IPv6 Protocol

IPv6 Protocol (headers & options) 6DEPLOY. IPv6 Deployment and SupportCopy …RightsThis slide set is the ownership of the 6DISS project via its partnersThis slide set is the ownership of the6DISS project via its partnersThe Powerpoint version of this material may be reused and modified only with written authorization Using part of this material must mention 6DISS courtesyPDF files are available from Looking for a contact ?•Mail to : martin.potts@martel-consulting.ch•Or bernard.tuy@renater.fr2Droits d’auteur …L ensemble des présentations utilisées dans le cadre de cet atelier est la propriété de 6DISS,L’ensemble des présentations utilisées dans le cadre de cet atelier est la propriétéde6DISS représenté par ses différents partenaires.La version Powerpoint des présentations peut être réutilisée et modifiée après qu’une autorisation écrite ait été obtenueL’usage de tout ou partie de ce matériel doit mentionné que sa source est le projet 6DISSLa version PDF des présentations est disponible sur p p gPour tout contact :•Mail à Martin.Potts@martel-consulting.ch•Ou Bernard.Tuy@renater.fr3ContribsB. Tuy, RENATER,L. Toutain, ENST-BUpdatesB. Tuy20/05/2008AgendaIPv6 HeaderIPv6Header•Comparison with IPv4IPv6 optional headers (extensions) IPv6optional headers(extensions) Processing IPv6 headers•Comparison with IPv4Comparison with IPv4IPv6 HeaderThe IPv6 header is designed•To minimize header overhead•and reduce the header process for most of the packets and reduce the header process for most of the packets •Less important information and option fields are moved toextension headers⇒IPv6 & IPv4 headers are not interoperableIPv4 Header32 bitsVer.Total Length e sToS IHL fragmentIdentifier flags B y t TTL ProtocolChecksum So rce Address 20Source Address Destination AddressOptions32 bitsIPv6 Header simplificationVer.Hop LimitPayload length Flow labelNext Header Traffic ClassHop Limit Payload length Next Header Source Addresst e s40 B y Destination Address(Extensions)DataIPv6 header fieldsVersionV i• 4 bitsTraffic class(next slide)Traffic class (see next slide)•8 bitsFlow label (see next slide)•20 bitsPayload lengthUse Ju bog a o spec c cases(pay oad0)•Use Jumbogram for specific cases (payload = 0)•16 bitsHop limit8bits•8 bitsNext header•8 bitsThe Traffic Class field:used as in IPv4CoS support in IPv6The Traffic Class field: used as in IPv4•Work done in diffserv wg (closed): RFCs 2474, 2475, 2597, 3260, …6 bits 2 bitsCU is Currently Unused (reserved)DSCP CUThe Flow Label field: designed to enable classification of packets belonging to a specific flow• A flow is a sequence of packets that should receive specific non-default handling from the network•Intuitively: 5-tuple of the same source/destination address/port and transport protocol valuesWithout the flow label the classifier must use transport next header value and port •Without the flow label the classifier must use transport next header value and port numbersLess efficient (need to parse the option headers)May be impossible (fragmentation or IPsec ESP)•Further info:RFC 3697 (PS)IPv6: optional ExtensionsNew mechanism replacing IPv4 optionsNew“mechanism”replacing IPv4optionsAn IPv6 extension :•Every extension has its own message formatIs a n x 8byte datagram•Is a n x8-byte datagram•Starts with a 1-byte ‘Next Header’ fieldPointing to either another extension or a L-4 protocol p y p(j g,)Hop-by-hop (jumbogram, router alert)•Always the first extension•Analyzed by every router.DestinationRouting (loose source routing) FragmentationSecurityecu y•Authentication (AH)•Encapsulating Security Payload (ESP) : confidentialityOrder is important (RFC 2460)IPv6Hop by hopProcessed by every router DestinationProcessed by routers listed in Routing extension List of routers to cross RoutingFragmentationList of routers to cross Processed by the destination AuthenticationSecurityAfter reassembling the packet Cipher the content of the remaining information DestinationProcessed only by the destinationUpper LayerIPv6: Optional headersIPv6 Header Next Header= TCP TCP Header + DATAIPv6 HeaderRouting Header TCP Header Next Header= Routing Next Header = TCP TCP Header + DATAIPv6 HeaderNe t Header Routing Header Ne t Header TCP Header Fragment Header Next Header= Routing Next Header = Fragment + DATA Next Header = TCPIPv4 header options processingAR1A -> BA -> R1R1Bp pIPv4 options : processed in each routerslow down packetsBIPv6 ext. header processingAR1A -> R1 A -> BB R1IPv6extensions (except Hop-by-Hop)are processed onlyby the destination.by the destinationBConclusionMain changes in IPv6 protocol are within address format and datagram headersA l t f fi ld i th IP6h d h• A lot of fields in the IPv6 header have disappeared⇒More efficient processing in the (intermediate) routers More efficient processing in the(intermediate)routers •Optional extensions allow more functionalities (source routing, authentication, …)(source routing,authentication,…)•Optional header mechanism allows new options introduction without modifying the protocoly g pQuestions …。