Presentation et configuration du protocole spanning tree. Understanding and configuring spanning tree protocol. To be able to deal with these potential loops that could be caused by these redundant paths the spanning tree protocol stp can be deployed. 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.
While this may work in small deployments, when dealing with switched networks that are a bit larger the deployment of redundancy is a required element. Bpdu guard is used to protect the spanning tree topology of a network by enforcing stp domain borders. Cisco spanning tree protocol guide stp examples and. Rapid spanning tree protocol incorporates several of ciscos stp enhancements and ensures a safe and quick transition to a forwarding state and topology convergence by removing the overdependence on. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. How to configure and verify spanning tree protocol stp portfast. Configuring spanning tree protocol costs on a cisco switch. Disabling spanning tree protocol stp can cause broadcast storms and layer 2 switching loops. How spanning tree protocols work, choosing a spanning tree protocol. It is quite useful and should be enabled on the switch interfaces. How to enable or disable spanning tree protocol stp. Presentation et configuration du protocole spanning tree stp. For what reasons would we want to configure spanning tree on router. In order to simplify the configuration of spanning tree on a switch, global settings are configured using what are known as spanning tree templates.
Cisco network troubleshooting spanning tree lab 01. Configure stp settings on a switch through the cli cisco. This is because with rstp each state has a much shorter timer. To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. Lan switching configuration guide, cisco ios xe release 3s. Configuring pervlan spanning tree protocol free ccna workbook. These two protocols operate with the same end goal in mind, yet one has a much more rapid convergence time rstp. Spanning tree protocol stp protects layer 2 broadcast domains from broadcast storms by selectively setting links to standby mode to prevent.
Never disable spanning tree protocol stp if there is no valid reason to disable it. Spanning tree protocolsome links below may open a new browser window to display the document you selected. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks. Configure spanningtree on cisco router network engineering. Remember, every time we modify the spanning tree topology, like changing priorities, spanning tree will need to converge. Cisco ccna spanning tree protocolroot bridge, root. The unique access pointbridge id wireless access pointbridge priority and mac address associated with each vlan on each wireless access pointbridge the spanningtree path cost to the spanningtree root the port identifier port priority and mac. First, it prevents problems caused by loops on a network.
On a cisco 1900 switch, up to four templates can be. Previously in the 7304 we used a bvi with our primary and redundant physical interfaces that connected to our service provider. 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. I recently noticed that show spanning tree command works on a cisco 1841 router as well. Root selection varies depending on the bid of each switch in your lab. Switches running stp will build a map or topology of the entire switching network. You can find the cisco configuration guide used to interpret their commands here. Alternatively, you can also use the following command to make a switch as root bridge. To prevent bridging loops redundant paths must be identified and blocked. The unique bridge id wireless bridge priority and mac address associated with each vlan on each wireless bridge the spanningtree path cost to the spanningtree root the port identifier port priority and mac address associated with each layer 2 interface. Configure stp spanning tree protocol in switches youtube. Edc0 hello time 2 sec max age 20 sec forward delay 15 sec aging time 20 interface role sts cost prio. 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.
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. When you have 20 vlans, it means there are 20 instances of spanning tree. Spanningtree protocol is a protocol used in switching network to create a loopfree topology. I have seen spanning tree being configured on switches to prevent switching loops. Bpdus bridge protocol data units are informational messages communicated between all switches in a spanning tree instance to maintain stp consistency. Learn how to configure the spanning tree protocol on cisco switches.
In this sample chapter from scaling networks v6 companion guide, explore potential redundancy problems, symptoms, and protocols to manage them. Not only does spanning tree blocks redundant paths but also reopens them in case of a link failure. We are migrating from a cisco 7304 to a asr 1002x for our internet router. Rootthe port given this role is the selected best path to reach the root switch. When you enable spanning tree protocol stp, every port in the switch, vlan, or network goes through the blocking state and transitory states. Stp can take up to a minute to converge, while rstp typically converges under 10 seconds in normal operation. Jul 11, 2015 configure stp spanning tree protocol in switches. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network. All the switches exchange information for use in the root switch selection and for subsequent configuration of the network. Pervlan spanning tree protocol is the default stp mode on cisco catalyst series switches. Second, when redundant loops are planned on a network, stp deals with remediation of network. Spanning tree protocol stp is a link management protocol that provides path redundancy while preventing undesirable loops in the network. The following table lists some of the differences among the.
The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. Configure and troubleshoot cisco spanning tree stp. The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. As the name suggests, it creates a spanning tree within a mesh network of connected layer2 bridges typically ethernet switches, and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes. This chapter describes how to configure the spanning tree protocol stp on a catalyst 4500 series switch. Stp will identify if there are any loops, and then disable or block. Stp switches send bpdus bridge protocol data units to each other to form their topology databases. For an ethernet network to function properly, only one active path can exist between two devices. 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. As the name implies, stp computes a tree that spans all. Understanding and configuring spanning tree protocol stp. Network redundancy is a key to maintaining network reliability.
Stp is enabled by default on all vlans on catalyst switches. Ex series,qfx series,mx series,srx series,m series,nfx series,t series,acx series. Lan switching configuration guide spanning tree protocol cisco. Stp spanning tree protocol step by step ciscoforall. Configuring spanning tree on meraki switches ms cisco meraki. May 24, 2016 user already knows cisco ios format and wants translation to mstpd spanning tree daemon for linux. 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. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Aug 04, 2011 spanning tree protocol stp is standardized as ieee 802. Vrrp is configured on the hp 8200zl switches in the core. This way, we are setting the priority for both vlan 1 and 10. 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. Spanning tree protocol was designed to avoid loops by finding redundant links in a network and shutting them down. Understanding and configuring spanning tree protocol stp cisco. This article aims to show you how to configure stp on sx250, sx300, sx350, sg350x, sx500, and sx550x series switches. This means that each vlan is mapped to a single spanning tree instance. Like alwaysit depends, lets take a look at an example. To configure spanning tree protocol stp portfast on a switch running ios, run spanningtree portfast command as shown below. Spanning tree protocol concepts and configuration cisco press. The stable, active spanningtree topology of a network is determined by the following factors. Supermicro l2l3 switches configuration guide 5 spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology. These templates include settings such as bridge priority, hello interval, and so forth. Spanningtree protocol stp prevents loops from being formed when switches or bridges are interconnected via multiple paths. Please refer to the spanning tree protocol documentation for more information. Ospfopen shortest path first configuration in cisco packet tracer duration.
Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. Spanning tree interoperability between hp and cisco switches. The stable, active spanningtree topology of your network is determined by these elements. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails. Configure spanning tree protocol stp on a switch cisco.
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