Networkshop 34 - Multicast Questions

• Where does the Mac address to Multicast address mapping occur? - Hosts and Routers?? [slide 11]
• Which address is elected for the IGMP querier, higher or lower address? - Lower [slide 14]
• Do you send an IGMP(v2) report for each group you wish to join? - Yes [slide 15]
• If an IGMPv2 report is seen the router will fall back to v2, if you upgrade the host when will the router upgrade to v3? v2 & v3 are set per group and thus if there is a v2 client then that group will be v2. A timeout is used to enable that group to be v3 again in the future. [slide 20]
• Do you have to enable IGMP snooping on switches? You need to turn it on specifically on most switches, it's on by default with Cisco routers [slide 25]
• What is the multicast address 239.255.255.250? - plug and play
• What is the multicast address 224.0.1.40? - cisco auto rp discovery
• How do we see in Windows which multicast groups have been joined? - netsh -> interface -> ip -> show joins
• When would you use PIM Dense Mode? When you're sure almost every host wishes to receive the multicast traffic.
• Is the MRIB checked for every multicast packet? - Yes.
• Is the DR specifically set up?
• Can you have dual RP's for fail over?
• When creating the SPT, will the Receive DR fail the RPF check? - No as it checks the source address first and then tries the RP address if the source address is not known.
• Turnabout router - why didn't the RP prune the join?
• What happens if you have two local RP's handling the same group[s]?
• Explain include and exclude mode in IGMPv3?
• Why do you have to use MBGP for multicast when we're using static unicast routes?