4.2.2 Spanning Tree Root Protect

Information

This sequence describes configuring Spanning Tree's Root Protect feature

Root protection secures the active topology by preventing other switches from declaring their ability to propagate superior BPDUs, containing both better information on the root bridge and path cost to the root bridge which would normally replace the current root bridge selection. This is typically carried out between the core that is required to be the root and access switches to prevent ports that are not expected to originate root information such as server ports and access switch ports.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

switch(config)# interface 1/1/21
switch(config-if)# no shutdown
switch(config-if)# no routing
switch(config-if)# vlan trunk allow all
switch(config-if)# vlan trunk native 1
switch(config-if)# spanning-tree root-guard
switch(config-if)# exit

Impact:

Enabling the Spanning Tree Protocol (STP) Root Guard feature, also known as Root Protect, is a crucial security measure in network switches. It helps prevent unauthorized switches from becoming the root bridge in your network's STP topology. However, like any network configuration, there can be potential side effects if not implemented correctly:

Ports in Root-Inconsistent State: If a port receives a superior Bridge Protocol Data Unit (BPDU) the port enters a "root-inconsistent" state and stops forwarding traffic.

Potential for Unexpected Topology Changes: If Root Guard is erroneously enabled on ports that are supposed to be part of the root path, it could block legitimate switches from becoming the root bridge in case of a failure, which could lead to network instability. Root Guards implementation can influence how the spanning tree converges. Incorrectly chosen root bridges can lead to suboptimal paths for data traffic, potentially impacting network performance.

See Also

https://workbench.cisecurity.org/benchmarks/24202

Item Details

Category: ACCESS CONTROL, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|AC-3, 800-53|SC-5

Plugin: ArubaOS

Control ID: 49a5313ca12586d011cedfcdf468dbaff0ac40d53dfdc23d8e464e085d0e08d9