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

Topology 01

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

flokinet-002 - Introduction to the Arista CLI, continued