Open Standard Versions vs Cisco
Sections:
- Open Spanning Tree Standards
- Cisco Proprietary Spanning Tree Standards
- Spanning Tree Standard Comparison
- Configuration
Overview:
- Primarily through the evolution of network technology, the need for better performance and the requirement for compatibility across different network environments enabled different standards of Spanning Tree to be introduced
- Each version of STP was developed to address specific limitations of previous versions to provide more efficient or reliable ways to prevent network loops in diverse network topologies
Open Spanning Tree Standards
- 802.1D (Original STP)
- This form of STP is legacy in today's standards and should not be used for the following reason:
- Slow convergence time up to 50 sec if a topology change occurs
- This form of STP is legacy in today's standards and should not be used for the following reason:
- 802.1W (Rapid STP)
- Today's open standard of choice as it benefited with faster convergence times up to 5-10 sec
- 802.1S (MST)
- Recommended use if managing multiple VLANs
- Utilized to group VLANs to a single STP instance
- The previous open STP standards only define a single STP instance for all VLANs
Cisco Proprietary Spanning Tree Standards
- PVST
- PVST uses the 802.1D open format rules but with the addition of being able to define an STP instance for each VLAN
- RPVST+
- RPVST+ uses the open standard 802.1W format rules with the addition of being able to define an STP instance for each VLAN
- MST
- Cisco can utilize the Open Standard MSTP to group VLANs to a single STP instance
Spanning Tree Version Comparisons
- 802.1D Rules = (Open Standard) STP or (Cisco Proprietary) PVST
- 802.1W Rules = (Open Standard) RSTP or (Cisco Proprietary) RPVST+
- 802.1S Rules = (Open Standard) MSTP
Cisco Configuration Options
Cisco Spanning Tree Modes Available.
'ieee' defines PVST / 802.1D form of Cisco switches.
'rstp' defines RPVST+ / 802.1w form of Cisco Switches.
'mstp' / 802.1s Open Standard.
