3.4.3 Spanning tree

The following table describes the capacity limits for each type of Spanning Tree Protocols.

The number of VLAN ports in a Spanning Tree Protocol is the total number of ports belonging to a VLAN for which the Spanning Tree Protocol is deployed. For channel groups, the number of physical ports per channel group is calculated. However, the following VLANs and ports are excluded from the number of VLAN ports.

VLANs for which the suspend parameter is set by the state configuration command
Ports for which VLAN tunneling is set
Ports for which the BPDU filter functionality is not set when the BPDU guard functionality is used
Access ports for which the PortFast functionality and BPDU filter functionality are set

Table 3-12 PVST+ accommodation conditions
Model	Number of target VLANs	VLAN ports*1
All models	250	256^#2

#1

This is the total number of ports configured in each VLAN incorporated in the Spanning Tree Protocol (the product of the VLAN count and port count).

For example, if 100 VLANs are defined and two lines participate in each VLAN, the total number of ports incorporated in the Spanning Tree Protocol will be 100 x 2 = 200.

When the Spanning Tree Protocol is used with VLAN tunneling, the access ports are not included in the number of ports.

#2

Excludes ports that have PortFast enabled.

Table 3-13: Capacity limits for Single Spanning Tree
Model	Number of target VLANs	VLAN ports*1	VLAN ports1 (When using PVST + together2)
All models	1024^#3	5000	1000

#1

This is the total number of ports configured in each VLAN incorporated in the Spanning Tree Protocol (the product of the VLAN count and port count).

For example, if 100 VLANs are defined and two lines participate in each VLAN, the total number of ports incorporated in the Spanning Tree Protocol will be 100 x 2 = 200.

When the Spanning Tree Protocol is used with VLAN tunneling, the access ports are not included in the number of ports.

#2

The total maximum value when PVST+ target ports are included is 1000.

#3

When used together with PVST+, the number of PVST+ target VLANs is subtracted from the value.

Table 3-14: Capacity limits for Multiple Spanning Tree
Model	Number of target VLANs	VLAN ports*1	Number of MST instances	Target VLAN per MST instance*2
All models	1024	5000	16	200

#1

This is the total number of ports configured in each VLAN incorporated in the Spanning Tree Protocol (the product of the VLAN count and port count).

For example, if 100 VLANs are defined and two lines participate in each VLAN, the total number of ports incorporated in the Spanning Tree Protocol will be 100 x 2 = 200.

When the Spanning Tree Protocol is used with VLAN tunneling, the access ports are not included in the number of ports.

#2

Excludes MST instance 0. The number of target VLANs in MST instance 0 is 1024. You can check the numbers of target VLANs and VLAN ports by using the show spanning-tree port-count operation command during operation.