You might have done it already but let me ask this again?   Tried to set pim spt threshold to 0? ip pim spt-threshold 0 Maybe try highly aggressive igmp query interval. Not highly advisable but still to check results?ip igmp query-interval 5ip igmp q...

Can you please share how much delay (in seconds) you see when you power off the Core Switch A? Where are the receivers and source? Connected to same LAN or another site connected by routing? Were you able to isolate if it is only the Multicast traffi...

ip igmp query-interval To configure the frequency at which the IGMP querier sends IGMP host-query messages from an interface. The IGMP querier sends query-host messages to discover which multicast groups have members on the attached networks of the r...

Yes, sure. You can use below document for understanding BGP with two ISPs.https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/217964-configure-sample-for-bgp-with-two-differ.htmlDocument for BGP on ASA:https://www.cisco.com/c/en...

thanks for sharing this information. pretty helpful.