Cisco spanning tree protocol guide stp examples and. It is known that stp start making issues once the ring goes beyond 6 or 7 switches. 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. In spanning tree protocol configuration, the shortest path to the root bridge switch is called the root port. Spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops.
It will be helpful if i get more info on this or a link to that. 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. In addition to configuring stp on the switch, you will also configure port 2 on the switch for portfast, which allows the port to immediately transition to forwarding mode. Stp is a layer 2 link management protocol that provides path redundancy. Consolidated platform configuration guide, cisco ios release 15. Stp spanning tree protocol step by step configuration. What is spanning tree protocol stp sysnettech solutions. This factor of time is not an issue for many people, but it can cause problems for some. Lets start to configure rstp rapid spanning tree protocol on cisco packet tracer. Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. If a loop does occur after using stp, then we need to follow a sequence of steps to stop the loop.
Spanningtree bridge assurance is one of those stp features that help to prevent bridging loops in your network. I understand that once an etherchannel is defined, regardless of pagp or lacp, that the new portchannel is introduced into the spanning tree and the physical ports are removed. Root selection varies depending on the bid of each switch in your lab resulting in varying outputs. Switches running stp will build a map or topology of the entire switching network. Configure stp spanning tree protocol in switches youtube. The time spanning tree protocol stp takes to transition ports over to the forwarding state can cause problems. Check enable in the spanning tree state field to enable spanning tree. Pvst, rapid spanning tree protocolrstp and multi spanning tree.
Stp spanning tree protocol explained with examples. To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. Spanning tree protocol stp for ccna rs 200125 and icnd2 200105 candidates duration. We will focus on spanning tree protocol stp configuration and verification commands in this tutorial, as implemented on cisco switches. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. The bridges send configuration bpdus through the ethernet and radio ports. What is the default spanningtree mode on a 4507 swith with ios version 12. Check the spanning tree state check box to enable spanning tree.
Cisco introduced several enhancements to the standard stp operation that were later incorporated in rapid spanning tree protocol rstp defined as ieee 802. Enabling this feature checks if a root port or an alternate root port receives bridge protocol data units bpdus. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks. Spanning tree protocol configuration stp configuration. On each switch, display the spanning tree table with the show spanningtree command. Spanning tree protocol stp is a protocol which prevents layer 2 loops. Cisco nexus 5000 series switch cli software configuration guide ol1659701 1 configuring mst multiple spanning tree mst, which is the ieee 802.
When providing vlan support for stp you encounter two protocols on your cisco switches. So the same nomenclature for the different reference points lives to this day. This section describes how spanningtree features work. An open standards version of stp that allows you to initiate multiple copies of stp on your switch and manually configure separate zones or implementations. Portfast is a feature which can be used to speed up convergence on ports which are connected to a workstation or a server which will not cause layer 2 loops. To configure spanning tree protocol stp portfast on a switch running ios, run spanningtree portfast command as shown below. Edc0 hello time 2 sec max age 20 sec forward delay 15 sec aging time 20. Rapid spanning tree protocol rstprstp is defined in ieee 802. By default, the bridge priority value is set to 32768 in all cisco switches. Spanning tree protocol stp and vlan interaction dummies. You can use the debug spanningtree bpdu command to view bpdus are are sent or received. In practical scenario, redundant links are created to avoid complete network failure in an event of failure of one link. This is accomplished by configuring one switch to be elected the root bridge for half of the vlans in the network and a second switch. 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.
The bridge has a single instance of stp in nonvlan configurations and multiple instances of stp. So in essence you have two instances of spanning tree, instead of many different instances for every eventuality. Cbt nuggets trainer jeremy cioara explains how to configure spanning tree protocol as well as the different types of spanning tree protocols. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Mstp uses the same basic frame structure as rstp but after the rstp data in the frame concludes, mstp adds an. Click the radio button that corresponds to the desired operating mode for stp in the stp operation mode field. This document descibes spanning tree protocol stp in a wireless environment. Edc0 this bridge is the root hello time 2 sec max age 20 sec forward delay 15 sec bridge id priority 32769 priority 32768 sysidext 1 address 0001.
The ieee version of rapid pvst is called multiple spanning tree. The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. I dont know if the answer has changed because cisco has changed their protocols. Therefore, the switch2 and switch3 ethernet0 0 interfaces above will be configured as root ports. Configuring pervlan spanning tree protocol free ccna. Recently there was a debate among some folks about how stp is handled within an etherchannel.
For a layer 2 network to function properly, only one active path can exist between any two stations. Stp will identify if there are any loops, and then disable or block. Cisco saw the need for spanning tree on all vlans and create the proprietary pvst and. Configuring stp and rstp this chapter describes the ieee 802. This protocol was created by radia perlman for bridges, ethernet transparent bridges. The reason for the above stated question is that for the same category of switches with ios version of 12. In figure 332, port f03 on s2 is the forwarding port for vlan 20, and f02 on s2 is the forwarding port for vlan 10.
Spanning tree protocol concepts 45 in many ways, those last two paragraphs sum up what stp does. Portfast is a cisco network function which can be configured to resolve this problem. Observe and explain the default behavior of spanning tree protocol stp, 802. Spanning tree also allows a network design to include spare redundant links to provide automatic backup paths.
Cisco also published a proprietary version of rapid spanning tree protocol. Understanding issues related to intervlan bridging pdf. So, for stp, going through forwarding states needs 50 seconds. You will learn how spanningtree works and how you can verify the spanningtree config on cisco. Configure a password of cisco for console connections. This total time is 15 seconds in rstp rapid spanning tree protocol. According ccna outing and switching practice test editoria sybex in 2017 question 2. Stp is enabled by default on all cisco switches, for all vlans. By nature of the rapidpvst protocol being based on rstp, this also means that arista switches are backwardcompatible with cisco. Can someone please let me know the type of bpdus is stp and their funtion. Lan switching configuration guide spanning tree protocol.
The following table lists some of the differences among the. Root selection varies depending on the bid of each switch in your lab. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in. How to configure and verify spanning tree protocol stp. Before configuring stp, the network topology should be carefully planned. This first major section of the chapter begins by explaining the need for stp and the basic ideas of what stp does.
You complete three major steps to configure stp on the wmic. Ccna stp tutorial by jagvinder thind shows stp configuration in packet tracer in hindi or how to configure stp spanning tree protocol in hindi. It also explains how to configure stp and rstp on the mlseries card. Understanding and configuring spanning tree protocol stp. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. The following code will enable the cisco proprietary rapid per vlan spanning tree protocol pvst over the open standard of multiple spanning tree protocol mstp. When bridge assurance is enabled, bpdus are sent on all interfaces of your switch, including blocked interfaces like the alternate or backup port. The basic function of stp is to prevent bridge loops and ensuing broadcast radiation. Because rstp, bypasses the blocking and listenning states. There is only one active path for each spanning tree. However, the details of how stp does its work can take a fair amount of study and practice. And so, dont be too confused when we say root switch or root bridge, they are the same, they are the same. This tutorial explains what the stp protocol is and how it removes.
Optional check the stp loopback guard check box to enable the feature. It works on the premise that you have a number of vlans blocking on 1 port and forwarding on another, and bundles them together into an instance. Stp enables switches to become aware of each other so that they can negotiate a loopfree path through network. Configure spanning tree protocol stp on a switch cisco. The spanning tree protocol stp is a network protocol that ensures a loopfree topology for any bridged ethernet local area network. This will be discussed in lab 415 configuring multiple spanning tree protocol. 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. Spanning tree root port is used to select path cost. Stp is a layer 2 link management protocol that provides path redundancy while preventing loops in the network.
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