SVI Inter-VLAN Routing

1. Inter-VLAN Routing with Layer 3 Switches

A Layer 3 switch integrates the routing and switching functionalities within a single device, allowing it to handle Inter-VLAN Routing more efficiently than a separate router. This method is particularly useful in larger networks, where scalability and reduced latency are crucial.

The following diagram represents a typical topology for Inter-VLAN Routing using a Layer 3 switch:

SVI Switch Virtual Interface Topology

Key Topology Overview

In this setup:

  • SW1 (Layer 3 Switch) connects to PCs in different VLANs (VLAN 10, VLAN 20, and VLAN 30).
  • Each VLAN is assigned an SVI (Switch Virtual Interface) to act as its gateway for Inter-VLAN Routing.

2. Configuring SVIs (Switch Virtual Interfaces)

Step 1: Create VLANs on SW1

Define each VLAN on SW1 with a unique VLAN ID:

SW1(config)# vlan 10
SW1(config-vlan)# name Sales

SW1(config)# vlan 20
SW1(config-vlan)# name Engineering

SW1(config)# vlan 30
SW1(config-vlan)# name Accounting

Step 2: Configure SVIs for Each VLAN

An SVI serves as the default gateway for devices in each VLAN. Configure an IP address for each SVI that aligns with the respective VLAN’s subnet.

  • SVI for VLAN 10:
SW1(config)# interface vlan 10
SW1(config-if)# ip address 192.168.10.1 255.255.255.0
SW1(config-if)# no shutdown
  • SVI for VLAN 20:
SW1(config)# interface vlan 20
SW1(config-if)# ip address 192.168.20.1 255.255.255.0
SW1(config-if)# no shutdown
  • SVI for VLAN 30:
SW1(config)# interface vlan 30
SW1(config-if)# ip address 192.168.30.1 255.255.255.0
SW1(config-if)# no shutdown

Step 3: Assign Access Ports to VLANs

Assign each port connected to a PC to its respective VLAN.

  • Assign G0/1 to VLAN 10:
SW1(config)# interface GigabitEthernet0/1
SW1(config-if)# switchport mode access
SW1(config-if)# switchport access vlan 10
  • Assign G0/2 to VLAN 20:
SW1(config)# interface GigabitEthernet0/2
SW1(config-if)# switchport mode access
SW1(config-if)# switchport access vlan 20
  • Assign G0/3 to VLAN 30:
SW1(config)# interface GigabitEthernet0/3
SW1(config-if)# switchport mode access
SW1(config-if)# switchport access vlan 30

3. Verification

To verify the functionality of Inter-VLAN Routing, we are conducting a ping test from a PC in VLAN 10 (IP address 192.168.10.10) to a PC in VLAN 30 (IP address 192.168.30.10). This test will confirm whether devices in different VLANs can communicate with each other through the configured Layer 3 switch, ensuring proper routing across VLANs.

SVI Topology Verification 1
PC1> ping 192.168.30.10

Pinging 192.168.30.10 with 32 bytes of data:

Reply from 192.168.30.10: bytes=32 time<1ms TTL=64
Reply from 192.168.30.10: bytes=32 time<1ms TTL=64
Reply from 192.168.30.10: bytes=32 time<1ms TTL=64
Reply from 192.168.30.10: bytes=32 time<1ms TTL=64

Ping statistics for 192.168.30.10:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = <1ms, Maximum = <1ms, Average = <1ms

With this successful ping output and our configured Inter-VLAN Routing settings, we can confirm that Inter-VLAN Routing is operational, allowing communication between devices in VLAN 10 and VLAN 30 through the Layer 3 switch.

Dynamic NAT