Département Réseau, Sécurité et Multimédia Rapport d'Activités 2008

• - L2TP messages are carried over UDP tooffer NAT-traversal capabilities,• - PPP is used to carry IPv6 frames, so wecan rely on built-in authentication andconfiguration mechanisms, and have veryeasy interaction with AAA servers.• - PPP and L2TP hello messages may beused to detect when a tunnel is down, forinstance due to an IPv4 addressrenumbering and maintains contexts intothe NAT Box.The Point6Box removes the L2TPencapsulation and forwards incoming IPv6packets on the link. Generally SME or Homerouters interfaces are bridged with an IEEE802.11 network, so every equipmentconnected to that network will receive RouterAdvertisements. IPv6 traffic generated bythese equipments will be routed through thePoint6Box. IPv4 traffic will continue to beNATed by the IPv4 edge router.The Point6 Provider Edge is connected to theIPv6 backbone. It includes the server part andcan be connected to an AAA database to allowauthorization and monitoring. The followingpicture describes the service architecture.RADIUSserverDHCPv6serverIPv4/v6 ISPL2TP IPv6ServerDHCPv6 relayPE v6Connexion AccountingL2TP tunnelDHCPv6 request and replyRADIUS authorizationIPv6IPv4PE v4CPE v4NATb r i d g eCPE v6Point6 ClientXYZStateless autoconfusing RA mechanismFE80::XA:B:D:101::XFE80::YA:B:D:101::YFE80::ZA:B:D:101::ZAuto-configuration of the SME/Home networkis a major feature to rapidly spread IPv6. If theSME/Home network includes several routersconfiguration for IPv4 requires technical skills.We have study several approaches to offerinternal routers configuration (see[AINA2005]). In this proposal, we focus onDHCPv6 because it does not require anymodification, even if this approach is lessefficient in case of multi-homing.The Point6Box includes a DHCPv6 server toanswer the requests inside the domain. Thestatic parameters such as DNS resolver andthe DNS domain are given to other routers andA:B:D:101::1a pool of /64 prefixes is a constructed basedon the prefix received from the provider. Aninternal router will execute the followingalgorithm, when one of its interface getsconfigured through the Neighbor Discovery(ND) protocol:• - The router sends DHCPv6 requests for a/64 prefix (the interaction with ND asexplained in [2] is used to detect loops ordual prefixes allocation),• - The router waits for answers from thePoint6Box containing the prefix and otherparameters,• - The router assigns prefixes to interfaces.It starts unicast and multicast routing anda DHCPv6 relay. The relay functionality isused to allow downstream routers to talkwith the DHCPv6 server.At this point, the internal routers areconfigured, the equipment addresses can besetup through standard Neighbor Discoveryprotocol and other parameters throughDHCPv6.Future worksThe protocol used in the Point6Box is nowstandardized. We will now focused oninteroperability of Softwires equipement. TheRoHC protocol is being integrated as a featureto decrease the overhead of the tunnel. Weare also studying the interest of a Point6Boxsolution to provide IPv4 connectivity over IPv6network.References[1] B. Storer, C. Pignataro, M. Dos Santos J.Tremblay, B. Stevant, “Softwires Hub & SpokeDeployment Framework with L2TPv2”, draftietf-softwire-hs-framework-l2tpv2-08,.Work inProgress.[2] Chelius, G., Fleury, E., and L. Toutain, "NoAdministration Protocol (NAP) for IPv6 RouterAuto-Configuration", AINA 2005 IEEE 19thInternational Conference on AdvancedInformation Networking and Applications,March 2005.Pracom’s Annual Report 2008 7