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Which type of traffic can still be received on a switch interface that is in STP blocking mode?
BPDU frames
What is the frame containing STP information that is exchanged between switches?
All switches participating in STP exchange BPDU frames to determine which switch has the lowest bridge ID(BID) on the network.
What additional information is contained in the 12-bit extended system ID of a BPDU?
The 12-bit extended system ID in a Bridge Protocol Data Unit (BPDU) contains information about the VLAN (Virtual Local Area Network) associated with the bridge or switch. This extended system ID allows for the identification of the VLAN in which the BPDU is being transmitted, facilitating the proper functioning of Spanning Tree Protocol (STP) in environments with multiple VLANs. By incorporating the VLAN ID, the extended system ID helps manage traffic and prevent loops within VLANs effectively.
Cisco Catalyst feature automatically disables the port in an operational PortFast upon receipt of a BPDU?
Explanation/Reference: This question is to examine the BPDU Guard. To prevent loops from occurring in a network, the PortFast mode is supported only on nontrunking access ports because these ports typically do not transmit or receive BPDUs. The most secure implementation of PortFast is to enable it only on ports that connect end stations to switches. Because PortFast can be enabled on nontrunking ports connecting two switches, spanning tree loops can occur because BPDUs are still being transmitted and received on those ports. The PortFast BPDU guard feature prevents loops by moving a nontrunking port into an errdisable state when a BPDU is received on that port. When the BPDU guard feature is enabled on the switch, spanning tree shuts down PortFast-configured interfaces that receive BPDUs, instead of putting them into the spanning tree blocking state. In a valid configuration, PortFast-configured interfaces do not receive BPDUs. If a PortFast-configured interface receives a BPDU, an invalid configuration exists, such as connection of an unauthorized device. The BPDU guard feature provides a secure response to invalid configurations because the administrator must manually put the interface back in service.
Which type of frame contains information that is used in the election of the spanning tree root bridge?
BPDU
What is the mechanism used by bridges running STP to exchange information?
Bridge protocol data unit BPDU
Which spanning tree protection feature disables ports when a violation occurs?
The spanning tree protection feature that disables ports when a violation occurs is called "Bridge Protocol Data Unit (BPDU) Guard." When BPDU Guard is enabled on a port, it monitors for incoming BPDUs, and if a BPDU is received on a port configured with this feature, the port is immediately placed in an error-disabled state to prevent potential loops or misconfigurations in the network. This helps maintain network stability by safeguarding against unwanted topology changes.
What is 'err-disabled' error. it is frequently blocking the port of your cisco switch?
This is caused by port security being enabled and having the violation setting set to shutdown. This is triggered when you have two many MAC addresses listed for the port of if a BPDU is sent to that port, depending on how port security is configured.
What is spaning tree protocol?
STP stand for Spaning Tree Protocol. It's used to avoid the L2 loop in the network. many factor are belong to STP. such as Root Switch, BPDU, Root Port, Forward port, blocking port.
Which is the recommended option to reduce the STP convergence time in a network?
To reduce the Spanning Tree Protocol (STP) convergence time in a network, enabling Rapid Spanning Tree Protocol (RSTP), which is defined in IEEE 802.1w, is recommended. RSTP significantly improves convergence times to a few seconds by introducing new port states and roles that expedite the transition of ports to forwarding mode. Additionally, implementing features like Bridge Protocol Data Units (BPDU) guard and root guard can enhance stability and speed up the convergence process further.
