Cisco Nexus 9000 Series - Page 73

Be careful when you change STP timers. STP timers are dependent on each other, and
changes can impact the entire network.
Caution
SUMMARY STEPS
1.
(Optional) switch(config)# spanning-tree loopguard default
2.
switch(config)# spanning-tree bpduguard enable
3.
switch(config)# vlan vlan-range
4.
switch(config)# spanning-tree vlan vlan-range root primary
5.
switch(config)# spanning-tree vlan vlan-range root secondary
DETAILED STEPS
PurposeCommand or Action
(Optional)
Secures the network STP perimeter with root guard. Root guard and
BPDU guard allow you to secure STP against influence from the
outside.
switch(config)# spanning-tree loopguard
default
Example:
switch(config)# spanning-tree loopguard
default
Step 1
Enables BPDU guard on STP edge ports to prevent STP from being
affected by unauthorized network devices (such as hubs, switches, and
bridging routers) that are connected to the ports.
switch(config)# spanning-tree bpduguard
enable
Example:
switch(config)# spanning-tree bpduguard
enable
Step 2
Root guard prevents STP from outside influences. BPDU guard shuts
down the ports that are receiving any BPDUs (not only superior
BPDUs).
Short-living loops are not prevented by root guard or BPDU
guard if two STP edge ports are connected directly or through
the hub.
Note
Configures separate VLANs and avoids user traffic on the management
VLAN. The management VLAN is contained to a building block, not
the entire network.
switch(config)# vlan vlan-range
Example:
switch(config)# vlan 9
Step 3
Configures a predictable STP root.
switch(config)# spanning-tree vlan vlan-range
root primary
Step 4
Example:
switch(config)# spanning-tree vlan 9 root
primary
Configures a predictable backup STP root placement.
switch(config)# spanning-tree vlan vlan-range
root secondary
Step 5
You must configure the STP root and backup STP root so that
convergence occurs in a predictable way and builds optimal topology
in every scenario. Do not leave the STP priority at the default value.
Cisco Nexus 9000 Series NX-OS Troubleshooting Guide, Release 7.x
61
Troubleshooting STP
Securing the Network Against Forwarding Loops