Multiple Spanning Tree (MST) Ben Piper AUTHOR, CCNP ENTERPRISE - - PowerPoint PPT Presentation

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Multiple Spanning Tree (MST) Ben Piper AUTHOR, CCNP ENTERPRISE - - PowerPoint PPT Presentation

Nov 14, 2022 429 likes •724 views

Multiple Spanning Tree (MST) Ben Piper AUTHOR, CCNP ENTERPRISE CERTIFICATION STUDY GUIDE: EXAM 350-401 benpiper.com PVST+ vs. MST PVST+ MST One instance per VLAN VLANs can be arbitrarily mapped to instances 1 VLAN = 1 instance VLANs 1, 5,

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benpiper.com

AUTHOR, CCNP ENTERPRISE CERTIFICATION STUDY GUIDE: EXAM 350-401

Ben Piper

Multiple Spanning Tree (MST)

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PVST+

One instance per VLAN 1 VLAN = 1 instance 2000 VLANs = 2000 instances Can’t change VLAN-to-instance relationship

MST

VLANs can be arbitrarily mapped to instances VLANs 1, 5, 7 = 1 instance VLANs 2, 200, 2000 = 1 instance You define the VLAN-to-instance mappings

PVST+ vs. MST

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PVST+

A default instance for VLAN 1 always exists

MST

MST0 is the default instance for all VLANs (1-4094) MST0 is also called the Internal Spanning Tree (IST)

PVST+ vs. MST

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MST0: VLANs 100-4094 MST1: VLANs 1-99 MST0: VLANs 20-4094 MST1: VLANs 1-10 MST2: VLANs 11-19

SW-A SW-B

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VLAN-to-instance mappings Revision number Region name

MST Region

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Name: (null) Revision: 0 MST0: VLANs 100-4094 MST1: VLANs 1-99 Name: (null) Revision: 0 MST0: VLANs 20-4094 MST1: VLANs 1-10 MST2: VLANs 11-19

SW-A SW-B

Region Region

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Name: Pluralsight Revision: 0 MST0: VLANs 20-4094 MST1: VLANs 1-10 MST2: VLANs 11-19 Name: Pluralsight Revision: 0 MST0: VLANs 20-4094 MST1: VLANs 1-10 MST2: VLANs 11-19

SW-A SW-B

Region

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Uses RSTP Specified in 802.1s

Multiple Spanning Tree

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Configuring MST

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s h s

Enable MST on switches SW1, SW2, SW3, and SW4 as follows:

  • Use the region name “Pluralsight”
  • Map VLANs 1-199 to MST1
  • Map VLANs 200-400 to MST2

Requirement

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Name

MST BPDU

0xAC36177F50283CD 4B83821D8AB26DE62

MSTID 1 Priority 32768 Root 001d.45cf.e800 MSTID 2 Priority 24576 Root 0015.f9fb.1e80 Revision Hash of VLAN- to-instance mappings Instance topology information

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Root Bridges

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s h s

Make SW2 the root for MST1 Make SW3 the root for MST2

Requirement

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Modifying Port Cost and Port Identifiers

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s h s

Reconfigure MST to ensure MST2 traffic traverses the link between SW2 Fa0/6 and SW3 Fa0/21

Requirement

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Lower the port cost for MST2

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Summary

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Summary

Review the other modules to make sure you have a good grasp of spanning tree concepts

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Summary

MST lets you arbitrarily map VLANs to instances

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Summary

By default, all VLANs map to MST0 (IST)

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Summary

Switches in an MST region share the same name, revision number, and VLAN-to- instance mapping digest

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In the Next Module

You’re going to learn how to configure EtherChannels!