STP mode MST to STP mode RSTP

[Rafael Mendes]

Hello Everyone,

I have a network with spanning-tree mode mst, but, we want change this for spanning-tree mode rstp.

I have two cores(6500) and need know what is the better mode for change this with no impact in my network?

We dont have distributin layer, like a "topology" below.

ACCESS LAYER SWITCHES

                  |

                  |

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

|CORE1 ------ CORE2 |

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

                 |

                 |

           SERVERS

CORE1 CONFIG

spanning-tree mode mst

no spanning-tree optimize bpdu transmission

spanning-tree extend system-id

spanning-tree uplinkfast

spanning-tree backbonefast

!

spanning-tree mst configuration

name Balance

revision 1

instance 1 vlan 101, 103, 105, 107, 109, 111, 113, 115

instance 2 vlan 102, 104, 106, 108, 110, 112, 114, 116

instance 3 vlan 151-154

!

spanning-tree mst 1,3 priority 24576

spanning-tree mst 2 priority 28672

spanning-tree vlan 1 priority 8192

CORE2 CONFIG

spanning-tree mode mst

no spanning-tree optimize bpdu transmission

spanning-tree extend system-id

spanning-tree uplinkfast

spanning-tree backbonefast

!

spanning-tree mst configuration

name Balance

revision 1

instance 1 vlan 101, 103, 105, 107, 109, 111, 113, 115

instance 2 vlan 102, 104, 106, 108, 110, 112, 114, 116

instance 3 vlan 151-154

!

spanning-tree mst 1,3 priority 28672

spanning-tree mst 2 priority 24576

spanning-tree vlan 1 priority 16384

Any ideas?

Tks a lot.

Rafael

[Rafael Mendes]

Up!

[Kyle McKay]

May I ask what your goals are for this migration? MST has similar convergence timers to RSTP and is (in my opinion) a better choice to begin with, it offers a more scalable, customizable STP topology.

[Rafael Mendes]

I need to migrate this becasuse the time of convergence in my network.

I want to know what is the best way to do this.

[Peter Paluch]

Rafael,

I absolutely agree with Kyle and Karthik here - MSTP is internally built on RSTP and if properly configured, it has the same speed of convergence. If you are having issues with MSTP convergence times then it is not configured properly, and you are not going to save yourself any work by performing a network-wide downgrade to RSTP. You could even run into issues if the number of VLANs created in your network exceeds the maximum count of allowed STP instances on your switches.

It would be better to inspect your MSTP configuration. How large is your network, how many switches are there and what is their MST configuration? How do you measure the convergence times and how exactly do you know there is a problem with it?

Best regards,

Peter

[Rafael Mendes]

Hello Peter,

Sorry, i really don't know that.

I Have 50 access switches, and 2 core switches, connected in hight availability, like below.

ACCESS LAYER SWITCHES

       |                       |  

       |                       |

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

|CORE1 ------ CORE2 |

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

                 |

                 |

         SERVERS

MST configuration os present in my first post.

So, what is the better config? MST? RSTP? In the access switches, what is the best configuration? MST witch bpduguard and portfast?

Tks a lot!

[Karthik Kumar Thatikonda]

Hi,

When MST is configured, RSTP is automatically enabled. To test enable "spanning tree portfast" on a port going to host and check sh spanning-tree mst you would see edge ports as in RSTP.