nx.os.and.cisco.nexus.switching.2nd.edition.1587143046

Example 2-28 shows how to manually adjust the hello, forward-delay, and max-age timers.
Caution
Although it might be desirable to manipulate spanning tree timers for faster
reconvergence, these timers and the Layer 2 topology should be well understood.
Incorrect spanning tree timers can produce unwanted results.
Example 2-28. Modifying Spanning Tree Timers
Click here to view code image
Congo(config)# spanning-tree mode rapid-pvst
Congo(config)# spanning-tree vlan 10 hello-time 1
Congo(config)# spanning-tree vlan 10 forward-time 10
Congo(config)# spanning-tree vlan 10 max-age 15
Congo(config)#
Congo(config)# sho spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 4106
Address 001b.54c2.bbc1
This bridge is the root
Hello Time 1 sec Max Age 15 sec Forward
Delay 10 sec
Bridge ID Priority 4106 (priority 4096 sys-id-ext
10)
Address 001b.54c2.bbc1
Hello Time 1 sec Max Age 15 sec Forward
Delay 10 sec
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- -------------
-------------------
Po100 e Desg FWD 1 128.4195 (vPC peerlink)
Network P2p
To mitigate some of the risk associated with the manual manipulation of spanning tree
timers, NX-OS provides the diameter keyword, and if needed, adjusts these timers
according to best practices. In this topology, a single-tier Layer 2 design is implemented
with access switches connecting to both aggregation switches; therefore, the maximum
number of bridges between any two stations (diameter) is 3. If no diameter is specified, the
default of 7 applies. By specifying the diameter of the spanning tree domain, hello, forwarddelay,
and max-age timers are adjusted for optimal reconvergence in the event that a
spanning tree recalculation occurs.