nx.os.and.cisco.nexus.switching.2nd.edition.1587143046

Congo(config)# spanning-tree mst 2 root secondary
Example 2-37 shows how to verify the configuration of an MST instance.
Example 2-37. MST Verification
Click here to view code image
Congo# show spanning-tree mst 1
##### MST1 vlans mapped: 1-10
Bridge address
001b.54c2.bbc1 priority 4097 (4096 sysid 1)
Root
this switch for MST1
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- -------------
-------------------
Po100 Desg FWD 1000 128.4195 Network P2p
Eth2/1 Desg FWD 20000 128.257 Network P2p
Bound(PVST)
Congo#
The example shows that Congo is the root bridge for MST instance 1, which has VLANs 1–
10 mapped to it.
Additional Spanning Tree Configuration
The following sections cover the configuration required to manipulate some additional
spanning tree parameters.
Port Cost
Port cost is used to calculate the shortest path to the root bridge. By default, port costs are
automatically calculated by the device based on the transmission speed of the physical link.
Table 2-1 illustrates the default port costs.
From time to time, it might be necessary to statically define port costs; an example of this is
with port-channels in which the cost might change depending on the number of links active
within the bundle.
Table 2-1. Default Spanning Tree Costs