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Private VLANs — same subnet, no conversation
Enterprise Advanced 6 devices 6 checked tasks 100 points Plan lab
Four servers in one subnet. Two of them must not reach each other OR anything else except the gateway; two may talk to each other and the gateway. One VLAN, three rules, and nothing but switchport commands to do it with. 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
Four servers in one subnet. Two of them must not reach each other OR anything else except the gateway; two may talk to each other and the gateway. One VLAN, three rules, and nothing but switchport commands to do it with.
Your role: a network engineer on the enterprise team. Level: Advanced Done when: all 6 goals show as passed (100 points).
Network status
Devices: 1 switch, 1 router, 4 servers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. GW starts with addresses (G0/0 10.50.0.1/24). ISO-A is a host with 10.50.0.11/24, gateway 10.50.0.1. ISO-B is a host with 10.50.0.12/24, gateway 10.50.0.1. COM-A is a host with 10.50.0.13/24, gateway 10.50.0.1. COM-B is a host with 10.50.0.14/24, gateway 10.50.0.1. SW1 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
VLAN 100 is a primary private VLAN (10 pts) VLAN 101 is isolated and VLAN 102 is a community (15 pts) The two isolated servers cannot reach each other (25 pts) An isolated server cannot reach a community server (15 pts) The two community servers CAN reach each other (20 pts) Every server still reaches the gateway (15 pts) The activity, in order
VLAN 100 is a primary private VLAN Why: Each goal is a state the lab can check on the running device. Verify with: show running-config VLAN 101 is isolated and VLAN 102 is a community Why: Each goal is a state the lab can check on the running device. Verify with: show running-config The two isolated servers cannot reach each other Why: Blocking traffic is half of security. You prove a block by showing the same ping that worked before now fails. Verify with: ping 10.50.0.12 An isolated server cannot reach a community server Why: Blocking traffic is half of security. You prove a block by showing the same ping that worked before now fails. Verify with: ping 10.50.0.13 The two community servers CAN reach each other Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 10.50.0.14 Every server still reaches the gateway Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 10.50.0.1 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. Why this matters
Four servers in one subnet. Two of them must not reach each other OR anything else except the gateway; two may talk to each other and the gateway. One VLAN, three rules, and nothing but switchport commands to do it with.
What you will be able to do
VLAN 100 is a primary private VLAN
VLAN 101 is isolated and VLAN 102 is a community
The two isolated servers cannot reach each other
An isolated server cannot reach a community server
The network
Catalyst 9300-24, ISR 2921, Server — 6 devices in all, already cabled.
Gi1/0/1 Gi0/0 10.50.0.1/24 Gi1/0/11 Fa0 Gi1/0/12 Fa0 Gi1/0/13 Fa0 Gi1/0/14 Fa0 SW1 GW ISO-A 10.50.0.11/24 · gw 10.50.0.1 ISO-B 10.50.0.12/24 · gw 10.50.0.1 COM-A 10.50.0.13/24 · gw 10.50.0.1 COM-B 10.50.0.14/24 · gw 10.50.0.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
SW1 Catalyst 9300-24 configure it GW ISR 2921 configure it ISO-A Server 10.50.0.11 / 255.255.255.0 gw 10.50.0.1 ISO-B Server 10.50.0.12 / 255.255.255.0 gw 10.50.0.1 COM-A Server 10.50.0.13 / 255.255.255.0 gw 10.50.0.1 COM-B Server 10.50.0.14 / 255.255.255.0 gw 10.50.0.1
Cabling
SW1 Gi1/0/1 ↔ GW Gi0/0 SW1 Gi1/0/11 ↔ ISO-A Fa0 SW1 Gi1/0/12 ↔ ISO-B Fa0 SW1 Gi1/0/13 ↔ COM-A Fa0 SW1 Gi1/0/14 ↔ COM-B Fa0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
GW interface GigabitEthernet0/0
ip address 10.50.0.1 255.255.255.0
no shutdown
exit 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 VLAN 100 is a primary private VLAN 10 Checked automatically against the device’s live state (pvlanType). 2 VLAN 101 is isolated and VLAN 102 is a community 15 Checked automatically against the device’s live state (pvlanType). and Checked automatically against the device’s live state (pvlanType). 3 The two isolated servers cannot reach each other 25 On ISO-A: ping 10.50.0.12 must fail — the policy blocks it. and On ISO-B: ping 10.50.0.11 must fail — the policy blocks it. 4 An isolated server cannot reach a community server 15 On ISO-A: ping 10.50.0.13 must fail — the policy blocks it. 5 The two community servers CAN reach each other 20 On COM-A: ping 10.50.0.14 must succeed. 6 Every server still reaches the gateway 15 On ISO-A: ping 10.50.0.1 must succeed. and On COM-A: ping 10.50.0.1 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
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:
SW1 vlan 101
private-vlan isolated
exit
vlan 102
private-vlan community
exit
vlan 100
private-vlan primary
private-vlan association 101,102
exit
interface range GigabitEthernet1/0/11 - 12
switchport mode private-vlan host
switchport private-vlan host-association 100 101
exit
interface range GigabitEthernet1/0/13 - 14
switchport mode private-vlan host
switchport private-vlan host-association 100 102
exit
interface GigabitEthernet1/0/1
switchport mode private-vlan promiscuous
switchport private-vlan mapping 100 101,102
exit Where this is examined
This lab practises these topics in the zNetLaB certification courses:
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