The spanning tree protocol stp is a network protocol that ensures a loop free topology for any bridged ethernet local area network. Tp, which stands for spanning tree protocol, is a network layer protocol that helps in building a logical loop free topology for the ethernet networks. This webcast shows you the stp topics for which youre responsible. I did not disable the spanning tree, i just add in the vpc the spanning tree port type and in global configuration i set the spanning priority to the vlans. Second, when redundant loops are planned on a network, stp deals with remediation of network. The meaning of stp abbreviation is spanning tree protocol what does stp mean. Spanning tree enabled switches go through a root election process based on bridge p rotocol data unit. This protocol also allows a network design to include redundant links for providing automatic backup paths. Spanning tree protocol stp was developed to prevent the broadcast storms caused by.
Spanning tree protocol stp was developed before switches were created in order to deal with an issue that occurred with networks that were implementing network bridges. Cisco spanning tree protocol guide stp examples and. Arista switches support rapid spanning tree, multiple spanning tree, and rapidper vlan spanning tree protocols. The varieties of spanningtree protocols include the following. The following image shows how the stp changes a physically looped topology into a virtually looped free topology. Radia perlman, distinguished engineer at sun microsystems. The abbreviation for spanning tree protocol is stp. One of the topics on the ccna rs version 3 exam is spanning tree protocol stp. This standardized solution is called spanning tree protocol stp. To view the information about the stp operation, you can use the show spanningtree command from the privilegedexec mode. Stp was created to avoid the problems that arise when computers compete for the ability to use the shared telecommunications path on a local area network. Download spanning tree protocol interview questions and. Stp, rstp, and mstp page 3 overview of spanning trees overview of spanning trees the concept of the spanning tree protocol was devised to address broadcast storming. Each switch determines which port roles are assigned to each of its ports to create the loop free spanning tree.
Hence, the spanning tree protocol stp was developed to keep layer 2 networks loop free. The spanning tree protocol run my experiment on geni. Perlman devised a method by which bridges can obtain layer 2 routing utopia. Configure and troubleshoot cisco spanning tree stp learn how to configure stp, portfast and bpduguard on cisco switches free ccna course handson lab networking fundamentals switching troubleshooting written by alessandro maggio. Arista switches support the leading spanning tree protocols. Switches running stp will build a map or topology of the entire switching network. Skills covered in this course network administration it cisco.
Spanning treebasic idea discover a subset of the topology that is loop free a tree just enough connectivity so that. Spanningtree protocol stp has nowadays been implemented by most manufacturers in order to avoid loops in bridged networks. Stp allows bridges and switches to communicate with each other so they can create a loop free topology. Digital equipment corporation created a protocol called spanning tree protocol stp to prevent broadcast storms and network loops at layer 2. And so, dont be too confused when we say root switch or root bridge, they are the same, they are the same. Root bridge is a switch in a single vlan or whole topology according to the type of stp standard used which is responsible for distributing bpdus and block the least redundant port. Sta spanning tree algorithm used to calculate loop. The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. Spanningtree bridge assurance is one of those stp features that help to prevent bridging loops in your network. Pdf formal specification of spanning tree protocol using acp. Learn how to predict the spanning tree topology of a given environment. Therefore, the tree is free of loops that can cause havoc in a network. Spanning tree protocol in layer 2layer 3 environments. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network.
Stp versions supported by arista switches address two limitations of the original. Several varieties of spanningtree protocols have emerged since the original ieee 802. Stp as abbreviation means spanning tree protocol online search. Stp spanning tree protocol explained with examples. Spanning treeenabled switches go through a root election process based on bridge p rotocol data unit. Understanding spanning tree protocol this section describes how spanning tree features work. Spanning tree protocol and other advanced ethernet topics 2e1623 data links and local. Spanning tree protocol this document descibes spanning tree protocol stp in a wireless environment. Spanning tree also allows a network design to include spare redundant links to provide automatic backup paths if an active link fails. As layer 2 networks grew, it quickly became evident that a system to prevent loops was needed if lans were to continue to function. Layer 2 loops, spanning tree protocol, and optical networks. Routeros is capable of running bridge interfaces with rmstp support in order to create a loop free and layer2 redundant environment.
Chapter 5 spanning tree protocol stp part i ccna3 chapter 51 bridge id early stp implementation no vlans. An algorithm that runs in network bridges and switches to prevent loops, in which packets keep going around in circles. Spanning tree protocol spanning tree protocols prevent bridging loops in layer 2 ethernet networks. Introduction to spanning tree protocol contemporary controls.
It should take about 1 hour to run this experiment. The output of this command can be divided into three subsets. The basic function of stp is to prevent bridge loops and ensuing broadcast radiation. In this lecture, were gonna talk about layer two loops,spanning tree protocol, and optical networks. Spt is employed for the prevention of bridge loops and the broad cast radiation of them. Introduction to spanning tree protocol by george thomas, contemporary controls. The spanningtree algorithm calculates the best loop free path throughout a switched layer 2 network.
The latest version of spanning tree is rstp, this is 802. Pdf spanningtree protocol stp has nowadays been implemented by most. When bridge assurance is enabled, bpdus are sent on all interfaces of your switch, including blocked interfaces like the alternate or backup port. Spanning tree protocol stp is used to make a loop free network by monitoring the network to track all the links and shut down the least redundant ones. Spanningtreeinstanceinterfaceshavepriorities36 whatisspanningtreeinstanceinterfacecost. Spanning tree protocol spt is a network protocol which make sure of loop free topology for any bridged ethernet local area network. Understanding spanning tree protocol this section describes how spanningtree features work.
Algorithm that creates a loop free logical topology. Spanning tree protocol overview the plugandplay spanning tree protocol stp, a layer 2 protocol that ensures a loop free topology in bridged lans, has been around for decades. Switches send and receive spanning tree fram es, called bridge protocol data units bpdus, at regular intervals. This tutorial explains what the stp protocol is and how it removes loops. When too many computers try to send at the same time, overall network performance is affected and can bring all traffic to a near. The ieee defines the spanning tree protocol that provides a loop free redundant network topology by placing certain ports in the blocking state.
Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Lets look at this diagram over here,so we have three switches, switch a, switch b, and switch c. Stp relies on the exchange of bpdus to maintain a loop free environment. Cisco saw the need for spanning tree on all vlans and create the proprietary pvst and. Spanning tree basic idea discover a subset of the topology that is loop free a tree just enough connectivity so that. The spanning tree protocol stp is a network protocol that builds a loop free logical topology for ethernet networks. This will be discussed in lab 415 configuring multiple spanning tree protocol. Dear support, im implementing hsrp on core switch in my network, but spanning tree always block one port on the layer 2 switch. A free powerpoint ppt presentation displayed as a flash slide show on id.
Spanning tree was great when it came out in 1990, but there have been a number of changes to networking and a number of changes to spanning tree through the years. Switches send and receive spanningtree fram es, called bridge protocol data units bpdus, at regular intervals. The spanning tree algorithm calculates the best loop free path throughout a switched layer 2 network. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails as the name suggests, stp creates a spanning tree that.
This protocol was created by radia perlman for bridges, ethernet transparent bridges. In the last lecture we spoke about network devices. This is spanning tree standard called rapid spanning tree protocol. Stp defines a tree with a root device and a loopfree path from the root to all infrastructure devices in the layer 2 network. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Spanning tree protocol stp ensures a loop free topology in a local area network lan made up of switches. Spanning tree protocol stp is a layer 2 network protocol used to prevent looping within a network topology.
So the same nomenclature for the different reference points lives to this day. Stp spanning tree protocol automatically removes layer 2. Stp will identify if there are any loops, and then disable or block. Up to now, we have used the terms spanning tree protocol and stp. In this spanning tree protocol tutorial, i will present in simplest terms the operation of stp and indicate how. Configure and troubleshoot cisco spanning tree stp. The spanning tree algorithm itself is defined by the ieee standard 802. Stp calculates the distance to the root bridge to build a loopfree topology that. Root path cost known in the mstp specification as the cist root identifier and. In a small network with one or two switches, the spanning tree protocol stp. Then, we will see how the spanning tree protocol creates a loop free logical topology in a network with physical loops, so that a broadcast storm cannot occur. Stp overview stp is a layer 2 link management protocol that prov ides path redundancy while preventing loops in the network.
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