Basicaly,the answer is yes,but not always…
Consider these…
1.suppose your hub site is directly connected to ur bsc with 16*2m channel. One of d channel is droped at that site,and rest 15 r forwarded…then if the link bet’n bsc n hub site gets down,all depended sites including hub will be down….
Now,
2.same 16*2m is connected bet’n bsc n hub..but hub site is getting e1 from another hop having 8*2m (or whatever)..
Now,in this case if any link gets down,not all depending sites will be down….
(exceptions r always there…what during d power issue….?!!!)