Dell PowerSwitch S4112F-ON EMC SmartFabric OS10 User Guide Release 10.5.1 - Page 503
Spanning-tree protocol, Introduction to STP, Supported STP modes, Change STP modes
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Example (Dynamic) Example (Ethernet) Supported Releases OS10# show mac address-table dynamic VlanId Mac Address Type Interface 1 90:b1:1c:f4:a6:8f dynamic ethernet1/1/3 OS10# show mac address-table interface ethernet 1/1/3 VlanId Mac Address Type Interface 1 66:38:3a:62:31:3a dynamic ethernet1/1/3 10.2.0E or later Spanning-tree protocol This section describes how spanning-tree features work and also about the different variants of STP. Configuration notes Dell EMC PowerSwitch S5200-ON Series and Z9332F-ON Series: For RPVST with force-version STP convergence to work, ensure that the default VLAN is set to VLAN1. You must not configure it to any VLAN number other than VLAN1. Introduction to STP The spanning-tree protocol is a Layer 2 network protocol that prevents loops in a network topology. Spanning-tree is useful when more than one network path exists and devices in the network are either competing for or sharing these paths. By eliminating loops, the protocol improves scalability in a large network and allows you to implement redundant paths, which can be activated when the active paths fail. Layer 2 loops occur in a network due to poor network design and without enabling xSTP protocols, can cause high switch CPU utilization and memory consumption. NOTE: In L2 single rack, OS10 CLI is used to configure the spanning tree. For L3 fabric, SFS GUI is used to configure the spanning tree. Supported STP modes The following variants of spanning-tree protocols are used in OS10 to provide a loop free layer 2 topology: ● Rapid Spanning Tree protocol can be seen as an evolution of the 802.1D standard. Primarily RSTP is created to address the slow convergence nature of STP protocol (802.1D). ● Multiple Spanning Tree protocol (MSTP) defined in IEEE standard (802.1s), is an evolution of spanning tree protocols allowing creation of multiple instance of spanning tree and mapping multiple VLANs to a specific spanning tree instance. ● Rapid per-VLAN spanning-tree protocol (Rapid-PVST) is a variant of RSTP protocol and supports creation of per VLAN spanning tree instance to isolate link fluctuations only to a particular VLAN segment and also helps in load balancing across different links. ● 802.1D STP Compatibility mode support. This mode enables the bridge to function as an IEEE Std 802.1D legacy STP compatible mode while the system is running RSTP or MSTP modes of the spanning tree protocol. ● RSTP and MSTP are backward compatible with STP 802.1D. When an interface receives STP BPDU, the system responds with the STP version of BPDU. Change STP modes The default xSTP variant running in OS10 is Rapid-PVST. You can change the mode to RSTP or MSTP using the spanningtree mode {rstp | mst | rapid-pvst} command. Layer 2 503
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