Understanding and configuring spanning tree protocol stp. In 1990, the ieee published the first standard for the protocol as 802. Stp can take up to a minute to converge, while rstp typically converges under 10 seconds in normal operation. An example of pvst per vlan spanning tree configuration on. You can find the cisco configuration guide used to interpret their commands here. As shown in example 310, the show spanningtree active command displays spanningtree configuration details for the active interfaces only. Spanning tree protocolsome links below may open a new browser window to display the document you selected.
As shown in example 310, the show spanning tree active command displays spanning tree configuration details for the active interfaces only. Rapid spanning tree protocol rstp is the second stp type. Cisco introduced several enhancements to the standard stp operation that were later incorporated in rapid spanning tree protocol rstp defined as ieee 802. Configuring vstp on a trunk port with tagged traffic, reverting to rstp or vstp from forced ieee 802. Spanning tree interoperability between hp and cisco switches. Catalyst 4500 series switch software configuration guide. You can use the debug spanning tree bpdu command to view bpdus are are sent or received. Many people struggle with stp so in this video, we try to break it down as much as possible. Dec, 2006 spanning tree protocol enhancements using loop guard and bpdu skew detection features. This table shows the support of mst in catalyst switches and the minimum software required for that support. The main purpose of stp is to ensure that switches do not create loops when they have redundant paths in a network. This chapter describes how to configure the spanning tree protocol. The problem is that when we create redundancyat a layer 2 level of our networks,we create loops that traffic will traverse indefinitely. Spanning tree protocol states when the stp is enabled, every bridge and switch in the network starts in the blocking state and transitions to the listening and learning states.
Configure spanningtree on cisco router network engineering. There are no specific requirements for this document. 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. Rstp excellent summary of rapid spanning tree protocol. Aug 29, 2017 spanning tree protocol stp is a big topic on the ccna exam. Understanding spanningtree instance interfaces techlibrary.
Rstp bypass the blocking state and listenning state of stp, and provide forwarding state in 15 seconds. We will focus on spanning tree protocol stp configuration and verification commands in this tutorial, as implemented on cisco switches. Portfast on switch ports connected to a single workstation or server allows those devices to connect to the network immediately, instead of waiting for the port to transition from the listening and learning. Configuration examples and technotes view documents by topic choose a topic multiple instance stp mistp 802. A console cable that is suitable for the supervisor engine in the switch. Nexus 7000 stp priority change in peer switch setup impact assessment and configuration example. 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.
Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. Spanning tree protocol stp is a link management protocol that provides path redundancy while preventing undesirable loops in the network. 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. Learn how to configure the spanning tree protocol on cisco switches. Configure stp spanning tree protocol in switches youtube. 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. In some cases, rapid spanning tree protocol is similar to.
A number of cisco ios command parameters are associated with the show spanning tree command. Second, when redundant loops are planned on a network, stp deals with remediation of network. Configure and troubleshoot cisco spanning tree stp. For example, if the idlefree interfaces are closed by the system administrator, you will be able to view only the active interfaces with this command. Cisco saw the need for spanning tree on all vlans and create the proprietary pvst and. Cisco spanning tree protocol guide stp examples and. Spanning tree protocol explained step by step youtube. Nov 22, 2014 dear all, regarding best practice related to spanning tree and etherchannel, we have decided to configure following.
For example, if all devices in a network have the bridge priority for vlan 100 set to the default value of 32768, entering the spanningtree vlan. The following is the topology for this configuration example where 5 switches are full mesh connected. This table shows the support for mst in various catalyst switches. Configuring vstp protocol techlibrary juniper networks. This document assumes that the reader is familiar with rapid stp rstp 802. Switches running stp will build a map or topology of the entire switching network. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Just like every coin has two sides, a redundant link, along with several advantages, has some disadvantages.
Introduction to spanning tree spanning tree is a protocol that runs on our switches that helps us to solve loops. For example, assume that one port on switch b is a fiberoptic link, and. Stp spanning tree protocol explained with examples. On ports connecting to other switches enable root guard. Bridge id priority 32773 priority 32768 sysidext 5. However, this setup creates the possibility of a bridging loop. Lan switching configuration guide spanning tree protocol. Spanning tree protocol configuration examples and technotes. Vlan0005 spanning tree enabled protocol ieee root id priority 32773 address 00. May 24, 2016 user already knows cisco ios format and wants translation to mstpd spanning tree daemon for linux. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. Multi spanning tree protocol allows for resource conservation by now requring an instance for every single vlan in the layer 2 network. It was first introduced as cst common spanning protocol then ieee introduced its advanced version as stp with specification ieee 802.
Lldp configuration example cisco lldp configuration example huawei multiple. Rootthe port given this role is the selected best path to reach the root switch. Stp will identify if there are any loops, and then disable or block. Stp spanning tree protocol step by step configuration. Three spanning tree modes can be configured on cisco switches as shown in the output below. To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network. The first spanning tree protocol was invented in 1985 at the digital equipment corporation by radia perlman. Dec 09, 2017 spanning tree protocol utilizes the fact that just like the spanning tree from the graph theory, this network protocol can calculate the least cost path from any node to the root bridge. Configuring pervlan spanning tree protocol free ccna workbook. Spanning tree protocol stp is a layer 2 protocol that runs on switches. This lab will discuss and demonstrate the configuration and verification of 802.
Lan switching configuration guide spanning tree protocol cisco. I recently noticed that show spanning tree command works on a cisco 1841 router as well. For an ethernet network to function properly, only one active path can exist between two devices. Please refer to the spanning tree protocol documentation for more information. Understanding vstp, global and specific vstp configurations for switches, example. This command shows only the interfaces that are active on the cisco switch. These two protocols operate with the same end goal in mind, yet one has a much more rapid convergence time rstp. Supermicro l2l3 switches configuration guide 5 spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology. Understanding and configuring spanning tree protocol. Configuring multiple spanning tree protocol mstp free.
Portfast feature causes a switch port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states. 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. A redundant link is usually created for backup purposes. A number of cisco ios command parameters are associated with the show spanningtree command. First, it prevents problems caused by loops on a network.
Cisco spanning tree protocol guide stp examples and configuration spanning tree protocol stp ensures a loopfree topology in a local area network lan made up of switches. This is because with rstp each state has a much shorter timer. For what reasons would we want to configure spanning tree on router. Catalyst 4500 series switch software configuration guide, 15. This way, we are setting the priority for both vlan 1 and 10. To enable spanning tree, connect to your switch and type spanning tree mode while in global configuration mode. Ospfopen shortest path first configuration in cisco packet tracer duration. The following table lists some of the differences among the.
Remember, every time we modify the spanning tree topology, like changing priorities, spanning tree will need to converge. It is a fast converged version of spanning tree protocol as its name implies. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Spanning tree protocol concepts and configuration cisco press. Understanding and configuring spanning tree protocol stp cisco. Vrrp is configured on the hp 8200zl switches in the core. I have seen spanning tree being configured on switches to prevent switching loops. This is because layer 2 ethernet frameshave no time to live or time out mechanismbuilt into the frame.
Although this document uses cisco catalyst 5500 5000 switches, the spanning tree principles that the document presents are applicable to almost all devices that support stp. Refer to understanding multiple spanning tree protocol 802. A redundant link is an additional link between two switches. It is quite useful and should be enabled on the switch interfaces. If properly configured, the ports then stabilize to the forwarding or blocking state until a change in the network is made. It is recommended to read understanding rapid spanning tree protocol 802. Cisco network troubleshooting spanning tree lab 01. One for network vlan, two for isolated subscriber vlans and another two for nonisolated subscriber vlans.