A mid-to-advanced CCNA lab that brings VoIP, PoE, EtherChannels, and OSPF together in one topology. One of my favorites.

📞 Networking Lab: Hold Please…VoIP & PoE

by: Anthony Gardés

# networking

# ccna

# labs

# voip

This lab covers a pretty solid chunk of CCNA-related material, along with a couple of topics that aren't covered that much. This is one I'd tackle maybe around the halfway mark of your studies, but if you're up for a challenge and want to learn, this is the one for you! I personally haven't seen any labs that put these ideas together like this, so I really hope you enjoy this one. Below is a list of topics covered, along with some pre-reqs.

Difficulty: 7/10

Topics Covered: VLANs, Trunking, PoE, VoIP, SVI's, DHCP, CME, Subnetting, EtherChannels, and OSPF.

Pre-Reqs:

• Cisco Packet Tracer
• Computer
• Basic/Intermediate knowledge of networking (some CCNA studies)
• Cisco IOS CLI commands (? is your friend)

Below is the unconfigured starting point for this lab. If you get stuck, I'll have a completed version of this lab at the end of this post, along with some troubleshooting tips.

This is the topology we will be deploying. Quick heads-up: the access switch is Layer 3-capable, but we're only using it that way to get PoE working in Packet Tracer. In the real world, this would typically be a Layer 2 device, so don't let that throw you off. This isn't a step-by-step configuration guide; the goal is to get your brain juices flowing. I'll drop some hints along the way in dropdowns, but try to struggle through it first before peeking! Lastly, if you forget commands, try using the ? to troubleshoot your way through. This is hands down the best way to get these commands to stick and speed up your CLI skills.

ASW1 Configuration

Start at the access layer and work your way up. Get your VLANs and ports sorted here before touching anything else.

1. Create VLANs 10, 20, 30, and 99 — name them DATA, VOICE, SERVERS, and NATIVE respectively
2. Configure Fa0/1 through Fa0/5 as access ports on VLAN 10 with VLAN 20 as the voice VLAN
3. Configure Fa0/6 as an access port on VLAN 30 for the server
4. Create a Layer 2 EtherChannel using four interfaces for the uplink to DSW1, then trunk it up, allow VLANs 10, 20, and 30, and set VLAN 99 as the native VLAN

vlan
name
interface
switchport
channel-group
show vlan brief
show etherchannel summary

DSW1 Configuration

Now that ASW1 is good to go, head up to the distribution layer. This is where all the routing magic happens, so take your time here.

1. Enable IP routing — don't forget this one, it'll drive you crazy if you do
2. Create a loopback address for DSW1; this is used as a router ID for OSPF (I used 2.2.2.2)
3. Create VLANs 10, 20, 30, and 99 — use the same names as ASW1
4. Create a Layer 2 EtherChannel using four interfaces for the downlink to ASW1, and match the trunk config on ASW1 exactly
5. Create a Layer 3 EtherChannel using two interfaces for the uplink to R1 and assign the appropriate IP address
6. Create SVIs for VLANs 10, 20, and 30 and assign the appropriate gateway IP
7. Configure the DHCP relay on the data and voice SVIs pointing to the server outlined in the topology
8. Configure OSPF and advertise all appropriate networks, including your loopback

ip routing
vlan
name
interface
switchport
no switchport
channel-group
ip address
ip helper-address
router ospf
network
show ip route
show ip ospf neighbor

Server Configuration

Short and sweet, just need to get DHCP sorted for both the data and voice VLANs.

1. Configure the server with a static IP address and assign the appropriate gateway address
2. Configure a DHCP pool for the data VLAN and set the default gateway to DSW1's VLAN 10 SVI
3. Configure a DHCP pool for the voice VLAN, then set the default gateway to DSW1's VLAN 20 SVI and point the TFTP server to R1's loopback (this will be 1.1.1.1)
4. Exclude the gateway addresses from both pools so they don't get handed out to clients

R1 Configuration

Last stop, the router. This is where we tie everything together with OSPF and get CME up and running for the phones.

1. Create a loopback address (1.1.1.1) — this will be used for both OSPF and CME
2. Create a port channel with two interfaces and assign the appropriate IP address to the port channel
3. Configure OSPF and add the appropriate networks
4. Enable telephony-service and configure a max of 5 ephones and 5 dns
5. Set the CME source address to your loopback and enable auto assign
6. Configure 4 ephone-dns with extension numbers 101–104
7. Configure 4 ephones, assign each one a MAC address and map it to its ephone-dn

interface 
Loopback0 
ip address 
interface 
Port-channel 
channel-group
router ospf
network
telephony-service
ip source-address
auto assign
ephone-dn
number
ephone
mac-address
type
button
show ephone 

Verification

Alright, let's see if it all works. Pick up one of the phones in PT and dial another extension. If the call connects, you nailed it. If not, it's time to troubleshoot. Below are some troubleshooting ideas, as well as the completed file to cross-reference, but try troubleshooting it without first.

On ASW1 and DSW1:

show vlan brief
show etherchannel summary

On DSW1:

show ip ospf neighbor
show ip route

On R1:

show ip ospf neighbor
show ip route
show ephone

Troubleshooting and Issues Faced

When building this out, I ran into a couple of issues initially. I wanted to share issues I had come across.

• Missing helper-address on DATA SVI: I missed configuring the IP helper-address on my DATA SVI on DSW1. I was getting IPs on my phones, but nothing on my PCs. Looked over the running config and saw I had omitted the helper-address on VLAN 10.
• Phones not getting numbers: Ensure the telephony service IP points to R1’s loopback address, where the service lives, and ensure the DHCP server’s TFTP server points to R1's loopback.
• EtherChannel bundling issue: I had a duplex mismatch on one of the ports in the bundle, which caused an error. I had to manually fix the switchport to ensure full duplex on all ports on both sides.

Other Troubleshooting Tips

• Check your VLANs: ensure all VLANs match, and that trunks allow the appropriate VLANs.
• L3 EtherChannel: Verify that configurations are created on the port channel, not on the interfaces; it's easy to accidentally configure a single port.
• L2 EtherChannel: Same note as L3, but also ensure that the appropriate VLANs are enabled on both sides. It's very easy to overwrite VLAN assignments. If you are adding VLANs, don't forget to use add; otherwise, you risk wiping all your prior assignments.
• This lab has no ACLs; you should be able to use ping and traceroute to troubleshoot and pinpoint issues.
• Routing: We rely on OSPF to handle a large portion of routing, ensure OSPF forms adjacencies, and ensure that routing tables contain all necessary routes, including loopback routes. R1's loopback can easily be overlooked when configuring OSPF in this lab.