: some questions

Hi,
I am begginer in MPLS field. I have just started
reading MPLS. I have some questions (I tried to answer
myself but i want to confirm/correct/verify them!!)

Q1: Why each LSP created is unidirectional?
POSSIBLE ANSWER:
It is hardware dependent or It depends upon the label
distribution protocol e.g. in case of LDP it is
unidirectional but in case of RSVP it is
bidirectional? 

Q2: Upto what time LSP session persists? or in other
words when and how LSP is terminated?
POSSIBLE ANSWER:
It is terminated when there is request of termination
from upstream/downstream? (usual termination)
It may terminate when there is link failure or device
problem etc. (unusual termination).

Q3: LSP session is created for one time data
transmission (e.g. of all the packets of one FEC)? or
this session will continue for other packets which
arrive when upstream was delivering data?

Thanks a lot

Tahir