Restrictions and Cautions for Implementing STP
This section presents restrictions and cautions when implementing the different STP versions:
STP can be enabled on a physical interface using only one of these configurations:
- Different STP versions are configured within a routing instance of the type virtual-switch. Currently under L2CPD, a virtual switch can only be configured under the default logical-router hierarchy.
- Creating a routing instance of type layer2-control
- Different STP versions are configured within the default virtual switch of the default logical system.
These are the restrictions when STP is enabled on a physical interface within a virtual-switch configuration:
- No other virtual switch can have logical interfaces on this physical interface.
- Logical interfaces on this physical interface cannot belong to any routing instance of the type vpls.
- If other logical interfaces on this physical interface have routing/ccc/tcc enabled, then this traffic is not affected by the STP state of the physical interface.
- Different STP versions are supported on CE interfaces of VPLS routing-instance by creating a routing instance of type layer2-control, which cannot have any bridge domains defined.
- If STP is not configured on a physical interface, the restrictions listed above do not apply. Different logical interfaces on a physical interface can span virtual switches as well as routing instances of the type vpls.
- Virtual switches cannot have any logical interfaces corresponding
to physical interfaces that are referenced within a routing instance
of the type layer2-control, as shown in the following example
configuration.routing-instance l2control-4-green {instance-type layer2-control;protocols {rstp {interface ge-1/2/3 ;interface ge-2/2/3 ;interface ge-3/2/4 ;}}}routing-instance green {instance-type vpls ;interface ge-1/2/3.11 ;interface ge-2/2/3.1 ;interface ge-3/2/4.2 ;}
- Any given logical interface of a bridge domain can be associated with only one MSTI. All VLANs that are part of a VLAN range of a logical interface must be associated with the same MSTI. An MSTI must be a super-set of all VLANs that are associated with a logical interface.
- A bridge domain on the MX Series is either associated with a specific VLAN or all VLANs (vlan-all); you cannot use vlan-range. If a bridge domain is configured as vlan-all, it represents multiple broadcast domains, and it can be associated with multiple MSTIs. Each VLAN within vlan-all is an independent and separate broadcast domain.
- If you include the vlan statement within a bridge domain and specify the none option, then MSTP cannot be enabled on physical interfaces corresponding to the logical interfaces defined under the bridge domain.
MSTP cannot be configured on physical interfaces that have logical interfaces with VLAN translation. MSTP is not allowed within a bridge domain if none of the logical interfaces in the bridge domain has a vlan-range and:
- All of the logical interfaces in the bridge domain do
not have the same VLAN
OR
- All of the logical interfaces in the bridge domain have the same VLAN, but the vlan-id defined for the bridge domain is different.
- All of the logical interfaces in the bridge domain do
not have the same VLAN
- STP and RSTP can be configured on physical interfaces that have logical interfaces with VLAN translation.
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
- Spanning Tree Protocol Operation
- Spanning Tree Protocol States
- STP Scaling and Performance on Juniper Networks MX Series 3D Universal Edge Routers
- VLAN Spanning Tree Protocol
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