STP Scaling and Performance on Juniper Networks MX Series 3D Universal Edge Routers

These are the critical scaling and performance parameters for different STP versions on Juniper Networks MX Series 3D Universal Edge Routers:

• Up to 64 MSTI instances
• Up to 256 routing instances
• Maximum 480 ports
• RSTP switchover time of < 50 ms in point-to-point links in case of link failures
• RSTP switchover time of < 50 ms in case of root bridge failover
• STP switchover time of two times forwarding delay for link failures
• 8,000 STP indices in hardware; maximum number of port and MSTI pairs is 8,000
• Maximum number of MSTP routing instances (including default) is 31

MAC Address Block

The bridge reserves a block of MAC addresses to be used as bridge MAC addresses for different STP, RSTP, and MSTP routing instances. Currently, 32 MAC addresses are reserved.

These rules apply to allocating MAC addresses to protocols running under different routing instances:

• All STP and RSTP routing instances share the same bridge MAC address.
• All MSTP routing instances get a unique bridge MAC address.
• All routing instances preserve their bridge MAC address across a restart or RE switchover.

Related Topics

• Decision Sequence for a Loop-Free STP Topology
• Key Concepts in Spanning Tree Protocols
• Multiple Spanning Tree Protocol
• Overview of Spanning Tree Protocol on Juniper Networks MX Series 3D Universal Edge Routers
• Port Roles in STP
• Rapid Spanning Tree Protocol Port States and Port Roles
• Restrictions and Cautions for Implementing STP
• Spanning Tree Protocol Operation
• Spanning Tree Protocol States
• VLAN Spanning Tree Protocol