Sends ICMPv6 RA messages
IPv6 routing is not enabled by default. To enable a router as an IPv6 router, the ipv6 unicast-routing global configuration command must be used.
Note: Cisco routers are enabled as IPv4 routers by default.
The ICMPv6 RA message contains the prefix, prefix length, and other information for the IPv6 device. The RA message also informs the IPv6 device how to obtain its addressing information. The RA message can contain one of the following three options, as shown in the figure:
Option 1 – SLAAC Only – The device should use the prefix, prefix-length, and default gateway address information contained in the RA message. No other information is available from a DHCPv6 server.
Option 2 – SLAAC and DHCPv6 – The device should use the prefix, prefix-length, and default gateway address information in the RA message. There is other information available from a DHCPv6 server such as the DNS server address. The device will, through the normal process of discovering and querying a DHCPv6 server, obtain this additional information. This is known as stateless DHCPv6 because the DHCPv6 server does not need to allocate or keep track of any IPv6 address assignments, but only provide additional information such as the DNS server address.
Option 3 – DHCPv6 only – The device should not use the information in this RA message for its addressing information. Instead, the device will use the normal process of discovering and querying a DHCPv6 server to obtain all of its addressing information. This includes an IPv6 global unicast address, prefix length, a default gateway address, and the addresses of DNS servers. In this case, the DHCPv6 server is acting as a stateful DHCP server similar to DHCP for IPv4. The DHCPv6 server allocates and keeps track of IPv6 addresses so it does not assign the same IPv6 address to multiple devices.
Routers send ICMPv6 RA messages using the link-local address as the source IPv6 address. Devices using SLAAC use the router’s link-local address as their default gateway address.

IPv6 Unicast Addresses
Dynamic Configuration of a Global Unicast Address using SLAAC (cont.)
The IPv6 unicast-routing command enables IPv6 routing.
RA message can contain one of the following three options:
SLAAC Only – Uses the information contained in the RA message.
SLAAC and DHCPv6 – Uses the information contained in the RA message and get other information from the DHCPv6 server, stateless DHCPv6 (for example, DNS).
DHCPv6 only – The device should not use the information in the RA, stateful DHCPv6.
Routers send ICMPv6 RA messages using the link-local address as the source IPv6 address

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8.2.4.3 Dynamic Configuration of a Global Unicast Address using SLAAC (cont.)

IPv6 Unicast Addresses
Dynamic Configuration of a Global Unicast Address using SLAAC (cont.)

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8.2.4.3 Dynamic Configuration of a Global Unicast Address using SLAAC (cont.)

IPv6 Unicast Addresses
Dynamic Configuration of a Global Unicast Address using DHCPv6 (cont.)
Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
Similar to IPv4
Automatically receives addressing information, including a global unicast address, prefix length, default gateway address and the addresses of DNS servers using the services of a DHCPv6 server.
Device may receive all or some of its IPv6 addressing information from a DHCPv6 server depending upon whether option 2 (SLAAC and DHCPv6) or option 3 (DHCPv6 only) is specified in the ICMPv6 RA message.
Host may choose to ignore whatever is in the router’s RA message and obtain its IPv6 address and other information directly from a DHCPv6 server.

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8.2.4.4 Dynamic Configuration of a Global Unicast Address using DHCPv6 (cont.)

IPv6 Unicast Addresses
Dynamic Configuration of a Global Unicast Address using DHCPv6 (cont.)

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63/ 8.2.4.4 Dynamic Configuration of a Global Unicast Address using DHCPv6 (cont.)
IPv6 Network Addresses
IPv6 Unicast Addresses
DHCPv6
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) is similar to DHCP for IPv4. A device can automatically receive its addressing information including a global unicast address, prefix length, default gateway address and the addresses of DNS servers using the services of a DHCPv6 server.
A device may receive all or some of its IPv6 addressing information from a DHCPv6 server depending upon whether option 2 (SLAAC and DHCPv6) or option 3 (DHCPv6 only) is specified in the ICMPv6 RA message. Additionally, the host OS may choose to ignore whatever is in the router’s RA message and obtain its IPv6 address and other information directly from a DHCPv6 server.
Before deploying IPv6 devices in a network it is a good idea to first verify whether the host observes the options within the router’s ICMPv6 RA message.
A device may obtain its IPv6 global unicast address dynamically and also be configured with multiple static IPv6 addresses on the same interface. IPv6 allows for multiple IPv6 addresses, belonging to the same IPv6 network, to be configured on the same interface.
A device may also be configured with more than one default gateway IPv6 address. For further information about how the decision is made regarding which address is used as a source IPv6 address or which default gateway address is used, refer to RFC 6724, Default Address Selection for IPv6.
The Interface ID
If the client does not use the information contained within the RA message and relies solely on DHCPv6, then the DHCPv6 server will provide the entire IPv6 global unicast address, including the prefix and the Interface ID.
However, if option 1 (SLAAC only) or option 2 (SLAAC with DHCPv6) is used, the client does not obtain the actual Interface ID portion of the address from this processes. The client device must determine its own 64-bit Interface ID, either by using the EUI-64 process or by generating a random 64-bit number.

IPv6 Unicast Addresses
EUI-64 Process or Randomly Generated
EUI- Extended Unique Identifier
EUI-64 Process
Uses a client’s 48-bit Ethernet MAC address and inserts another 16 bits in the middle of the 48-bit MAC address to create a 64-bit Interface ID.
Advantage is that the Ethernet MAC address can be used to determine the interface; is easily tracked.

EUI-64 Interface ID is represented in binary and comprises three parts:
24-bit OUI from the client MAC address, but the 7th bit (the Universally/Locally bit) is reversed (0 becomes a 1).
Inserted as a 16-bit value FFFE.
24-bit device identifier from the client MAC address.
OUI- Organizationally Unique Identifier

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64/ 8.2.4.5 EUI-64 Process or Randomly Generated
IPv6 Network Addresses
IPv6 Unicast Addresses
EUI-64 Process
IEEE defined the Extended Unique Identifier (EUI) or modified EUI-64 process. This process uses a client’s 48-bit Ethernet MAC address, and inserts another 16 bits in the middle of the 48-bit MAC address to create a 64-bit Interface ID.
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.
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
The EUI-64 process is illustrated in Figure 1, using R1’s GigabitEthernet MAC address of FC99:4775:CEE0.
Step 1: Divide the MAC address between the OUI and device identifier.
Step 2: Insert the hexadecimal value FFFE, which in binary is: 1111 1111 1111 1110.
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.
The result is an EUI-64 generated Interface ID of FE99:47FF:FE75:CEE0.
Note: The use of the U/L bit and the reasons for reversing its value are discussed in RFC 5342.
The advantage of EUI-64 is the Ethernet MAC address can be used to determine the Interface ID. It also allows network administrators to easily track an IPv6 address to an end-device using the unique MAC address. However, this has caused privacy concerns among many users. They are concerned that their packets can be traced to the actual physical computer. Due to these concerns, a randomly generated Interface ID may be used instead.
Randomly Generated Interface IDs
Depending upon the operating system, a device may use a randomly generated Interface ID instead of using the MAC address and the EUI-64 process. For example, beginning with Windows Vista, Windows uses a randomly generated Interface ID instead of one created with EUI-64. Windows XP and previous Windows operating systems used EUI-64.
An easy way to identify that an address was more than likely created using EUI-64 is the FFFE located in the middle of the Interface ID, as shown in Figure 2.
After the Interface ID is established, either through the EUI-64 process or through random generation, it can be combined with an IPv6 prefix to create a global unicast address or a link-local address:
Global unicast address – When using SLAAC, the device receives its prefix from the ICMPv6 RA and combines it with the Interface ID.
Link-local address – A link-local prefix begins with FE80::/10. A device typically uses FE80::/64 as the prefix/prefix-length, followed by the Interface ID.

IPv6 Unicast Addresses
EUI-64 Process or Randomly Generated (cont.)

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8.2.4.5 EUI-64 Process or Randomly Generated

IPv6 Unicast Addresses
EUI-64 Process or Randomly Generated (cont.)

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8.2.4.5 EUI-64 Process or Randomly Generated (cont.)

IPv6 Unicast Addresses
EUI-64 Process or Randomly Generated (cont.)
Randomly Generated Interface IDs
Depending upon the operating system, a device can use a randomly generated Interface ID instead of using the MAC address and the EUI-64 process.
Beginning with Windows Vista, Windows uses a randomly generated Interface ID instead of one created with EUI-64.
Windows XP (and previous Windows operating systems) used EUI-64.

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8.2.4.5 EUI-64 Process or Randomly Generated (cont.)

IPv6 Unicast Addresses
Dynamic Link-local Addresses
Link-Local Address
After a global unicast address is assigned to an interface, an IPv6-enabled device automatically generates its link-local address.
Must have a link-local address that enables a device to communicate with other IPv6-enabled devices on the same subnet.
Uses the link-local address of the local router for its default gateway IPv6 address.
Routers exchange dynamic routing protocol messages using link-local addresses.
Routers’ routing tables use the link-local address to identify the next-hop router when forwarding IPv6 packets.

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68/ 8.2.4.6 Dynamic Link-local Addresses
IPv6 Network Addresses
IPv6 Unicast Addresses
When using SLAAC (SLAAC only or SLAAC with DHCPV6), a device receives its prefix and prefix length from the ICMPv6 RA. Because the prefix of the address has been designated by the RA message, the device must provide only the Interface ID portion of its address. As stated previously, the Interface ID can be automatically generated using the EUI-64 process, or depending on the OS, randomly generated. Using the information from the RA message and the Interface ID, the device can establish its global unicast address.
After a global unicast address is assigned to an interface, the IPv6-enabled device will automatically generate its link-local address. IPv6-enabled devices must have, at a minimum, the link-local address. Recall that an IPv6 link-local address enables a device to communicate with other IPv6-enabled devices on the same subnet.
IPv6 link-local addresses are used for a variety of purposes including:
A host uses the link-local address of the local router for its default gateway IPv6 address.
Routers exchange dynamic routing protocol messages using link-local addresses.
Routers’ routing tables use the link-local address to identify the next-hop router when forwarding IPv6 packets.
A link-local address can be established dynamically or configured manually as a static link-local address.
Dynamically Assigned Link-Local Address
The link-local address is dynamically created using the FE80::/10 prefix and the Interface ID.
By default, Cisco IOS routers use EUI-64 to generate the Interface ID for all link-local address on IPv6 interfaces. For serial interfaces, the router will use the MAC address of an Ethernet interface. Recall that a link-local address must be unique only on that link or network. However, a drawback to using the dynamically assigned link-local address is its length, which makes it challenging to identify and remember assigned addresses.

IPv6 Unicast Addresses
Dynamic Link-local Addresses (cont.)

Dynamically Assigned

The link-local address is dynamically created using the FE80::/10 prefix and the Interface ID.

IPv6 Unicast Addresses
Static Link-local Addresses

Configuring Link-local

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70/ 8.2.4.7 Static Link-local Addresses
IPv6 Network Addresses
IPv6 Unicast Addresses
Static Link-Local Address
Configuring the link-local address manually provides the ability to create an address that is recognizable and easier to remember.
Link-local addresses can be configured manually using the same interface command used to create IPv6 global unicast addresses but with an additional parameter:
Router(config-if)#ipv6 address link-local-address link-local
Figure 1 shows that a link-local address has a prefix within the range FE80 to FEBF. When an address begins with this hextet (16-bit segment) the link-local parameter must follow the address.
Figure 2 shows the configuration of a link-local address using the ipv6 address interface command. The link-local address FE80::1 is used to make it easily recognizable as belonging to router R1. The same IPv6 link-local address is configured on all of R1’s interfaces. FE80::1 can be configured on each link because it only has to be unique on that link.
Similar to R1, router R2 would be configured with FE80::2 as the IPv6 link-local address on all of its interfaces.

IPv6 Unicast Addresses
Static Link-local Addresses (cont.)

Configuring Link-local

IPv6 Global Unicast Addresses
Verifying IPv6 Address Configuration

Each interface has two IPv6 addresses –

global unicast address that was configured
one that begins with FE80 is automatically added as a link-local unicast address

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72/ 8.2.4.8 Verifying IPv6 Address Configuration
IPv6 Network Addresses
IPv6 Unicast Addresses
As shown in Figure 1, the command to verify the IPv6 interface configuration is similar to the command used for IPv4.
The show interface command displays the MAC address of the Ethernet interfaces. EUI-64 uses this MAC address to generate the Interface ID for the link-local address. Additionally, the show ipv6 interface brief command displays abbreviated output for each of the interfaces. The [up/up] output on the same line as the interface indicates the Layer 1/Layer 2 interface state. This is the same as the Status and Protocol columns in the equivalent IPv4 command.
Notice that each interface has two IPv6 addresses. The second address for each interface is the global unicast address that was configured. The first address, the one that begins with FE80, is the link-local unicast address for the interface. Recall that the link-local address is automatically added to the interface when a global unicast address is assigned.
Also, notice that R1’s Serial 0/0/0 link-local address is the same as its GigabitEthernet 0/0 interface. Serial interfaces do not have an Ethernet MAC addresses so Cisco IOS uses the MAC address of the first available Ethernet interface. This is possible because link-local interfaces only have to be unique on that link.
The link-local address of the router interface is typically the default gateway address for devices on that link or network.
As shown in Figure 2, the 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. The show ipv6 route command will only display IPv6 networks, not IPv4 networks.
Within the route table, a C next to a route indicates that this is a directly connected network. When the router interface is configured with a global unicast address and is in the “up/up” state, the IPv6 prefix and prefix length is added to the IPv6 routing table as a connected route.
The IPv6 global unicast address configured on the interface is also installed in the routing table as a local route. The local route has a /128 prefix. Local routes are used by the routing table to efficiently process packets with a destination address of the router’s interface address.
The ping command for IPv6 is identical to the command used with IPv4, except that an IPv6 address is used. As shown in Figure 3, the command is used to verify Layer 3 connectivity between R1 and PC1. When pinging a link-local address from a router, Cisco IOS will prompt the user for the exit interface. Because the destination link-local address can be on one or more of its links or networks, the router needs to know which interface to send the ping.
Use the Syntax Checker in Figure 4 to verify IPv6 address configuration.

IPv6 Global Unicast Addresses
Verifying IPv6 Address Configuration (cont.)

IPv6 Multicast Addresses
Assigned IPv6 Multicast Addresses
IPv6 multicast addresses have the prefix FF00::/8
There are two types of IPv6 multicast addresses:
Assigned multicast
Solicited node multicast

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74/ 8.2.5.1 Assigned IPv6 Multicast Addresses
IPv6 Network Addresses
IPv6 Multicast Addresses
IPv6 multicast addresses are similar to IPv4 multicast addresses. Recall that a multicast address is used to send a single packet to one or more destinations (multicast group). IPv6 multicast addresses have the prefix FF00::/8.
Note: Multicast addresses can only be destination addresses and not source addresses.
There are two types of IPv6 multicast addresses:
Assigned multicast
Solicited node multicast
Assigned Multicast
Assigned multicast addresses are reserved multicast addresses for predefined groups of devices. An assigned multicast address is a single address used to reach a group of devices running a common protocol or service. Assigned multicast addresses are used in context with specific protocols such as DHCPv6.
Two common IPv6 assigned multicast groups include:
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 Internet Control Message Protocol version 6 (ICMPv6) RA messages to the all-node multicast group. The RA message informs all IPv6-enabled devices on the network about addressing information, such as the prefix, prefix length, and default gateway.
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.
IPv6-enabled devices send ICMPv6 Router Solicitation (RS) messages to the all-routers multicast address. The RS message requests an RA message from the IPv6 router to assist the device in its address configuration.

IPv6 Multicast Addresses
Assigned IPv6 Multicast Addresses (cont.)
Two common IPv6 assigned multicast groups include:
FF02::1 All-nodes multicast group –
All IPv6-enabled devices join
Same effect as an IPv4 broadcast address
FF02::2 All-routers multicast group
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 mode command.
A packet sent to this group is received and processed by all IPv6 routers on the link or network.

IPv6 Multicast Addresses
Assigned IPv6 Multicast Addresses (cont.)

IPv6 Multicast Addresses
Solicited Node IPv6 Multicast Addresses
Similar to the all-nodes multicast address, matches only the last 24 bits of the IPv6 global unicast address of a device
Automatically created when the global unicast or link-local unicast addresses are assigned
Created by combining a special FF02:0:0:0:0:0:FF00::/104 prefix with the right-most 24 bits of its unicast address

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77/ 8.2.5.2 Solicited Node IPv6 Multicast Addresses
IPv6 Network Addresses
IPv6 Multicast Addresses
A solicited-node multicast is similar to the all-nodes multicast address. Recall that the all-nodes multicast address is essentially the same thing as an IPv4 broadcast. All devices on the network must process traffic sent to the all-nodes address. To reduce the number of devices that must process traffic, use a solicited-node multicast address.
A solicited-node multicast address is an address that matches only the last 24 bits of the IPv6 global unicast address of a device. The only devices that need to process these packets are those devices that have these same 24 bits in the least significant, far right portion of their Interface ID.
An IPv6 solicited-node multicast address is automatically created when the global unicast or link-local unicast addresses are assigned. The IPv6 solicited-node multicast address is created by combining a special FF02:0:0:0:0:1:FF00::/104 prefix with the far right 24 bits of its unicast address.
The solicited-node multicast address consists of two parts:
FF02:0:0:0:0:1:FF00::/104 multicast prefix – This is the first 104 bits of the all solicited-node multicast address.
Least significant 24-bits – These are the last or far right 24 bits of the solicited-node multicast address. These bits are copied from the far right 24 bits of the global unicast or link-local unicast address of the device.
Note: Only 104 bits are taken from the special solicited node prefix. The last byte (00) is not used when creating the solicited node address. It is necessary to include the 00 when referring to the solicited node prefix because the compressed address of ff02:0:0:0:0:1:ff/104 is expanded to ff02:0000:0000:0000:0000:0001:00ff/104, which is not the correct prefix.
It is possible that multiple devices will have the same solicited-node multicast address. Although rare, this can occur when devices have the same far right 24 bits in their Interface IDs. This does not create any problems because the device will still process the encapsulated message, which will include the complete IPv6 address of the device in question.

IPv6 Multicast Addresses
Solicited Node IPv6 Multicast Addresses (cont.)
The solicited node multicast address consists of two parts:
FF02:0:0:0:0:0:FF00::/104 multicast prefix – First 104 bits of the all solicited node multicast address
Least significant 24-bits – Copied from the right-most 24 bits of the global unicast or link-local unicast address of the device

9.3 Design Considerations for IPv6

Subnetting an IPv6 Network
Subnetting Using the Subnet ID
An IPv6 Network Space is subnetted to support hierarchical, logical design of the network

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9.3.1.1 Subnetting Using the Subnet ID
Design Considerations for IPv6
Subnetting an IPv6 Network
IPv6 subnetting requires a different approach than IPv4 subnetting. The primary reason is that with IPv6 there are so many addresses, that the reason for subnetting is completely different. An IPv6 address space is not subnetted to conserve addresses; rather, it is subnetted to support hierarchical, logical design of the network. While IPv4 subnetting is about managing address scarcity, IPv6 subnetting is about building an addressing hierarchy based on the number of routers and the networks they support.
Recall that an IPv6 address block with a /48 prefix has 16 bits for subnet ID, as shown in Figure 1. Subnetting using the 16 bit subnet ID yields a possible 65,536 /64 subnets and does not require borrowing any bits from the interface ID, or host portion of the address. Each IPv6 /64 subnet contains roughly eighteen quintillion addresses, obviously more than will ever be needed in one IP network segment.
Subnets created from the subnet ID are easy to represent because there is no conversion to binary required. To determine the next available subnet, just count up in hexadecimal. As shown in Figure 2, this means counting by hexadecimal in the subnet ID portion.
The global routing prefix is the same for all subnets. Only the subnet ID quartet is incremented for each subnet.

Subnetting an IPv6 Network
IPV6 Subnet Allocation: Figure 1

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9.3.1.2 IPv6 Subnet Allocation
Design Considerations for IPv6
Subnetting an IPv6 Network
With over 65,000 subnets to choose from, the task of the network administrator becomes one of designing a logical scheme to address the network.
As shown in Figure 1, the example topology will require subnets for each LAN as well as for the WAN link between R1 and R2. Unlike the example for IPv4, with IPv6 the WAN link subnet will not be subnetted further. Although this may “waste” addresses, that is not a concern when using IPv6.
As shown in Figure 2, the allocation of 5 IPv6 subnets, with the subnet ID field 0001 through 0005 will be used for this example. Each /64 subnet will provide more addresses than will ever be needed.
As shown in Figure 3, each LAN segment and the WAN link is assigned a /64 subnet.
Similar to configuring IPv4, Figure 4 shows that each of the router interfaces has been configured to be on a different IPv6 subnet.

Subnetting an IPv6 Network
Subnetting into the Interface ID: Figure 2
IPv6 bits can be borrowed from the interface ID to create additional IPv6 subnets.

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9.3.1.3 Subnetting into the Interface ID
Design Considerations for IPv6
Subnetting an IPv6 Network
Similar to borrowing bits from the host portion of an IPv4 address, with IPv6 bits can be borrowed from the interface ID to create additional IPv6 subnets. This is typically done for security reasons to create fewer hosts per subnet and not necessarily to create additional subnets.
When extending the subnet ID by borrowing bits from the interface ID, the best practice is to subnet on a nibble boundary. A nibble is 4 bits or one hexadecimal digit. As shown in the figure, the /64 subnet prefix is extended 4 bits or 1 nibble to /68. Doing this reduces the size of the interface ID by 4 bits, from 64 to 60 bits.
Subnetting on nibble boundaries means only using nibble aligned subnet masks. Starting at /64, the nibble aligned subnet masks are /68, /72, /76, /80, etc.
Subnetting on a nibble boundary creates subnets by using the additional hexadecimal value. In the example, the new subnet ID consists of the 5 hexadecimal values, ranging from 00000 through FFFFF.
It is possible to subnet within a nibble boundary, within a hexadecimal digit, but it is not recommended or even necessary. Subnetting within a nibble takes away the advantage easily determining the prefix from the interface ID. For example, if a /66 prefix length is used, the first two bits would be part of the subnet ID and the second two bits would be part of the interface ID.

IP Addressing
Summary
The depletion of IPv4 address space is the motivating factor for moving to IPv6.
Each IPv6 address has 128 bits verses the 32 bits in an IPv4 address.
The prefix length is used to indicate the network portion of an IPv6 address using the following format: IPv6 address/prefix length.
There are three types of IPv6 addresses: unicast, multicast, and anycast.
An IPv6 link-local address 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 link-local address cannot be routed beyond the link from where the packet originated.
IPv6 link-local addresses are in the FE80::/10 range.
ICMP is available for both IPv4 and IPv6.

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90/ Summary
Summary
Summary
IP addresses are hierarchical with network, subnetwork, and host portions. An IP address can represent a complete network, a specific host, or the broadcast address of the network.
Understanding binary notation is important when determining if two hosts are in the same network. The bits within the network portion of the IP address must be identical for all devices that reside in the same network. The subnet mask or prefix is used to determine the network portion of an IP address. IP addresses can be assigned either statically or dynamically. DHCP enables the automatic assignment of addressing information such as IP address, subnet mask, default gateway, and other configuration information.
IPv4 hosts can communicate one of three different ways: unicast, broadcast, and multicast. Also, blocks of addresses that are used in networks that require limited or no Internet access are called private addresses. The private IPv4 address blocks are: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
The depletion of IPv4 address space is the motivating factor for moving to IPv6. Each IPv6 address has 128 bits verses the 32 bits in an IPv4 address. IPv6 does not use the dotted-decimal subnet mask notation. The prefix length is used to indicate the network portion of an IPv6 address using the following format: IPv6 address/prefix length.
There are three types of IPv6 addresses: unicast, multicast, and anycast. An IPv6 link-local address 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 link-local address cannot be routed beyond the link from where the packet originated. IPv6 link-local addresses are in the FE80::/10 range.
ICMP is available for both IPv4 and IPv6. ICMPv4 is the messaging protocol for IPv4. ICMPv6 provides the same services for IPv6 but includes additional functionality.
After it is implemented, an IP network needs to be tested to verify its connectivity and operational performance.

IP Addressing
Summary (cont.)
IPv6 address space is subnetted to support the hierarchical, logical design of the network.
Size, location, use, and access requirements are all considerations in the address planning process

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Summary
Summary
The Internet of Everything…Naturally!
In this chapter, you learned about how small to medium-sized businesses are connected to networks in groups. The Internet of Everything was also introduced in the beginning modeling activity.
For this activity, choose one of the following:
Online banking
World news
Weather forecasting/climate
Traffic conditions
Devise an IPv6 addressing scheme for the area you chose. Include in your addressing scheme how you would plan for:
Subnetting
Unicasts
Multicasts
Broadcasts
Keep a copy of your scheme to share with the class or learning community. Be prepared to explain:
How subnetting, unicasts, multicasts and broadcasts would be incorporated.
Where your addressing scheme could be used.
How small to medium-size businesses would be impacted by using your plan.
Class Activity – The Internet of Everything…Naturally Instructions

IP Addressing
Reference
Chapters 7 & 8, CCNA Routing and Switching: Introduction to Networks
Available at: www.netacad.com

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89/ Summary
Summary
Summary
The Internet of Everything…Naturally!
In this chapter, you learned about how small to medium-sized businesses are connected to networks in groups. The Internet of Everything was also introduced in the beginning modeling activity.
For this activity, choose one of the following:
Online banking
World news
Weather forecasting/climate
Traffic conditions
Devise an IPv6 addressing scheme for the area you chose. Include in your addressing scheme how you would plan for:
Subnetting
Unicasts
Multicasts
Broadcasts
Keep a copy of your scheme to share with the class or learning community. Be prepared to explain:
How subnetting, unicasts, multicasts and broadcasts would be incorporated.
Where your addressing scheme could be used.
How small to medium-size businesses would be impacted by using your plan.
Class Activity – The Internet of Everything…Naturally Instructions

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