CIT 384: Network AdministrationSlide #1 CIT 384: Network Administration IPv6

CIT 384: Network AdministrationSlide #2 Topics 1.Why IPv6? 2.IPv6 Addressing 3.Stateless autoconfiguration 4.Special Addresses 5.IPv4 to IPv6 Transition

CIT 384: Network AdministrationSlide #3 Why IPv6? We’re running out of IP addresses –IPv4 lifetime extended by CIDR and NAT. –Only 14% of addresses are unallocated. –At current rate, all addresses used by 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 IPv6 with its 128-bit addresses.

CIT 384: Network AdministrationSlide #4 IPv4 to IPv6 Transition

CIT 384: Network AdministrationSlide #5 IPv4 to IPv6 Transition

CIT 384: Network AdministrationSlide #6 Why IPv6? Security –IPsec is part of IPv6 backported to IPv4. Mobility –Better support for mobile devices. QoS –Support for multimedia QoS features. Header Improvements –No need to recalculate checksum at each hop.

CIT 384: Network AdministrationSlide #7 IPv4 vs IPv6 Addresses FeatureIPv4IPv6 Size of Address32 bits128 bits Example Address :0000:0000: 0000:FFFF:FFFF :0A01:0101 Abbreviated Address -::FFFF:FFFF:0A 01:0101 Localhost ::1/128 Possible Addresses 2 32 (~4 billion)2 128 (~3.4 x )

CIT 384: Network AdministrationSlide #8 IPv4 and IPv6 Address Composition

CIT 384: Network AdministrationSlide #9 IPv6 Prefixes PrefixExplanation 2000::/3All addresses whose first 3 bits are equal to the first 3 bits of :1140::/26All addresses whose first 26 bits match 2340: :1111::/32All addresses whose first 32 bits match 2340:1111

CIT 384: Network AdministrationSlide #10 Global Route Aggregation Grouping by geographic region Grouping by ISP within geographic region Grouping by customer within ISP

CIT 384: Network AdministrationSlide #11 Global Routes Example

CIT 384: Network AdministrationSlide #12 IPv6 Prefix Assignment Example

CIT 384: Network AdministrationSlide #13 Subnetting IPv6 Addresses Company 1 is assigned a /48 Needs 4 subnets Uses 16 of the 80 provided bits for subnets.

CIT 384: Network AdministrationSlide #14 Subnetting IPv6 Addresses Possible subnets: 2 16 Possible hosts/subnet: 2 64 Allows use of automatic IPv6 address assignment.

CIT 384: Network AdministrationSlide #15 IPv6 Address Format with EUI-64 Autoconfigure IPv6 addr using MAC EUI-64 = MAC + FFEE Universal/Local bit: 1=local, 0=burned in MAC

CIT 384: Network AdministrationSlide #16 Stateless Autoconfiguration Use Neighbor Discovery Protocol (NDP) –Router solicitation (RS) multicast messages –Router responds with IPv6 prefix, router IPv6 –IPv6 = IPv6_prefix + EUI-64 –Another part of NDP replaces ARP DHCPv6 is stateful alternative –Works like DHCP for IPv4 –Must maintain client state (leases) –Can use stateless DHCP to provide DNS servers

CIT 384: Network AdministrationSlide #17 IPv6 Address Types Unicast –Unicast addresses like IPv4. 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 AdministrationSlide #18 IPv6 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 IPv4 private addresses. Loopback Address 0:0:0:0:0:0:0:1 is the one and only loopback addr Unspecified Address 0:0:0:0:0:0:0:0 used when a dev does not know own addr

CIT 384: Network AdministrationSlide #19 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 AdministrationSlide #20 Stateless Autoconfiguration Process 1.Host computes its IPv6 link local address. 2.Host sends an NDP router solicitation (RS) Source addr: link local address Dest addr: FF02::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 AdministrationSlide #21 IPv6 Routing Protocols Routing protocol updates –Support for larger IPv6 addresses. –Use of IPv6 multicast addresses –Advertise link local IP as next hop. ProtocolFull NameRFC RIPngRIP next generation2080 OSPFv3OSPF version MP-BGP4Multiprocol BGP-42545/4760 EIGRP for IPv6 Cisco

CIT 384: Network AdministrationSlide #22 IPv6 Transition Dual Stacks –Devices that use both IPv4 and IPv6 at once. –Can use both protocols during transition. –Useful for intranets. Tunneling –Encapsulate IPv6 packets in IPv4 packets. –Manual tunnels can be configured btw routers. –Dynamic 6to4 tunnels can be created as needed using public 6to4 relay routers.

CIT 384: Network AdministrationSlide #23 IPv6 to IPv4 Tunnel

CIT 384: Network AdministrationSlide #24 NAT-PT NAT-Protocol Translation –Translates IPv4/6 addresses at boundary. –Dynamically assigns IPv4 addrs to IPv6 nodes. –Needs a pool of IPv4 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 AdministrationSlide #25 Transition Problems IPv6 is incompatible with IPv4 Not every site is reachable with IPv6. Every site will need some IPv4 addresses. –NAT is going to stay with us for some time. Routers don’t support IPv6 in hardware. –Software routing is slower than hardware. Home routers/cable modems don’t do IPv6

CIT 384: Network AdministrationSlide #26 Key Topics IPv6 Addresses –128-bit addresses: 64-bit network, 64-bit host –Global route aggregation –Site local and link local addresses –Stateless autoconfiguration with EUID-64 IPv4 to IPv6 Transition –Dual Stacks –Tunnels –NAT-PT

CIT 384: Network AdministrationSlide #27 References 1.Randy Bush, IPv6 Transition & Operational Reality, reality.pdf, reality.pdf 2.Cisco, Cisco Connection Documentation, Cisco, Internetworking Basics, m m 4.Silvia Hagan, IPv6 Essentials, O’Reilly, Charles M. Kozierok, The TCP/IP Guide, No Starch Press, IPv4 Address Report, 7.Wendell Odom, CCNA Official Exam Certification Library, 3 rd edition, Cisco Press, 2007.