RCNI Practice Questions

The show inline power command on a RUCKUS ICX switch provides a concise summary of the Power over Ethernet (PoE) status. This summary explicitly includes the total power budget, the currently consumed power, and the remaining available power.

The show inline power detail command provides the same power budget summary as the base command but adds granular, per-port information, such as the port's priority, class, voltage, and current. Both commands are the most direct and specific tools for viewing the operational PoE power budget on the device.

A. show configuration: This command displays the switch's running or startup configuration file; it does not show real-time operational states like the PoE budget.

C. show version: This command provides details about the device's software, hardware versions, serial number, and uptime, not power statistics.

D. show chassis: While this command shows the maximum PoE power capacity of the installed power supplies, it does not display the current power consumption or remaining budget.

1. RUCKUS FastIron Command Reference, 08.0.95, Page 1588, "show inline power". The documentation states this command "displays the status of inline power for all PoE-capable ports on a device." The sample output clearly shows the "PoE Power Budget" section with "Total Power", "Power Consumed", and "Power Remaining".

2. RUCKUS FastIron Command Reference, 08.0.95, Page 1591, "show inline power detail". This section describes the command as providing a more detailed view, which includes the same power budget summary block as the base command in addition to per-port specifics.

3. RUCKUS FastIron Command Reference, 08.0.95, Page 1558, "show chassis". The documentation for this command shows that it displays hardware component status. The output for power supplies lists the "PoE Power" capacity but lacks the real-time consumption and remaining budget details provided by show inline power.

RUCKUS ICX switches support long-distance stacking using standard Ethernet ports with optical transceivers. The maximum distance is dictated by the optic's capability. By using 10 GbE SFP+ or 40 GbE QSFP+ Extended Reach (ER) transceivers, which are specified for distances up to 40 kilometers, a stack can be created over a significant geographical area. This method utilizes standard single-mode fiber to connect stack members, for example, between different buildings on a large campus. While many documents specify a qualified distance of 10 km, the hardware's capability with ER optics defines the maximum potential distance.

B. 3 meters: This is a typical length for short-range, direct-attach copper (DAC) stacking cables and is not the maximum possible distance.

C. 9 meters: This distance is not a standard maximum for any common stacking media; it is significantly less than what is achievable with fiber optics.

D. 1 kilometer: This distance is easily achievable with multi-mode or short-reach single-mode fiber optics but is not the maximum supported distance.

1. CommScope RUCKUS Optics Datasheet (2022), Page 4, Table "10 GBE SFP+ TRANSCEIVERS". The entry for part number 10G-SFPP-ER specifies a reach of "40 km". The compatibility table on page 10 confirms its use in various ICX 7000 series switches.

2. CommScope RUCKUS Optics Datasheet (2022), Page 6, Table "40 GBE QSFP+ TRANSCEIVERS". The entry for part number 40G-QSFP-ER4 specifies a reach of "40 km" and is listed as compatible with stacking-capable ICX switches.

3. RUCKUS FastIron Stacking Configuration Guide, 9.0.10, Chapter 1, "Stacking overview", Section: "Long-distance stacking". This section states: "You can use 10-Gbps, 25-Gbps, 40-Gbps, or 100-Gbps ports for stacking. This feature allows you to use optical transceivers and fiber-optic cables to create a stack over a long distance." This confirms the method of using standard optical transceivers for stacking links.

In Spanning Tree Protocol (STP), when a non-root switch has multiple, equal-cost links to the root bridge, it must select one port as its Root Port to forward traffic and block the others to prevent a loop. The selection is based on the Bridge Protocol Data Units (BPDUs) received from the root bridge. After path cost, the tie-breaker is the lowest Sender (Designated) Bridge ID, which is the same for both links. The next tie-breaker is the lowest Sender Port ID. The root bridge's port with the lowest number will have the lowest Port ID (assuming default priorities). The non-root switch will select its port connected to this link as its Root Port, keeping the link in a forwarding state on both ends.

A. The non-root switch's port number is only used as a final tie-breaker if all preceding criteria, including the Sender Port ID from the root bridge, are identical.

C. Spanning Tree Protocol always prefers lower values for costs, bridge IDs, and port IDs during its election and tie-breaking processes, not higher values.

D. The non-root switch's port number is not the primary tie-breaker in this scenario, and STP prioritizes lower values, not higher ones.

1. RUCKUS FastIron Layer 2 Switching Configuration Guide, 08.0.95, Chapter 13: Spanning Tree Protocols, Section: "How a RUCKUS device selects the root port", Page 338. This section outlines the tie-breaking criteria for Root Port selection, stating: "4. The port connected to the bridge that has the lowest port ID." This confirms the decision is based on the sender's (root bridge's) port ID.

2. RUCKUS ICX 7850 Layer 2 Switching Configuration Guide, 08.0.95, Chapter 10: Spanning Tree Protocol (STP), Section: "Root port selection", Page 239. The guide specifies the selection process: "If the path cost and the designated bridge ID are the same, the port that is attached to the upstream device port with the lowest port ID is selected as the root port." In this scenario, the root bridge is the upstream device.

Open Shortest Path First (OSPF) is a link-state Interior Gateway Protocol (IGP). A core function of OSPF is to calculate the shortest path to a destination based on a cumulative metric called "cost." The cost is typically derived from the interface's bandwidth, and the path with the lowest total cost is installed in the routing table. As a dynamic routing protocol, OSPF continuously monitors the network topology. When a change occurs, such as a link failure, routers exchange Link State Advertisements (LSAs) to update their topological databases and recalculate the best routes, ensuring the routing table remains current and accurate.

A. OSPF is a link-state protocol, which builds a complete map of the network topology, unlike distance-vector protocols (e.g., RIP) that rely on hop counts.

C. Route redistribution between OSPF and other routing protocols is a manual configuration process performed by a network administrator; it is not automatic.

E. OSPF is an Interior Gateway Protocol (IGP) used for routing within an Autonomous System (AS), not an Exterior Gateway Protocol (EGP) like BGP, which routes between ASes.

1. RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95, Chapter 18: OSPF Overview, Page 429.

"OSPF is a link-state routing protocol..." (Confirms A is incorrect).

"The cost of a route is described in terms of a metric. OSPF uses a reference bandwidth of 100 Mbps for cost calculation." (Confirms B is correct).

"When the topology of an OSPF internetwork changes, link-state advertisements (LSAs) are flooded throughout the network." (Confirms D is correct).

"OSPF is an Interior Gateway Protocol (IGP)." (Confirms E is incorrect).

2. IETF RFC 2328, OSPF Version 2, Section 1.2, "Protocol overview".

"OSPF is a dynamic routing protocol. It will quickly detect topological changes in the AS (such as router interface failures) and calculate new loop-free routes after a period of convergence." (Confirms D is correct).

"OSPF is a link-state routing protocol." (Confirms A is incorrect).

3. RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95, Chapter 20: Route Redistribution, Page 511.

This chapter details the manual commands, such as redistribute, required to configure the exchange of routing information between different protocols, demonstrating that the process is not automatic. (Confirms C is incorrect).

The ipv6 unicast-routing command is the fundamental global configuration command required to enable the IPv6 protocol stack on a RUCKUS ICX device. This command activates the device's ability to process and forward IPv6 unicast packets between its configured interfaces, effectively turning it into an IPv6 router. Without this command, the device will not perform Layer 3 forwarding for IPv6 traffic, even if IPv6 addresses are configured on its interfaces. It is the prerequisite for all other IPv6 routing functions.

A. ipv6 dhcp6-server enable: This command enables the DHCPv6 server service on the device. It is a specific application-level feature and does not enable the core IPv6 routing functionality.

C. ipv6 multicast: This command specifically enables IPv6 multicast routing protocols like PIM-SM. It is a separate feature from unicast routing and requires unicast routing to be enabled first.

D. ipv6 nd proxy: This enables the Neighbor Discovery (ND) proxy feature, a specialized function for specific network designs. It does not enable the global IPv6 routing capability.

1. RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95

Page 439, Section: "Enabling IPv6 routing": "To enable IPv6 routing on a Layer 3 switch, enter the ipv6 unicast-routing command at the global CONFIGURATION level of the CLI. This command globally enables IPv6 routing."

2. RUCKUS FastIron Command Reference, 08.0.95

Page 1688, Command: ipv6 unicast-routing: "This command enables IPv6 routing on a Layer 3 switch... By default, IPv6 routing is disabled on the device. You must enable IPv6 routing before the device can forward IPv6 packets."

3. RUCKUS Campus Fabric Configuration Guide, 08.0.95

Page 411, Section: "Configuring IPv6": The guide details IPv6 configuration steps, starting with the prerequisite of enabling IPv6 routing globally using the ipv6 unicast-routing command before any other IPv6 routing features can be configured.

On RUCKUS ICX devices, a Layer 3 (IP) address can be assigned to logical or virtual interfaces to enable routing and IP-based management.

Virtual Ethernet (VE): A VE is a logical Layer 3 interface that represents a specific VLAN, enabling inter-VLAN routing.

Loopback: A loopback is a virtual interface that is always active. It is commonly used for stable router identification in routing protocols (like OSPF or BGP) and for management access.

GRE tunnels: A Generic Routing Encapsulation (GRE) tunnel interface is a logical interface that encapsulates traffic over an IP network. The tunnel interface itself requires an IP address to establish the tunnel and route traffic through it.

A. Stack Interface: This is not a standard configurable Layer 3 interface. Management of a RUCKUS ICX stack is performed using an IP address assigned to a Virtual Ethernet or a dedicated management port.

B. VxLAN: VXLAN (Virtual Extensible LAN) is a Layer 2 overlay technology. While its tunnel endpoints (VTEPs) use Layer 3 addresses, the VXLAN segment (VNI) itself represents a Layer 2 domain.

C. Virtual LAN: A VLAN is a Layer 2 broadcast domain. To give it a Layer 3 presence for routing, you must create a corresponding Virtual Ethernet (VE) interface and assign the IP address to the VE.

1. Virtual Ethernet (VE): RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95 | Part Number: 53-1005930-01, Chapter 2: Configuring IP, Section: "Configuring a virtual routing interface", Page 33. "A virtual routing interface, also called a VE, is a logical Layer 3 interface that you can configure on a Layer 3 switch... You must assign an IP address to the virtual routing interface..."

2. Loopback: RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95 | Part Number: 53-1005930-01, Chapter 2: Configuring IP, Section: "Configuring a loopback interface", Page 37. "A loopback interface is a virtual interface that is always up... You can assign an IP address to a loopback interface."

3. GRE tunnels: RUCKUS FastIron Layer 3 Routing Configuration Guide, 08.0.95 | Part Number: 53-1005930-01, Chapter 10: Configuring Tunnels, Section: "Configuring a GRE tunnel", Page 218. The configuration example explicitly shows the ip address command being applied under the interface tunnel context.

4. VLAN vs. VE: RUCKUS FastIron Layer 2 Switching Configuration Guide, 08.0.95 | Part Number: 53-1005928-01, Chapter 3: Configuring VLANs, Page 43. This chapter describes VLANs as Layer 2 constructs. The Layer 3 configuration is handled by VE interfaces as documented in the Layer 3 guide.

5. Stack Management: RUCKUS FastIron Stacking Configuration Guide, 08.0.90 | Part Number: 53-1005561-01, Chapter 3: Stack Management, Section: "Stack management options", Page 37. This section details that stack management is achieved via the management port or an IP address on a VLAN (VE interface). It makes no mention of a configurable "stack-interface".

The show statistics ethernet 1/1/1 command is used on RUCKUS ICX switches to display detailed traffic and error counters for a specific interface. The output includes various metrics essential for troubleshooting, such as packet counts, broadcast/multicast traffic, and different types of errors. Among these are the Cyclic Redundancy Check (CRC) error counters, which are critical for identifying physical layer problems like faulty cabling, bad connectors, or malfunctioning network interface cards (NICs) that lead to frame corruption.

show interfaces brief ethernet 1/1/1: This command provides a summary of the interface's operational status (e.g., link state, speed, duplex) but lacks detailed error statistics.

show mac-address ethernet 1/1/1: This command displays the Layer 2 MAC address table entries learned on the specified port, not physical layer error counters.

show port security ethernet 1/1/1: This command is used to view the configuration and status of port security features, such as MAC address limits and violation actions.

1. RUCKUS FastIron Command Reference Guide, 08.0.95:

Section: Monitoring Commands

Page: 1598 (PDF page)

Content: The description for the show statistics command states it "Displays statistics for all ports or a specified port." The sample output on the following pages clearly shows a counter for "CRC & Alignment" errors, confirming this command is used to identify CRC errors.

2. RUCKUS ICX 7150 Switch Administration Guide, 08.0.95:

Section: Monitoring Port Statistics

Page: 228 (PDF page)

Content: This section explains how to monitor port statistics for troubleshooting. It explicitly mentions using the show statistics command to view error information, including CRC errors, to diagnose potential hardware issues. The guide notes, "A large number of CRC errors can indicate a problem with the cable or the network interface card (NIC) in the attached device."

The Ruckus ICX 7850-48F is built for high-capacity core/aggregation roles and ships with 48 × 1/10/25 GbE SFP28 ports plus 8 × 40/100 GbE QSFP28 ports that are permanently integrated on the base chassis. None of the other listed ICX models provides eight onboard QSFP28 interfaces; they offer fewer QSFP28 ports or only QSFP+ (40 GbE) ports. Therefore, ICX7850-48F is the sole model in the options meeting the “eight integrated QSFP28 ports” requirement.

A. ICX7550-48F – Only 2 × 40/100 GbE QSFP28 uplinks; not eight.

C. ICX7650-48F – Provides 2 × 100 GbE QSFP28 and 6 × 40 GbE QSFP+; total QSFP28 count is two.

D. ICX7750-48F – Uses QSFP+ (40 GbE) uplinks; series predates QSFP28, so zero QSFP28 ports.

1. Ruckus ICX 7850 Switch Series Data Sheet, “ICX7850-48F specifications,” Table 1, p. 1–2.

2. Ruckus ICX 7650 Switch Series Data Sheet, “ICX7650-48F port configuration,” p. 1.

3. Ruckus ICX 7550 Switch Series Data Sheet, “Base ports and uplinks,” p. 1.

4. Ruckus ICX 7750 Switch Series Data Sheet, “ICX7750-48F interface summary,” p. 1.

In an 802.1D Spanning Tree Protocol (STP) domain, network-wide timers—specifically the Hello Time, Forward Delay, and Max Age—are determined and dictated by the root bridge. The root bridge embeds these timer values into the Bridge Protocol Data Units (BPDUs) it sends out. All other switches in the STP domain, including the legacy 802.1D switches, receive these BPDUs and adopt the timer values set by the root. To influence the convergence time for these legacy switches, the timers must be modified at their source, which is the root bridge, typically located at the network core in a Core/Aggregation/Edge topology.

A. the route-only port on the upstream gateway: "Route-only port" is not a standard STP term. Furthermore, modifying timers on any non-root device is ineffective as they are overridden by the root bridge's BPDUs.

B. on the two legacy 802.1D switches at the edge: These switches are not the root bridge. Any local timer configuration on them will be ignored and replaced by the values received in BPDUs from the root bridge.

C. on the Aggregation switches connected to the legacy edge switches: Although these switches form the boundary between RSTP and legacy STP, they are not the root bridge and will simply propagate the timer values received from the root.

1. RUCKUS FastIron Command Reference, 8.0.90 (fi-8090-commandref.pdf): In the chapter for Layer 2 Switching Commands, the descriptions for the spanning-tree forward-time, spanning-tree hello-time, and spanning-tree max-age commands explicitly state: "These parameters are significant only on the root bridge. The root bridge sends BPDUs containing these parameters to the other bridges in the network." (See pages related to Spanning Tree global configuration).

2. IEEE Std 802.1D-2004, "IEEE Standard for Local and Metropolitan Area Networks--Media Access Control (MAC) Bridges": Clause 8.4, "Bridge Protocol Data Units (BPDUs)," specifies that Configuration BPDUs carry the timer values (Message Age, Max Age, Hello Time, Forward Delay) and that these values are originated by the Root Bridge for the Spanning Tree. Non-root bridges use these values from the received BPDUs.

3. Kurose, J. F., & Ross, K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson. In the section on Link-Layer Switches, the operation of the Spanning Tree Protocol is described, clarifying that the root bridge is responsible for sending configuration messages that dictate the topology and its parameters, including timers, for the entire switched network.

The Address Resolution Protocol (ARP) is a fundamental Layer 2 protocol used to map a known Layer 3 address (specifically an IPv4 address) to its corresponding Layer 2 physical address (such as a MAC address). When a device needs to send a packet to another device on the same local network, it uses an ARP request, broadcast to the network, to ask which device is using a specific IP address. The target device responds with an ARP reply containing its MAC address, allowing the source to build the complete Layer 2 frame for transmission.

B. discover directly connected neighbors

While ARP helps find the MAC address of a known IP neighbor, protocols like Link Layer Discovery Protocol (LLDP) are specifically designed for neighbor discovery, exchanging device capabilities and identity.

C. build and maintain switch MAC tables

A switch builds its MAC address table by inspecting the source MAC address of all incoming frames on its ports, a process called MAC learning. This is a function of the switch, not the ARP protocol itself.

D. resolve host name

Resolving a hostname (e.g., www.ruckus.com) to an IP address is the function of the Domain Name System (DNS) protocol, which operates at the Application Layer.

1. RUCKUS FastIron IP Routing Configuration Guide, 08.0.90

Section: Chapter 2, "Configuring IP," page 33.

Quote: "Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address (MAC address) that is recognized in the local network." This directly confirms that ARP's function is to resolve IP addresses to MAC addresses.

2. Internet Engineering Task Force (IETF) RFC 826: An Ethernet Address Resolution Protocol

Section: Abstract.

Quote: "A protocol for the conversion of 32-bit internet addresses to 48-bit Ethernet addresses is presented." This is the foundational document defining the primary purpose of ARP.

3. MIT OpenCourseWare, 6.02 Introduction to EECS II: Digital Communication Systems, Fall 2012

Section: Lecture 20 Notes, "Protocols & Layering."

Content: The lecture notes explicitly describe ARP's role in the networking stack: "ARP (Address Resolution Protocol) is used by a node to determine the MAC address of a node whose IP address is known." It also separately describes how switches learn MAC addresses by observing source addresses on frames, clearly distinguishing this function from ARP.