Spanningtree protocol notes with interview questions. Spanning tree protocol timing protocol is timer driven too short timers can. The bridge priority making up the left most bits, is a value of 0 to 61440. The flavor of spanning tree protocol, we have been discussing, so far in this module has been the traditional 802.
Understanding spanning tree protocol this section describes how spanning tree features work. Spanningtree protocol stp is a layer 2 protocol that utilizes a specialpurpose algorithm to discover physical loops in a network and effect a logical loopfree topology. Aug 04, 2011 spanning tree protocol stp is standardized as ieee 802. How does stp decides in which state to port will be placed. Spanning tree protocol concepts and configuration spanning. Rapid spanning tree protocol rstprstp is defined in ieee 802. The following table lists some of the differences among the.
To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. Multiple spanning tree protocol gives you the ability to configure a hierarchical spanning tree topology. Thats where we can have a convergence time of 50 seconds and that. The spanning tree protocol has been disabled on both switches. 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. The output of show spanningtree summary command below shows that spanning tree. Stp or spanning tree protocol is a protocol used on switches that prevents layer 2 switching loops and layer 2 broadcast storms. Stp was created to avoid the problems that arise when computers compete for the ability to. This webcast shows you the stp topics for which youre.
This webcast shows you the stp topics for which youre responsible on the ccna rs 200125 or icnd2 200105. Remember, every time we modify the spanning tree topology, like changing. Spanning tree follows a strict set of rules which when learnt, will allow you to. To elect a root bridge from all switches of the network, stp uses two. Apr 27, 2019 the command spanningtree portfast bpduguard default was issued in global configuration mode. The spanning tree protocol has been disabled on one switch. Spanning tree protocol stp is a big topic on the ccna exam. Nov 16, 2016 one of the topics on the ccna rs version 3 exam is spanning tree protocol stp. This section describes how spanningtree features work. For a layer 2 network to function properly, only one active path can exist between any two stations.
The specification for spanning tree protocol is 802. Free cisco ccna lab guide pdf from neil anderson esx. To prevent loops, spa places some interfaces into forwarding state and some interfaces into blocking state. Stp spanning tree protocol automatically removes layer 2 switching loops by shutting down the redundant links. Spanning tree protocol understanding spanning tree protocol 4 cisco 3200 series wireless mic software configuration guide when you change the bridge priority value, you change the probability that the br idge will be elected as the root device. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops.
Root selection varies depending on the bid of each switch in your lab. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology in, the ieee introduced rapid spanning tree protocol rstp as w. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. The node with the smallest id is selected the root bridge 2. Jun 21, 2011 you are not allowed to use the spanning tree root command. Spanning tree protocol stp ensures a loopfree topology in a local area network lan made up of switches. With stp in place, you can have redundant links between switches in order to provide redundancy. Just like every coin has two sides, a redundant link, along with several advantages, has some disadvantages. The basic function of stp is to prevent bridge loops and the broadcast radiation. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Stp uses the spanningtree algorithm spa to create a topology database of the nework. Make sure switch grasshopper is the root bridge for vlan 40, switch butterfly should be the backup in case switch butterfly fails.
Ccna training spanning tree protocol stp tutorial 9tut. 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 ccna spanning tree protocol stp spanning tree protocols stps main task is to stop network loops from occurring on your layer2 network bridges or switches. Spanning tree protocol variants best cisco ccna ccnp and. Dec 22, 2012 spanning tree protocol stp stp often accounts for more than 50 % of the configuration, troubleshooting, and maintenance headaches in real world campus networks especially if they are poorly designed. The original stp was developed by radia perlman while working for dce back in 1990. It is an evolution of stp that provides faster convergence than stp. Spanning tree protocol stp in packet tracer part 1. Cisco developed, implemented and published the per vlan spanning tree pvst proprietary protocol using its own proprietary inter switch. The guide is free, you just need to give your email to neil. 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 single active path between any two network nodes.
This document descibes spanning tree protocol stp in a wireless environment. Ccnp switch chapter 4 exam answers version 7 score 100%. Before we talk about spanning tree protocol, lets organize the. Cisco ccna icnd2 exam practice questions on spanning tree alogorithm stp. Switches running stp will build a map or topology of the entire switching network. Pvst stands for pervlan spanning tree protocol and this mode runs an instance of ieee 802. Jul, 2019 the spanning tree protocol stp is a network protocol that builds a loopfree logical topology in, the ieee introduced rapid spanning tree protocol rstp as w. Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. So to assist you, below we will discuss one of the more difficult ccna concepts. First, it prevents problems caused by loops on a network. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network. Modern extensions of stp will be covered later in this guide. Follow along with packet tracer download the following packet tracer file. It consists of bridge priority and the base mac address of the switch.
Dads pop, poppa, wearing khakis, quiet, tearing down the old house one board at. Dads pop, poppa, wearing khakis, quiet, tearing down the old house one board at a time, tagging along at the cow sales barn, walking the property, and napping during the sunday morning sermon. This lab will discuss and demonstrate the configuration and verification of 802. The spanningtree protocol prevents loops in a redundant network. Spanningtree protocol is a protocol used in switching network to create a loopfree topology. Stp spanning tree protocol explained with examples this tutorial explains what the stp protocol is and how it removes loops from the network. Stp uses the spanning tree algorithm spa to create a topology database of the nework. Learn the benefits of cisco switching and stp basics, today.
The spanning tree protocol stp is a network protocol that ensures a loopfree topology for any bridged ethernet local area network. Jan 31, 2016 hi guys, this post got awarded best publication at the cisco support community. Stp allows bridges and switches to communicate with each other so they can create a loop free topology. Multi spanning tree protocol allows for resource conservation by now requring an instance for every single vlan in the layer 2 network. Cisco switching and spanning tree protocol stp basics. Spanning tree protocol interoperability with cisco arista networks. The command spanningtree etherchannel guard misconfig was issued in interface configuration mode. Feb 22, 2012 a beginners tutorial on the function and purpose of stp spanning tree protocol in a local area network. Stp is enabled by default on all vlans on catalyst switches. Spanning tree protocol vs rapid spanning tree protocol. Spanning tree protocol this document descibes spanning tree protocol stp in a wireless environment.
Complex protocol that is generally poorly understood. Understanding and configuring spanning tree protocol stp. Thats where we can have a convergence time of 50 seconds and that where even, if we have multiple vlans, all of the vlans are using the same instances of spanning tree protocol, its called a cst or common spanning tree. In rstp, portfast ports are called edge ports and the way to activate them is with the same command as in stp. All of these problems can be solved with the spanning tree protocol stp. Configuring pervlan spanning tree protocol free ccna. The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. Configuring a higher value decreases the probability. Introduction to stp, spanning tree protocol, broadcast storm, topological loop, switch macaddress table corruption,stp pdf file download, pdf file download, ethernet bridge, ethernet switch,layer 2. Learn stp features and functions in detail with examples. Spanningtree protocol assigns a root bridge, root ports for nonroot bridges, and designated port segments. Cisco networking allinone for dummies add to cart amazon. He has created a free pdf guide 350 pages called free cisco ccna guide.
Understanding spanning tree protocol this section describes how spanningtree. Stp spanning tree protocol cis 187 multilayer switched networks ccnp switch rick graziani spring 2010 2. May 28, 2008 this document descibes spanning tree protocol stp in a wireless environment. Links that will cause a loop are put into a blocking state. A redundant link is usually created for backup purposes. At this time there were no switches yet, only bridges, but because bridges and switches technically. Spanning tree protocol stp is a network protocol designed to prevent layer 2 loops. Stp is a layer 2 link management protocol that provides path redundancy while preventing loops in the network. The command no spanningtree backbonefast was issued in global configuration mode. 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.
Spanning tree protocol explained step by step youtube. This is very necessary in large networks that are designed to have redundancy like backup switches and multiple paths across the network. Spanningtree protocol stp premium ccna exam questions. Network redundancy is a key to maintaining network reliability. The spanningtree protocol requires network devices to exchange messages to detect bridging loops.
The message that a switch sends, allowing the formation of a loop free logical topology, is called a bridge protocol data unit bpdu. On each switch, display the spanning tree table with the show spanningtree command. I discuss how stp mitigates layer 2 loops and layer 2 broadcast storms. Configuring multiple spanning tree protocol mstp free. This will be discussed in lab 415 configuring multiple spanning tree protocol. In this exercise, we will explain how does the spanning tree protocol work. This tutorial explains what the stp protocol is and how it removes loops from. A beginners tutorial on the function and purpose of stp spanning tree protocol in a local area network. Stp overview stp is a layer 2 link management protocol that prov ides path redundancy while preventing loops in the network. But there is a protocol called spanningtree protocol stp that is used to stop switching loops in a layer2 switched network.
The command spanningtree portfast bpduguard default was issued in global configuration mode. In this sample chapter from scaling networks v6 companion guide, explore potential redundancy problems, symptoms, and protocols to manage them. The default bridge priority of a cisco switch is 32768. This section describes how spanning tree features work. Introduction to stp, spanning tree protocol, broadcast storm, topological loop, switch macaddress table corruption,stp pdf file download, pdf file download, ethernet bridge, ethernet switch,layer 2 topological loop,ieee 802. On each switch, display the spanning tree table with the show spanning tree command. Configuring pervlan spanning tree protocol free ccna workbook. Configure and troubleshoot cisco spanning tree stp.
A redundant link is an additional link between two switches. Spanning tree protocol stp is a layer 2 network protocol used to prevent looping within a network topology. It vigilantly monitors the network to find all links, making sure that no loops occur by blocking any redundant ones. Stp creates a loopfree tree structure consisting of leaves and branches that span the entire layer 2 network. Digital equipment corporation created a protocol called spanning tree protocol stp to prevent broadcast storms and network loops at layer 2. Cisco spanning tree protocol guide stp examples and.
But there is a protocol called spanning tree protocol stp that is used to stop switching loops in a layer2 switched network. Learn vocabulary, terms, and more with flashcards, games, and other study tools. All switches from cisco ship with spanning tree protocol stp enabled by default, but if stp is misconfigured for any reason, you can easily enable it. Spanning tree protocol stp for ccna rs 200125 and icnd2. Stp blocks some ports on switches with redundant links to prevent broadcast storms and ensure loopfree topology. Hi guys, this post got awarded best publication at the cisco support community. Stp overview stp or spanning tree protocol is a protocol used on switches that prevents layer 2 switching loops and layer 2 broadcast storms.
During the exchange of bdpus, to choose the ports that will be forwarding and ports that will be blocked, the spanningtree algorithm on a switch may. By default, the bridge priority value is set to 32768 in all cisco switches. In preparation of your ccna exam, we want to make sure we cover the various concepts that we could see on your cisco ccna exam. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks. The spanning tree protocol requires network devices to exchange messages to detect bridging loops. Root selection varies depending on the bid of each switch in your lab resulting in varying outputs. Mst is commonly used in extremely large networks where running pvst would tax switch resources. Second, when redundant loops are planned on a network, stp deals with remediation of network. Spanning tree protocol is a layer 2 protocol that works on bridges and switches. Stp will identify if there are any loops, and then disable or block.
Stp spanning tree protocol explained with examples. Create the following topology in cisco packet tracer and connect the switches using the crossover cables. Without manual configuration all switches have the same priority therefore it is up to the mac. One of the topics on the ccna rs version 3 exam is spanning tree protocol stp. Change the hello timer on all switches for vlan 10 to 4 seconds. This way, we are setting the priority for both vlan 1 and 10. Before we talk about spanning tree protocol, lets organize the different variants of stp. The bridge priority value and the extended system id extension together make up a 16 bit 2byte value.