1. IPv6
Chapter 12

2. Objectives Discuss the fundamental concepts of IPv6
Describe IPv6 practices
Implement IPv6 in a TCP/IP network

3. Overview

4. IPv4 and IPv6 Internet Protocol version 4 (IPv4)
Created around 1979
32-bit IP address space ► four billion IP addresses
Allocation methods wasted addresses
Internet Protocol version 6 (IPv6)
128-bit addresses
Improved security, routing, other features
3.4 x 1038 addresses
Note (p. 347): If you really want to know how many IP addresses IPv6 provides, here’s your number: 340,282,366,920,938,463,463,374, 607,431,768,211,456.

5. Test Specific
IPv6 Basics

6. IPv6 Basics IPv6 and IPv4 differ in implementation
Addressing numbers work differently
Addressing numbers do not look alike
IPv6 always uses link-local addressing
Subnetting works differently

7. IPv6 Address Notation (1 of 3)
128 bits written in hexadecimal 2001:0000:0000:3210:0800:200c:00cf:1234
Colon separator rather than the period used in IPv4
Quartet (or hextet) groups: 0000 to ffff
Exam Tip (p. 348): You’ll see the hexadecimal letters in IPv6 written both uppercase and lowercase. It doesn’t matter to the computer, but the people behind IPv6 insist (per RFC 5952) that notation should be lowercase. That’s the convention used here. You might see the letters uppercase on the CompTIA Network+ exam. It’s all the same, so don’t get thrown off!
Note (p. 348): For those who don’t play with hex regularly, one hexadecimal character (for example, f) represents 4 bits, so four hexadecimal characters make a 16-bit group.

8. IPv6 Address Notation (2 of 3)
Leading zeros can be dropped from any group
Example: 00cf becomes cf 2001:0000:0000:3210:0800:200c:00cf:1234 becomes 2001:0:0:3210:800:200c:cf:1234
A pair of colons (::) can represent a string of consecutive groups with a value of zero
Only one double colon allowed per address
Example: 2001::3210:800:200c:cf:1234

9. IPv6 Address Notation (3 of 3)
IPv6 loopback address
::1
Represents 0000:0000:0000:0000:0000:0000:0000:0001
IPv6 uses the “/x” Classless Inter-Domain Routing (CIDR) nomenclature
Example address and subnet for a typical IPv6 host: fe80::cf:0:ba98:1234/64
Cross Check: Loopback (p. 349)
You learned about the IPv4 loopback address in Chapter 6, “TCP/IP Basics,” so check your memory as you read about the IPv6 loopback address here. What IP address or addresses could you use for a loopback address? When might you ping the loopback address? How would this differ from loopback testing discussed in Chapter 5, “Installing a Physical Network”?
Note (p. 349): The unspecified address (all zeroes) can never be used, and neither can an address that contains all ones (all fs in IPv6 notation).

10. Link-Local Address (1 of 2)
Self-generated (in manner of IPv4 APIPA)
In implementation, the first 64 bits are always fe80::/64
Interface identifier: the second 64 bits
Since Windows Vista, Windows clients have generated a 64-bit random number
Old operating systems use a device’s MAC address to create an Extended Unique Identifier (EUI-64)
Note (p. 349): Although only the fe80::/10 denotes the link-local address, according to the Request for Comments that defined link-local addressing (RFC 4291), the next 54 bits have to be zeroes. That means in implementation, a link-local address will start with fe80::/64.
Note (P.349): There’s no scenario today for EUI-64.

11. Link-Local Address (2 of 2)
Figure Link-local address in Windows

12. IPv6 Prefix Lengths (1 of 2)
Used to determine where to send packets
Local MAC address
Default gateway to send the packets out to the Internet

13. IPv6 Prefix Lengths (2 of 2)
Two rules
Last 64 bits of an IPv6 address are generated by the NIC, leaving a maximum of 64 bits for the subnet—no subnet is ever longer than /64
Five Regional Internet Registries (RIRs) pass out /48 subnets to big ISPs and end users who need large allotments
Other types of IPv6 addresses get subnet information automatically from their routers

14. The End of Broadcast IPv6 link-local address is a unicast address
Multicast has existed a long time
Multicast address: a set of reserved addresses designed to go to certain systems
In IPv4, used Class D addresses ( /4)
Only specific applications used multicast
In IPv6, several IPv6-only multicast addresses are added to get specific jobs done

15. Multicasting (1 of 3)
Multicast packets are encapsulated into Ethernet frames
Address e-xx-xx-xx are reserved for IPv4 multicast frame destination addresses
Address xx-xx-xx-xx is used on Ethernet frames encapsulating IPv6 multicast packets
Every computer sees the multicast frame
Only processed by computers set up to process the frame
Note (p.351): Here’s a bit of geeky trivia for you. Why 33-33? That’s the address of Xerox PARC (Palo Alto Research Center), the birthplace of Ethernet and many other networking technologies used today.
Note (p.351): All-Nodes multicasts are pretty much just used by routers, not typical traffic.

16. Figure 12.3 Multicast to routers
Multicasting (2 of 3)
Figure Multicast to routers

17. Multicasting (3 of 3) Table 12.1 IPv6 Multicast Addresses Address
Function
ff02::1
All Nodes Address
ff02::2
All Routers Address
ff02::1:ffxx:xxxx
Solicited-Node Address

18. Anycast Used commonly in DNS
Every DNS server keeps IP addresses of root servers in a root hints file
Anycasting gives clusters of computers the same IP address
Routers use the Border Gateway Protocol (BGP) to determine the closest computer and sends to its anycast address

19. Global Unicast Address (1 of 5)
A global unicast address is required for Internet access
An IPv6-capable gateway router passes out global IPv6 addresses
When booted, the computer sends out a router solicitation message looking for a router
The router tells the computer the prefix

20. Global Unicast Address (2 of 5)
Figure Getting a global address

21. Global Unicast Address (3 of 5)
An IPv6-capable computer boots and sends out a router solicitation message (ff02::2)
Router sends the prefix
The computer takes the prefix and adds the interface identifier or EUI-64 address
Global address results from the combination
Exam Tip (p. 352): Computers using IPv6 need a global address to access the Internet.

22. Global Unicast Address (4 of 5)
Figure IPv6 configuration on macOS

23. Global Unicast Address (5 of 5)
Figure 12.6 Enabling prefix delegation on a SOHO router
(called DHCP-PD on this router)

24. Aggregation (1 of 10) Most routers have a default path
Tier-one routers that connect to other tier-one routers cannot have any default route
Known as no-default routers
Huge routing table (750,000 routes)

25. Figure 12.7 No-default routers
Aggregation (2 of 10)
Figure No-default routers

26. Aggregation (3 of 10)
Aggregation: Every router uses a subset of the next higher router’s existing routes
Reduces size and complexity of routing tables
Gives detailed geographic picture of Internet organization
IP address indicates location
Part of IPv6

27. Aggregation (4 of 10)
Figure Aggregation

28. Aggregation (5 of 10) How aggregation works
The default gateway gives the first 64 bits of the IP address to computers
The router gets its 48-bit prefix from the upstream router
The router adds its own 16-bit subnet
Note (p. 354): Keep this formula in mind: A 48-bit prefix from upstream router + 16-bit subnet from default gateway + 64-bit unique number = 128-bit IPv6 address.
Tech Tip: Regional Internet Registries (p. 355)
The IANA doesn’t actually pass out IPv6 prefixes. This job is delegated to the five Regional Internet Registries (RIRs):
American Registry for Internet Numbers (ARIN) supports North America.
RIPE Network Coordination Centre (RIPE NCC) supports Europe, the Middle East, and Central Asia.
Asia-Pacific Network Information Centre (APNIC) supports Asia and the Pacific region.
Latin American and Caribbean Internet Addresses Registry (LACNIC) supports Central and South America and parts of the Caribbean.
African Network Information Centre (AfriNIC) supports Africa.

29. Figure 12.9 An IPv6 group of routers
Aggregation (6 of 10)
Figure An IPv6 group of routers

30. Figure 12.10 Adding the first prefix
Aggregation (7 of 10)
Figure Adding the first prefix

31. Figure 12.11 Adding the second prefix
Aggregation (8 of 10)
Figure Adding the second prefix

32. Aggregation (9 of 10) Example: change from ISP1 to ISP2
The new ISP passes out a different 32-bit prefix
Example: 2ab0:3c05/32
The downstream routers make an “all nodes” multicast ► all clients get the new IP addresses
IPv6 address changes are rare but a normal aspect of using IPv6

33. Figure 12.12 New IP address updated downstream
Aggregation (10 of 10)
Figure New IP address updated downstream

34. Using IPv6

35. It Just Works (1 of 5)
IPv6 works with almost no interference or interaction from anyone
Rarely need static IP addresses
DHCP is almost nonexistent in IPv6
Neighbor Discovery Protocol (NDP) makes the IPv6 automation work
Neighbor Solicitation/Advertisement
Exam Tip (p.357): You’ll see the term neighbor discovery in documentation about uses of the Neighbor Discovery Protocol. You’ll also see the term on the CompTIA Network+ exam.

36. It Just Works (2 of 5) Router Solicitation/Advertisement
Router advertisements create unique IDs for IPv6 networks
IPv6 relies on router advertisements instead of NAT and private network IDs
Router receives global prefix (usually 48 bits) and a unique subnet ID for the LAN (usually 16 bits)
Router sends that information to all the LAN hosts via a router advertisement

37. It Just Works (3 of 5) Is IP Working?
Check the IP status to see if IPv6 is running
ipconfig in Windows
ip addr in Linux or macOS

38. Figure 12.13 IPv6 enabled in Windows
It Just Works (4 of 5)
Figure IPv6 enabled in Windows

39. Figure 12.14 IPv6 enabled in Ubuntu
It Just Works (5 of 5)
Figure IPv6 enabled in Ubuntu

40. DHCPv6 (1 of 2) DHCPv6 works differently than in IPv4
The IP address and subnet are received from the gateway router
DHCPv6 provides other information
Two modes of DHCPv6
Stateful - works like DHCP in IPv4
Stateless - only passes out optional information
Stateless is the norm
Note (p. 359): IPv6 DHCP servers use DHCPv6. This is not the sixth version of DHCP, mind you, just the name of DHCP for IPv6.
Cross Check: DHCP with IPv4 (p. 359)
You read about the IPv4 version of DHCP in Chapter 6, so check your memory now. How does DHCP work? What does a DHCP lease do for you? What happens if your computer can’t get to a DHCP server but is configured for DHCP?
Check out the excellent pair of Sims for Chapter 12 at You’ll find both a Show! and a Click! called “IPv6 Configuration” that walk you through the process of configuring IPv6 in Windows.

41. Figure 12.15 DHCPv6 server in action
DHCPv6 (2 of 2)
Figure DHCPv6 server in action

42. DNS in IPv6 (1 of 2) Most DNS servers now support IPv6 addresses
DNS servers supporting IPv6 use AAAA records

43. Figure 12.16 IPv6 addresses on DNS server
DNS in IPv6 (2 of 2)
Figure IPv6 addresses on DNS server

44. Moving to IPv6

45. Moving to IPv6 (1 of 3) IPv4 and IPv6
Can run both IPv4 and IPv6 on your computers and routers at the same time
Parts of the Internet ready for IPv6
All root DNS servers support IPv6 resolution
Almost all tier-one ISP routers properly forward IPv6 packets
Routers and servers may not yet be IPv6-ready
Note: (p. 360): Depending on when you’re reading this chapter, you may not need a tunnel for typical Internet traffic because the gap won’t exist. Read through this next section specifically for items you’ll find on the N exam.

46. Figure 12.17 IPv4 and IPv6 on one computer
Moving to IPv6 (2 of 3)
Figure IPv4 and IPv6 on one computer

47. Moving to IPv6 (3 of 3)
Figure The IPv6 gap

48. Transition Mechanisms
IPv4-to-IPv6 tunnels bridge the gap
Encapsulate IPv6 traffic into an IPv4 tunnel to get to an IPv6-capable router
Exam Tip (p.361): You might see a now-deprecated tunneling protocol called 6to4 on the CompTIA Network+ exam. In theory, this protocol enabled IPv6 traffic over the IPv4 Internet. In practice, it proved unsuitable for widespread deployment. (See RFC 7526 for more information if you’re curious.)

49. 4to6 tunnels (1 of 2) IPv4-to-IPv6 tunnel works like any other tunnel
Encapsulate IPv4 traffic into an IPv6 tunnel to get to an IPv6-capable router
Download a tunneling client and install it on your computer
Fire up client and make the tunnel connection

50. Figure 12.19 The IPv4-to-IPv6 tunnel
4to6 tunnels (2 of 2)
Figure The IPv4-to-IPv6 tunnel

51. 6in4 Also called IPv6-in-IPv4
One of the most popular tunneling standards
One of only two tunneling protocols that can go through a NAT

52. Teredo Tunnels Teredo: second NAT-traversal IPv6 tunneling protocol
Built into Microsoft Windows
Addresses start with 2001:0::/32
Most people prefer to skip Windows built-in support
Get third-party tool that supports 6to4 or 6in4

53. Miredo Tunnels
Open-source implementation of Teredo for Linux and other UNIX-based systems

54. Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
Works within an IPv4 network
Adds IPv4 address to an IPv6 prefix for endpoints
Example address: 2001:db8::98ca:200:
Other tunneling standards have more common IPv6 addressing structure
Note (p. 362): You rarely have a choice of tunneling protocol. The tunneling protocol you use is the one your tunnel broker provides and is usually invisible to you.

55. Tunnel Brokers Someone must act as the far endpoint
Must know the tunneling standard and how to connect to the endpoint
Create the actual tunnel
Usually offer a custom-made endpoint client
May use automatic configuration protocols
Tunnel Setup Protocol (TSP)
Tunnel Information and Control protocol (TIC)
Note (p.362): The biggest tunnel broker player is Hurricane Electric, based in Fremont, California. They have a huge IPv6 global transit network, offer IPv6 certifications, and more. Check them out at

56. Overlay Tunnels (1 of 2)
Enables two IPv6 networks to connect over an existing IPv4 infrastructure, e.g., the Internet
The routers that connect the IPv6 networks to the IPv4 infrastructure:
Run dual stack—both IPv4 and IPv6
Can encapsulate the traffic from the local network into IPv4 packets

57. Overlay Tunnels (2 of 2)
Can connect an IPv4 client to an IPv6 network:
Using protocols—like 4to6, ISATAP, and others—or
By creating manual tunnels

58. NAT64
IPv6 has no need or use for classic network address translation (NAT)
NAT64 is a transition mechanism that embeds IPv4 packets into IPv6 packets for network traversal
NAT64 gateway handles traffic between the IPv4 and IPv6 segments
Does translation on-the-fly
Keeps track of who’s who on either end