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Zorluk: OrtaTroubleshooting VLAN, Trunking, and Switching Issues

During a planned network maintenance window, an administrator installs a new central switch (Switch-Core) to serve as the core switching node. After connecting Switch-Core to the access switches, network traffic follows sub-optimal paths across the campus topology. Troubleshooting reveals that an old edge switch (Switch-Access-3) with a configured Spanning Tree Protocol (STP) bridge priority of 4096 has been elected as the STP root bridge because Switch-Core is using the default STP priority of 32768. Which configuration change on Switch-Core will resolve this issue and establish Switch-Core as the STP root bridge?

  1. Configure the STP bridge priority value on Switch-Core to a number lower than 4096, such as 0 or 2048.Cevap
  2. B
    Increase the STP bridge priority value on Switch-Core to 65535 to give it the highest election weight.
  3. C
    Change the native VLAN on all Switch-Core trunk ports to match Switch-Access-3 so STP BPDUs can be processed.
  4. D
    Configure static inter-VLAN routing on Switch-Access-3 to bypass the Spanning Tree Protocol root bridge election.

Cevap

Configure the STP bridge priority value on Switch-Core to a number lower than 4096, such as 0 or 2048.
In 802.1D and 802.1w Spanning Tree Protocol, the switch with the lowest Bridge ID (BID) is elected as the root bridge. The BID begins with the bridge priority field. Because Switch-Access-3 has a priority of 4096 and Switch-Core is at the default value of 32768, Switch-Access-3 wins the election. Assigning Switch-Core a bridge priority lower than 4096 (such as 0 or 2048) guarantees it has the lowest BID and becomes the root bridge.

Adım Adım Çözüm

1
Identify the election criteria for Spanning Tree Protocol (STP) Root Bridge selection.
STP elects the root bridge based on the lowest Bridge ID (BID), which combines Bridge Priority and the switch MAC address.
Understanding BID comparison rules determines how to influence root bridge election.
2
Compare the current bridge priority of Switch-Access-3 (4096) with Switch-Core (32768).
Switch-Access-3 has a lower numerical priority (4096 < 32768), making it the current root bridge.
Lower numerical values take precedence in STP root bridge elections.
3
Determine the necessary configuration change on Switch-Core.
Setting Switch-Core's priority to a value lower than 4096 (e.g., 0 or 2048 in standard 4096 increments) forces Switch-Core to win the root bridge election.
Configuring a lower priority than 4096 ensures Switch-Core advertises the lowest BID across the broadcast domain.

Anahtar Kavram

STP Root Bridge Priority Election
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