Most newer Cisco switches use RSTP by default. RSTP prevents frame looping out of the box and no additional configuration is necessary. To check whether a switch runs RSTP, the show spanning-tree command is used:
SW1#show spanning-tree
VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 32769
Address 0004.9A47.1039
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0004.9A47.1039
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/3 Desg FWD 19 128.3 P2p
Fa0/2 Desg FWD 19 128.2 P2p
If RSTP is not being used, the following command will enable it:
SW1(config)#spanning-tree mode rapid-pvst
Most other configuration options (electing root switch, selecting root and designated ports) are similar to the ones used in STP.
Download our Free CCNA Study Guide PDF for complete notes on all the CCNA 200-301 exam topics in one book.
We recommend the Cisco CCNA Gold Bootcamp as your main CCNA training course. It’s the highest rated Cisco course online with an average rating of 4.8 from over 30,000 public reviews and is the gold standard in CCNA training:
