Nexus Mstp And Mxl Mstp - Greater Than 64 Instances; Nexus Rapid Pvst+ And Mxl Pvst Observations - Dell Force10 C150 Manual

Deploying the Dell Force10 MXL into a Cisco Nexus Network Environment
Root Bridge. This scenario was observed with only a single ping being lost during the failback,
indicating that the re-convergence took about 1 second.
3) Failover: Backbone Failure Simulation (Backbone Fast). In this test a shutdown was issued on
N5K1's interface 1/25. This caused MXL2 to place its interface 1/43 interface into the Role of
Designated. This scenario was observed with only a single ping being lost, indicating that the
re-convergence took about 1 second.
4) Failback: Backbone Failure Simulation (Backbone Fast). ). In this test a no shutdown was
issued on NX5K1's interface 1/25. This caused STP on MXL2 to place its interface 1/43 into a
Role of Alternate. This scenario was observed with only a single ping being lost, indicating that
the re-convergence took about 1 second.
Nexus MSTP and MXL MSTP – Greater than 64 Instances
The Force10 MXL supports up to 64 MSTIs (Multiple Spanning Tree Instances). MSTI 0 is reserved for
the CIST (Common Internal Spanning Tree) leaving Multiple Spanning Tree Instances 1 – 63 on which
VLANs can be assigned. In the event that the Nexus switches are using more than 64 Instances, then
the question arises regarding how to configure and interoperate with the Force10 MXL blade
switch. The best practice is that VLANs assigned to instances greater than 63 on the Nexus
switches, should be left to default to MSTI 0 (Common Internal Spanning Tree) on the Force10 MXL
blade switch. The previous six tests were conducted in 2 MSTP environments:
1) VLANs on Multiple Spanning Tree Instances in the 1 – 63 range.
2) VLANs left on Multiple Spanning Tree Instance 0 (CIST) as the Instance numbers as assigned
on the Nexus switches could not be matched since they were greater than 63.
The failover / failback results described above were observed in both environments.

Nexus Rapid PVST+ and MXL PVST Observations

As previously mentioned, the Nexus switches can run in one of two Spanning Tree modes, MSTP or
Rapid PVST+
Here is the command for configuring the Nexus Switches to run Rapid PVST+:
N5K2#configure
N5K2 (conf)#spanning-tree mode rapid-pvst
N5K2 (conf)#exit
N5K2#
The process for configuring the MXL switch to run MSTP:
First, check to see if STP is already configured. If it is, then disable and remove it from the
configuration, before configuring PVST.
Determine if Spanning Tree is already enabled
In this example, RSTP is already running so it was disabled before configuring PVST.
MXL2#show run | grep spanning
protocol spanning-tree rstp
MXL2#configure
MXL2#protocol spanning-tree rstp
38