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Layer-3 switch — inter-VLAN routing with SVIs
Enterprise Intermediate 3 devices 4 checked tasks 100 points Plan lab
No router-on-a-stick: the multilayer switch routes between VLANs itself. Create the VLANs, give each an SVI as its gateway, turn routing on, and put the PCs in their VLANs — then a PC in VLAN 10 reaches one in VLAN 20 at wire speed, through the switch alone. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
No router-on-a-stick: the multilayer switch routes between VLANs itself. Create the VLANs, give each an SVI as its gateway, turn routing on, and put the PCs in their VLANs — then a PC in VLAN 10 reaches one in VLAN 20 at wire speed, through the switch alone.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 4 goals show as passed (100 points).
Network status
Devices: 1 switch, 2 PCs, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. Sales-PC is a host with 10.10.10.11/24, gateway 10.10.10.1. Eng-PC is a host with 10.10.20.11/24, gateway 10.10.20.1. L3-Switch starts with an empty configuration. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
VLANs 10 and 20 exist (15 pts) Each PC’s port is an access port in its VLAN (25 pts) IP routing is on and both SVIs are up (30 pts) Sales reaches Engineering through the switch (30 pts) The activity, in order
VLANs 10 and 20 exist Why: A port assigned to a VLAN that does not exist carries nothing. Verify with: show vlan brief Each PC’s port is an access port in its VLAN Why: A VLAN is a separate broadcast domain; the port’s VLAN decides which devices can talk without a router. Verify with: show vlan brief IP routing is on and both SVIs are up Why: Without it the device only switches and never routes between subnets. Verify with: show running-config | include ip routing Sales reaches Engineering through the switch Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 10.10.20.11 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Forgetting “ip routing” on the switch Common mistake: An SVI that stays down because no port in its VLAN is up Common mistake: Creating the SVI without creating the VLAN Why this matters
A multilayer switch can route between VLANs itself, using a switched virtual interface as each VLAN’s gateway. It is the design most campuses use instead of router-on-a-stick.
What you will be able to do
Enable IP routing and create SVIs
Place ports in access VLANs
Verify inter-VLAN reachability through the switch
The network
Catalyst 3560-24PS, PC — 3 devices in all, already cabled.
Fa0/1 Fa0 Fa0/2 Fa0 L3-Switch Sales-PC 10.10.10.11/24 · gw 10.10.10.1 Eng-PC 10.10.20.11/24 · gw 10.10.20.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
L3-Switch Catalyst 3560-24PS configure it Sales-PC PC 10.10.10.11 / 255.255.255.0 gw 10.10.10.1 Eng-PC PC 10.10.20.11 / 255.255.255.0 gw 10.10.20.1
Cabling
L3-Switch Fa0/1 ↔ Sales-PC Fa0 L3-Switch Fa0/2 ↔ Eng-PC Fa0
What is configured at the start
Nothing is configured to start with beyond the addresses above: you build the configuration from a clean start.
Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 VLANs 10 and 20 exist 15 On L3-Switch: show vlan brief lists VLAN 10. and On L3-Switch: show vlan brief lists VLAN 20. 2 Each PC’s port is an access port in its VLAN 25 On L3-Switch: show vlan brief — Fa0/1 is an access port in VLAN 10. and On L3-Switch: show vlan brief — Fa0/2 is an access port in VLAN 20. 3 IP routing is on and both SVIs are up 30 On L3-Switch: show ip route works (routing is enabled). and On L3-Switch: show running-config contains the line(s) matching interface Vlan10 … ip address 10\.10\.10\.1. and On L3-Switch: show running-config contains the line(s) matching interface Vlan20 … ip address 10\.10\.20\.1. 4 Sales reaches Engineering through the switch 30 On Sales-PC: ping 10.10.20.11 must succeed.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Forgetting “ip routing” on the switch
An SVI that stays down because no port in its VLAN is up
Creating the SVI without creating the VLAN
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
L3-Switch ip routing
vlan 10
name SALES
vlan 20
name ENG
exit
interface Fa0/1
switchport mode access
switchport access vlan 10
exit
interface Fa0/2
switchport mode access
switchport access vlan 20
exit
interface vlan 10
ip address 10.10.10.1 255.255.255.0
no shutdown
exit
interface vlan 20
ip address 10.10.20.1 255.255.255.0
no shutdown
exit Where this is examined
CCNA (inter-VLAN routing), CCNP ENCOR (campus design).
This lab practises these topics in the zNetLaB certification courses:
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