In an MPLS environment with above scenario I am learning 0.0.0.0/0 route from CE1 (As-path contains one AS) at PE1 and from CE2 (AS-path contains three AS) at PE2 . In this case route from PE1 will became best even at PE2.
PE2 has installed route 0.0.0.0/0 from PE1 as best one because it contains shortest AS-PATH
Does PE2 shows this 0.0.0.0/0 (Non-best route) in advertised route to RR. if not why?
Thanks in advance
>> Does PE2 shows this 0.0.0.0/0 (Non-best route) in advertised route to RR. if not why?
No, PE2 shouldn't advertise back 0.0.0.0/0 to RR because its best path is learned from RR itself.
See this as a split-horizon loop avoidance rule.
So a side effect of PE2 installing the route coming from PE1 is that PE2 stops to advertise the 0.0.0.0/0 received from CE2.
if you want PE2 to still advertise that prefix you need to use weight or local preference to make PE2 to prefer the eBGP path from CE2
Hope to help