Download pdf stp spanning tree protocol step by step configuration tutorial when sw3 start receiving inferior bpdus at its interface from sw2, switch3 would ignore the inferior information until the bpdus stored with the blocked port expires max age timer 20 seconds. Rbridges are compatible with and can incrementally replace previous ieee 802. You will learn how spanning tree works and how you can verify the spanning tree config on cisco switches. Spanning tree root port is used to select path cost. By definition a tree is loop free stp does its work at layer 2 datalink of the osi model. Understanding spanning tree protocol this section describes how spanning tree features work.
Infrastructure devices such as wireless bridges and switches send and receive spanningtree frames, called bridge protocol data units bpdus, at regular. Based on the exchanged bpdu information, the spanning tree algorithm selects one of the switches on the network as the root switch for the tree topology. Switches running stp will build a map or topology of the entire switching network. So if you are not sure about stp, please read my article about spanning tree protocol tutorial first. Loops are created when multiple paths exist between two. Spanning tree protocol stp provide the loop avoidance in a network, where multiple switches are connected with each other as shown in below image.
The spanning tree protocol is a link management protocol that is designed to support redundant links while at the same time preventing switching loops in the network. Multiple spanning tree multiple spanning tree protocol mstp network organized in regions regions have their own multiple spanning tree instances spanning tree topologies vlans are associated to mstis one common spanning tree cst for the entire network. Spanning tree is basically used to find a minimum path to connect all nodes in a graph. Tutorial on stp, spanning tree protocol algorithm, which finds the minimum spanning tree for packet forwarding between switches in a network. What is spanning tree protocol stp sysnettech solutions. Most lans are designed to provide redundancy so that if a read more. Understanding and configuring spanning tree protocol stp. The golden rule of spanningtree protocol is lower is better.
This standardized solution is called spanning tree protocol stp. This tutorial explains what the stp protocol is and how it removes loops from the network. On each switch, display the spanning tree table with the show spanning tree command. Stp spanning tree protocol step by step configuration. The spanning tree protocol stp is layer 2 protocol. Ccna training spanning tree protocol stp tutorial 9tut. Stp, otherwise known as the spanning tree protocol 802. The spanning tree algorithm itself is defined by the ieee standard 802. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails. Spanning tree protocol stp is a big topic on the ccna exam. Root selection varies depending on the bid of each switch in your lab resulting in varying outputs. However, the most common you will encounter will be loops. 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.
Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. When you connect two or more layer 2 devices, an election is run to designate the root bridge. Spanning tree protocol in layer 2layer 3 environments. Enabling the portfast causes the switch or trunk port to enter the stp forwardingstate immediately.
The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. 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. Spanning tree protocol overview the plugandplay spanning tree protocol stp, a layer 2 protocol that ensures a loopfree topology in bridged lans, has been around for decades. There are two famous algorithms for finding the minimum spanning tree.
Spanning tree protocol through softwaredefined networking tutorial fabiobentostpmininetryu tutorial. Types of spanning tree protocol tutorial and example. Root selection varies depending on the bid of each switch in your lab. Introduction to spanning tree protocol by george thomas, contemporary controls introduction in an industrial automation application that relies heavily on the health of the ethernet network that attaches all the controllers and computers together, a concern exists about what would happen if the network fails. Kruskals algorithm follows greedy approach as in each iteration it finds an edge which has least weight and add it to the growing spanning tree.
Many people struggle with stp so in this video, we try to break it down as much. Introduction to spanning tree protocol stp in bigger networks, having a redundant design is crucial. Trill combines techniques from bridging and routing and is the application of link state routing to the vlanaware customerbridging problem. Trill transparent interconnection of lots of links is an ietf standard implemented by devices called rbridges routing bridges or trill switches. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Stp is on by default, but it only really comes alive when we have two or more switches interconnected with each other. Digital equipment corporation created a protocol called spanning tree protocol stp to prevent broadcast storms and network loops at layer 2. Stp automatically shut down the redundant links which creates the loops.
Uplinkfast is used to improve the convergence time of stp in case of a link failure. Consider, city network as a huge graph and now plans to deploy telephone lines in such a. For an ethernet network to function properly, only one active. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. In spanning tree protocol configuration, the shortest path to the root bridge switch is called the root port. The basic function of stp is to prevent bridge loops and ensuing broadcast radiation. Spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. This article explain the spanning tree protocol stp.
In this spanning tree protocol tutorial, i will present in simplest terms the operation of stp and indicate how. Spanning tree also allows a network design to include spare redundant links to provide automatic backup paths if an active link fails. There are the following types of spanning tree protocol 1. Dell networking and cisco spanningtree interoperability. Spanning tree protocol stp is standardized as ieee 802. Cisco switching and spanning tree protocol stp basics. 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. As layer 2 networks grew, it quickly became evident that a system to prevent loops was needed if lans were to continue to function.
Spanning tree protocol stp is a layer 2 protocol that runs on switches. As the name suggests, it creates a spanning tree within a mesh network of connected layer2 bridges typically ethernet switches, and disables those links that are not part of the spanning tree, leaving a. Loops and duplicate frames can have severe consequences on a network. The spanning tree protocol stp is a network protocol that ensures a loopfree topology for any bridged ethernet local area network. Multiple spanning tree multiple spanning tree protocol mstp network organized in regions regions have their own multiple spanning tree instances spanning tree topologies vlans are associated to mstis one common spanning tree cst for the entire network mstp based on rstp rapid stp. The spanning tree protocol stp is a method for dynamically calculating the best spanning tree of a computer network with or without loops. Redundant network designs allows service continuity in case of link failure. Cisco developed, implemented and published the per vlan spanning tree pvst proprietary protocol using its own proprietary inter switch. Pdf rapid spanning tree protocol rstp tutorial jhon.
Spanning tree protocol stp determines the least cost path from the root bridge to other nodes in the networks. Rapid spanning tree protocol rstp one big disadvantage of stp is the low. Spanningtree protocol is a link management protocol that provides path redundancy while preventing undesirable loops in the network. Spanning tree enabled switches go through a root election process based on bridge p rotocol data unit. Download pdf 1,901k view the full article as a pdf this document characterizes and provides some insight into the network traffic behavior when different flavors of spanning tree and device redundancy configurations are deployed between a cisco environment and a dell switching environment. Introduction to spanningtree spanning tree is a protocol that runs on our switches that helps us to solve loops.
Stp is used by switches to prevent loops occurring on a network, this process is implemented by using spanning tree algorithm in disabling unwanted links and blocking ports that could cause loop. It was first introduced as cst common spanning protocol then ieee introduced its advanced version as stp with specification ieee 802. Spanning tree protocol uses a clever mechanism or algorithms. Thats to say it runs at the ethernet layer and is totally unrelated to dynamic ipbased routing protocols like rip, ospf or olsr which can take into account. So therefore, if there is a tie in our value with spanningtree protocol, there has to be a tiebreaker mechanism. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks. The different terms in the stp model are explained here. Before reading this article you should understand how stp works. It is quite useful and should be enabled on the switch interfaces. Spanning tree protocol this document descibes spanning tree protocol stp in a wireless environment. Therefore, the switch2 and switch3 ethernet0 0 interfaces above will be configured as root ports. Spanning tree protocol explained step by step youtube.
This is because layer 2 ethernet frameshave no time to live or time out mechanismbuilt into the frame. Kruskals algorithm builds the spanning tree by adding edges one by one into a growing spanning tree. Supermicro l2l3 switches configuration guide 5 spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology. Spanning tree protocol, or stp, prevents switching loops in the layer 2 portion of our network. The problem is that when we create redundancyat a layer 2 level of our networks,we create loops that traffic will traverse indefinitely. 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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