Spanningtree protocol is a protocol used in switching network to create a loopfree topology. It is desirable to have redundant links in a switched lan so that a single link failure cannot interrupt normal operation of the network. In this sample chapter from scaling networks v6 companion guide, explore potential redundancy problems, symptoms, and protocols to manage them. Configure stp settings on a switch through the cli cisco.
Ex series,qfx series,mx series,srx series,m series,nfx series,t series,acx series. First, it prevents problems caused by loops on a network. The main purpose of stp is to ensure that you do not create loops when you have redundant paths in your network. Spanning tree protocolsome links below may open a new browser window to display the document you selected. We are migrating from a cisco 7304 to a asr 1002x for our internet router. Cisco ccna spanning tree protocolroot bridge, root. Spanning tree protocol stp spanning tree protocol stp was developed to prevent the broadcast storms caused by switching loops. Next, execute the following command to verify the spanning tree configuration. Configure spanning tree protocol stp on a switch cisco. Alternatively, you can also use the following command to make a switch as root bridge. 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 pervlan spanning tree protocol free ccna workbook.
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. Disabling spanning tree protocol stp can cause broadcast storms and layer 2 switching loops. On a cisco 1900 switch, up to four templates can be. Bpdu guard is used to protect the spanning tree topology of a network by enforcing stp domain borders. Configuring spanning tree protocol costs on a cisco switch. Stp can take up to a minute to converge, while rstp typically converges under 10 seconds in normal operation. Lan switching configuration guide, cisco ios xe release 3s. Configure and troubleshoot cisco spanning tree stp. This way, we are setting the priority for both vlan 1 and 10.
Cisco spanning tree protocol guide stp examples and. You can find the cisco configuration guide used to interpret their commands here. You can use the debug spanning tree bpdu command to view bpdus are are sent or received. Previously in the 7304 we used a bvi with our primary and redundant physical interfaces that connected to our service provider. 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. Root selection varies depending on the bid of each switch in your lab. 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. This article aims to show you how to configure stp on sx250, sx300, sx350, sg350x, sx500, and sx550x series switches. Configure stp spanning tree protocol in switches youtube. All the switches exchange information for use in the root switch selection and for subsequent configuration of the network. The spanning tree protocol stp is a network protocol that builds a loopfree logical topology for ethernet networks.
Spanning tree protocol was designed to avoid loops by finding redundant links in a network and shutting them down. 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. Never disable spanning tree protocol stp if there is no valid reason to disable it. Understanding and configuring spanning tree protocol. Lan switching configuration guide spanning tree protocol cisco. Pervlan spanning tree protocol is the default stp mode on cisco catalyst series switches. Remember, every time we modify the spanning tree topology, like changing priorities, spanning tree will need to converge. Spanning tree protocol stp is a layer 2 protocol that runs on bridges and switches. Spanning tree protocol stp is a link management protocol that provides path redundancy while preventing undesirable loops in the network.
The basic function of stp is to prevent bridge loops and the broadcast radiation that results from them. 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. Cisco network troubleshooting spanning tree lab 01. When you have 20 vlans, it means there are 20 instances of spanning tree. Stp switches send bpdus bridge protocol data units to each other to form their topology databases. Learn how to configure the spanning tree protocol on cisco switches. How to enable or disable spanning tree protocol stp. Stp spanning tree protocol step by step ciscoforall.
These two protocols operate with the same end goal in mind, yet one has a much more rapid convergence time rstp. Configure spanningtree on cisco router network engineering. Once the root switch is elected, each of the ports is given a role depending on its place within the stp topology. Not only does spanning tree blocks redundant paths but also reopens them in case of a link failure.
Switches running stp will build a map or topology of the entire switching network. Rootthe port given this role is the selected best path to reach the root switch. Presentation et configuration du protocole spanning tree. Spanning tree protocol concepts and configuration cisco press. 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 also allows a network design to include backup links providing fault tolerance if an active link fails. I recently noticed that show spanning tree command works on a cisco 1841 router as well. Spanning tree protocol stp protects layer 2 broadcast domains from broadcast storms by selectively setting links to standby mode to prevent. Presentation et configuration du protocole spanning tree stp. It is quite useful and should be enabled on the switch interfaces. Jul 11, 2015 configure stp spanning tree protocol in switches. Like alwaysit depends, lets take a look at an example. As the name implies, stp computes a tree that spans all. These templates include settings such as bridge priority, hello interval, and so forth.
The stable, active spanningtree topology of your network is determined by these elements. 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. 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. Spanning tree interoperability between hp and cisco switches. Edc0 hello time 2 sec max age 20 sec forward delay 15 sec aging time 20 interface role sts cost prio. Vrrp is configured on the hp 8200zl switches in the core. Bpdus bridge protocol data units are informational messages communicated between all switches in a spanning tree instance to maintain stp consistency. 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. Understanding and configuring spanning tree protocol stp. May 24, 2016 user already knows cisco ios format and wants translation to mstpd spanning tree daemon for linux.
Understanding and configuring spanning tree protocol stp cisco. How spanning tree protocols work, choosing a spanning tree protocol. 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. On each switch, display the spanning tree table with the show spanning tree command. To configure spanning tree protocol stp portfast on a switch running ios, run spanningtree portfast command as shown below. Supermicro l2l3 switches configuration guide 5 spanning tree enabled switches exchange spanning tree protocol messages bpdu to form a loopfree topology. When you enable spanning tree protocol stp, every port in the switch, vlan, or network goes through the blocking state and transitory states. To enable spanning tree, connect to your switch and type spanningtree mode while in global configuration mode. Network redundancy is a key to maintaining network reliability. Stp will identify if there are any loops, and then disable or block.
The following table lists some of the differences among the. The stable, active spanningtree topology of a network is determined by the following factors. Spanningtree protocol stp prevents loops from being formed when switches or bridges are interconnected via multiple paths. For what reasons would we want to configure spanning tree on router. 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. This means that each vlan is mapped to a single spanning tree instance.
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. Stp is enabled by default on all vlans on catalyst switches. In order to simplify the configuration of spanning tree on a switch, global settings are configured using what are known as spanning tree templates. Ospfopen shortest path first configuration in cisco packet tracer duration. Configuring spanning tree on meraki switches ms cisco meraki. Second, when redundant loops are planned on a network, stp deals with remediation of network. Aug 04, 2011 spanning tree protocol stp is standardized as ieee 802. 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.
Please refer to the spanning tree protocol documentation for more information. To prevent bridging loops redundant paths must be identified and blocked. This chapter describes how to configure the spanning tree protocol stp on a catalyst 4500 series switch. How to configure and verify spanning tree protocol stp portfast.
1006 46 940 1293 632 708 1014 480 699 146 926 282 1178 1309 1266 708 1117 361 1244 159 1121 110 585 1275 156 446 487 1186 1222 40 67 1433 135 952 933 937