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Check Spanning tree status.
Hello,
I having configed MST like following:
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spanning-tree mode mst
spanning-tree mst configuration
instance 1 add vlan 2-4093
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Q. However, when I check the spanning tree status in below, it give out two spanning tree summary, so which one I should follow up?
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#show spanning-tree
Spanning Tree: Enabled BPDU Flooding: Disabled Portfast BPDU Filtering: Disabled
Mode: mst
CST Regional Root: 80:00:F8:B1:56:0F:2D:E5
Regional Root Path Cost: 0
###### MST 0 Vlan Mapped: 1
ROOT ID
Priority 32768
Address 0014.2287.351B
Path Cost 20200
Root Port Te2/0/21
Hello Time: 2s Max Age: 20s Forward Delay: 15s
Bridge Max Hops: 20
Bridge ID
Priority 32768
Address F8B1.560F.2DE5
Hello Time: 2s Max Age: 20s Forward Delay: 15s Transmit Hold Count: 6s
###### MST 1 Vlan Mapped: 2-4093
ROOT ID
Priority 32768
Address F8B1.560F.2DE5
Path Cost 0
Root Port
Bridge ID
Priority 32768
Address F8B1.560F.2DE5
Hello Time: 2s Max Age: 20s Forward Delay: 15s Transmit Hold Count: 6s
======================
Thanks!
DELL-Josh Cr
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April 13th, 2017 10:00
Hi,
Since you configured Multiple Spanning tree, both are being used just on different VLANs. Instance 0 is VLAN 1 and instance 1 is all of the other VLANs.
jammac
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April 13th, 2017 15:00
Josh's answer is not wrong, but doesn't explain a thing...
MSTI 0 is called the CIST, the Common and Internal Spanning Tree. If you google, you will find lots of docs. You should especially be aware about the concept of regions once you start using MSTP.
But why did you configure Multiple Spanning Tree in the first place? My advice is: if you don't know what it is, then you probably don't need it, so don't use it. You'll do better with RSTP because it will be much simpler. RSTP has no disadvantages in case you believe that MSTP is "better" than RSTP.
While RSTP would allow you to use only one topology, that is, only one of a pair of redundant links can be used, MSTP allows you to use some VLANs on one of the redundant links and other VLANs on the other, therefore increasing your aggregate throughput. However, since they were redundant links, you should plan such that you don't get into trouble in case one of the redundant link actually fails.
Hope I gave you enough keywords. Read up on it, or forget it.