STP is the short form for Spanning Tree Protocol & RSTP (Rapid Spanning Tree Protocol), MSTP (Multiple Spanning Tree Protocol) are all. The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology In , the IEEE introduced Rapid Spanning Tree Protocol ( RSTP) as w. .. Cisco developed, implemented and published the Per- VLAN Spanning Tree (PVST) proprietary protocol using its own proprietary Inter- Switch. This lesson explains what is Rapid Spanning Tree Protocol (RSTP) Tutorials and Cisco enhanced the original Spanning Tree Protocol (STP) IEEE D.

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Rapid spanning tree will accept inferior BPDUs.

What is Rapid Spanning Tree Protocol (RSTP)

It also blocks all the other higher cost links to avoid looping in the network. A final tie-breaker is required as noted in the section “The final tie-breaker. Basically it combines the blocking and listening port state. Link tutorual at Edge port is not considered as topology change. But how does Sw2 select its Designated and Backup port? If a switch misses three BPDUs from a neighbor switch it will assume connectivity to this switch has been lost and it will remove all MAC addresses immediately.

Transition speed convergence time is the most important feature of rapid spanning tree. The interfaces that are cisxo will be blocked:.

The alternative port moves to the forwarding state if there is a failure on the designated port for the segment. If a RSTP enabled port receives a legacy It will instead go through a number of states while it processes BPDUs and determines the topology of the network.


Remember the port states of spanning-tree? SW1 as a root bridge will always have the best ports so all of interfaces will be designated. Alternative Port and Backup Port are in discarding state. Spanning tree also allows a network design to include backup links to provide fault tolerance if an active link fails.

I enabled RSTP in my switch. Breaking ties for designated ports: I thought it was C?! Send this to a friend Your email Recipient email Send Cancel. The Root Switch is the Central reference Switch.

Do you remember portfast? TCNs are injected into the network by a non-root switch and propagated to the root. Find out more or Sign In.

Once the cost of all possible paths to the root bridge have been added up, each switch assigns a port as root port which connects to the path with the lowest cost, or highest bandwidth, that will eventually lead to the root bridge.

Administrators can influence the protocol’s choice of the preferred path by configuring the port cost, the lower the port cost the more likely it is that the protocol will choose the connected link as root port for the preferred path.

Before reading this article you should understand how STP works. These ports are allowed to immediately enter the forwarding state rather than passively wait for the network to converge.

Once the switches have been assigned a bridge ID and the protocol has chosen the root bridge switch, the best path to the root bridge is calculated based on port cost, path cost and port priority. In each case, a single bridge may have multiple candidates for its root port.


If two or more ports have the same path cost, then the switch with the lowest BID is chosen.

Switches running the old version of spanning-tree will drop this new BPDU version. Besides moving the interface to the forwarding state it will also not generate topology changes when the interface goes up or down. It is eight bytes in length. From Wikipedia, the free encyclopedia. This preferred link is used for all Ethernet frames unless it fails, in which case the non-preferred redundant link is enabled.

I had read multiple documents to understand the RSTP concepts but still I have multiple questions to get clarity. I hope this helps. When a device is first attached to a switch port, it will not immediately start to forward data. BPDUs are now sent every hello time. BTW…Yes I am recommonding this site. It will use a negotiation mechanism for this. This is an excellent article.

Rapid Spanning Tree Protocol RSTP Tutorial

Which two spanning-tree port states does RSTP combine to allow faster convergence? By using our website, you agree to our use of cookies Read more. When multiple paths from a bridge are least-cost paths, the chosen path uses the neighbor bridge with the tutofial bridge ID. More Lessons Added Every Week! The other switches in the network are called designated switches.

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