I have three switches I'd like to configure in a loop - a Cisco stack (3750s) and two HP 2900 series. Each is connected to the next with a 10 gig backplane of one form or another.

How do I configure the spanning tree on these systems to make this function correctly? From the documents I've looked at it looks like I need to set both sets of hardware to use MST mode but I'm not sure past that point. The trunking, etc is all set up as needed.

HP Switch 1 A4 connected to Cisco 1/0/1. HP Switch 2 B2 connected to Cisco 2/0/1. HP Switch 1 A2 connected to HP Switch 2 A1.

HP Switch 1

show spanning-tree

Multiple Spanning Tree (MST) Information

  STP Enabled   : Yes
  Force Version : MSTP-operation
  IST Mapped VLANs : 1-4094
  Switch MAC Address : 0021f7-126580
  Switch Priority    : 32768
  Max Age  : 20
  Max Hops : 20
  Forward Delay : 15

  Topology Change Count  : 352,485
  Time Since Last Change : 2 secs

  CST Root MAC Address : 0018ba-c74268
  CST Root Priority    : 1
  CST Root Path Cost   : 200000
  CST Root Port        : 1

  IST Regional Root MAC Address : 0021f7-126580
  IST Regional Root Priority    : 32768
  IST Regional Root Path Cost   : 0
  IST Remaining Hops            : 20

  Root Guard Ports     :
  TCN Guard Ports      :
  BPDU Protected Ports :
  BPDU Filtered Ports  :
  PVST Protected Ports :
  PVST Filtered Ports  :

                  |           Prio            | Designated    Hello
  Port  Type      | Cost      rity State      | Bridge        Time PtP Edge
  ----- --------- + --------- ---- ---------- + ------------- ---- --- ----
  ...
  A1              | Auto      128  Disabled   |
  A2    10GbE-CX4 | 2000      128  Forwarding | 0021f7-126580 2    Yes No
  A3    10GbE-CX4 | Auto      128  Disabled   |
  A4    10GbE-SR  | 2000      128  Forwarding | 0021f7-126580 2    Yes No

HP Switch 2

show spanning-tree

 Multiple Spanning Tree (MST) Information

  STP Enabled   : Yes
  Force Version : MSTP-operation
  IST Mapped VLANs : 1-4094
  Switch MAC Address : 0024a8-cd6000
  Switch Priority    : 32768
  Max Age  : 20
  Max Hops : 20
  Forward Delay : 15

  Topology Change Count  : 19,623
  Time Since Last Change : 32 secs

  CST Root MAC Address : 0018ba-c74268
  CST Root Priority    : 1
  CST Root Path Cost   : 202000
  CST Root Port        : A1

  IST Regional Root MAC Address : 0024a8-cd6000
  IST Regional Root Priority    : 32768
  IST Regional Root Path Cost   : 0
  IST Remaining Hops            : 20

  Root Guard Ports     :
  TCN Guard Ports      :
  BPDU Protected Ports :
  BPDU Filtered Ports  :
  PVST Protected Ports :
  PVST Filtered Ports  :

                  |           Prio            | Designated    Hello
  Port  Type      | Cost      rity State      | Bridge        Time PtP Edge
  ----- --------- + --------- ---- ---------- + ------------- ---- --- ----
  ...
  A1    10GbE-CX4 | 2000      128  Forwarding | 0021f7-126580 2    Yes No
  A2    10GbE-CX4 | Auto      128  Disabled   |
  B1    SFP+SR    | 2000      128  Blocking   | a44c11-a67c80 2    Yes No
  B2              | Auto      128  Disabled   |

Cisco Stack 1

show spanning-tree

...    (additional VLANs)

VLAN0100
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0018.bac7.426e
             Cost        2
             Port        107 (TenGigabitEthernet2/1/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32868  (priority 32768 sys-id-ext 100)
             Address     a44c.11a6.7c80
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Te1/1/1             Desg FWD 2         128.53   P2p
Te2/1/1             Root FWD 2         128.107  P2p