0 123456 IPv 6 National Dong Hwa University

0 123456 IPv 6簡介 National Dong Hwa University Director of Computer Center Han-Chieh Chao 趙涵捷 中華民國九十年三月三十日 0

Overview • • Limitations of current Internet Protocol (IP) How many address do we need? IPv 6 addressing IPv 6 header format IPv 6 features Mobile IPv 6 v. s. IPv 4 Summary 0

IPv 4 Addresses • Example: 203. 64. 105. 100 =1100 1011: 0100 0000: 0110 1001: 0110 0100 = CB: 40: 69: 64 (32 bits) • • Maximum = 232 = 4 Billion Class A Network: 15 Million nodes Class B Network: 64, 000 nodes or less Class C Network: 250 nodes or less 0

IPv 4 Address • Class A 0 Network 1 17 • Class B 10 2 • Class C 110 3 Network 21 • Class D 1110 4 Host Group (Multicast) 28 Network 14 Local 24 Local 16 Local 8 bits 0

IPv 4 Address • Local = Subnet + Host (Variable length) Router Subnet 0

IPv 4 Address Format • Three all-zero network numbers are reserved • 127 Class A + 16, 381 Class B + 2, 097, 151 Class C Network = 2, 113, 659 networks total • Class B is most popular • 20% of Class B were assigned by 7/90 and doubling every 14 months => Will exhaust by 3/94 • Question: Estimate how big will you become? Answer: more than 256! Class C is too small. Class B is just right. 0

IPv 6 Main Features/Functionality • Expanded Address Space • Header Format Simplification • Auto-configuration • Multi-Homing • Class of Service/Multimedia support • Authentication and Privacy Capabilities • No more broadcast Multicast • IPv 4 IPv 6 Transition Strategy 0

How many address? • 10 Billion people by 2020 • Each person will be served by more than one computer • Assuming 100 computers person => 1012 computers • More addresses maybe required since – Multiple interfaces per node – Multiple addresses per interfaces 0

How many address? • Some believe 26 to 28 address per host • Safety margin => 1015 addresses • IPng Requirements => 1012 end systems and 109 networks. Desirable 1012 to 1015 networks 0

Colon-Hex Notation • Dot-Decimal: 203. 64. 105. 100 • Colon-Hex: FEDC: 0000: 3243: 0000: ABCD – Can skip leading zeros of each word – Can skip one sequence of zero words, e. g. , FEDC: : 3243: 0000: ABCD – Can leave the last 32 bits in dot-decimal, e. g. , : : 203. 64. 105. 100 – Can specify a prefix by /length, e. g. , 2345: BA 23: 7: : /40 0

IPv 6 Addressing Examples • Global unicast address(es) is : – 2001: 304: 101: 1: : E 0: F 726: 4 E 58, –subnet is 2001: 304: 101: 1: : 0/64 • • link-local address is FE 80: : E 0: F 726: 4 E 58 Unspecified Address is 0: 0: 0 or : : Loopback Address is 0: 0: 1 or : : 1 Group Addresses (Multicast), ie: FF 02: : 9 for RIPv 6 –Joined group address(es): –FF 02: 0: 0: 1: FF: xxxx (solicited Node Multicast) –Unicast : 4037: : 01: 800: 200 E: 8 C 6 C is FF 02: : 1: FF 0 E: 8 C 6 C 0

IPv 6 Address • 128 -bit long. Fixed size • 2128 = 3. 4× 1038 addresses => 665× 1021 addresses per m 2 of earth surface • If assigned at the rate of 106/ s, it would take 20 years • Expected to support 8× 1017 to 2× 1033 addresses 8× 1017 => 1, 564 address per m 2 • Allows multiple interfaces per host • Allows multiple addresses per interface 0

IPv 6 Address • Allows unicast, multicast, anycast • Allows provider based, site-local, link-local • 85% of the space is unassigned 0

IPv 6 Addressing • IPv 6 Addressing rules are covered by multiples RFC’s –Architecture defined by RFC 2373 • Address Types are : –Unicast : One to One (Global, Link local, Site local, Compatible) –Anycast : One to Nearest (Allocated from Unicast) –Multicast : One to Many –Reserved • A single interface may be assigned multiple IPv 6 addresses of any type (unicast, anycast, multicast) –No Broadcast Address -> Use Multicast 0

Unicast Anycast Multicast 0

IPv 6 Addressing • Prefix Format (PF) Allocation –PF = 0000 : Reserved –PF = 0000 001 : Reserved for OSI NSAP Allocation (see RFC 1888), so far only way to embedded E. 164 addresses (Vo. IP) –PF = 0000 010 : Reserved for IPX Allocation (under Study) –PF = 001 : Aggregatable Global Unicast Address –PF = 1111 1110 10 : Link Local Use Addresses –PF = 1111 1110 11 : Site Local Use Addresses –PF = 1111 : Multicast Addresses –Other values are currently Unassigned (approx. 7/8 th of total) • All Prefix Formats have to have EUI-64 bits Interface ID –But Multicast 0

Global Unicast Addresses (RFC 2374) • Aggregatable Global Unicast Format - RFC 2374 • Address hierarchy matches Internet Service Provider hierarchy FP 3 bits TLA ID 13 bits Reserved NLA ID SLA ID Interface ID 8 bits 24 bits 16 bits 64 bits • Terminology: –FP - Format Prefix: Unicast (001), Multicast, Anycast –TLA - Top Level Aggregator Global ISP –NLA - Next Level Aggregator ISP –SLA - Site Level Aggregator “Customer” –Interface ID - Host 0

IPv 6 Prefix Allocation 0

IPv 6 Addressing Model • Addresses are assigned to interfaces – No change from IPv 4 Model • Interface can have multiple addresses • Addresses have scope – Link Local – Site Local – Global Site-Local Link-Local • Addresses have lifetime – Valid and Preferred lifetime 0

Local-Use Address • Link Local: Not forwarded outside the link, FE 80: : xxx 10 n 118 -n bits 1111 1110 10 0 Interface ID • Site Local: Not forwarded outside the site, FEC 0: : xxx 10 1111 1110 11 n 0 m Subnet ID 118 -n-m bits Interface ID 0

Multicast Address 8 bits 1111 4 bits 112 bits Flags Scope Group ID 0 0 0 T • T=0 => Permanent (well-known) multicast address, T=1 => Transient • Scope: 1 Node-local, 2 Link-local, 5 Site-local, 8 Organization-local, E Global • Predefined: 1=>All nodes, 2=>Routers, 1: 0=>DHCP Servers 0

Multicast Address • Example: 43 => Network Time Protocol Servers – FF 01: : 43 => All NTP servers on this node – FF 02: : 43 => All NTP servers on this link – FF 05: : 43 => All NTP servers in this site – FF 08: : 43 => All NTP servers in this organization – FF 0 F: : 43 => All NTP servers in the Internet 0

IPv 6 Addresses Bootstrap phase • Bootstrap process - RFC 2450 FP 3 bits TLA ID 13 bits sub. TLA ID 13 bits NLA ID SLA ID Interface ID 19 bits 16 bits 64 bits • Definitions: –TLA - special TLA 0 x 0001 –sub. TLA - Top Level Aggregator Transit ISP –NLA - Next Level Aggregator ISP –SLA - Site Level Aggregator “Customer” –Interface ID - Host 0

IPv 6 Addresses Bootstrap phase • Minimum assignment to ISP is a /35 • ISP creates own NLA boundary - or • ISP assigns /48 SLAs to each customer – 16 bits for subnetworks – 65536 subnetworks per site – 64 bits for hosts – 18446744073710 million hosts per subnetwork!! 0

IPv 6 Addresses Bootstrap phase • sub. TLA holder ISP allocates SLAs to end-customers ISP addresses ISP allocated sub. TLA 35 bits site addresses NLA ID SLA ID Interface ID 13 bits 16 bits 64 bits • sub. TLA holder ISP creates its own NLA boundary for customer ISPs ISP allocated sub. TLA 35 bits site addresses ISP addr ISP 2 addr NLA 1 NLA 2 SLA ID Interface ID 6 bits 7 bits 16 bits 64 bits 0

IPv 6 Addresses Bootstrap phase • Where to get address space? –Real IPv 6 address space now allocated by APNIC, ARIN and RIPE NCC – APNIC 2001: 0200: : /23 – ARIN – RIPE NCC 2001: 0400: : /23 2001: 0600: : /23 –Go to your existing IPv 4 address registry. . . 0

• IPv 6 Address Space Current Allocations APNIC (whois. apnic. net) –WIDE-JP-19990813 2001: 200: : /35 –NUS-SG-19990827 2001: 208: : /35 –CONNECT-AU-199909162001: 210: : /35 –NTT-JP-19990922 2001: 218: : /35 –KIX-KR-19991006 2001: 220: : /35 –JENS-JP-19991027 2001: 228: : /35 –ETRI-KRNIC-KR-19991124 2001: 230: : /35 –HINET-TW-20000208 2001: 238: : /35 –IIJ-JPNIC-JP-20000308 2001: 240: : /35 –IMNET-JPNIC-JP-20000314 2001: 248: : /35 –CERNET-CN-20000426 2001: 250: : /35 –INFOWEB-JPNIC-JP-2000502 2001: 258: : /35 –BIGLOBE-JPNIC-JP-20000719 2001: 260: : /35 – 6 DION-JPNIC-JP-20000829 2001: 268: : /35 –DACOM-BORANET-20000908 • ARIN (whois. arin. net) – – – – – ESNET-V 6 ARIN-001 VBNS-IPV 6 CANET 3 -IPV 6 VRIO-IPV 6 -0 CISCO-IPV 6 -0 QWEST-IPV 6 -0 DEFENSENET ABOVENET-IPV 6 SPRINT-V 6 2001: 400: : /35 2001: 400: : /23 2001: 408: : /35 2001: 410: : /35 2001: 418: : /35 2001: 420: : /35 2001: 428: : /35 2001: 430: : /35 2001: 438: : /35 2001: 440: : /35 This output current as of 16 -Oct-2000 0

• IPv 6 Address Space Current Allocations RIPE (whois. ripe. net) –EU-UUNET-19990810 2001: 600: : /35 –DE-SPACE-19990812 2001: 608: : /35 –NL-SURFNET-19990819 2001: 610: : /35 –UK-BT-19990903 2001: 618: : /35 –CH-SWITCH-19990903 2001: 620: : /35 –AT-ACONET-19990920 2001: 628: : /35 –UK-JANET-19991019 2001: 630: : /35 –DE-DFN-19991102 2001: 638: : /35 –RU-FREENET-19991115 2001: 640: : /35 –GR-GRNET-19991208 2001: 648: : /35 –DE-ECRC-19991223 2001: 650: : /35 This output current –DE-TRMD-20000317 2001: 0658: : /35 –FR-RENATER-20000321 2001: 0660: : /35 –DE-NACAMAR-20000403 2001: 0668: : /35 –EU-EUNET-20000403 2001: 0670: : /35 –DE-IPF-20000426 2001: 0678: : /35 –DE-XLINK-20000510 2001: 0680: : /35 –FR-TELECOM-20000623 2001: 0688: : /35 –PT-RCCN-20000623 2001: 0690: : /35 –SE-SWIPNET-20000828 2001: 0698: : /35 –PL-ICM-20000905 as of 2001: 06 A 0: : /35 16 -Oct-2000 0

IPv 4 Header 20 Octets+Options : 13 fields, include 3 flag bits Changed 0 bits Ver 4 8 IHL 16 24 Service Type Identifier Time to Live Removed Total Length Flags Protocol 31 Fragment Offset Header Checksum 32 bit Source Address 32 bit Destination Address Options and Padding 0

IPv 6 - So what’s really changed ? ! IPv 4 Header Version IHL Type of Service • Defined by RFC 2460 • Address space 16 bytes • quadrupled to Fixed length – (Optional headers daisy-chained) • Flags Identification Time to Live Protocol – (Path MTU discovery) • Flow label/Class (Integrated Qo. S support) • Concatenated Extension Headers Header Checksum Destination Address Options No checksumming No hop-by-hop segmentation Fragment Offset Source Address Padding IPv 6 Header – (Done by Link Layer) • Total Length Version Traffic Class Payload Length Flow Label Next Header Hop Limit Source Address Destination Address 0

IPv 6 Header 40 Octets, 8 fields 0 4 Version 12 Class 16 24 31 Flow Label Payload Length Next Header Hop Limit 128 bit Source Address 128 bit Destination Address 0

Protocol and Header Types 0

IPv 6 Extension Headers • IP options have been moved to a set of optional Extension Headers • Extension Headers are chained together IPv 6 Header TCP Header Application Data Next = TCP IPv 6 Header Routing Hdr Next = Routing TCP Header Application Data Next = TCP IPv 6 Header Security Hdr Fragment Hdr TCP Header Next = Security Next = Frag Next = TCP Data Frag 0

Routing Header Next Header Reserved Routing Type Num. Address Next Address Strict/Loose bit mask Address 1 Address 2 …. . Address n 0

Next header and extension headers 0

Routing Header • Strict => Discard if Address[Next-Address] neighbor • Type = 0 => Current source routing • Type > 0 => Policy based routing (later) • New Functionality: Provider selection, Host mobility, Auto-readdressing (route to new address) 0

IPv 6 Features • • • Larger Addresses Flexible header format Improved options Support for resource allocation Provision for protocol extension Built-in Security: Both authentication and confidentiality 0

Address Autoconfiguration • • • Allow plug and play BOOTP and DHCP are used in IPv 4 DHCPng will be used with IPv 6 Two Methods: Stateless and Stateful Stateless: – A system uses link-local address as source and multicasts to "All routers on this link" – Router replies and provides all the needed prefix info – All prefixes have a associated lifetime – System can use link-local address permanently if no router 0

Messages communication of the Stateless Autoconfiguration. 0

Flow Chart of the Stateless Autoconfiguration. 0

Address Autoconfiguration • Stateful: – Problem w stateless: Anyone can connect – Routers ask the new system to go DHCP server (by setting managed configuration bit) – System multicasts to "All DHCP servers" – DHCP server assigns an address 0

Automatic Renumbering • Renumbering IPv 6 Hosts is easy – Add a new Prefix to the Router – Reduce the Lifetime of the old prefix – As nodes depreciate the old prefix the new Prefix will start to be used for new connections • Renumbering in IPv 6 is designed to happen! • An end of ISP “lock in”! – Improved competition 0

Putting the IT Director back in control • IPv 6 Address Scope – Some addresses are GLOBAL – Others are Link or Site LOCAL – Addressing Plan also controls network access • Configuration Policy Control – Stateless – Stateful (DHCPv 6) • Routers Dictate the Configuration Policy – Router Managers are “in control” of the network – Routers also dictate MTU size for the Link 0

Mobile IPv 6 • IPv 6 Mobility is based on core features of IPv 6 – The base IPv 6 was designed to support Mobility – Mobility is not an “Add-on” features • All IPv 6 Networks are IPv 6 -Mobile Ready • All IPv 6 nodes are IPv 6 -Mobile Ready • All IPv 6 LANs / Subnets are IPv 6 Mobile Ready • IPv 6 Neighbor Discovery and Address Autoconfiguration allow hosts to operate in any location without any special support 0

Mobile IPv 6 • No single point of failure (Home Agent) • More Scalable : Better Performance – Less traffic through Home Link – Less redirection / re-routing (Traffic Optimisation) 0

Mobile IPv 6 Status • Interactions with IPsec fully worked out • Mobile IPv 6 testing event – Bull, Ericsson, NEC, INRIA • Internet Draft is ready for Last Call 0

IPv 6 - Mandates Security • Security features are standardized and mandated – All implementations must offer them – No Change to applications • Authentication (Packet signing) • Encryption (Data Confidentiality) • End-to-End security Model – – Protects DHCP Protects DNS Protects IPv 6 Mobility Protects End-to-End traffic over IPv 4 networks 0

IPv 6 v. s. IPv 4 • 1995 v. s. 1975 • IPv 6 only twice the size of IPv 4 header • Only version number has the same position and meaning as in IPv 4 • Removed: header length, type of service, identification, flags, fragment offset, header checksum • Datagram length replaced by payload length • Protocol type replaced by next header 0

IPv 6 v. s. IPv 4 • • • Time to live replaced by hop limit Added: Priority and flow label All fixed size fields No optional fields. Replaced by extension headers 8 -bit hop limit = 255 hops max (Limits looping) Next Header = 6 (TCP), 17 (UDP) 0

IPv 6 Features and Advantages • • • Larger Address Space Efficient and Extensible IP datagram Efficient Route Computation and Aggregation Improved Host and Router Discovery Mandated New Stateless and Stateful Address Autoconfiguration • Mandated Security for IP datagrams • Easy renumbering 0

Application Issues • Most application protocols will have to be upgraded: FTP, SMTP, Telnet, Rlogin • 27 of 51 Full Internet standards, 6 of 20 draft standards, 25 of 130 proposed standards will be revised for IPv 6 • No checksum => checksum at upper layer is mandatory, even in UDP • non-IETF standards: X-Open, Kerberos, . . . will be updated • Should be able to request and receive new DNS records 0

IPv 6 Routing • Uses same “longest-prefix match” routing as IPv 4 CIDR • Key to scalable routing—hierarchical addressing • Assignment of production IPv 6 Sub-TLA address prefixes obtainable from Registries (RIPE-NCC, APNIC, ARIN) since 1999 • Existing routing protocols require extensions for IPv 6 • Neighbor discovery—dynamic host <—> router • Can use Routing header with anycast addresses to route packets through particular regions –e. g. , for provider selection, policy, performance, etc. 0

IPv 6 Routing Protocols • Update to existing IPv 4 routing protocols to handle bigger addresses –RIPv 6 (RFC 2080) - Similar to RIPv 2 –BGP 4+ - Multi-Protocols Extensions defined in RFC 2283, 2545 –Integrated IS-IS - Large Address support facilitates IPv 6 address –family. Draft-ietf-isis-ipv 6 -01. –OSPFv 6 (RFC 2740) Packet formats changed to reflect 128 bits • IPv 6 Multicast Routing –PIM, MOSPF, MBGP have IPv 6 extensions –IPv 6 Multicast has larger address space removing potential –IP addresses collision 0

What Will IPv 6 Do for Routing? • Primarily give us a second chance to delegate addresses • Assume: –~60 Top level addresses –~2000 next level addresses delegated to small ISPs – 48 addresses in one TLA for multihoming • Result: Your route table has –~60 TLAs, –Your customers and subnets, and… –Routes you incorporate by bilateral agreement 0

Router Advertisement 0

Router Solicitation 0

IPv 6 Standards Status • IPv 6 documents are at various points in the standards process, core documents are done • Document review for completeness, followed by issues or additional work. • To know more about IPv 6 specifications –www. ietf. org/html. charters/ipngwg-charter. html • Main covered areas are : –Architecture, Addressing, Routing, Security, Transition, DNS, Management, Discovery & Auto-Configuration, Mobility, Multicast, Applications API, . . . 0

IPv 6 Current Status Standardisation • Several key components now on Standards Track: Specification (RFC 2460) Neighbour Discovery (RFC 2461) ICMPv 6 (RFC 2463) IPv 6 Addresses (RFC 2373/4/5) RIP (RFC 2080) BGP (RFC 2545) IGMPv 6 (RFC 2710) OSPF (RFC 2740) Router Alert (RFC 2711) Jumbograms (RFC 2675) Autoconfiguration (RFC 2462) IPv 6 over: PPP (RFC 2023) FDDI (RFC 2467) NBMA(RFC 2491) Frame Relay (RFC 2590) Ethernet (RFC 2464) Token Ring (RFC 2470) ATM (RFC 2492) ARCnet (RFC 2549) 0

IPv 6 Current Status - Work in Progress to Standardisation • Issues remaining open Multihoming Ongoing work at the moment eg: draft-ietf-ipngwg-ipv 6 -2260 -00. txt draft-ietf-ipngwg-ipv 6 multihome-with-aggr-01. txt ISIS draft-ietf-isis-ipv 6 -01. txt DHCPv 6 draft-ietf-dhcpv 6 -15. txt 0

NGTrans Working Group • Define the processes by which networks can be transitioned from IPv 4 to IPv 6 • Define & specify the mandatory and optional mechanism that vendors are to implement in Hosts, Routers and other components of the Internet in order for the Transition. • Http: //www. ietf. org/html. charters/ngtranscharter. html 0

Transition Philosophy — Requirements • Let sites and ISPs transition at their own pace – No global coordination – Minimize any dependencies during the transition • Provide a multitude of “tools” – Different sites might have different constraints – Early adopters different than production users? • Try to provide IPv 6 benefits during transition – Lack of IPv 4 address and/ or features will drive transition • Maintain 100% compatibility with installed base – Protocols as well as applications 0

Transition Scenarios • Start with name service upgrade – – Need DNS AAAA support (BIND 4. 9. 4 or later) Need “ipnodes” map/ table in NIS/ NIS+ Upgrade primary server as well as secondaries Separate zone for IPv 6 nodes or same zone? • Experimental - hosts only • Incremental - one subnet at a time + internal tunnels • Routers first - all routers then hosts – No need for internal tunnels 0

Current Transition Tools • Dual stack approach • Name service support (DNS, NIS+, LDAP) • Tunneling across IPv 4 routers • See RFC 1933 and RFC 2529 • Enables communication between IPv 6 -only devices and dual stack “servers” 0

Transition Mechanisms • • Dual-IP Hosts, Routers, Name servers Tunneling IPv 6 over IPv 4 Hosts and Routers can be gradually upgraded to IPv 6 It is better (though not required) to upgrade routers before upgrading hosts HITACHI Toolnet 6 http: //www. hitachi. co. jp/Prod/comp/network/pexv 6 -e. htm 0

Interoperability • 6 over 4 – Isolated v 6 to isolated v 6 node – IPv 4 used as link layer • 6 to 4 – v 6 domain to v 6 domain – IPv 4 used as transport tunnel • NAT-PT – v 6 only to v 4 only • SIIT, AIIH, DTI, BIS, … 0

IPv 4 -IPv 6 Transition Approach • Hosts—dual stack • Networks—tunneling • Network boundaries IPv 4 IPv 6 NAT • Expect combinations of each to be used… APPLICATION TCP/UDP IPv 4 IPv 6 DRIVER More Pragmatic than Building New IPv 6 Topology 0

APPLICATION TCP/UDP IPv 4 IPv 6 DRIVER Dual-Stack Approach • When adding IPv 6 to a system, do not delete IPv 4 – this multi-protocol approach is familiar and well-understood (e. g. , for Apple. Talk, IPX, etc. ) – note: in most cases, IPv 6 will be bundled with new OS releases, not an extra-cost add-on • Applications (or libraries) choose IP version to use – when initiating, based on DNS response: – if (dest has AAAA or A 6 record) use IPv 6, else use IPv 4 – when responding, based on version of initiating packet • This allows indefinite co-existence of IPv 4 and IPv 6, and gradual, app-by-app upgrades to IPv 6 usage 0

Dual Stack Approach • IPv 6 hosts and routers support both IPv 4 and IPv 6 – Interoperates with IPv 4 and IPv 6 • The same applications and transport protocols run on both IP versions • Upgrading from IPv 4 to dual IPv 4/ IPv 6 does not break anything – As part of regular new OS release – Enable IPv 6 and record IPv 6 address in DNS to turn on the IPv 6 features 0

Tunnels to Get Through IPv 6 -Ignorant Routers / Switches • Encapsulate IPv 6 packets inside IPv 4 packets (or MPLS frames) • any methods exist for establishing tunnels: –configured tunnels - manual –automatic tunnels - IPv 4 compatible addresses : : <ipv 4> –“tunnel brokers” (using web-based service to create a tunnel) –“ 6 -over-4” (intra-domain, using IPv 4 multicast as virtual LAN) –“ 6 -to-4” (inter-domain, using IPv 4 addr as IPv 6 site prefix) • Can view this as: –IPv 6 using IPv 4 as a virtual link-layer, or –an IPv 6 VPN (virtual public network), over the IPv 4 Internet (becoming “less virtual” over time, we hope) 0

IPv 6 Tunnelling • Configured tunnels—manual point-2 -point links • Automatic IPv 6 tunnels—via 6 to 4 mechanism Network 2002: : /16 prefix IPv 6 Tunnel Service Provider IPv 4 Backbone IPv 6 Network IPv 6 Tunnel IPv 4 Header IPv 6 Header Transport Layer Header Data IPv 6 Tunnel Mobile Data Network 0

Translation • May prefer to use IPv 6 -IPv 4 protocol translation for: –New kinds of IPv 6 devices (e. g. , cell phones, cars, appliances) accessing IPv 4 servers resources over the Internet –Smoothly deploying IPv 6 on a campus network, providing v 4 -v 6 communications • This is a simple extension to NAT techniques, to translate header format as well as addresses –IPv 6 nodes behind a translator get full IPv 6 functionality when talking to other IPv 6 nodes located anywhere –Methods used to improve NAT functionality (e. g. , ALGs, RSIP) can be used equally to improve IPv 6 -IPv 4 functionality 0

IPv 4 -IPv 6 Translation: NAT-PT IPv 4 Network IPv 4/v 6 Network v 4 -only host, router v 4 + v 6 host, router v 4 -only link v 4 + v 6 link v 6 -only tunnel 0

Summary • IPv 6 uses 128 -bit addresses • Allows provider-based, site-local, link-local, multicast, anycast addresses • Fixed header size. Extension headers instead of options. Extension headers for provider selection, security • Allows autoconfiguration • Dual IP router and host implementations for transition 0