CIS 116 IPv6 Fundamentals 2 – Primer Rick Graziani Cabrillo College graziani@cabrillo.edu

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 2460 1995 obsoleted by RFC 2460 1998 Great book: Where Wizards Stay Up Late, by Katie Hafner and Paul Lyon

Hexadecimal Number System

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

IPv6 Address Types

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

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

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

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

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

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.

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.

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

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.

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.

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 http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/command/ipv6-cr-book/ipv6-i3.html#wp3800310030

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

Terminology

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.

CIS 116 IPv6 Fundamentals 2 – Primer Rick Graziani Cabrillo College graziani@cabrillo.edu