IPv6, MPLSIPv6Slide 3IPv6 AddressesSlide 5IPv4 Packet FormatIPv6 Packet FormatSlide 8Slide 9IPv6 Extension HeadersSlide 11Slide 12Slide 13Slide 14IPv6 Design ControversiesSlide 16Slide 17Slide 18Slide 19Slide 20Transition From IPv4 To IPv6TunnelingSlide 23Multiprotocol label switching (MPLS)MPLS capable routersMPLS forwarding tablesIPv6, MPLSIPv6HistoryNext generation IP (AKA IPng)Intended to extend address space and routing limitations of IPv4Requires header changeAttempted to include everything new in one changeIETF moderatedBased on Simple Internet Protocol Plus (SIPP)IPv6Wish list128-bit addressesMulticast trafficMobilityReal-time traffic/quality of service guaranteesAuthentication and securityAutoconfiguration for local IP addressesEnd-to-end fragmentationProtocol extensionsSmooth transition!NoteMany of these functionalities have been retrofit into IPv4IPv6 Addresses128-bit3.4 x 1038 addresses (as compared to 4 x 109)Classless addressing/routing (similar to CIDR)Address notationString of eight 16-bit hex values separated by colons5CFA:0002:0000:0000:CF07:1234:5678:FFCDSet of contiguous 0’s can be elided5CFA:0002::CF07:1234:5678:FFCDAddress assignmentProvider-basedgeographic010 Region ID Provider ID Subscriber ID Subnet Host3 m n o p 125-m-n-o-pIPv6Prefix Address type0000 0000 Reserved (includes transition addresses)0000 0001 ISO NSAP (Network Service Point) Allocation0000 010 Novell IPX allocation010 Provider-based unicast100 Geographic multicast1111 1110 10 Link local address1111 1110 11 Site local address1111 1111 Multicast addressOther unassignedIPv4 Packet Format20 Byte minimumMandatory fields are not always usede.g. fragmentationOptions are an unordered list of (name, value) pairsTTLsource addressdestination addressoptions (variable)version length offsetident 0 8 16 31hdr len TOSflagschecksumprotocolpad (variable)IPv6 Packet Formatdestination address word 4options (variable number, usually fixed length)version flow label hop limitpayload length 0 8 16 31prioritynext headersource address word 1source address word 2source address word 3source address word 4destination address word 1destination address word 2destination address word 3IPv6 Packet Format40 Byte minimumMandatory fields (almost) always usedStrict order on options reduces processing timeNo need to parse irrelevant optionsoptions (variable number, usually fixed length)version flow label hop limitpayload length 0 8 16 31prioritynext headersource address 4 words destination address 4 wordsIPv6 Packet FormatVersion6Priority and Flow LabelSupport service guaranteesAllow “fair” bandwidth allocationPayload LengthHeader not includedNext HeaderCombines options and protocolLinked list of optionsEnds with higher-level protocol header (e.g. TCP)Hop LimitTTL renamed to match usageIPv6 Extension HeadersMust appear in orderHop-by-hop optionsMiscellaneous information for routersRoutingFull/partial route to followFragmentationIP fragmentation infoAuthenticationSender identificationEncrypted security payloadInformation about contentsDestination optionsInformation for destinationIPv6 Extension HeadersHop-by-Hop extensionLength is in bytes beyond mandatory 8next header typevalue0 8 16 31lengthnext header 194Payload length in bytes0 8 16 310 0Jumbogram option (packet longer than 65,535 bytes)Payload length in main header set to 0IPv6 Extension HeadersRouting extensionUp to 24 “anycast” addresses target AS’s/providersNext address tracks current targetStrict routing requires direct linkLoose routing allows intermediate nodesnext header # of addressesstrict/loose routing bitmap0 8 16 310 next address1 – 24 addressesIPv6 Extension HeadersFragmentation extensionSimilar to IPv4 fragmentation13-bit offsetLast fragment mark (M)Larger fragment identification fieldnext header offsetident0 8 16 31reserved reserved MIPv6 Extension HeadersAuthentication extensionDesigned to be very flexibleIncludesSecurity parameters index (SPI)Authentication dataEncryption ExtensionCalled encapsulating security payload (ESP)Includes an SPIAll headers and data after ESP are encryptedIPv6 Design ControversiesAddress length8 byteMight run out in a few decadesLess header overhead16 byteMore overheadGood for foreseeable future20 byteEven more overheadCompatible with OSIVariable lengthIPv6 Design ControversiesHop limit65,53532 hop paths are common nowIn a decade, we may see much longer paths255Objective is to limit lost packet lifetimeGood network design makes long paths unlikelySource to backboneAcross backboneBackbone to destinationIPv6 Design ControversiesGreater than 64KB dataGood for supercomputer/high bandwidth applicationsToo much overhead to fragment large data packets64 KB dataMore compatible with low-bandwidth lines1 MB packet ties up a 1.5MBps line for more than 5 secondsInconveniences interactive usersIPv6 Design ControversiesKeep checksumRemoving checksum from IP is analogous to removing brakes from a carLight and fasterUnprepared for the unexpectedRemove checksumTypically duplicated in data link and transport layersVery expensive in IPv4IPv6 Design ControversiesMobile hostsDirect or indirect connectivityReconnect directly using canonical addressUse home and foreign agents to forward trafficMobility introduces asymmetryBase station signal is strong, heard by mobile unitsMobile unit signal is weak and susceptible to interference, may not be heard by base stationIPv6 Design ControversiesSecurityWhere?Network layerA standard serviceApplication layerNo viable standardApplication susceptible to errors in network implementationExpensive to turn on and offHow?Political import/export issuesCryptographic strength issuesTransition From IPv4 To IPv6Not all routers can be upgraded simultaneousno “flag days”How will the network operate with mixed IPv4 and IPv6 routers? Tunneling: IPv6 carried as payload in IPv4 datagram among IPv4 routersTunnelingABEFIPv6IPv6IPv6IPv6tunnelLogical view:Physical view:ABEFIPv6IPv6IPv6IPv6IPv4IPv4TunnelingABEFIPv6IPv6IPv6IPv6tunnelLogical view:Physical view:ABEFIPv6IPv6IPv6IPv6CDIPv4IPv4Flow:
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