Thanks for that interesting lesson.
I have some simple questions :
**-1-**
For fixing the issue by the “sub-interfaces” solution ; I guess, there will create 2 sub-interfaces (one for each PVC) ? I guess also that the 2 sub-interfaces will be configured with 2 different subnets ? According to my understanding of split-horizon ; 1 (only 1) sub-interface on R1 will have the same point-to-multipoint issue as the physical interface ?
**-2-**
I do not understand how the tunnel between R2 and R3 could work, if there’s no PVC between the two routers and there is nothing on R1 for “forwarding” information between R2 and R3.
**-3-**
By the way ; there’s a copy/paste error in first configuration lines. See below :
**R1**(config)#interface serial 0/0
R2(config-if)#ip pim sparse-dense-mode
**R1**(config)#interface serial 0/0
R3(config-if)#ip pim sparse-dense-mode