Spanning tree protocol

Hi,

how to validate RSTP BPDU flags
What are the required conditions...?
Quote:
I know few conditions like
1.when TC flag is set TCA should be reset in BPDU packet and vice versa
2.when proposal flag is set then port role must be designated port
3.when agrement flag is set then port role must be root port
4.In a valid BPDU only one flag should be set either TC or TCA bit, either
proposal or agrement bit.
I need few more conditions like when learning state is set and forwarding state is set.
I am receiving few BPDU's with both learning and forwarding state flag set,is it the valid BPDU or not?
to my Knowledge a port must be in one state it can't be in 2 states...how to validate these flags.
Please guide me.