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Which two statements are true about routed ports on a multilayer switch? (Choose two.)

• A routed port behaves like a regular router interface and supports VLAN subinterfaces.
• A routed port is a physical switch port with Layer 2 capability.
• A routed port is not associated with a particular VLAN.
• To create a routed port requires removal of Layer 2 port functionality with the no switchport interface configuration command.
• The interface vlan global configuration command is used to create a routed port.

Correct Answers:

1. A routed port is not associated with a particular VLAN.
2. To create a routed port requires removal of Layer 2 port functionality with the no switchport interface configuration command.

Detailed Explanation:

Routed ports on a multilayer switch are physical interfaces configured to function as Layer 3 ports. Unlike traditional switch ports that operate at Layer 2 and forward traffic based on MAC addresses within VLANs, routed ports forward traffic based on IP addresses and can be configured with Layer 3 routing protocols, much like a traditional router interface.

1. A routed port is not associated with a particular VLAN.

A critical distinction between routed ports and traditional switch ports is that routed ports do not belong to any VLAN. By default, switch ports are Layer 2 interfaces and are associated with VLANs, meaning they forward traffic based on the VLAN tag and switch the traffic based on MAC addresses within the VLAN. When you convert a switch port to a routed port, it no longer operates at Layer 2; instead, it functions purely as a Layer 3 interface.

• VLAN Membership: Since a routed port is a Layer 3 interface, it does not have VLAN membership. It operates similarly to a router interface that is not tied to any VLAN, allowing it to communicate with devices on different subnets. This makes routed ports particularly useful for inter-VLAN routing on a multilayer switch, as they can forward traffic between different VLANs without requiring an external router.
• IP Configuration: Routed ports are typically assigned IP addresses, and traffic is routed to other networks based on these IP addresses, independent of VLAN configurations.

2. To create a routed port requires removal of Layer 2 port functionality with the no switchport interface configuration command.

The process of converting a switch port into a routed port involves removing its Layer 2 functionality. By default, all ports on a switch are Layer 2 ports. To transform a port into a routed port, you must use the no switchport command in interface configuration mode.

• no switchport Command: This command disables the Layer 2 capabilities of the port, effectively removing any association with VLANs and transitioning the port into a Layer 3 mode. Once the no switchport command is applied, the interface can be configured with an IP address, and it can participate in routing processes, such as OSPF or EIGRP.
  Example:

  Switch(config)# interface GigabitEthernet0/1
  Switch(config-if)# no switchport
  Switch(config-if)# ip address 192.168.1.1 255.255.255.0
  Switch(config-if)# no shutdown

  In the example above, the GigabitEthernet0/1 interface is converted into a routed port using the no switchport command. An IP address is then assigned to the interface, making it ready for Layer 3 operations.

• Implications: After a port has been converted to a routed port, it can no longer switch traffic at Layer 2. It will drop any Layer 2 frames (like those used in VLANs) and will only forward Layer 3 packets based on the routing table.

Incorrect Statements:

1. “A routed port behaves like a regular router interface and supports VLAN subinterfaces.”

   This statement is incorrect because routed ports do not support VLAN subinterfaces. VLAN subinterfaces are typically created on a router or a Layer 3 switch using a Layer 3 interface (such as a trunk link) and are used for inter-VLAN routing. Routed ports, however, operate purely as Layer 3 interfaces without the capability to handle VLAN tagging or subinterfaces. To handle VLAN subinterfaces, a different configuration is required, typically on a trunk port.

2. “A routed port is a physical switch port with Layer 2 capability.”

   This statement is also incorrect because a routed port does not have Layer 2 capabilities. Once you configure a port as a routed port using the no switchport command, it loses its Layer 2 functionality entirely. It no longer switches traffic based on MAC addresses, nor does it belong to any VLAN. The port now functions solely at Layer 3, forwarding traffic based on IP addresses.

3. “The interface vlan global configuration command is used to create a routed port.”

   This statement is incorrect. The interface vlan command is used to create or configure an SVI (Switched Virtual Interface) on a switch, not to create a routed port. An SVI represents a VLAN and provides Layer 3 processing for packets entering or leaving that VLAN. To create a routed port, the no switchport command must be used on a physical interface, not the interface vlan command.

Importance of Routed Ports in Network Design:

Routed ports play a significant role in modern network designs, especially in environments where a multilayer switch is used to perform both switching and routing functions. By converting switch ports into routed ports, a network can achieve the following benefits:

• Inter-VLAN Routing: Routed ports simplify inter-VLAN routing by enabling direct Layer 3 connectivity between VLANs without the need for external routers. This capability allows for more efficient traffic flow and reduces the dependency on additional routing devices.
• Scalability: In large networks, using routed ports on a multilayer switch can reduce network complexity by centralizing routing decisions within the switch. This approach can lead to more straightforward network management and greater scalability.
• Performance: Multilayer switches are designed to perform high-speed routing and switching within the same device, often at wire speed. By utilizing routed ports, networks can benefit from the performance advantages of these devices, especially in environments with high data throughput requirements.
• Security: Routed ports can be used to segment different parts of the network, enforcing security policies between different subnets or VLANs. For example, sensitive data could be kept on a separate subnet, accessible only through a routed port with strict access control lists (ACLs) applied.

In conclusion, understanding the function and configuration of routed ports is essential for network administrators and designers working with multilayer switches. Routed ports provide the flexibility to integrate Layer 2 and Layer 3 functionality within a single device, enabling efficient and scalable network designs. By correctly applying the no switchport command and recognizing that routed ports are not associated with VLANs, network professionals can optimize their network infrastructure for performance, security, and manageability.