This section describes how spanningtree features work. This lab will discuss and demonstrate the configuration and verification of 802. On each switch, display the spanning tree table with the show spanning tree command. 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. Understanding and configuring spanning tree protocol stp. 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. Fundamentals of stp spanning tree protocol part i the logic.
The node with the smallest id is selected the root bridge 2. Stp can be considered to be converged after what three steps have taken place. This webcast shows you the stp topics for which youre responsible on the ccna rs 200125 or icnd2 200105. This document presents an overview of rapid spanning tree protocol rstp and multiple spanning tree protocol mstp and how to implement each. Make sure that the routers and switches have been erased and have no startup configurations. By default a cisco switch use pvst per vlan spanning tree but if we use the command show spanning tree with the default configuration the output is. Root selection varies depending on the bid of each switch in your lab resulting in varying outputs. Spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology.
In a converged network, ports are either in forwarding or blocking state. At this time there were no switches yet, only bridges, but because bridges and switches technically. Unless you change this value, a switch that has the lowest mac address. To overcome this problem, in 2001, the ieee with document 802. First, it prevents problems caused by loops on a network. In 2008 free ccna workbook originally started as a sharable pdf but quickly evolved into the largest ccna training.
Configuring pervlan spanning tree protocol free ccna. This exam tests a candidates knowledge and skills related to network fundamentals, network access, ip connectivity, ip services, security fundamentals, and automation and programmability. I will be concentrating on the main topics covered in the ccna icnd 2 exam. It vigilantly monitors the network to find all links, making sure that no loops occur by blocking any redundant ones.
Spanning tree protocol this document descibes spanning tree protocol stp in a wireless environment. Root selection varies depending on the bid of each switch in your lab. The biggest issue with stp is that some hardware failures can cause it to fail. Before we talk about spanning tree protocol, lets organize the different variants of stp.
The bridge id is made up of the mac address and priority. This document explains the spanning tree protocol stp root guard feature. On each switch, display the spanning tree table with the show spanningtree command. This failure creates forwarding loops or stp loops. This documentation is based primarily on the common stp. Configuring the spanning tree protocol j web procedure. 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. Detailed explanations of the basic functionality of each spanning tree protocol is outside the scope of this document.
Just like every coin has two sides, a redundant link, along with several advantages, has some disadvantages. Modify spanning tree to achieve load balancing modify the spanning tree configuration so that all six trunks are in use. Learn vocabulary, terms, and more with flashcards, games, and other study tools. If the main link goes down, the spanning tree activates the standby path. The spanning tree protocol stp is designed to prevent layer 2 loops. Before proceeding, save as stp configuration lab1working. Rapid spanning tree protocol rstp is another name for the 802. Spanningtree protocol stp premium ccna exam questions. This document descibes spanning tree protocol stp in a wireless environment.
Root selection varies depending on the default bid of each switch. At this time there were no switches yet, only bridges, but because bridges and switches technically do the same job only switches do it more efficiently and have more features they suffer from. The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. Stp spanning tree protocol explained with examples. This feature is one of the stp enhancements that cisco created. Understanding spanning tree protocol this section describes how spanningtree features work.
Networks should be designed to reconverge rapidly so that a fault is bypassed fault tolerance is achieved by redundancy. This documents main purpose is to explain the logic behind the functioning of spanning tree protocol. Pvst, rapid spanning tree protocolrstp and multi spanning tree protocol mstp. Spanning tree protocol root guard enhancement cisco. These presentations are the result of a collaboration among the instructors at st.
Intended audience this document is an implementation guide for deploying the recently ratified 802. Jan 31, 2016 hi guys, this post got awarded best publication at the cisco support community. All other switches on the network choose a best loop free path to reach the root. 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.
Switches running stp will build a map or topology of the entire switching network. Spanning tree protocol operation is transparent to end stations. How to configure spanning tree loop guard ccna ask itmen. Spanning tree protocol stp for ccna rs 200125 and icnd2. The original stp was developed by radia perlman while working for dce back in 1990. The spanning tree protocol prevents looping traffic in a redundant switched network by blocking traffic on the redundant links. I have attached the complete document in pdf format at the end, for download. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. Stp will identify if there are any loops, and then disable or block.
However, the contents of this document cannot be altered, without my written consent. Spanning tree protocol stp in packet tracer part 1. This lesson is an introduction to spanning tree, you will learn why we need it, how it works and how you can check the spanning tree topology on your cisco switches. The spanning tree feature cannot be turned off in switches on a perport basis. Components used although this document uses cisco catalyst 55005000 switches, the spanning tree principles that the document presents are applicable to almost all devices that support stp. The spanning tree protocol prevents loops in a redundant network. In a bridge or switch topology for purposes of stp, bridges and switches are identical in operation, it is desirable to physically cable redundant paths to provide fault tolerance. Understanding spanning tree protocol this section describes how spanning tree features work.
There are no specific requirements for this document. When you are adding a spanning tree, select a protocol name. Stp configuration lab1 open the packet tracer scenario. On each bridge, select a root port port with the least cost path to the root bridge. Spanning tree protocol interoperability with cisco arista networks.
The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks. Fundamentals of stp spanning tree protocol part i the. Introduction to spanning tree spanning tree is a protocol that runs on our switches that helps us to solve loops. How to configure spanning tree loop guard, spanning tree protocol stp resolves physically redundant topologies into loopfree, tree like topologies. 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. Ccna lab manual router infotech, confidential document only for internal circulation page 2 lab. Stp creates a loopfree tree structure consisting of leaves and branches that span the entire layer 2 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. Spanning treeenabled switches go through a root election process based on bridge p rotocol data unit. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. 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. Mst is commonly used in extremely large networks where running pvst would tax switch resources. Prerequisites requirements there are no specific requirements for this. Start studying ccna 200120 chapter 2 spanning tree protocol implementation. Nor can this document be sold or published without my expressed consent. Select the ports tab to configure the ports associated with this spanning tree. Stp is a layer 2 link management protocol that provides path redundancy while preventing loops in the network. This document is targeted at ses and other technical audiences as an. The router commands and output in this lab are from a cisco 1941 router using cisco ios software. A redundant link is an additional link between two switches.
Second, when redundant loops are planned on a network, stp deals with remediation of network. Path of packet i count this as a technology topic because it involves the forwarding mechanisms for the various catalyst platforms, spanning tree protocol, multicast, and quality of service. 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. Stp spanning tree protocol automatically removes layer 2 switching loops by shutting down the redundant links. Thanks must go out to rick graziani of cabrillo college.
Spanning tree 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. Nov 16, 2016 one of the topics on the ccna rs version 3 exam is spanning tree protocol stp. By default, the bridge priority value is set to 32768 in all cisco switches. The first spanning tree protocol was invented in 1985 at the digital equipment corporation by radia perlman.
Spanning tree protocol ccnax 200120 ccna practice tests. Ccna 200120 chapter 2 spanning tree protocol implementation. It also includes the contents as well as explanation for certain sections of the bpdu. Multi spanning tree protocol allows for resource conservation by now requring an instance for every single vlan in the layer 2 network. Ccna training rapid spanning tree protocol rstp tutorial.
Rapid spanning tree protocol rstprstp is defined in ieee 802. Configuring multiple spanning tree protocol mstp free. Spanning tree enabled switches go through a root election process based on bridge p rotocol data unit. Observe and explain the default behavior of spanning tree protocol stp, 802. Understanding and configuring spanning tree protocol stp on.
Rapid spanning tree protocol rstp one big disadvantage of stp is the low convergence which is very important in switched network. Stp overview stp is a layer 2 link management protocol that prov ides path redundancy while preventing loops in the network. Spanning tree protocol stp is another name for the 802. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Vlan0005 spanning tree enabled protocol ieee root id priority 32773 address 00.
For a layer 2 network to function properly, only one active path can exist between any two stations. Multiple spanning tree protocol gives you the ability to configure a hierarchical spanning tree topology where you have a common spanning tree instance known as the cist, technically instance 0 in mst configuration mode. Stp is enabled by default on all cisco switches, for all vlans. Spanning tree protocol in layer 2layer 3 environments.
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. You can use your network topology drawing to document the initial state of all trunk ports. This document is freely given, and can be freely distributed. In 1990, the ieee published the first standard for the protocol as 802.
All the ports in forwarding state are considered to be in the current spanning tree. Rstp keeps the same bpdu format as the original ieee 802. Spanning tree protocol assigns a root bridge, root ports for nonroot bridges, and designated port segments. The collective set of forwarding ports creates a single path over which frames are sent between ethernet segments. A redundant link is usually created for backup purposes.
1313 943 434 458 467 238 934 593 238 774 1232 570 163 220 1499 1549 473 176 162 60 537 219 537 1346 1305 1552 322 683 1445 488 181 1000 389 1366 1343 812 134 341 1227