1. as per my understanding about the OSPF downbit, this bit is set by the receiving PE router that redistributes the route from MP-iBGP to OSPF.
just read the following from MPLS-Fundamentals:
"The PE2-AS1 router receives the external (O E1) OSPF route from CE2-A with the OSPF down bit set and then redistributes it into MP-BGP"
as per my understanding the above statement may be right, because of following ospf rule:
"If an ABR receives a summary LSA from a non-backbone area, it should ignore the summary if it has connectivity to area "since as per above figure CE2-A is an ABR (since connected to area-0).
but here comes another query:
"The PE will propagate summary LSAs received from the CE into the OSPF-MPLS/VPN backbone only if the down-bit is not set."
how will the PE accept a route whose down-bit is set ????????????