Unicast flooding seen when using MST

Folks,

We have an issue of unicast flooding in our network when we use MSTP.
the topology is like this. Would like to see if anyone has seen similar issue
in their networks
When we add trunk link to the csw's or when we bounce the
trunk we see the flooding also the MAC table doesn't flush. What things would
you check in such a scenario? please share if you had any previous
experiences..

csw01---asw---csw02. asw is connected to both csw01 and csw02
and MSTP is running between them.

eat1-22164-csw02.corp# sh spanning-tree int
eth2/9-----------> this link connects to t1/50 of asw

Mst Instance Role
Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
MST0000 Desg FWD 2000 128.265
 P2p

MST0001 Desg FWD 2000 128.265 P2p
eat1-22164-csw01.corp# sh spanning-tree int eth2/9------------> this link
connects to t1/49 of asw

Mst Instance Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
MST0000 Desg FWD 2000 128.265 P2p

MST0001 Desg FWD
2000 128.265 P2p

eat1-22164-asw324.corp#sh spanning-tree int t1/49
Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ----
--- --------- -------- --------------------------------
MST0
 Root FWD 2000 128.49 P2p Bound(RSTP)
MST1 Mstr FWD
2000 128.49 P2p Bound(RSTP)

eat1-22164-asw324.corp#sh spanning-tree
int t1/50

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
MST0 Altn BLK 2000 128.50
  P2p Bound(RSTP)
MST1 Altn BLK 2000 128.50 P2p
Bound(RSTP)

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Received on Sun Dec 16 2012 - 04:03:35 ART