1. CIS 116 IPv6 Fundamentals 2 – Primer Rick Graziani Cabrillo College

2. Objectives In this chapter we will introduce:
Hexadecimal Number System
IPv6 Address Types
Address Terminology
ICMPv6 Neighbor Discovery Protocol (NDP or ND)
Dynamic address allocation
Everything we introduce in this chapter is also discussed in much more detail in later chapters
RFC 760 Jan 1980 obsoleted by RFC 791 Sep 1981
RFC obsoleted by RFC
Great book: Where Wizards Stay Up Late, by Katie Hafner and Paul Lyon

3. Hexadecimal Number System

4. The Beauty of Hexadecimal: 4 bits = 1 hex digit
Binary
8421
0000
0001
0010
0011
0100
0101
0110
0111
Binary
8421
1000
1001
1010
1011
1100
1101
1110
1111
Dec 1 2 3 4 5 6 7
Hex 1 2 3 4 5 6 7
Dec 8 9 10 11 12 13 14 15
Hex 8 9 A B C D E F
Any combination of 4 bits (16 possibilities) can be represented by a single hexadecimal digit

5. IPv6 Address Types

6. IPv6 Addresses Unicast Multicast Anycast Well-Known Transient
Solicited-Node
ff00::/12
ff10::/12
ff02:0:0:0:0:1:ff00::/104
Global Unicast
Link-Local
Loopback
Unspecified
Unique Local
Embedded IPv4
2000::/3
fe80::/10
::1/128
::/128
fc00::/7
::/80

7. IPv6 Source and Destination Addresses
IPv6 Source – Always a unicast
IPv6 Destination – Unicast, multicast or anycast.
IPv4
IPv6
Much more in later lessons

8. Unicast Addresses IPv6 Internet Global Unicast Address (GUA)
2000::/3 (Range 2000::/64 thru 3fff:fff:fff:fff::/64)
Globally unique, routable, similar to public IPv4 addresses
2001:DB8::/32 - RFC 2839 reserves this range of addresses for documentation
These are the addresses we will be referring to the most.
More in lesson 4

9. Unicast Addresses Link-local Unicast
FE80::/10 (First hextet: FE80::/10 to FEBF::/10)
Not routable off the link (link = network or subnet)
Unique only on the link
An IPv6 device must have at least a link-local address.
Used by:
Hosts to communicate to the IPv6 network before it has a GUA.
Router’s link-local address is used by hosts as the default gateway address.
Adjacent routers to exchange routing updates.
Next-hop addresses in IPv6 routing tables.
More in lesson 4

10. X Internet Global Unicast Addresses Globally routable
Begins with a 2 or 3
Internet X
Link-Local Addresses
Not routable
Usually begin with fe80:
Unspecified Address (::)
All 0’s address
Indicates the absence or anonymity of an IPv6 address
Only used as a source address and never forwarded by an router
Figure 2-1 – Comparison between IPv6 global unicast addresses and link-local addresses

11. Solicited-Node IPv6 Multicast Addresses
IPv6 Addresses
Multicast
Assigned
Solicited-Node
Unicast: GUA, Link-Local,…
FF00::/8
FF02::1:FF00:0000/104
In addition to every unicast address assigned to an interface, a device will also have a special multicast address known as a solicited-node multicast address.

12. Advantages of Solicited-Node Multicast
IPv4 ARP Requests
Destination MAC Address: Layer 2 Broadcast
Data must be passed by NIC to upper layer for processing – examine target IPv4 address.
Ethernet Broadcast passed to upper layer
Ethernet
ARP Message
DA: Broadcast
ARP Message with Target IPv4 Address
IPv6 Address Resolution
Destination IPv6: Solicited-Node Multicast
Destination MAC Address: Layer 2 Multicast
Ethernet Multicast filtered by the NIC
Ethernet
IPv6
ICMPv6 NS
DA: Multicast
DA: Solicited-Node Multicast
ICMPv6 NS with Target IPv6 Address
ARP Requests: Layer 2 broadcasts:
Ethernet broadcasts are sent to all devices.
Flood the entire broadcast domain (subnet/VLAN).
Ethernet NIC must process the frame.
Any filtering is done by a higher layer protocol such as ARP.
Solicited Node Multicasts: Layer 2 and Layer 3 multicasts:
Although solicited node multicasts are forwarded out all ports by the switch, ….
Layer 2 multicast allows frames to be filtered by the NIC and not have send data to an upper layer protocol for inspection.

13. ICMPv6 Neighbor Discover Protocol
ICMPv6 Neighbor Discovery defines 5 different packet types:
Router Solicitation Message
Router Advertisement Message
Used with dynamic address allocation
Neighbor Solicitation Message
Neighbor Advertisement Message
Used with address resolution (IPv4 ARP)
Redirect Message
Similar to ICMPv4 redirect message
Router-to-Device messaging
Router-Device Messaging
Device-Device Messaging
See these processes with:
R1# debug ipv6 nd

14. Dynamic IPv4 Address Allocation
I need an IPv4 addressing information from a DHCP server.
DHCP Server
DHCP Client
Here is your IPv4 address, subnet mask, default gateway and DNS server addresses.

15. All Dynamic Addressing Begins with the RA Message
Multicast: To all IPv6 routers, I need IPv6 address information
ICMPv6 Router Advertisement
ICMPv6 Router Solicitation
DHCPv6 Server
Multicast: To all IPv6 devices,
let me tell you how to do this …
I might not even be needed. 
An ICMPv6 Router Advertisement (RA) suggests to all IPv6 devices on the link how it will receive IPv6 Address Information.
Sent periodically by an IPv6 router or…
… when the router receives a Router Solicitation message from a host.

16. Router Advertisement: 3 Options
Option 1 and 2: Stateless Address Autoconfiguration
DHCPv6 Server does not maintain state of addresses
Option 3: Stateful Address Configuration
Address received from DHCPv6 Server
DHCPv6
Router(config)# ipv6 unicast-routing
DHCPv6 Server
Option 1: SLAAC – No DHCPv6 (Default on Cisco routers)
“I’m everything you need (Prefix, Prefix-length, Default Gateway)”
Option 2: SLAAC + Stateless DHCPv6 for DNS address
“Here is my information but you need to get other information such as DNS addresses from a DHCPv6 server.” (DNS can be in RA)
Option 3: All addressing except default gateway use DHCPv6
“I can’t help you. Ask a DHCPv6 server for all your information.” RA
Option 1 mostly what you need. Still need DNS server and domain name info.
Router(config-if)# ipv6 nd ra dns server 2001:DB8:1::1 600

17. ICMPv6 ND – Address Resolution
Know IPv4, what is the MAC?
My IPv4! Here is the MAC… 2 1
PC2
ARP Reply
ARP Request
PC1
ARP Cache 3 1
My IPv6! Here is the MAC… 2
Neighbor Advertisement
Neighbor Solicitation
Know IPv6, what is the MAC?
Neighbor Cache 3
IP to data link (MAC) address mapping:
IPv4 addresses use ARP
IPv6 addressing use ICMPv6 Neighbor Discovery messages
Neighbor Solicitation (via Solicited-Node)
Neighbor Advertisement
Devices store this mapping in their Neighbor Cache
ICMPv6 Neighbor Discovery
Neighbor Solicitation
Neighbor Advertisement

18. Terminology

19. Terminology 2001:DB8:CAFE:1::0001/64 Prefix Interface ID Terminology:
Prefix equivalent to the network address of an IPv4 address
Prefix length equivalent to subnet mask in IPv4
Interface ID equivalent to host portion of an IPv4 address
Node or device: An IPv6 node or device is anything that can have an IPv6 address, including traditional devices such as computers and printers, along with other types of devices such as webcams, embedded devices, and Internet of Things (IoT) devices.

20. CIS 116 IPv6 Fundamentals 2 – Primer Rick Graziani Cabrillo College