UUG Routing Lab

• Step 0 - Booting up
• Step 1 - Connecting to a friend
• Step 2 - Establishing dynamic routing
• Step 3 - Redundant paths
• Step 4 - Path costs
• Step 5 - Breaking things

Background Information

Networking Overview Slides

Step 0

For this lab, we're building a network with dynamic routing. We have eight routers, so break yourself into eight teams and take a router. These routers are small Linux powered devices made by MikroTik. For the first few steps, we'll build two separate networks as an A and B team.

Once you've chosen a router and powered it up, connect to its wireless network. All of the routers can be managed by browsing http://192.168.50.1. The username is admin with no password.

Take a moment to explore the MikroTik web interface (though they also have an SSH interface with a similar structure). Pay particular attention to these pages:

• Interfaces
• IP -> Addresses
• IP -> Neighbors
• IP -> Routes
• Routing -> OSPF
• Tools -> Ping
• Tools -> Traceroute

These routers come preconfigured to act much like you'd expect of a home router, ie one Internet/WAN port, several internal/LAN ports, wireless connected to the internal side, address translation (NAT) to rewrite internal IP addresses to a single outside address, and a handful of firewall rules to filter out malicious traffic. Most of that has been deleted, and replaced with a configuration that accelerates this lab, and more closely resembles an Internet backbone router.

Each port will need to be configured with its own address and subnet. Ports 1 and 2 have been configured as shown on the router's label sticker. They also have a DHCP Server configured, that will hand out addresses to anyone who connects to that port. Ports 3 and 4 have been configured as DHCP clients, so they will try to request an address from the other end of the cable.

Important: to keep things simple, make sure to connect Port 1 or 2 to Port 3 or 4.

Step 1

Now we're going to build four tiny networks. If you have Router 1, find the corresponding Router 2, if you have Router 3, find Router 4. As mentioned above, you want to connect Port 1 to Port 3, as shown here:

Now let's look around RouterOS and make sure it understands what we've done. Start with the Interfaces page, where you should see an R next to the connected port. On Router 2 and 4 only go to the IP -> Addresses page to confirm that you've received an address from DHCP. Give that address to your router friend and ask them to ping it. Also try to ping the 192.168.xxx.1 address.

Dynamic Address

Neighbor Discovery

Go to the IP -> Routes page and note that you should have a Connected route.

Step 2

At this point, connect Router 2 to Router 3 following the Port 1 to 3 rule, as shown below. Visit the pages from Step 1 to see the current state of the network. Interfaces should show the correct connections. IP -> Addresses should show an address on all connected ports. IP -> Routes should show several Connected routes.

Now let's discover a small problem with our network. Since we only have Connected routes, ping will only work over one hop. You can ping from Router 1 to 2, 2 to 3, or 3 to 4. However, you can't ping over two hops, such as from Router 1 to 3, or 2 to 4. Try this!

Step 3 - Establish OSPF

Navigate to Routing -> OSPF and choose Interfaces. Select Add New and accept the defaults to enable OSPF on all interfaces.

On the Instances tab, edit the default instance and change the Router ID to your loopback address.

On the Networks tab, select Add New and accept the defaults.

Now to confirm your configuration worked, go to the OSPF -> Routes tab.

Step 4

Step 5

Breaking things!

BGP Session

Though less documented here, materials for a BGP follow-up session are here.