2002 - cesnet

Missing in this list are especially universities and institutes of the Czech Academyof Science, connected through the Pasnet – Prague metropolitan network,which does not support IPv6. We have already initiated some negotiations and,hopefully in 2003, we will manage to connect these institutions through Pasnet.The prefix 2001:718::/48 has been reserved for the needs of backbone networkaddressing. Individual backbone connections are allocated networks withthe mask length of 64 bits. Loopback interfaces are addressed from the prefix2001:718::/64.5.2.4 Internal RoutingAs the interior routing protocol (IGP) we use RIPng combined with BGP. TheRIPng protocol is the only IGP supported for IPv6 by both platforms used inthe backbone network (Zebra and Cisco IOS). Its disadvantages (particularlythe slow convergence) are, to a great extent, eliminated by the method of use:RIPng is used only for propagating information about the reachability of thebackbone prefixes, while external networks are routed with the use of an internalBGP. In other words, RIPng serves only for the identification of the nexthop for BGP. Next year, we would like to test other alternative IGP’s whoseimplementations have lately appreared in the beta versions of Cisco IOS andZebra – OSPFv3 and IS-IS.The IBGP protocol is configured in the backbone network with the use of reflectorsaccording to [RFC2796] (BGP route reflector). Two reflectors are usedin order to ensure higher robustness – prg-v6-gw and r1-prg. Other backbonenetwork routers have BGP sessions only with these two reflectors.5.2.5 External ConnectivityThe exchange of routing information with neighbouring autonomous systems issubject to the rules of the 6NET network, enabling individual partners to informthe 6NET core about the prefixes of their own National Research and EducationNetwork (NREN), as well as the prefixes of other networks, with which NRENmaintains peering. Other partners can make use of the 6NET network transitfor their access to these external entities. However, two external entities cannotcommunicate with each other through 6NET.In order to implement these rules, 6NET uses the BGP community mechanism[RFC 1997] within its autonomous system 6680:High-speed National Research Network and its New Applications 200267