Dell PowerConnect J-EX4200-24T Software Manual page 1402

Dell PowerConnect J-Series Ethernet Switch Complete Software Guide for Junos OS
1330
The interface is blocked from becoming the root port.
Root protection is enabled for all STP instances on that interface.
The interface is blocked only for instances for which it receives superior BPDUs.
Otherwise, it participates in the spanning-tree topology.
CAUTION: An interface can be configured for either root protection or loop
protection, but not for both.
Four J-EX Series switches are displayed in Figure 38 on page 1330. In this example, they are
configured for RSTP and create a loop-free topology. Interface
a designated port on an administrative boundary. It connects to Switch 4. Switch 3 is the
root bridge. Interface ge-0/0/6
This example shows how to configure root protection on interface
it from transitioning to become the root port.
Figure 38: Network Topology for Root Protection
on Switch 1 is the root port.
on Switch 1 is
ge-0/0/7
to prevent
ge-0/0/7