Enterprise VLAN Deployment with Cisco Catalyst 9300-24P-E

Executive Summary

Modern enterprise networks rely on logical segmentation to boost performance and security. Using Cisco VLANs (Virtual LANs) on a Catalyst 9300-24P-E switch allows IT teams to isolate traffic into distinct subnets – for example, VLAN 10 (USERS) on 192.168.10.0/24, VLAN 20 (SERVERS) on 192.168.20.0/24, VLAN 30 (VOICE) on 192.168.30.0/24, with a dedicated native VLAN 999. This segmented design reduces broadcast domains and limits congestion, improving speed【24†L132-L140】. It also shrinks the attack surface by isolating devices into controlled groups【24†L119-L124】. The Catalyst 9300-24P-E is a high-performance access switch featuring 24 × 1 Gigabit PoE+ ports (30 W per port, ~370 W total budget) and four 10 Gigabit SFP+ uplinks【37†L548-L554】. Advanced capabilities (like Cisco StackWise stacking, TrustSec/SGT security, and Cisco DNA Center integration) make this platform ideal for scalable, secure VLAN deployments【19†L1-L5】【29†L334-L336】.

Catalyst 9300-24P-E Key Features

· 24×1G PoE+ Ports: Supports PoE+ up to 30 W per port (total ~370 W) on 24 Gigabit copper ports【37†L548-L554】.

· High-speed Uplinks: Four 10G SFP+ uplink slots (modular uplinks) for fiber connectivity and stacking.

· Cisco StackWise Stacking: Delivers up to 1 Tbps stacking bandwidth (StackWise-1T) across up to 8 switches for resiliency【19†L1-L5】.

· Advanced Security: Built-in support for Cisco TrustSec and Security Group Tags (SGT) for dynamic, policy-based segmentation across the network.

· Cisco DNA Visibility: Integrates with Cisco DNA Center and ThousandEyes for end-to-end network and application visibility【29†L334-L336】.

· Robust Power Budget: 715W AC power supply provides ample headroom for PoE devices (IP phones, cameras, APs, etc.).

These features ensure the 9300-24P-E can power modern access networks and enforce fine-grained policies while keeping traffic visible and manageable.

VLAN Configuration and Topology

To implement VLANs on the 9300-24P-E, you would typically perform these steps:

1. Create VLANs with Names/Subnets: Define VLAN 10 as USERS, VLAN 20 as SERVERS, VLAN 30 as VOICE, and reserve VLAN 999 as the (unused) native VLAN. Assign each VLAN a subnet (e.g. 192.168.10.0/24 for VLAN 10) so that L3 routing can occur.

2. Assign Access Ports: Put switch ports into access mode and assign them to the appropriate VLAN. For example, ports Fa0/1–Fa0/8 for VLAN 10 (Users), Fa0/9–Fa0/16 for VLAN 20 (Servers), and Fa0/17–Fa0/24 for VLAN 30 (Voice).

3. Configure the Trunk Port: Designate a Gigabit uplink (Gi1/0/25) as a trunk carrying multiple VLANs. Use IEEE 802.1Q tagging so all VLAN frames can traverse a single link【26†L132-L139】. Set the native VLAN to 999 (and avoid using it for data) to prevent untagged traffic from joining a user VLAN.

4. Verify and Save: Check VLAN and trunk status with show vlan brief and show interfaces trunk. Then save the configuration (copy running-config startup-config or write memory) to make it persistent across reboots.

These steps ensure the switch ports and uplinks are correctly segmented. The table below summarizes the VLAN assignments:

graph LR
    subgraph Switch [Catalyst 9300-24P-E]
        Gi1_0_25[Gi1/0/25: Trunk (802.1Q)]
    end
    Users[VLAN 10: Users<br>192.168.10.0/24]
    Servers[VLAN 20: Servers<br>192.168.20.0/24]
    Voice[VLAN 30: Voice<br>192.168.30.0/24]
    Gi1_0_25 ---|Trunk carrying VLANs 10,20,30| Users
    Gi1_0_25 ---|Trunk carrying VLANs 10,20,30| Servers
    Gi1_0_25 ---|Trunk carrying VLANs 10,20,30| Voice

Figure: Simplified topology. Gi1/0/25 is configured as a trunk carrying VLANs 10, 20, 30 (802.1Q tagging) with native VLAN 999. Access ports on Fa0/1–24 are assigned by VLAN as indicated.

CLI Snippet

The following shows a concise example of the key CLI commands:

Switch# configure terminal
Switch(config)# vlan 10
Switch(config-vlan)# name USERS
Switch(config)# vlan 20
Switch(config-vlan)# name SERVERS
Switch(config)# vlan 30
Switch(config-vlan)# name VOICE

Switch(config)# interface range gi1/0/1-8
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 10

Switch(config)# interface range gi1/0/9-16
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 20

Switch(config)# interface range gi1/0/17-24
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 30

Switch(config)# interface gi1/0/25
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport trunk allowed vlan 10,20,30
Switch(config-if)# switchport trunk native vlan 999

Switch# copy running-config startup-config

This snippet shows VLAN creation (vlan 10, name USERS, etc.), assigning ranges of ports to access mode and their VLAN, and configuring the trunk port with allowed VLANs and native VLAN. Cisco IOS automatically tags frames on trunk links per IEEE 802.1Q【26†L132-L139】; any untagged traffic is placed in the native VLAN (here VLAN 999)【26†L140-L147】.

Verification and Best Practices

After configuration, use these commands to verify status:

· show vlan brief – Lists all VLANs, names, and their active ports (ensure VLAN 10, 20, 30 show correct ports).

· show interfaces trunk – Confirms which ports are trunks, their encapsulation (802.1Q) and native VLAN.

VLAN Benefits: Segmenting at Layer 2 limits broadcast domains, reducing unnecessary traffic and improving throughput【24†L132-L140】. It also isolates traffic, strengthening security by preventing lateral movement【24†L119-L124】. This logical segmentation is foundational to modern network design.

Implementation Tips: Plan your VLAN scheme ahead of deployment. Use clear, descriptive names (like “USERS” or “VOICE”) for readability. Avoid putting any user traffic on the native VLAN (“untagged” VLAN); leave it unused or reserved. Always verify configurations after making changes and save the running configuration to startup-config to prevent loss. As Cisco emphasizes, segmentation makes networks “easier for IT teams to understand, organize, and maintain”【24†L132-L140】.

By following these steps and best practices, network engineers can quickly set up a robust, segmented switch fabric. The Catalyst 9300-24P-E combines PoE power and advanced software features (StackWise, TrustSec, Cisco DNA, etc.) to deliver a secure, high-performance access layer. Consider evaluating the Catalyst 9300 series for your next campus or branch deployment to take full advantage of these capabilities.