1. 4: Global Unicast Addresses (GUA) Rick Graziani Cabrillo College Rick.Graziani@cabrillo.edu

2. © For more information please check out my Cisco Press book and video series: IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6 By Rick Graziani ISBN-10: 1-58714-313-5 IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6 By Rick Graziani ISBN-10: 1-58720-457-6

3. 4.1: Purpose and Format of GUA

4. © IPv6 Address Types IPv6 Addresses FF00::/8FF02::1:FF00:0000/104 ::/128::1/1282000::/3FE80::/10FC00::/7::/80 Unicast Multicast Anycast Assigned Solicited Node Global Unicast Link-Local Loopback Unspecified Unique Local Embedded IPv4 IPv6 does not have a “broadcast” address.

5. © IPv6 Source and Destination Addresses IPv6 Source – Always a unicast (link-local or GUA) IPv6 Destination – Unicast, multicast, or anycast. IPv4 IPv6

6. © Global Unicast Address Global Unicast Address (GUA) 2000::/3 (First hextet: 2000::/3 to 3FFF::/3) Globally unique and routable Similar to public IPv4 addresses 2001:DB8::/32 - RFC 2839 and RFC 6890 reserves this range of addresses for documentation These are the addresses we will be referring to the most. IPv6 Internet

7. © Global Unicast Address Range Interface IDSubnet IDGlobal Routing Prefix 001 0010 0000 0000 0000 : 0011 1111 1111 1111 : IANA’s allocation of IPv6 address space in 1/8 th sections Range: 2000: 3FFF: Global Unicast Address (GUA) 2000::/3 Range 2000::/64 thru 3fff:fff:fff:fff::/64 1/8 th of IPv6 address space First hextet

8. © Global Unicast Address Range Except under very specific circumstances, all end users will have a global unicast address. Note: A host (an interface) can potentially have multiple IPv6 addresses on the same or different networks. 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 Interface IDSubnet IDGlobal Routing Prefix 001 Range: 2000::/64 thru 3fff:fff:fff:fff::/64

9. © Parts of a Global Unicast Address 64-bit Interface ID = 18 quintillion (18,446,744,073,709,551,616) devices/subnet 16-bit Subnet ID (initially recommended) = 65,536 subnets IPv4 Unicast Address 32 bits Network portionHost portion Subnet portion /? IPv6 Global Unicast Address 128 bits Global Routing Prefix Interface ID 16-bit Subnet ID /64 /48

10. © /64 Global Unicast Address and the 3-1-4 Rule Interface ID Subnet ID Global Routing Prefix 2001 : 0DB8 : CAFE : 0001 : 0000 : 0000 : 0000 : 0100 3 + 1 = 4 (/64) : 4 2001:0DB8:CAFE:0001:0000:0000:0000:0100/64 2001:DB8:CAFE:1::100/64 16 bits 314 /48/64

11. 4.2: Subnetting IPv6

12. © Subnetting IPv6 Can you count in hex? Just increment by 1 in Hexadecimal: 2001:0DB8:CAFE:0000::/64 2001:0DB8:CAFE:0001::/64 2001:0DB8:CAFE:0002::/64... 2001:0DB8:CAFE:0009::/64 2001:0DB8:CAFE:000A::/64 Valid abbreviation is to remove the leading 0s: 2001:DB8:CAFE:1::/64 3-1-4 Rule

13. © For Demonstration Purposes Only Extending the Subnet ID Prefix 2001 : 0DB8 : CAFE : 0000 : 0000 : 0000 : 0000 : 0000 2001 : 0DB8 : CAFE : 0000 : 0001 : 0000 : 0000 : 0000 2001 : 0DB8 : CAFE : 0000 : 0002 : 0000 : 0000 : 0000 thru 2001 : 0DB8 : CAFE : FFFF : FFFE : 0000 : 0000 : 0000 2001 : 0DB8 : CAFE : FFFF : FFFF : 0000 : 0000 : 0000 Global Routing PrefixSubnet-IDInterface ID Global Routing Prefix 48-bit Interface ID 32-bit Subnet ID /80 /48 Global Routing Prefix Interface ID 16-bit Fixed Subnet ID /64 /48 Note: It is highly recommended to NOT subnet into the /64 interface ID portion of the address to configure subnets. The only exception would be for network infrastructure (router-to-router links, router-to-switch links, etc.). Networks with an end system attached should be a /64.

14. © For Demonstration Purposes Only Subnetting on a Nibble Boundary /68 Prefix Subnetting on a nibble (4 bit) boundary makes it easier to list the subnets: /64, /68, /72, etc. 2001:0DB8:CAFE:0000:0000::/68 2001:0DB8:CAFE:0000:1000::/68 2001:0DB8:CAFE:0000:2000::/68 through 2001:0DB8:CAFE:FFFF:F000::/68 /68 Global Routing Prefix Interface IDSubnet ID /68 /48 20 bits 60 bits

15. © For Demonstration Purposes Only Subnetting within a Nibble /70 Prefix 2001:0DB8:CAFE:0000:0000::/70 2001:0DB8:CAFE:0000:0400::/70 2001:0DB8:CAFE:0000:0800::/70 2001:0DB8:CAFÉ:0000:0C00::/70 Global Routing Prefix Interface IDSubnet ID /70 /48 22 bits 58 bits 00 0100 1000 1100 Four Bits: Two leftmost bits: Subnet-ID Two rightmost bits: Associated with the Interface ID Binary 

16. © RFC 6164 - Using 127-Bit IPv6 Prefixes on Inter-Router Links Ping-Pong Attack Neighbor Cache Exhaustion Issue There are mitigation techniques for both. If you want to use a /127, reserve a separate /64 for each /127…. Really! Do I Need the IPv6 Equivalent to an IPv4 /30? Global Routing Prefix Subnet ID /127 /48 79 bits1bit

17. © 2001:DB8:CAFE:F000::/64 2001:DB8:CAFE:F000::0/127 2001:DB8:CAFE:F000::1/127 2001:DB8:CAFE:F001::/64 2001:DB8:CAFE:F001::0/127 2001:DB8:CAFE:F001::1/127 Allocate Separate /64’s Global Routing Prefix Subnet ID /127 /48 79 bits1bit 0 or 1 2001:DB8:CAFE:F000::/64 2001:DB8:CAFE:F001::/64 2001:DB8:CAFE:F002::/64 2001:DB8:CAFE:F003::/64 And so on... For each /127 allocate an entire /64: 000F000F001 3 bits All 0s “::” can be confusing

18. © Use a Different Last 3 bits for the Subnet ID Global Routing Prefix Subnet ID /127 /48 79 bits1bit 0 or 1 2001:DB8:CAFE:F000::/64 2001:DB8:CAFE:F000::A/127 2001:DB8:CAFE:F000::B/127 2001:DB8:CAFE:F001::/64 2001:DB8:CAFE:F001::A/127 2001:DB8:CAFE:F001::B/127 101 F000F001 3 bits Be careful which two interfaces addresses you choose. ::9 and ::A are not on the same /127 subnet

19. © 2001:DB8:CAFE:F000::/64 2001:DB8:CAFE:F000::8/127 2001:DB8:CAFE:F000::9/127 2001:DB8:CAFE:F000::/64 2001:DB8:CAFE:F000::A/127 2001:DB8:CAFE:F000::B/127 Be Careful! Global Routing Prefix Subnet ID /127 79 bits 1bit 0 or 1 Be careful which two intefaces addresses you choose. ::9 and ::A are not on the same /127 subnet 101 Global Routing Prefix Subnet ID 1bit 100 0 or 1

20. © IPv6 Addressing Plan IPv4 subnetting is used to help conserve IPv4 address space. Managing a limited space VLSM /30s for point-to-point links IPv6 address conservation does not need to be as aggressive as IPv4. Developing an address plan that is: Makes sense. Easy to manage. NANOG BCOP: IPv6 Subnetting Cisco: IPv6 Address Guide RIPE NCC: Preparing an IPv6 Addressing Plan - RIPE Network RFC 1878 VLSM

21. 4.3: IPv6 Address Allocation

22. © /48/64/32 /23 *RIR *ISP Prefix *Site Prefix Subnet Prefix * This is a minimum allocation. The prefix-length may be shorter if it can be justified. /56 Possible Home Site Prefix I am getting a /64 at home Global Routing Prefix Interface ID Subnet ID Sub IPv6 Address Allocation Internet Service Provider

23. © Global Routing Prefix determines number of /64 subnets * 2001:DB8:0000:0000:0000:0000:0000:0000 /32 = 65,536 /48’s /64 /60 = 16 /64’s /56 = 256 /64’s /52 = 4,096 /64’s /48 = 65,536 /64’s (Many sites will get this prefix length) 64-bit Interface ID /44 = 1,048,576 /64’s /40 = 16,777,216 /64’s /36 = 268,435,456 /64’s /32 = 4,294,967,296 /64’s

24. © PI versus PA Address Space Provider Independent (PI) Address Space Address space that is assigned by the RIR. Remains assigned to the customer regardless of provider No prefix renumbering needed if change providers Provider Aggregatable (PA) Address Space Address space that is typically assigned by an ISP to a customer. Change provider, must get new address space Customer must do prefix renumbering (Helpful IETF RFCs) Global Routing Prefix Interface ID /48/32 Subnet ID ISPRIR

25. 4.4: Configuring a Static GUA

26. © Configuring a Global Unicast Address Details, including the operations and configurations of SLAAC (Stateless Address Autoconfiguration) in Lesson 7 and DHCPv6 in Lessons 8. Global Unicast Manual Dynamic Static IPv6 unnumbered Static + EUI 64 SLAAC DHCPv6 SLAAC + DHCPv6 Similar to IPv4 unnumbered StatelessStateful Overview only DHCPv6-PD

27. © Exactly the same as an IPv4 address only different. No space between IPv6 address and Prefix-length. IOS commands for IPv6 are very similar to their IPv4 counterpart. All 0’s and all 1’s are valid IPv6 host IPv6 addresses. No space R1(config)#interface gigabitethernet 0/0 R1(config-if)#ipv6 address 2001:db8:cafe:1::1/64 R1(config-if)#no shutdown R1(config-if)#exit 2001:DB8:CAFE:3::/64 2001:DB8:CAFE:1::/64 2001:DB8:CAFE:2::/64 G0/0 :1 G0/1 :1 S0/0/0 :100 Static GUA Configuration R1 A B

28. © 2001:DB8:CAFE:3::/64 2001:DB8:CAFE:1::/64 2001:DB8:CAFE:2::/64 G0/0 :1 G0/1 :1 S0/0/0 :100 Static GUA Configuration R1 A B R1(config)#interface gigabitethernet 0/1 R1(config-if)#ipv6 address 2001:db8:cafe:2::1/64 R1(config-if)#no shutdown R1(config-if)#exit R1(config)#interface serial 0/0/0 R1(config-if)#ipv6 address 2001:db8:cafe:3::1/64 R1(config-if)#no shutdown R1(config-if)#exit I love the 3-1-4 rule and subnetting IPv6! The ipv6 unicast-routing global configuration command is required for forward IPv6 packets – it is not required to configure IPv6 addresses.

29. © R1# show running-config interface GigabitEthernet0/0 no ip address duplex auto speed auto ipv6 address 2001:DB8:CAFE:1::1/64 ! 2001:DB8:CAFE:3::/64 2001:DB8:CAFE:1::/64 2001:DB8:CAFE:2::/64 G0/0 :1 G0/0 :1 S0/0/0 :100 Verifying Address Using Running Configuration R1 A B IPv4 address IPv6 address

30. © R1# show ipv6 interface brief GigabitEthernet0/0 [up/up] FE80::FE99:47FF:FE75:C3E0 2001:DB8:CAFE:1::1 ! Global unicast address Link-local unicast address Link-local and global unicast addresses are displayed. Link-local address automatically created when (before) the global unicast address is. Link-local addresses are used for communicating with other devices on the same link (not routable). We will discuss link-local addresses in Lesson 5. Verifying Unicast Addresses on R1

31. © Same as IPv4 devices: Servers, printers, routers, etc. Can also be a link- local unicast address of the router. Static GUA Configuration on PC

32. © PCA> ipconfig Windows IP Configuration Ethernet adapter Local Area Connection: Connection-specific DNS Suffix : IPv6 Address.......... : 2001:db8:cafe:1::100 Link-local IPv6 Address.... : fe80::50a5:8a35:a5bb:66e1 Default Gateway....... : 2001:db8:cafe:1::1 Verifying Unicast Addresses on PC Link-local addresses are created automatically. Recent Microsoft operating systems use a random 64-bit Interface ID for link- local address… (coming soon)

33. © PCA> ping 2001:db8:cafe:1::1 Pinging 2001:db8:cafe:1::1 from 2001:db8:cafe:1::100 with 32 bytes of data: Reply from 2001:db8:cafe:1::1: time=1ms Ping statistics for 2001:db8:cafe:1::1: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 1ms, Maximum = 1ms, Average = 1ms PCA> Verifying IPv6 Connectivity

34. © Router(config)# ipv6 general-prefix ? WORD General prefix name Router(config)# ipv6 general-prefix MyGUA 2001:db8:cafe::/48 Router(config)# interface gigabitethernet 0/0 Router(config-if)# ipv6 address MyGUA 0:0:0:88::1/64 Router(config-if)# no shutdown Router(config-if)# exit Router(config)# interface gigabitethernet 0/1 Router(config-if)# ipv6 address MyGUA 0:0:0:99::1/64 Router(config-if)# no shutdown Router(config-if)# end Router# show ipv6 interface brief GigabitEthernet0/0 [up/up] FE80::7EAD:74FF:FECC:5380 2001:DB8:CAFE:88::1 GigabitEthernet0/1 [[up/up] FE80::7EAD:74FF:FECC:5381 2001:DB8:CAFE:99::1 IPv6 General Prefix: Making your life easier The general-prefix option can be used as a short-cut or alias for just about any command requiring an IPv6 address, addressing, ACLs, etc.

35. © Router(config)# no ipv6 general-prefix MyGUA 2001:db8:cafe::/48 Router(config)# ipv6 general-prefix MyGUA 2001:db8:beef::/48 Router(config-if)# end Router# show ipv6 interface brief GigabitEthernet0/0 [up/up] FE80::7EAD:74FF:FECC:5380 2001:DB8:BEEF:88::1 GigabitEthernet0/1 [[up/up] FE80::7EAD:74FF:FECC:5381 2001:DB8:BEEF:99::1 Router# show running-config ipv6 general-prefix MyGUA 2001:DB8:BEEF::/48 ! interface GigabitEthernet0/0 ipv6 address MyGUA ::88:0:0:0:1/64 ! interface GigabitEthernet0/1 ipv6 address MyGUA ::99:0:0:0:1/64 ! IPv6 General Prefix: Renumbering It is also greatly simplifies network renumbering and allows for automated prefix definition.

36. 4.5: Configuring a Static GUA with EUI- 64

37. © Configuring a Static GUA + EUI-64 Global Unicast Manual Dynamic Static IPv6 unnumbered Static + EUI 64 SLAAC DHCPv6 SLAAC + DHCPv6 Similar to IPv4 unnumbered StatelessStateful DHCPv6-PD

38. © R1(config)# interface gigabitethernet 0/1 R1(config-if)# ipv6 address 2001:db8:cafe:99::/64 ? eui-64 Use eui-64 interface identifier R1(config-if)# ipv6 address 2001:0db8:cafe:99::/64 eui-64 R1(config-if)# 2001:DB8:CAFE:99::/64 G0/1 R1 Configuring a Static GUA + EUI-64 All 0s is ok! A 64-bit Interface ID is created with EUI- 64 using: 48-bit MAC address Inserting 16 bits: FF-FE Flipping the U/L (Universal/Local) bit

39. © Modified EUI-64 Format (Extended Unique Identifier–64) 00036BE9D48080 OUI (24 bits)Device Identifier (24 bits) 00036BE9D48080FFFE 036BE9D48080FFFE 0000 00 U/L bit flipped 0000 0010 0202036BE9D48080FFFE Insert FF-FE

40. © R1(config)# interface gigabitethernet 0/1 R1(config-if)# ipv6 address 2001:db8:cafe:99::/64 eui-64 R1# show interface gigabitethernet 0/1 GigabitEthernet0/1 is up, line protocol is up Hardware is AmdFE, address is 0003.6be9.d480 (bia 0003.6be9.d480) R1# show ipv6 interface gigabitethernet 0/1 GigabitEthernet0/1 is up, line protocol is up IPv6 is enabled, link-local address is FE80::203:6BFF:FEE9:D480 Global unicast address(es): 2001:DB8:CAFE:99:203:6BFF:FEE9:D480, subnet is 2001:DB8:CAFE:99::/64 Configuring a Static GUA + EUI-64 64-bit prefix from configuration 64-bit Interface ID using EUI-64 EUI-64: 48-bit MAC address with FFFE (16 bits) inserted and 7 th bit flipped

41. 4.6: Overview of Dynamic IPv6 Address Allocation (SLAAC and DHCPv6)

42. © Dynamic IPv6 Address Allocation Global Unicast Manual Dynamic Static IPv6 unnumbered Static + EUI 64 SLAAC DHCPv6 SLAAC + DHCPv6 Similar to IPv4 unnumbered StatelessStateful Overview only DHCPv6-PD

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

44. © ICMPv6 Internet Control Message Protocol for IPv6 ICMPv6 than just “messaging” but “how IPv6 conducts business”. ICMPv6 Neighbor Discovery (RFC 4861) – used in dynamic address allocation. More later!

45. © Once again… ICMPv6 Neighbor Discovery ICMPv6 informational messages used by Neighbor Discovery (RFC 4861): Router Solicitation Message Router Advertisement Message Used for dynamic address allocation. Neighbor Solicitation Message Neighbor Advertisement Message Used with address resolution (IPv4 ARP) and with DAD Redirect Message (Similar to ICMPv4) Router-Device Messaging Device-Device Messaging

46. © It Begins with the RA Message 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. DHCPv6 Server ICMPv6 Router Advertisement ICMPv6 Router Solicitation Multicast: To all IPv6 routers, I need IPv6 address information Multicast: To all IPv6 devices, let me tell you how to do this … I might not even be needed. 

47. © It Begins with the RA Message Router Advertisement (RA) Message Part of ICMPv6 (Internet Control Message Protocol for IPv6) RA messages are sent by an “IPv6 router”, ipv6 unicast-routing command Forwards IPv6 Packets Enables IPv6 dynamic routing Sends ICMPv6 Router Advertisements Routers can be configured with IPv6 addresses without being an IPv6 router. IPv6 static routes can be configured but the router will only forward locally generated packets – it will not forward packets that transit through the router. DHCPv6 Server ICMPv6 Router Advertisement Router(config)# ipv6 unicast-routing

48. © Router Advertisement: 3 Options DHCPv6 Server RA Router(config)# ipv6 unicast-routing 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 – DHCPv6 “I can’t help you. Ask a DHCPv6 server for all your information.” DHCPv6 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

49. © Dynamic IPv6 Address Allocation Global Unicast Manual Static IPv6 unnumbered Static + EUI 64 SLAAC DHCPv6 SLAAC + DHCPv6 Similar to IPv4 unnumbered StatelessStateful DHCPv6-PD ICMPv6 – Lesson 9 ICMPv6 Neighbor Discovery including packet captures – Lesson 10 Dynamic Stateful Lesson 8 Lesson 7

50. © For more information please check out my Cisco Press book and video series: IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6 By Rick Graziani ISBN-10: 1-58714-313-5 IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6 By Rick Graziani ISBN-10: 1-58720-457-6

51. 4: Global Unicast Addresses (GUA) Rick Graziani Cabrillo College Rick.Graziani@cabrillo.edu