CIT 384 Network Administration IPv 6 CIT 384

CIT 384: Network Administration IPv 6 CIT 384: Network Administration 1

Topics 1. 2. 3. 4. 5. Why IPv 6? IPv 6 Addressing Stateless autoconfiguration Special Addresses IPv 4 to IPv 6 Transition CIT 384: Network Administration 2

Why IPv 6? We’re running out of IP addresses – IPv 4 lifetime extended by CIDR and NAT. – Only 14% of addresses are unallocated. – At current rate, all addresses used by 2011. Solutions – Reclamation: reclaim unused/underused spaces. • We allocate a /8 every few months, so too slow. • Address space fragmentation increasing rtr table sizes. – Upgrade to IPv 6 with its 128 -bit addresses. CIT 384: Network Administration 3

IPv 4 to IPv 6 Transition CIT 384: Network Administration 4

IPv 4 to IPv 6 Transition CIT 384: Network Administration 5

Why IPv 6? Security – IPsec is part of IPv 6 backported to IPv 4. Mobility – Better support for mobile devices. Qo. S – Support for multimedia Qo. S features. Header Improvements – No need to recalculate checksum at each hop. CIT 384: Network Administration 6

IPv 4 vs IPv 6 Addresses Feature Size of Address Example Address IPv 4 32 bits 10. 1. 1. 1 IPv 6 128 bits 0000: FFFF: FFFF : 0 A 01: 0101 Abbreviated Address Localhost Possible Addresses - : : FFFF: 0 A 01: 0101 : : 1/128 2128 (~3. 4 x 1038) 127. 0. 0. 1 232 (~4 billion) CIT 384: Network Administration 7

IPv 4 and IPv 6 Address Composition CIT 384: Network Administration 8

IPv 6 Prefixes Prefix 2000: : /3 2340: 1140: : /26 2340: 1111: : /32 Explanation All addresses whose first 3 bits are equal to the first 3 bits of 2000 All addresses whose first 26 bits match 2340: 1140 All addresses whose first 32 bits match 2340: 1111 CIT 384: Network Administration 9

Global Route Aggregation • Grouping by geographic region • Grouping by ISP within geographic region • Grouping by customer within ISP CIT 384: Network Administration 10

Global Routes Example CIT 384: Network Administration 11

IPv 6 Prefix Assignment Example CIT 384: Network Administration 12

Subnetting IPv 6 Addresses Company 1 is assigned a /48 Needs 4 subnets Uses 16 of the 80 provided bits for subnets. CIT 384: Network Administration 13

Subnetting IPv 6 Addresses Possible subnets: 216 Possible hosts/subnet: 264 Allows use of automatic IPv 6 address assignment. CIT 384: Network Administration 14

IPv 6 Address Format with EUI-64 Autoconfigure IPv 6 addr using MAC EUI-64 = MAC + FFEE Universal/Local bit: 1=local, 0=burned in MAC CIT 384: Network Administration 15

Stateless Autoconfiguration Use Neighbor Discovery Protocol (NDP) – Router solicitation (RS) multicast messages – Router responds with IPv 6 prefix, router IPv 6 – IPv 6 = IPv 6_prefix + EUI-64 – Another part of NDP replaces ARP DHCPv 6 is stateful alternative – Works like DHCP for IPv 4 – Must maintain client state (leases) – Can use stateless DHCP to provide DNS servers CIT 384: Network Administration 16

IPv 6 Address Types Unicast – Unicast addresses like IPv 4. Multicast – Represents a group of devices. Anycast – Used when message can be sent to any member of a group but does not need to be sent to all. CIT 384: Network Administration 17

IPv 6 Special Addresses Reserved Addresses Addrs beginning with 00 are reserved. 1/256 of entire address space. Private Addresses Addrs beginning with FE[8 -F] are private Similar to RFC 1918 IPv 4 private addresses. Loopback Address 0: 0: 1 is the one and only loopback addr Unspecified Address 0: 0: 0 used when a dev does not know own addr CIT 384: Network Administration 18

Private Address Types Site Local – Scope is an entire site or network. – Local routers will fwd, internet routers will not. – Begin with FE[C-F] Link Local – Scope is local subnet. – Routers will not fwd link local addresses. – Used for address configuration, resolution, ND. – Begin with FE[8 -B] CIT 384: Network Administration 19

Stateless Autoconfiguration Process 1. Host computes its IPv 6 link local address. 2. Host sends an NDP router solicitation (RS) Source addr: link local address Dest addr: FF 02: : 2 all-routers multicast 3. Routers reply w/ router advertisement (RA) Reply includes prefix + router IP address 4. Host builds its unicast IP address 1. Prefix from RA + EUI-64 2. Host asks stateless DHCP svr for DNS svr IPs CIT 384: Network Administration 20

IPv 6 Routing Protocols Routing protocol updates – Support for larger IPv 6 addresses. – Use of IPv 6 multicast addresses – Advertise link local IP as next hop. Protocol RIPng OSPFv 3 MP-BGP 4 EIGRP for IPv 6 Full Name RIP next generation OSPF version 3 Multiprocol BGP-4 EIGRP for IPv 6 CIT 384: Network Administration RFC 2080 2740 2545/4760 Cisco 21

IPv 6 Transition Dual Stacks – Devices that use both IPv 4 and IPv 6 at once. – Can use both protocols during transition. – Useful for intranets. Tunneling – Encapsulate IPv 6 packets in IPv 4 packets. – Manual tunnels can be configured btw routers. – Dynamic 6 to 4 tunnels can be created as needed using public 6 to 4 relay routers. CIT 384: Network Administration 22

IPv 6 to IPv 4 Tunnel CIT 384: Network Administration 23

NAT-PT NAT-Protocol Translation – Translates IPv 4/6 addresses at boundary. – Dynamically assigns IPv 4 addrs to IPv 6 nodes. – Needs a pool of IPv 4 addresses. – Can use PAT for greater efficiency. ALGs (Application Level Gateways) – Some protocols embed IPs w/i payload. – NAT-PT must use ALGs for DNS, FTP, etc. CIT 384: Network Administration 24

Transition Problems • IPv 6 is incompatible with IPv 4 • Not every site is reachable with IPv 6. • Every site will need some IPv 4 addresses. – NAT is going to stay with us for some time. • Routers don’t support IPv 6 in hardware. – Software routing is slower than hardware. • Home routers/cable modems don’t do IPv 6 CIT 384: Network Administration 25

Key Topics IPv 6 Addresses – 128 -bit addresses: 64 -bit network, 64 -bit host – Global route aggregation – Site local and link local addresses – Stateless autoconfiguration with EUID-64 IPv 4 to IPv 6 Transition – Dual Stacks – Tunnels – NAT-PT CIT 384: Network Administration 26

References 1. 2. 3. 4. 5. 6. 7. Randy Bush, IPv 6 Transition & Operational Reality, http: //www. nanog. org/mtg-0710/presentations/Bush-v 6 -opreality. pdf, 2007. Cisco, Cisco Connection Documentation, http: //www. cisco. com/univercd/home. htm Cisco, Internetworking Basics, http: //www. cisco. com/univercd/cc/td/doc/cisintwk/ito_doc/introint. ht m Silvia Hagan, IPv 6 Essentials, O’Reilly, 2002. Charles M. Kozierok, The TCP/IP Guide, No Starch Press, 2005. IPv 4 Address Report, http: //www. potaroo. net/tools/ipv 4/index. html Wendell Odom, CCNA Official Exam Certification Library, 3 rd edition, Cisco Press, 2007. CIT 384: Network Administration 27