Understanding VSTP for EX Series Switches
VLAN Spanning Tree Protocol (VSTP) allows Juniper Networks EX Series Ethernet Switches to run one or more Spanning Tree Protocol (STP) or Rapid Spanning Tree Protocol (RSTP) instances for each VLAN on which VSTP is enabled. For networks with multiple VLANs, VSTP improves intelligent tree spanning by defining best paths within the VLANs instead of within the entire network.
You can configure VSTP for a maximum of 253 VLANs. If you need to run a spanning-tree protocol on more than 253 VLANs, you must configure VSTP and RSTP concurrently. When VSTP and RSTP are configured, up to 253 VLANs can use VSTP and the remaining VLANs use RSTP. You can selectively configure which VLANs use VSTP when VSTP and RSTP are configured.
VSTP and RSTP are the only spanning-tree protocols that can be configured concurrently on the switch.
 | Note: We recommend that you enable VSTP on all VLANs that could receive VSTP bridge protocol data units (BPDUs). |
