[c-nsp] Question about Multiple Spanning Tee (MST)

[Andy Saykao]

Hi All,
 
Our switch network needs to be migrated from PVST+ to MST in order for
our Cisco switches to be able to speak RSTP to some non-cisco switches.
Given that we have a few hundred vlans configured, is there some best
practice to determine how many instances we need or can we basically do
whatever we want?
 
For example:
 
Option 1/ If we have 500 vlans, do we split them into two instances
(instance 1 vlan 1-250 and instance 2 vlan 251-500). 
 
Options2/ Or would you split the vlans up based on their business
requirements.
Eg: vlan 1,10,100 Marketing-related vlans, vlan 2,20,200 Sales-related
vlans - therefore create instance 1 vlan 1,10,100 and instance 2 vlan
2,20,200???
 
Secondly, what if you went with option 2, and added a new vlan into
Marketing (eg: vlan 1000). Would you have to manually update the
spanning-tree mst config on all MST switches to include the new vlan in
the instance??? 
 
Thanks.
 
Andy
 
 

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