In a converged network, ports are either in forwarding or blocking state. The bridge id is made up of the mac address and priority. A tree is a connected undirected graph with no cycles. Stp overview stp is a layer 2 link management protocol that prov ides path redundancy while preventing loops in the network. When you connect two or more layer 2 devices, an election is run to designate the root bridge. Second, when redundant loops are planned on a network, stp deals with remediation of network. This section describes how spanningtree features work. Spanning tree protocol networking mcq questions and answers. Spanning tree protocol premium ccna exam questions. Root selection varies depending on the bid of each switch in your lab resulting in varying outputs. To prevent switching loops in networks with redundant switched paths. The other requirement is that all leaves are connected. The ccna candidate guide to the spanning tree protocol ine. At this time there were no switches yet, only bridges, but because bridges and switches.
Stp is on by default, but it only really comes alive when we have two or more switches interconnected with each other. On each switch, display the spanning tree table with the show spanning tree command. We will focus on spanning tree protocol stp configuration and verification commands in this tutorial, as implemented on cisco. As you already know, what we have just seen is a loop and such loops can bring a network to a grinding halt. Choose 3 best answers path cost subnet mask bridge id.
The spanning tree algorithm places each bridgeswitch port in either a forwarding state or a blocking state. Spanning tree protocol introduction 11012015 jonathan leave a comment this is the first in a series of posts on spanning tree, in this post i will be describing the need for spanning tree protocol stp in modern lan environments. One of the topics on the ccna rs version 3 exam is spanning tree protocol stp. Spanning tree protocol, rapid stp port costs port states. The spanningtree protocol prevents loops in a redundant network. The spanning tree protocol stp, defined by ieee 802. Therefore, the tree is free of loops that can cause havoc in a network. Spanning tree protocol ccnax 200120 ccna practice tests. Spanning tree protocol protocol to calculate a spanning tree convergence all bridges should reach a unified view of the spanning tree special frames sent between neighbour switches bridge protocol data units, bpdus not forwarded. 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 use which three components. Cisco ccna spanning tree protocol tutorial jared heinrichs. Cisco ccna icnd2 exam practice questions on spanning tree alogorithm stp.
Spanning tree protocol variants best cisco ccna ccnp and. Learn vocabulary, terms, and more with flashcards, games, and other study tools. This document explains the spanning tree protocol stp root guard feature. Multiple spanning tree mst is an ieee standard inspired from the cisco proprietary multiple instances spanning tree protocol mistp implementation. Spanning tree protocol study guide by etoner includes 35 questions covering vocabulary, terms and more. The ports along lessdesirable paths are placed in blocking mode. Spanning tree protocol assigns a root bridge, root ports for nonroot bridges, and designated port segments. Spanning tree protocol stp for ccna rs 200125 and icnd2. This way, we are setting the priority for both vlan 1 and 10. Spanning tree protocol the basics ccnp journey switch. Configuring pervlan spanning tree protocol free ccna. The number tg of spanning trees of a connected graph is a wellstudied invariant in specific graphs. Stp creates a loopfree tree structure consisting of leaves and branches that span the entire layer 2 network.
Posted by rene molenaar june 21, 2011 in switching. This document descibes spanning tree protocol stp in a wireless environment. Complex protocol that is generally poorly understood. The icnd2 exam validates a candidates ability to install, configure, operate, and troubleshoot mediumsized routed and switched networks. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Can someone share videos and tutorials of advanced level stp with me personally please. Configure and troubleshoot cisco spanning tree stp. Configuring rapid pervlan spanning tree protocol free. The election decides which switch will become the root bridge, as well as the.
Configuring rapid pervlan spanning tree protocol free ccna. Spanningtree protocol assigns a root bridge, root ports for nonroot bridges, and designated port segments. While most people like the effects of redundancy, the redundancy can cause problems at layer 2. Microsegmentation decreases the number of collisions on the network. The spanning tree protocol stp is a network protocol that ensures a loopfree topology for any bridged ethernet local area network. The golden rule of spanningtree protocol is lower is better. Stp will identify if there are any loops, and then disable or block. The spanning tree protocol is a layer 2 protocol used to avoid loops in a switched network. On this post i will look to cover what spanning tree is, the reason we use it and the several different varieties of stp. Ive oddly found it fun to figure out spanning tree diagrams.
Contains answers, notes, and other information about packet tracers, tests, and much more. The original stp was developed by radia perlman while working for dce back in 1990. Root selection varies depending on the bid of each switch in your lab. It is quite useful and should be enabled on the switch interfaces. Spanning tree protocol stp is a big topic on the ccna exam.
Just like every coin has two sides, a redundant link, along with several advantages, has some disadvantages. It does this by placing ports along the most desirable path into forwarding mode. Spanning tree protocol or stp for short was created to solve these kinds of problems. Spanning tree protocol root guard enhancement cisco. You are the leading network engineer of an international reptile and insects museum. Ssl is a form of vpn that can be used with a standard web browser. 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.
Apr 18, 20 spanning tree protocol or stp for short was created to solve these kinds of problems. Cisco spanning tree protocol guide stp examples and. Jan 05, 2018 the spanning tree protocol is a layer 2 protocol used to avoid loops in a switched network. A redundant link is an additional link between two switches. Ipsec is a framework for a set of protocols for security at the network or packet processing layer of network communication. Establishing vlans increases the number of broadcast domains. It is easy to find one or two but finding more than that has been hard. Spanning tree protocol 90425 the cisco learning network. Remember, every time we modify the spanning tree topology, like changing priorities, spanning tree will need to converge. Switches running stp will build a map or topology of the entire switching network. Apr 22, 2014 ccnaccent routing and switching training series 100101 icnd1, 200101 icnd2, 200120 ccnax exams watch the ccnaccent routing and switching training series playlist. Ccna icnd2 essential training covers the second part of the exam that networking candidates need to take to earn their cisco certified network associate routing and switching ccna rs certification.
Spanningtree protocol stp a layer 2 switch, which functions as a transparent bridge, offers no additional links for redundancy purposes. In discussing the spanning tree protocol here, i will try to be as practical about it as possible. If g is itself a tree, then tg 1 when g is the cycle graph c n with n vertices, then tg n for a complete graph with n vertices, cayleys formula gives the number of spanning trees as n n. We will look at why you need the spanning tree protocol, one of the cases involving the spanning tree. What is the purpose of spanning tree protocol in a switched lan. 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.
Spanning tree protocol networking mcq questions and. Overview network redundancy at layer 2 can introduce the potential for bridging loops, where packets loop endlessly between devices, crippling the network. 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. Cisco ccna spanning tree protocol tutorial in most networks larger than your typical smb switched networks, there will be path redundancy. Stp is enabled by default on all cisco switches, for all vlans. What is the purpose of spanning tree protocol in a ccna.
The collective set of forwarding ports creates a single path over which frames are sent between ethernet segments. First, it prevents problems caused by loops on a network. In some cases, it is easy to calculate tg directly. The internet seems to lack a lot of spanning tree protocol topologies for practice. Hi guys, this post got awarded best publication at the cisco support community. Spanning tree protocol allows switches to automatically share vlan information. Recently the museum has been experiencing trouble with their switched network due to loops. Vlan0005 spanning tree enabled protocol ieee root id priority 32773 address 00. Tree topology to avoid loops we need a tree topology consisting of a root, a succession of branches and then leaves. To provide a mechanism for network monitoring in switched environments. When a failure occurs, spanning tree recalculates the topology, and makes use of the redundant path.
I have studied much about stp but still there are many ques 90425. 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. Switches that are configured with vlans make forwarding decisions based on both layer 2 and layer 3 address information. To prevent routing loops in networks with redundant paths. So therefore, if there is a tie in our value with spanningtree protocol, there has to be a tiebreaker mechanism.
For a layer 2 network to function properly, only one active path can exist between any two stations. Try to determine the root bridge, designated ports, root ports, and blocked ports. The flavor of spanning tree protocol, we have been discussing, so far in this module has been the traditional 802. This section describes how spanning tree features work. Multiple spanning tree protocol mstpmstp, defined in ieee 802. Understanding and configuring spanning tree protocol stp. Before we talk about spanning tree protocol, lets organize the different variants of stp. Spanning tree protocol this document descibes spanning tree protocol stp in a wireless environment. It effectively eliminates logical loops, while allowing physical loops to still exist. This table shows the support for mst in various catalyst switches. This is the first in a series of posts on spanning tree, in this post i will be describing the need for spanning tree protocol stp in modern lan environments. Cisco introduced several enhancements to the standard stp operation that were later incorporated in rapid spanning tree protocol rstp defined as ieee 802. Nov 16, 2016 one of the topics on the ccna rs version 3 exam is spanning tree protocol stp. Quizlet flashcards, activities and games help you improve your grades.
Learn spanning tree protocol mcq questions and answers with easy and logical explanations for various competitive examination, interview and entrance test. The spanning tree protocol prevents loops in a redundant network. Spanningtree protocol, or stp, prevents switching loops in the layer 2 portion of our network. Now two switches offer the transparent bridging function in parallel. The spanning tree feature cannot be turned off in switches on a perport basis. This webcast shows you the stp topics for which youre responsible on the ccna rs 200125 or icnd2 200105.
In this article, we will learn how stp prevents loops, and how it handles the layer 2 convergence. If you keep this in mind as youre trying to understand the protocol, youll really find that spanning tree isnt that complex. So therefore, if there is a tie in our value with spanning tree protocol, there has to be a tiebreaker mechanism. Many people struggle with stp so in this video, we try to break it down as much. Ccnaccent routing and switching training series 100101 icnd1, 200101 icnd2, 200120 ccnax exams watch the ccnaccent routing and switching training series playlist. Infrastructure devices such as wireless bridges and switches send and receive spanningtree frames, called bridge protocol data units bpdus, at regular. Spanning tree protocol interoperability with cisco arista networks. Spanning tree protocol timing protocol is timer driven too short timers can give loops and instabilities too long timers can give long convergence times until network reaches a stable spanning tree configuration proto id 2 root id 8 ver 1 bpdu type 1 flags 1 root path cost 4 bridge id 8 port id 2 msg age 2 max age 2 hello time 2. In the previous lab if you read andor completed it you learned about ciscos proprietary per vlan spanning tree protocol which enables a spanningtree. A redundant link is usually created for backup purposes. Stp spanning tree protocol automatically removes layer 2 switching loops by shutting down the redundant links. 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. A xuong tree and an associated maximumgenus embedding can be found in polynomial time.
Configuring pervlan spanning tree protocol free ccna workbook. Radia perlman, distinguished engineer at sun microsystems. The golden rule of spanning tree protocol is lower is better. 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. Up to you to optimize the spanning tree configuration.
The spanning tree protocol identifies and prevents such layer. Jan 31, 2016 hi guys, this post got awarded best publication at the cisco support community. The leaves represent end stations, and there is one and only one path from a leaf to another leaf. Spanning tree protocol is standardized as ieee 802. May 28, 2008 this document descibes spanning tree protocol stp in a wireless environment. Understanding spanning tree protocol this section describes how spanningtree features work. Spanning tree protocol explained step by step youtube. Spanningtree protocol stp premium ccna exam questions. I will be concentrating on the main topics covered in the ccna icnd 2 exam. This feature is one of the stp enhancements that cisco created. Routing and switching 200120 12 spanning tree protocol concepts 2.
It is a spanning tree of a graph g if it spans g that is, it includes every vertex of g and is a subgraph of g every edge in the tree belongs to g. All the ports in forwarding state are considered to be in the current spanning tree. Stp is a layer 2 link management protocol that provides path redundancy while preventing loops in the network. This document assumes that the reader is familiar with rapid stp rstp 802. Stp spanning tree protocol explained with examples. Catalyst 2960, 3560, 3750, 3850, 4500, 6500 mst was developed to reduce the number of spanning tree instances to reasonable value thus reducing cpu cycles needed to calculate stp for each vlan separately. 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. Instead of a network with loops, with spanning tree what you end up with is a treelike structure of branches. Cisco ccna prep spanningtree protocol stp section 1. Perlman devised a method by which bridges can obtain layer 2 routing utopia.
1517 925 1399 1247 1068 1595 1502 299 348 1408 44 236 1628 558 426 1383 379 1166 86 1498 483 943 1575 1630 942 204 360 1537 419 540 1203 1480 318 779 932 133 1390 382 968 1328 1001 376 287 1328 241