Operation Manual – MulticastH3C S5500-EI Series Ethernet SwitchesChapter 9 Multicast Routing andForwarding Configuration9-6z Request, with the IGMP Type field set to 0x1F, andz Response, with the IGMP Type field set to 0x1E.III. Process of multicast traceroute1) The querier sends a query to the last-hop router.2) Upon receiving the query, the last-hop router turns the query packet into a requestpacket by adding a response data block containing its interface addresses andpacket statistics to the end of the packet, and forwards the request packet viaunicast to the previous hop for the given multicast source and group.3) From the last-hop router to the multicast source, each hop adds a response datablock to the end of the request packet and unicasts it to the previous hop.4) When the first-hop router receives the request packet, it changes the packet typeto indicate a response packet, and then sends the completed packet via unicast tothe multicast traceroute querier.9.2 Configuration Task ListComplete these tasks to configure multicast routing and forwarding:Task RemarksEnabling IP Multicast Routing RequiredConfiguring Multicast Static Routes OptionalConfiguring a Multicast Route Match Rule OptionalConfiguring Multicast Load Splitting OptionalConfiguring a Multicast Forwarding Range OptionalConfiguring the Multicast Forwarding Table Size OptionalTracing a Multicast Path Optional9.3 Configuring Multicast Routing and Forwarding9.3.1 Configuration PrerequisitesBefore configuring multicast routing and forwarding, complete the following tasks:z Configure a unicast routing protocol so that all devices in the domain areinteroperable at the network layer.z Enable PIM (PIM-DM or PIM-SM).Before configuring multicast routing and forwarding, prepare the following data:z The minimum TTL value required for a multicast packet to be forwardedz The maximum number of downstream nodes for a single route in a multicastforwarding table
