white paper

cu.ipv6tf.org

white paper

white paperThe Benefits of IPv6 for theMobile Internet


white paperTable of contentsExecutive Summary 3Introduction 4The Benefits of IPv6 4Addressing 4Security 6Performance 6Administration 7Mobility 7IPv6 in the Mobile Internet 7IP in 3G Networks 8Migration 8Security Features 9Efficiency Over the Air 9Mobility 9Abbreviations 112


white paperExecutive SummaryEricsson was founded on the principle thatcommunication is a basic human need, and thisprinciple still guides us as we look to the future.The two foremost trends in communication over thepast decade have been the growth of mobiletelephony and the Internet. In the near future, it will bemore common to make a telephone call using amobile telephone than a traditional fixed-linetelephone. The Internet, and especially the World WideWeb, continues to revolutionise the way that people,businesses, and machines communicate.We foresee that these two technology trends willcombine to form the next major change incommunication — the Mobile Internet — such that bythe year 2003 there will be more Internet connectionsmade from mobile devices than from fixed ones. Newservices will become available that are built on theconcepts of personalization, mobility, location andsecurity. Many devices will communicate over theInternet using built-in miniature mobile telephones.These devices are expected to number in the billions,and may be present in cars, vending machines, keyrings, alarm systems, cameras and a multitude ofother items as the cost of technology falls.These changes will accelerate as third generation(3G) of mobile networks and services becomeavailable in the near future, allowing up to onehundred times more bandwidth than the wirelessservices we have today.The Internet Protocol (IP) will form one of thecornerstones of these networks. Ericsson’s vision isthat all mobile users in the near future will be ‘alwaysconnected and always online’.Ericsson believe that IP version 6 (IPv6) is essentialin making this vision real; IPv6 helps to solve manyproblems that will appear with the rapid growth of theMobile Internet. Tremendous opportunities willbecome available for service providers and networkoperators to create new business opportunities and todifferentiate services.IPv6 supports functions crucial to the deployment ofscalable IP networks as a basis for new and exciting3G services. Consequently, Ericsson is fully committedto introduce IPv6 in all of its products to provideseamless end-to-end services.With long experience in cellular technologies andearly pioneering work in IPv6, Ericsson is uniquelycapable of combining IP technology and wirelessnetworks to create the Mobile Internet.3


white paperIntroductionThe rapid increase in the number of Internet users,combined with the expected growth in the number ofwireless Internet devices requires a scalable andflexible IP technology to accommodate such fastgrowth (see Figure 1). IPv6 was developed by theInternet Engineering Task Force (IETF) to satisfy therequirements of the future Internet.Subscribers (Millions)20001500100050002000Worldwide Internet SubscribersMobile InternetFixed Internet2001 2002 2003 2004 2005YearFigure 1 Rapid growth of fixed and mobile Internet subscribersThe feature of IPv6 that receives most attention is thatit has a much larger range of available addresses thanIPv4, but this is far from being the only benefit. Inreality, IPv6 considers a wide range of capabilities andintegrates a number of important features that havebeen treated as add-ons to IPv4.Unsurprisingly, given IP’s now venerable age, thesefeatures were not foreseen as being important when IPwas originally conceived during the 1970s. Proponentsof IPv4 often claim that the extensions made to it willserve quite adequately for some years yet. While atheoretical case can be made for this view whenconsidering each feature in isolation, it is difficult tosustain this opinion when considering the broaderpicture, taking into account how these featuresinteract. IPv6 then becomes the only complete solutionavailable.Always connected and always onlineIPv6 is an essential technology to realise the vision ofa large number of people being ‘always connected andalways online’, particularly due to the limited numberof IPv4 addresses available. New services, such asmultimedia, require globally unique addressing. IPv6,with its very large address space, will guarantee aglobally unique IP address for each device for manyyears to come.Nevertheless, IPv6 hosts and terminals will need tointer-operate with IPv4 hosts and terminals for a longtime. Therefore it is important to plan for IPv6migration and coexistence of IPv4 and IPv6. Themigration strategy must be based on business needsand benefits, for both network operators and theircustomers and ensure that both IPv6 and IPv4 can beused in routers, hosts and terminals and thatappropriate interworking mechanisms between the twoprotocol suites are available.The Benefits of IPv6Wireless networks have very stringent requirements interms of scalability, quality of service and security.IPv6 addresses all of these issues. Standardisation ofIPv6 has reached a point where it is ready forcommercial service and is being promoted throughindustrial forums of major operators and vendors.The IPv6 architecture and design includes a numberof attractive features that make it a valuablecomponent of an IP-based 3G wireless network. Thesebenefits can be grouped as:• Addressing• Security• Performance• Administration• MobilityAddressingMore addressesEvery online device or computer needs a globallyunique IP address to connect to the Internet. WhenIPv4 was designed in the 1970s, it was difficult toforesee that its 4 billion unique addresses would everbe exhausted. However, the way in which IPv4addresses have been allocated and the tremendoussuccess of the Internet have made IPv4 addresses ascarce resource. This problem is particularly serious incertain areas of the world, for example Asia, wherethere are far fewer IPv4 addresses than in Europe andin the United States.4


white paperThe limited number of IPv4 addresses is also anissue for those operators wishing to extend theirbusinesses from mobile telephony to the MobileInternet, as additional IPv4 addresses are now verydifficult to obtain.Demand for IP addresses is growing exponentiallydue to the Internet’s evolution. Further draining thepool of IP addresses is the aggressive rollout of‘always connected’ services and the proliferation oflaptops, Personal Digital Assistants (PDAs), digitalcameras, game consoles and telemetric devices.Currently in the Internet, addresses are often sharedbetween multiple connections, which helps toconserve addresses. This cannot be the case oncepersistent services become available, as eachconnection will rely on unique addresses. Today, manypeople have dial-up services with approximately onemodem for each ten subscribers to the ISP, and hence90% of the addresses are saved compared with‘always connected’ services. In addition, corporateusers of the Internet are commonly connected viatranslation devices that also conserve addresses byallowing many computers to share a single address.As there will probably be several permanently attacheddevices per person, it is obvious that IPv4 addresseswill be exhausted in the near future. Some estimatesare that this will happen before the end of 2005.Current approaches to solving these issues in IPv4networks, such as Network Address Translation (NAT),which translates between global and private IPaddresses, introduce new problems of their own. Forexample, NAT makes it virtually impossible to deployend-to-end security using IP Security (IPsec). NAT alsoeliminates the possibility of end-to-end conversationalmultimedia services, as these require unique IPaddresses for any-to-any connections.IPv6 allows 340 billion billion billion billion (3.4x10 38 )unique addresses, which is enough to provide billionsof addresses per person. Any device connected to thenext generation Internet may therefore have a uniqueaddress.Addressing HierarchyDue to the inefficient allocation of addresses, IPv4suffers from limited route aggregation possibilities andthus very complex routing. The introduction ofClassless Inter-Domain Routing (CIDR) to IPv4 hasallowed more aggressive route aggregation. This hashelped to slow-down the growth of routing tables inthe Internet’s core. Such growth would otherwisecause performance limitations and managementburdens. However, even this has not been enough toovercome the inefficiency created by the previousallocation of addresses, and there are now more than100,000 routing prefixes that need to be handled in theIPv4 Internet core.Having learnt an important lesson from the problemsfacing IPv4, IPv6 was designed from the start toprovide a hierarchical address structure, allowing routeaggregation and ensuring that the routing tables arekept small. Consequently, it provides a scalableaddress space that can be flexibly divided.Figure 2 shows an example of how this hierarchymight be used in practice. The long-haul provider inthe example shown uses a top-level route. Thecorresponding next-level route is assigned to anorganisation, e.g. a service provider that connects tothe long-haul provider. The site-level route is then usedby the service provider to create its own localaddressing hierarchy, for example to allocate pools ofaddresses to corporate customers or smaller serviceproviders.Figure 2 IPv6 unicast address allocation allows efficient route aggregationTop level exchanges in the IPv6 Internet core willpotentially only need to handle many fewer top-levelroutes, which may be an order of magnitude lowerthan the current IPv4 Internet core. This helps tosimplify router design, and assists in improving theirperformance.5


white paperSecurityIP security (IPsec) is built into IPv6 and can be utilisedto protect both application and network specific dataand signalling.IPv6 provides end-to-end security mechanisms forauthentication and encryption to all applications,without the need to integrate such support in allapplications. The IPsec algorithms can be updated asimproved cryptographic methods are developed.The benefit of having the same security mechanismsavailable for use by all applications lies primarily insimpler administration of both security policies andsecurity associations. Therefore, cost of ownership canbe reduced compared with administering multiplesecurity systems.In addition, as IPv6 does not impose restrictions onend-to-end security, it should allow much simplerdeployment of new, personalised services such asthose that rely on secure transactions.processing is avoided, providing IPv6 with acorresponding QoS advantage.MulticastMulticast is a technique typically used when a streamof information, e.g. audio, video, financial data, ornews, needs to be transmitted to many devices ratherthan to a single destination. This can help substantiallywith network efficiency as each packet is copied downthrough a tree-like structure, rather than being sentdirectly from the source to each destination pointdirectly, as shown in Figure 3.MulticastsenderMulticastdistributortPerformanceQuality of ServiceNetwork operators can use the Quality of Service(QoS) mechanisms in IP to help provide a range ofservice packages with different performancecharacteristics and price levels.The two main IETF standard protocol frameworks forsupporting IP QoS, namely Differentiated Services(DiffServ) and Integrated Services (IntServ), apply in asimilar way to both IPv4 and IPv6. Therefore, operatorsthat adopt DiffServ or IntServ for IPv4 will find itrelatively simple to migrate to services based on IPv6.IPv6 allows future possibilities to enhance theQuality of Service mechanisms in IPv4 by using the‘flow label’ field in the IPv6 header, whereby powerful,application flow-based resource reservation schemesand DiffServ enhancements can be added tocomplement the existing standards. It is worth notingthat the flow label can be used even when the packetpayload is encrypted, which renders otherclassification techniques, e.g. port numbers, to beunusable.Finally, the need to use NAT in IPv4, due to addressscarcity, is not necessary in IPv6. Therefore, the endto-endperformance degradation caused by NATMulticastreceiverFigure 3 MulticastMulticareceiverMulticastreceiverThis means that fewer packets are carried across thenetwork, which improves bandwidth efficiency andreduces the resource requirements on network nodes.The multicast support built into IPv6 extends thecapabilities of IPv4 multicast by defining a very largemulticast address range and expanding the scopeidentifiers that limit the degree to which multicastrouting information is propagated.AnycastIn addition, IPv6 introduces the concept of anycastservices, which are not as well defined in IPv4.Anycast behaves somewhat similarly to multicast,except that each packet is sent only to the nearestreachable member of the group, rather than to allmembers.Some of the benefits of anycast are that it can beused as a highly cost-effective method of discoveringa server of given type, e.g. a DNS-server, and it can6


white paperprovide redundant paths to a group of servers. In thiscase, if the route to the primary server becomesunavailable, subsequent sessions will automaticallyconnect to the next server in the group. This isillustrated in Figure 4.Figure 4 AnycastAdministrationAnycastgroupIPv6 provides a number of features that help tosimplify network administration. Address autoconfigurationand automatic Domain Name Server(DNS) configuration will help to reduce the number ofDynamic Host Configuration Protocol (DHCP) serversthat are widely used to dynamically allocate IPaddresses in IPv4 networks. Therefore, there will besavings in the effort and cost involved in maintainingsuch servers.IPv6 also provides capabilities for automatednetwork renumbering which cannot be achieved inIPv4 networks. This allows for smooth networkrenumbering over a period without manual reconfigurationof each router or host. This feature isextremely useful when expanding an existing network,merging two networks, or changing service providers.Multi-homing provided by IPv6, i.e. where there ismore than a single path to a destination, can be apowerful technique for delivering reliable services. Thiscan be achieved by establishing simultaneousconnections to two ISPs, hence providing a backupconnection to the Internet when service is lost at oneISP. Multi-homing in IPv6 differs from IPv4 in that IPv6allows the multihoming to be propagated to end hostsin a smooth manner, giving the possibility to place theresponsibility of multi-homing on the end systems (e.g.hosts), rather than on a router.MobilityMobile IP (MIP) was developed to manage a mobiledevice’s IP mobility, and allow devices to move withinthe IP network (i.e. between IP sub-networks) withminimum interruption to connections. MIP can also beused to achieve seamless handovers between differentaccess technologies, e.g. a cellular network and WLANhotspot.MIPv6 includes a number of advantages over theMIPv4 protocol such as route optimisation, whichhelps to avoid ‘triangular routing’. This is described inmore detail on page 9.Due to the abundance of IPv6 addresses, MIPv6eliminates the need for the additional mobilitymanagement functions that are required with MIPv4(e.g. the use of a Foreign Agent). Furthermore, thisallows network administrators to use securitymechanisms, like ingress filtering, which prevent theuse of invalid addresses within an operator’s IPnetwork.IPv6 in the Mobile InternetThe introduction of IPv6 within the cellular world willsignificantly affect cellular network terminals,infrastructure, and applications by enabling a widerangeof new ‘always connected and always online’services. These services, combined with the rapidgrowth in cellular devices, has led to the decision bythe 3G Partnership Project (3GPP), to make IPv6mandatory for all new services, of which the first ismultimedia. The 3GPP provides technical documentsfor 3rd Generation Mobile systems.Within this section, we will briefly consider thefollowing aspects of using IPv6 in mobile networks;• Migration• Security features• Efficiency• Mobility7


white paperIP in 3G NetworksWithin a 3G network, IP can be used for two purposes:• User-level IP is used for communication betweenmobile devices and application hosts• Transport-level IP is used for communicationbetween network nodes in the cellular infrastructureFigure 5 illustrates the use of IP in a 3G network.Radio AccessNetworkCoreNetworkTranslationSome devices may only support IPv6. Since manyexisting networks and hosts are expected to run IPv4for a long time, translation between IPv4 and IPv6 willbe required to allow such IPv6 only devices tocommunicate with IPv4 only hosts.For example, when an IPv6 terminal iscommunicating on the user level with an IPv4 host, anintermediate node is required to translate or reestablishthe connection. These nodes are commonlyknown as Translators or Application Level Gateways(ALGs), and their use is illustrated in Figure 6.Transport-level IPv4/6Figure 5 IP in a 3G networkTranslatorand/orALGThe two layers can use different connectivity protocolse.g. IP versions. For instance, the transport-level canuse IPv4, while the user-level provides the terminalwith global IPv6 connectivity.IPv6terminalIPv6NetworkIPv4NetworkIPv4hostMigrationIPv4 and IPv6 will co-exist for a number of years. Inthe early stages of 3G networks, IPv4 will bewidespread, with ‘islands’ of IPv6 connected via IPv4networks. This situation is expected to change asmore IPv6 capable devices are deployed, and IPv6 willgradually become the more widely deployed protocol.One implication of this is that IPv6 networks need tobe highly compatible with the installed base of IPv4devices, and considerable attention has been paid tothis issue as part of the standardisation work.There are three main approaches to dealing with thisissue: dual protocol stacks, translation, and tunnelling.Dual Protocol StacksDuring the initial deployment of IPv6, it is expectedthat most terminals will implement dual stacks, i.e.both IPv4 and IPv6. In this instance, no translation isneeded, as the terminal uses the appropriate IPv4 orIPv6 stack, depending on which host it iscommunicating with. This assumes that there aresufficient IPv4 addresses available; if this is not thecase then translation is still required.Figure 6 TranslationTunnellingCellular operators may re-use existing IPv4 backbonenetworks while introducing IPv6 networks at theedges. For these IPv6 domains to communicateeffectively on the transport level, tunnelling of IPv6packets between intermediate IPv4 points in thenetwork is required. Similarly, user level traffic alsoneeds to be tunnelled over the existing IPv4 network.Both cases are illustrated in Figure 7.IPv6NetworkUser-levelTransport-levelDualStackRouterIPv4NetworkDualStackRouterFigure 7 Tunnelling; connection of IPv6 sites via IPv4 networksIPv4hostIPv6Network8


white paperTunnelling is highly appropriate when using native IPv6terminals and services, and one or more IPv4 networksneed to be crossed to achieve an end-to-end connection.Tunnels may be established either dynamically; i.e.when the tunnel end point is selected based onanalysis of the destination IPv6 address, or by manualconfiguration.Security FeaturesConfidentiality of information is the majorconsideration that is relevant when exchanging databetween terminals and hosts. This leads to thenecessity to authenticate, authorise, and protect thistraffic in an end-to-end fashion. For example, thesesecurity mechanisms would be appropriate wheresomeone is using a mobile terminal to access acorporate Intranet via a Virtual Private Network (VPN).IPsec has an inherent benefit in that it allows theability to control the level of security offered to matchthe requirements of individual application flows.MobilityConsider the scenario in Figure 8 below, whentravelling from left to right with a mobile PDA switchedon. As the PDA moves, it is necessary to move theconnection between either radio cells or IP areas. Thisis commonly called a handover.The first handover is between Cells 1 and 2, whichare both within IP Network A, so there is no IPhandover. However, when the handover between Cells2 and 3 takes place, an IP handover is also required asCells 2 and 3 are connected to different IP Networks(A and B respectively).IP Network A IP Network BCell 1Cell 2Cell 3Efficiency over the AirIPv6 opens up new possibilities for the Mobile Internet.This involves the IP “all the way” concept, where theInternet Protocol is carried “end-to-end” from onemobile device to another. In wireless systems thismeans that IPv6 is carried over the air interface, withits high error rates and limited capacity.The large header of IPv6 causes high bandwidthconsumption. A solution that addresses this issue isHeader Compression, which maintains end-to-end IPconnectivity while reducing the size of the large IPv6packet header over the error-prone and limitedcapacity air interface. Ericsson has been a majorcontributor to the work on Robust HeaderCompression (ROHC), through the ROCCO (RObustChecksum-based header COmpression) algorithm.ROHC is more robust and achieves highercompression than earlier algorithms, leading to betterefficiency across the air interface.The simple structure of the IPv6 packet headershould allow improved performance and more efficientsilicon implementation compared with IPv4, eventhough the header is twice as large.Cell handoverIP handoverFigure 8 Mobility handoversMobile IP (MIP) is the most widely accepted solutionfor IP mobility. Mobility support is mandatory in everyIPv6 implementation by the use of Mobile IPv6(MIPv6). Since IPsec is in every IPv6 implementation, itis used to secure signalling between MIPv6 devices.3G terminals are expected to implement a number ofinterfaces for use with different access networks. Forexample, terminals may also support other radiotechnologies like Bluetooth, Infrared, or WLAN.Assuming that those access technologies areconnected to different access routers, a terminal’s IPaddress may change when moving between thosedifferent media.MIPv6 can be used to ensure seamless mobility andmaintenance of ongoing connections. MIPv6 can alsobe used when roaming between different 3G networks,thus allowing an optimized route to be used to reachthe device. This is illustrated in Figure 9.9


white paperDual InterfaceMobile IPv6 deviceMobile IPv6Home AgentIP trafficInternetMobile IPv6Correspondent nodeFigure 9 IP Roaming between different network interfacesMIPv4 is currently supported within the 3GPPstandards by the inclusion of the Foreign Agentcapability in the Gateway GPRS Support Node(GGSN). Since no Foreign Agents are required in IPv6,MIPv6 is easier to deploy than MIPv4.MIPv6 also provides an end-to-end mechanism foroptimised routing within the network, so that triangularrouting is avoided. Figure 10 illustrates this.HomeHomeFigure 10 Triangular routing and route optimisationThe left picture shows triangular routing; data from theserver to the PDA has to pass via the home network,as the server is only aware of the PDA’s homeaddress, not where it has roamed to in the network.On the right hand side, route optimisation has beenused, and now the data from the server can be sentdirectly to the PDA. The optimised route is much moreefficient, as the data is delivered with less delay, anduses fewer network resources since the data onlytravels across the network backbone once.10


Ericsson is shaping the future of Mobileand Broadband Internet communicationsthrough its continuous technology leadership.Providing innovative solutions in morethan 140 countries, Ericsson is helping tocreate the most powerful communicationcompanies in the world.Ericsson Radio Systems ABwww.ericsson.comAE/LZT 123 6997©Ericsson Radio Systems AB 2001

More magazines by this user
Similar magazines