Spanning tree protocol stp is a layer 2 protocol that runs on switches. It is a fast converged version of spanning tree protocol as its name implies. Multi spanning tree protocol allows for resource conservation by now requring an instance for every single vlan in the layer 2 network. 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. Stp spanning tree protocol step by step configuration. Multiple spanning tree protocol was developed to reduce the number of. Rstp bypass the blocking state and listenning state of stp, and provide forwarding state in 15 seconds. 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. Nexus 7000 stp priority change in peer switch setup impact assessment and configuration example. 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. These two protocols operate with the same end goal in mind, yet one has a much more rapid convergence time rstp.
The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. Lldp configuration example cisco lldp configuration example huawei multiple. To enable spanning tree, connect to your switch and type spanning tree mode while in global configuration mode. Stp spanning tree protocol automatically removes layer 2 switching loops by shutting down the redundant links. Configuration examples and technotes view documents by topic choose a topic multiple instance stp mistp 802. Cisco network troubleshooting spanning tree lab 01. As shown in example 310, the show spanning tree active command displays spanning tree configuration details for the active interfaces only. Understanding and configuring spanning tree protocol. Stp will identify if there are any loops, and then disable or block. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network. A number of cisco ios command parameters are associated with the show spanning tree command. Refer to understanding multiple spanning tree protocol 802. 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. Catalyst 4500 series switch software configuration guide, 15.
Spanning tree protocol configuration examples and technotes. 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. This is because with rstp each state has a much shorter timer. I have seen spanning tree being configured on switches to prevent switching loops. Configuring vstp on a trunk port with tagged traffic, reverting to rstp or vstp from forced ieee 802. It is recommended to read understanding rapid spanning tree protocol 802. Spanning tree protocol explained step by step youtube. For example, a broadcast or multicast packet that transmits from station m and is. Catalyst 4500 series switch software configuration guide. Lan switching configuration guide spanning tree protocol. I recently noticed that show spanning tree command works on a cisco 1841 router as well.
Just like every coin has two sides, a redundant link, along with several advantages, has some disadvantages. This chapter describes how to configure the spanning tree protocol. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Vrrp is configured on the hp 8200zl switches in the core. 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 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. The following is the topology for this configuration example where 5 switches are full mesh connected. This will be discussed in lab 415 configuring multiple spanning tree protocol.
Nov 22, 2014 dear all, regarding best practice related to spanning tree and etherchannel, we have decided to configure following. Configure spanningtree on cisco router network engineering. For what reasons would we want to configure spanning tree on router. It was first introduced as cst common spanning protocol then ieee introduced its advanced version as stp with specification ieee 802. A number of cisco ios command parameters are associated with the show spanningtree command.
This document assumes that the reader is familiar with rapid stp rstp 802. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Rootthe port given this role is the selected best path to reach the root switch. This lab will discuss and demonstrate the configuration and verification of 802. One for network vlan, two for isolated subscriber vlans and another two for nonisolated subscriber vlans. Portfast feature causes a switch port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states. Spanning tree protocol stp is a link management protocol that provides path redundancy while preventing undesirable loops in the network. Vlan0005 spanning tree enabled protocol ieee root id priority 32773 address 00. Cisco introduced several enhancements to the standard stp operation that were later incorporated in rapid spanning tree protocol rstp defined as ieee 802.
The main purpose of stp is to ensure that switches do not create loops when they have redundant paths in a network. For example, assume that one port on switch b is a fiberoptic link, and. A redundant link is usually created for backup purposes. A redundant link is an additional link between two switches. If properly configured, the ports then stabilize to the forwarding or blocking state until a change in the network is made. Lan switching configuration guide spanning tree protocol cisco. Spanning tree protocolsome links below may open a new browser window to display the document you selected. Remember, every time we modify the spanning tree topology, like changing priorities, spanning tree will need to converge. It is quite useful and should be enabled on the switch interfaces. Second, when redundant loops are planned on a network, stp deals with remediation of network. 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.
A console cable that is suitable for the supervisor engine in the switch. In some cases, rapid spanning tree protocol is similar to. Switches running stp will build a map or topology of the entire switching network. The problem is that when we create redundancyat a layer 2 level of our networks,we create loops that traffic will traverse indefinitely. The following table lists some of the differences among the.
Many people struggle with stp so in this video, we try to break it down as much as possible. For an ethernet network to function properly, only one active path can exist between two devices. Cisco spanning tree protocol guide stp examples and. This command shows only the interfaces that are active on the cisco switch. This way, we are setting the priority for both vlan 1 and 10. Introduction to spanning tree spanning tree is a protocol that runs on our switches that helps us to solve loops.
Configure stp spanning tree protocol in switches youtube. We will focus on spanning tree protocol stp configuration and verification commands in this tutorial, as implemented on cisco switches. 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. Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. This is because layer 2 ethernet frameshave no time to live or time out mechanismbuilt into the frame.
Spanning tree interoperability between hp and cisco switches. There are no specific requirements for this document. Rapid spanning tree protocol rstp is the second stp type. To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. 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. Ospfopen shortest path first configuration in cisco packet tracer duration.
You can find the cisco configuration guide used to interpret their commands here. In 1990, the ieee published the first standard for the protocol as 802. Stp spanning tree protocol explained with examples. However, this setup creates the possibility of a bridging loop. First, it prevents problems caused by loops on a network. Understanding and configuring spanning tree protocol stp. Configure and troubleshoot cisco spanning tree stp. 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 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.
You can use the debug spanning tree bpdu command to view bpdus are are sent or received. Bridge id priority 32773 priority 32768 sysidext 5. Learn how to configure the spanning tree protocol on cisco switches. Three spanning tree modes can be configured on cisco switches as shown in the output below. Understanding vstp, global and specific vstp configurations for switches, example. Cisco saw the need for spanning tree on all vlans and create the proprietary pvst and. Please refer to the spanning tree protocol documentation for more information. Spanning tree protocol concepts and configuration cisco press. Rstp excellent summary of rapid spanning tree protocol. Configuring vstp protocol techlibrary juniper networks.
Understanding spanningtree instance interfaces techlibrary. Supermicro l2l3 switches configuration guide 5 spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology. On ports connecting to other switches enable root guard. Aug 29, 2017 spanning tree protocol stp is a big topic on the ccna exam. Understanding and configuring spanning tree protocol stp cisco. The first spanning tree protocol was invented in 1985 at the digital equipment corporation by radia perlman. Configuring multiple spanning tree protocol mstp free. Stp can take up to a minute to converge, while rstp typically converges under 10 seconds in normal operation.