[c-nsp] MST Configuration

[Nicolaj Ottsen]

I can thing of one reason for running more instances ... We use
different instances to control trafic direction, that way we "double"
our bandwith by having half the vlans running clockwise and the other
half running counter clok wise. 

Regards

Nicolaj





-----Original Message-----
From: Alexandra Alvarado [mailto:aaaa at telconet.net] 
Sent: 12. august 2004 00:39
To: cisco-nsp at puck.nether.net; Alexandra Alvarado
Subject: [c-nsp] MST Configuration

Hello,

The company where I work has a layer 2 networks, to have loop free, we
have been configured STP, but now STP is not enough because it only
support 128 instance it means 128 vlans.
I need to configure more than 128 vlans, that's why I'm going to move to
MST to group all
4094 vlans in 1 or 2 instance MST.

My questions:

1.- I read "By default, all VLANs are mapped to instance 0.". I want to
divide my vlans in 2
instance:

        instance 0 : Vlan 1-10
        instance 1: Vlan 11-4094

What is de advantage to manage all vlans in 1 instace?, or is better to
divide the vlans in more the one instance.  

If I use 2 instance inspite 1 MST instance the broadcast wil reduce?

2.- Is the next config right or can I improve it and how?

Primary Root
-------------------
spanning-tree mode mst
spanning-tree loopguard default
spanning-tree portfast bpduguard default no spanning-tree optimize bpdu
transmission spanning-tree extend system-id !
spanning-tree mst configuration
 name region1
 revision 1
 instance 1 vlan 11-4094
!
spanning-tree mst 0-1 priority 24576

Secondary Root
-----------------------
spanning-tree mode mst
spanning-tree loopguard default
spanning-tree portfast bpduguard default no spanning-tree optimize bpdu
transmission spanning-tree extend system-id !
spanning-tree mst configuration
 name region1
 revision 1
 instance 1 vlan 11-4094
!
spanning-tree mst 0-1 priority 28672

Other switches
-----------------------
spanning-tree mode mst
spanning-tree loopguard default
spanning-tree portfast bpduguard default no spanning-tree optimize bpdu
transmission spanning-tree extend system-id !
spanning-tree mst configuration
 name region1
 revision 1
 instance 1 vlan 11-4094
!


Cost per Interfaces
---------------------------
spanning-tree mst 0-1 cost 1



Thanks

Alexandra Alvarado
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