If you’re working with network hardware, you’ve probably faced the challenge of connecting switches and routers in a way that supports both internal traffic and external internet access. It’s a common scenario, especially in multi-department organizations where different segments need controlled, secure, and reliable online access. In real-world projects, this isn’t just a theoretical exercise—it’s a fundamental requirement. Whether you’re deploying a new system or optimizing an existing one, understanding how to properly link Layer 3 switches and routers can make a huge difference in performance and security. In this guide, we’ll walk through a practical configuration example using Huawei switches, breaking down each step so you can apply it with confidence.
Understanding the Use Case
Imagine a company where each department operates on a different network segment, yet all need internet access. The goal is to use a Layer 3 switch as the gateway for users while a router handles external connectivity, including NAT for secure internet access. This kind of setup is common in mid-to-large-scale projects, and getting it right ensures smooth operations.
Configuration Overview
The process involves three main parts:
- •Configuring the Layer 3 switch as the user gateway and DHCP server.
- •Setting up the router for internal-external traffic routing and NAT.
- •Verifying connectivity across subnets and to the public internet.
Step-by-Step Switch Configuration
Start by preparing the switch. Create VLANs for each user group and assign access ports. Then set up the VLANIF interfaces—these virtual Layer 3 interfaces will act as the default gateways for each subnet.
For instance, if VLAN 10 corresponds to the 192.168.1.0/24 subnet, you would create VLANIF 10 and assign it an IP address (e.g., 192.168.1.1/24). Repeat this for other VLANs.
Next, enable the DHCP server on the switch to assign IP addresses dynamically to users in each VLAN. This avoids manual IP configuration and reduces errors.
Finally, configure the uplink port connecting the switch to the router. This is typically a trunk port allowing all necessary VLANs, or a Layer 3 interface with an IP address for routing.
Router Configuration Steps
On the router, configure the interface connected to the switch. If using a subinterface model, assign an IP address for each VLAN. Alternatively, use a single Layer 3 link.
Set up the external interface with a public IP address. Then configure a default route pointing to the ISP’s gateway.
For internet access, enable NAT overload (PAT) on the external interface, translating internal private IPs to the public address. Don’t forget to add a return route directing traffic back to the switch for internal subnets.
What Is VLANIF and How Is It Different from VLAN?
This is a common point of confusion. VLAN is a Layer 2 concept—it segments broadcast domains and tags traffic. VLANIF, however, is a virtual Layer 3 interface. You can assign an IP address to it, making it act like a router interface for that VLAN.
While VLANs allow communication within the same segment, VLANIF interfaces enable routing between different VLANs. Think of VLANIF as the gateway that connects isolated VLANs to the rest of the network.
Testing the Configuration
Assign static IPs to test devices: for example, PC1 in VLAN 10 (192.168.1.2/24, gateway 192.168.1.1) and PC2 in VLAN 20 (192.168.2.2/24, gateway 192.168.2.1). On the external side, simulate a public server with IP 200.0.0.1.
If everything is set up correctly, both PCs should be able to ping the external address and access the internet. This confirms inter-VLAN routing and NAT are working.
Configuring switches and routers for internet connectivity might seem complex, but it’s manageable when you break it down step by step. Using a Layer 3 switch as the user gateway offloads routing from the router and improves internal traffic efficiency. Meanwhile, the router focuses on what it does best: managing external traffic and securing NAT translations.
If you’re looking for reliable, high-performance switches and routers to implement such setups, visit telecomate.com. They offer a wide range of compatible devices from leading brands, along with resources to help you plan, configure, and optimize your network.
Ready to improve your network’s reliability and security? Explore telecomate.com’s selection of switches and routers today—and build a network that’s both robust and easy to manage.
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