VSTP

VLAN Spanning Tree Protocol (VSTP) allows switches to run one or more STP or RSTP instances for each VLAN on which VSTP is enabled. For networks with multiple VLANs, this enables more intelligent tree spanning, because each VLAN can have interfaces enabled or disabled depending on the paths available to that specific VLAN.

Prior to Junos 10.2, only one spanning tree protocol can be enabled: IEEE or VSTP.

Starting with 10.2, concurrent spanning-tree protocol (rstp + vstp ) is allowed, can interoperate with either PVST+ or R-PVST+.

Scalability numbers:
. 253 vstp instances plus 1 rstp


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example 1:
show protocols
rstp;
vstp {
vlan 2;
vlan 3;
vlan 4;
}

Any vlans that are not configured under vstp is part of the RSTP instance, vlan 2-4 are in each of their own vstp instance.


Example 2:
show protocols
rstp ;
vstp {
vlan-group {
group TRY {
vlan 2-100 ;
bridge-priority 4k;
}
group BACK {
vlan 101-200;
bridge-priority 16k;
}
}
Any vlans that ate configured under vstp is part of rstp, vlans 2-200 are in each of their own vstp instance. vlans that are grouped together will inherit there same stp parameters.