Connecting to the lab server

• Open your favourite Terminal Emulator
• SSH to the netlab server:

• $ ssh-keygen -R netlab.nanocat.net   <- delete the cached fingerprint
                                          (lab server rebuilt frequently)
  $ ssh [email protected]
  Password: (generated fresh each week)
  

• List the running containerlab devices:

• $ sudo containerlab inspect --all
  

• Connect to an Arista device:

• $ sudo docker exec -it clab-device–name Cli
  

• .. or connect to a Linux device:

• $ sudo docker exec -it clab-pcXX-name bash
  

Diagram

The Final Goal

• All PCs (pc1 through pc5) should be able to ping one another.
• Work step by step!
• Ask questions
• Experiment! You can’t break anything.

Step 0.5 - connect to your router

$ sudo containerlab inspect --all          <- show all running devices
$ sudo docker exec -it DEVICE-NAME Cli     <- connect to your device

Step 1 - configure eth1

The first step is to configure the IP address on your router’s eth1 interface.

Configure as follows:

rX#config                                   <- enter configuration mode

rX(config)#interface eth1                   <- enter the interface
                                               configuration context

rX(config-if-eth1)#show active              <- shows the configuration
                                               just for this context

rX(config-if-eth1)#description to Switch    <- create a human-readable
                                               description for this interface

rX(config-if-eth1)#no switchport            <- make this a routed (L3) port
                                               (default is switched (L2) port)

rX(config-if-eth1)#ip address 10.0.0.x/24   <- refer to the diagram
rX(config-if-eth1)#show active
rX(config-if-eth1)#end                      <- exit configuration mode

rX#show ip interface brief                  <- print a list of all interfaces
                                               with an IPv4 (L3) address

Step 1.5 - testing

Test by seeing if you can ping another router’s IP address. You might need to ask your lab-mates whether they have already configured their devices.

rX#ping 10.0.0.X
...

Step 2 - configure eth2

This is the interface that connects to the PC.

This interface will serve as the default gateway or gateway of last resort for the PC.

Configure as follows:

rX#config
rX(config)#interface eth2
rX(config-if-eth2)#show active
rX(config-if-eth2)#description to PC
rX(config-if-eth2)#no switchport
rX(config-if-eth2)#ip address 192.168.X.1/24   <- refer to the diagram
rX(config-if-eth2)#show active
rX(config-if-eth2)#end                         <- fully exit configuration mode
rX#show ip interface brief                     <- print a list of all interfaces with
                                                  a IPv4 (L3) address
...

Step 2.5 - testing

Test to see if you can ping your PC (192.168.X.2)

rX#ping 192.168.X.2

Step 3 - static routes

• The when the (layer 3) router receives a (layer 3) packet, it checks the destination IP address of the packet to decide which interface to forward it out of
• The router uses a routing table to make this decision.
• There are different ways for a routing table to become populated with data.
  • Static routes
  • Dynamic routes

Step 3.1 - configure the static routes

• Configure a static route:

• rX#show ip route                              <- look at the routing table
  ...
  rX#configure
  rX(config)#ip route 192.168.X.0/24 10.0.0.X   <- when I have a packet that
                                                   is destined for 192.168.X.X,
                                                   forward it on to 10.0.0.x
  rX(config)#end
  rX#show ip route                              <- take another look at the
                                                   routing table
  ...
  

• Repeat this for all of the remote networks.

Step 3.5 - testing

Test by pinging a remote PC from your own PC. You might have to check with the other lab members to make sure they’re up and running.

pcX$ ping 192.168.X.2

You can also try a traceroute:

pcX$ traceroute -n 192.168.X.2    <- the -n tells traceroute not to try to resolve
                                     the IP addresses into names
...

Things to try

• Run a tcpdump on your router:

• rX#bash
  $ tcpdump -i eth1 icmp             <- listen for traffic on eth1, and only print
                                        ICMP (ping) packets
  ...
  (press ctrl-c to terminate tcpdump)
  

• Watch what happens when you send a successful ping
• .. or an unsuccessful ping
• .. or a ping to an unknown network

Questions

• Are the routers in the same network, or different networks?
• Which devices are in the same network as the PCs?