Multiple Spanning Tree (MST)

Hello Rahul

Yes you’re right, and thanks for catching that. That’s a typo in the configuration output, it should be SW4. I’ll let Rene know to make the change.

The statement should read:

Here’s VLAN 10, which is mapped to instance 1. SW4 sees SW1 as the root bridge for this VLAN even though we configured SW2 as the root bridge for instance 1. This is perfectly normal because MST will only advertise BPDUs from the IST to the outside world. We won’t see any information from instance 1 or instance 2 on SW4.

The intent of the statement is to show that a switch outside of the MST topology, such as SW4, that connects using PVST, will receive BPDUs from the IST. Since the IST BPDUs are showing SW1 as the root bridge, SW4 will also use SW1 as the root bridge for VLAN 10. This is done in spite of the fact that within the MST topology, VLAN 10 belongs to instance 1 which has a root bridge of SW2. I will let Rene know to make the necessary adjustments to this statement as well…

Thanks for pointing those out!

I hope this has been helpful!

Laz