Debug outputs

EIGRP IPv6 Debug on 3 routers

R2  serial int 1/1 shut down

09:30:59.997   time when shut

09:31:02.957 confirmed link down on the router itself

R1receives query packet on int. fec0::3:0/112  Link-coal address fe80::172:16:4:2

09:31:26.633

09:31:41.181 second query processing

09:31:41.277 confirmed down removed from table

R3 receives holding time expiry

09:31:25.253

09:31:46.017 finally confirmed down

To calculate the time taken to process change= 09:31:46.017 minus 09:30:59.997secs

Which equals  46.026seconds.  This the time taken for the routers to have the same information –convergence of the network.