This is the ending address of the trusted router IP range, and when left at its default, equal to the start address, effectively an undefined range, the device forwards all leave and join messages to the router regardless of whether the multicast stream actually originates there, meaning the filtering behavior only narrows once an admin deliberately sets a real range spanning multiple addresses. An admin trying to reduce unnecessary join/leave signaling load on the router-facing link would define a real range here rather than leaving it at the default single-address, unfiltered, state. For example, setting the end address to 192.0.2.10 against a start of 192.0.2.1 would define a 10-address trusted router range, filtering out join/leave forwarding for any source outside that band.