RCNI Exam Dumps - RUCKUS High-stakes Industry Certifications Questions and Answers

In RUCKUS ICX switches, VLAN 1 is the default VLAN and is typically used for management purposes. By default, all ports are members of VLAN 1 as untagged. Attempting to configure VLAN 1 as tagged on a port can result in an error, as the system restricts tagging the default VLAN.

Understanding the Error:

RKUS-01(config)# vlan 1

RKUS-01(config-vlan-1)# tagged ethernet 1/2/1

Invalid input -> tagged ethernet 1/2/1

Type ? for a list

This error occurs because the switch does not allow tagging of the default VLAN (VLAN 1) on any interface.

Resolution:

Option 1: Use a Different VLAN for Tagging

Create a new VLAN (e.g., VLAN 2) and configure it as tagged on the desired port.

RKUS-01(config)# vlan 2

RKUS-01(config-vlan-2)# tagged ethernet 1/2/1

Option 2: Change the Default VLAN ID

If you must use VLAN 1 as tagged, you can change the default VLAN ID to another VLAN (e.g., VLAN 2), allowing VLAN 1 to be configured as tagged.

RKUS-01(config)# default-vlan-id 2

RKUS-01(config)# vlan 1

RKUS-01(config-vlan-1)# tagged ethernet 1/2/1

In the Spanning Tree Protocol (STP), the root bridge is the central reference point for all spanning tree calculations. The election of the root bridge is determined by the bridge ID (BID), which comprises two components:

Bridge Priority:

A configurable value ranging from 0 to 65,535, in increments of 4,096. The default priority is typically 32,768.

MAC Address:

The unique hardware address of the switch.

Root Bridge Election Process:

Lowest Bridge ID Selection:

STP elects the switch with the lowest bridge ID as the root bridge. The bridge ID is determined by combining the bridge priority and the MAC address.

Priority Comparison:

Switches first compare the bridge priority values. The switch with the lowest priority value is favored.

MAC Address Comparison:

If multiple switches share the same priority value, the switch with the lowest MAC address becomes the root bridge.

Example:

Switch A:

Priority: 32,768

MAC Address: 00:1A:2B:3C:4D:5E

Switch B:

Priority: 32,768

MAC Address: 00:1A:2B:3C:4D:5F

In this scenario, both switches have the same priority. Therefore, STP compares the MAC addresses, and Switch A, with the lower MAC address, is elected as the root bridge.

Key Points:

Enabling root guard on a device does not influence its election as the root bridge; instead, it prevents designated ports from becoming root ports.

The device with the lowest bridge ID (combination of priority and MAC address) is elected as the root bridge.

A lower bridge priority value increases the likelihood of a switch becoming the root bridge.

References:

Root Bridge Election in Spanning Tree Protocol

Spanning Tree Protocol – Part 3: Bridge ID, Priority, System ID

Sources

When a high CPU utilization alert is triggered on a RUCKUS ICX switch, it's essential to identify the processes consuming excessive CPU resources. The show cpu tasks command provides detailed information about active processes and their CPU usage.

Command Usage:

show cpu tasks

Output Example:

Task Name CPU Time (ms) Invocations Avg Time (us)

------------------ -------------- ------------ -------------

TaskA 5000 1000 5000

TaskB 3000 1500 2000

In this output:

Task Name lists the names of active processes.

CPU Time (ms) indicates the total CPU time consumed by each process in milliseconds.

Invocations shows how many times each process has been called.

Avg Time (us) represents the average time per invocation in microseconds.

By analyzing this data, administrators can pinpoint processes that are utilizing disproportionate CPU resources, facilitating targeted troubleshooting and optimization.

Understanding Bridge Priority:

The bridge priority in the Spanning Tree Protocol (STP) is represented in hexadecimal format in RUCKUS ICX switches.

In the output, the bridge priority is a combination of the priority value (default is 32768 or 0x8000 in hex) and the VLAN ID.

Why It Is 8000:

Unless explicitly modified, the default bridge priority is 8000 in hexadecimal.

Why Other Options Don't Apply:

B. 0: This value does not align with the default or modified priority values.

C. 9c49: This might represent a different component of the output, such as MAC address.

D. 20009: This is an incorrect representation of the bridge priority.

References:

ICX Spanning Tree Configuration Guide: RUCKUS Documentation