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MRIB Multicast Routing Information Base Site NREN PIM-SMv2 MLD snooping, CGMP… eMBGP & iMBGP MLD / IGMP multicast applications Multicast network topology ISP’ ISP Native multicast All network on the path are multicast enable Æ no problem Multicast network topology ISP Network not supporting multicast Æ Tunnels required Multicast tunnels Logical interface, abstracting underlying infrastructure Tunnel = logical point to point interface Multicast packets are encapsulated in unicast packets IPv4 multicast in IPv4 unicast IPv4 multicast dans GRE dans IPv4 unicast … A tunnel can be configured almost like any other physical interface Metrics Adresses … Multicast tunnels IP multicast packet IPv4 unicast header IPv4 multicast header Payload Payload of the unicast packet Æ Transparent for non multicast routers Topologies Multicast • Native • • • • • Much simpler to manage! No tunnels Routing is simpler Troubleshooting is much easier … • Not native • Encapsulation of multicast packets in unicast packets • Mind the routing protocols (precedence...) • MTU is smaller MRIB: Multicast Routing Information Base Site A B ISP unicast B Tunnel A A Routing Information Base (RIB) Multicast routing Information Base (MRIB) Site B MRIB: Multicast Routing Information Base • 2 instances of the routing table • One for unicast routing (RIB) • One for multicast routing (MRIB) • Better precedence for MRIB • Each table must respect the related topology • Multicast table • Static routes • MP-BGP • Multiprotocol extension for BGP4 • Address family (ipv4, ipv6, ipv4 multicast, ipv6 multicast, mpls …) Peupler la MRIB • Static routes ip mroute prefix mask @dest • MBGP (Multi-protocol BGP) router bgp 65051 neighbor 194.254.101.1 remote-as 1717 address family ipv4 multicast neighbor 194.254.101.1 activate exit-address-family • Multi-Topology IGP’s (coming soon !) • ... MRIB • Why ? • RPF check • PIM • MSDP • When unicast and multicast topologies are the same, you can forget the MRIB! • Maybe more appropriate for sites... PIM & MRIB • PIM must know where to send (*,G) and (S,G) joins/prunes • RPF on * et S to learn interfaces for sending the messages • PIM relies completely on the MRIB MSDP & MRIB • Can be very comlpex… linked with MBGP ! • Details to come later… DP MS MSDP PIM MBGP PIM GP B M RPF check in reality • CISCO : • Pas de MRIB per se (arrive bientôt!) sh ipv6 mrib • 1. 2. 3. 4. ne montre pas la MRIB !!! IPv6 RPF check: Removes BGP table by default. Can be enabled by ipv6 rpf use-bgp Longest match over all routing protocols tables (as unicast lookup) Look also in multicast BGP table and static multicast routes Break ties using administrative distances • • • • show ipv6 rpf ipv6-addr Differences to IPv4 RPF check: Unicast BGP routes disabled by default Longest match over all protocols is done. No option to configure it Recursive lookup is allowed in unicast routing table AND MP-BGP table Le RPF check en pratique • JUNIPER : • • sh multicast rpf inet6 ipv6-addr MRIB really implemented Table inet.2 populated with • • • MP-BGP Static routes For IPv4, RPF is made using inet.2 then inet.0 RPF check et IGP Routeur B Loopback = @B Non-multicast router Routeur A Loopback = @A • • Peering iMBGP A sends prefix P to router B using iMBGP RPF check for P on router B • • iMBGP says neighbor = @A Recursive lookup on @A avec IGP...