STP : CST Root changed from mac-address to mac-address

[nqaddomi]

dear sir ,

kindly know that i configured my hp access switch rstp as follows :

Multiple Spanning Tree (MST) Information

STP Enabled : Yes
Force Version : RSTP-operation
IST Mapped VLANs : 1-4094
Switch MAC Address : 082e5f-d07c80
Switch Priority : 61440
Max Age : 20
Max Hops : 20
Forward Delay : 15

Topology Change Count : 1
Time Since Last Change : 6 hours

CST Root MAC Address : 609c9f-1eff00
CST Root Priority : 0
CST Root Path Cost : 42000
CST Root Port : 51

IST Regional Root MAC Address : 082e5f-d07c80
IST Regional Root Priority : 61440
IST Regional Root Path Cost : 0
IST Remaining Hops : 20

Root Guard Ports :
Loop Guard Ports :
TCN Guard Ports :
Protected Ports :
Filtered Ports :

--------------------------------------------------------------

the second sh span

Multiple Spanning Tree (MST) Information

STP Enabled : Yes
Force Version : RSTP-operation
IST Mapped VLANs : 1-4094
Switch MAC Address : 082e5f-d07c80
Switch Priority : 61440
Max Age : 20
Max Hops : 20
Forward Delay : 15

Topology Change Count : 1
Time Since Last Change : 6 hours

CST Root MAC Address : 082e5f-d07c80 
CST Root Priority : 61440
CST Root Path Cost : 0
CST Root Port : This switch is root

IST Regional Root MAC Address : 082e5f-d07c80
IST Regional Root Priority : 61440
IST Regional Root Path Cost : 0
IST Remaining Hops : 20

Root Guard Ports :
Loop Guard Ports :
TCN Guard Ports :
Protected Ports :
Filtered Ports :

------------------------------------

so it gives me when i show log

20:57:28 stp: CST Root changed from 61440:082e5f-d07c80 to
0:609c9f-1eff00

20:57:29 stp: CST Root changed from 0:609c9f-1eff00 to
61440:082e5f-d07c80

and so on.

so where is the problem ????

notice : i used brocade switch ICX-7250 with this ProCurve J9088A Switch 2610-48

and this is : sh 80 

SSH@PU-11-SW-1#sh 80

--- VLAN 999 [ STP Instance owned by VLAN 999 ] ----------------------------

Bridge IEEE 802.1W Parameters:

Bridge Bridge Bridge Bridge Force tx
Identifier MaxAge Hello FwdDly Version Hold
hex sec sec sec cnt
f000cc4e24e343ce 20 2 15 Default 3

RootBridge RootPath DesignatedBri- Root Max Fwd Hel
Identifier Cost dge Identifier Port Age Dly lo
hex hex sec sec sec
0000609c9f1eff00 22000 4000609c9f278620 1/2/2 20 15 2

Port IEEE 802.1W Parameters:

<--- Config Params --><-------------- Current state ----------------->
Port Pri PortPath P2P Edge Role State Designa- Designated
Num Cost Mac Port ted cost bridge
1/2/1 128 0 F F DISABLED DISABLED 0 0000000000000000
1/2/2 128 20000 T F ROOT FORWARDING 2000 4000609c9f278620
1/2/3 128 20000 F F DESIGNATED FORWARDING 22000 f000cc4e24e343ce
1/2/4 128 0 F F DISABLED DISABLED 0 0000000000000000
1/2/5 128 20000 T F DESIGNATED FORWARDING 22000 f000cc4e24e343ce
1/2/6 128 20000 T F DESIGNATED FORWARDING 22000 f000cc4e24e343ce
1/2/7 128 20000 T F DESIGNATED FORWARDING 22000 f000cc4e24e343ce
1/2/8 128 20000 T F DESIGNATED FORWARDING 22000 f000cc4e24e343ce

thanx alot