Ostinato and Nokia SR Linux#

Description#

This lab consists of a Ostinato node with 2 ports connected to 2 ports on a Nokia SR Linux node via two point-to-point ethernet links. Both nodes are also connected with their management interfaces to the containerlab docker network.

Ostinato is a software based network packet traffic generator managed via a GUI or a Python script using the Ostinato API. This example will demonstrate how to use the Ostinato GUI included with the Ostinato for Containerlab image to verify IPv4 forwarding.

Deployment#

Change into the lab directory:

cd containerlab/lab-examples/ost-srl

Deploy the lab:

sudo containerlab deploy

Use cases#

This lab allows users to validate IPv4 forwarding on Nokia SR Linux (the DUT) using Ostinato as the traffic generator.

IPv4 Traffic forwarding#

This lab demonstrates a simple IPv4 traffic forwarding scenario where

• Ostinato with two test ports eth1 and eth2 connected to Nokia SR Linux ports e1-1 and e1-2 respectively.
• SR Linux is the DUT and its interfaces e1-1 and e1-2 are configured with IPv4 addresses 10.0.0.1/24 and 20.0.0.1/24 respectively.
• Ostinato will emulate host 10.0.0.100 on eth1 and 20.0.0.100 on eth2
• Ostinato will send bidirectional traffic at 100pps (eth1 → e1-1) and 200pps (eth2 → e1-2)
• The TX and RX traffic rates can be verified in the Port Stats window of the Ostinato GUI

Configuration#

During the lab deployment and test execution the following configuration is applied to the lab nodes to forward and receive traffic.

• SR Linux
  SR Linux node comes up pre-configured with the commands listed in srl.cfg file which configure IPv4 addresses on both interfaces.

• Ostinato
  Ostinato configuration is saved in the ost-srl.ossn file which will configure the emulated hosts and traffic streams. The configuration file needs to be loaded manually as explained in the next section

Execution#

1. Access the Ostinato GUI by connecting a VNC client to <host-ip>:5900
2. Once the GUI opens and the eth1, eth2 ports are listed, go to File | Open Session and open /root/shared/ost-srl.ossn
3. In the Ostinato Port Stats window, select both eth1 and eth2 port columns and click on (start transmit)

Verification#

1. Verify the port stats and rates in the same window
2. Keeping both eth1 and eth2 selected, click on (stop transmit)

Here's a short video showing the above steps -

Next Steps#

You can edit the Ostinato emulated devices and streams to experiment further.

Here are some suggestions -

• Override the IPv4 checksum to an invalid value and verify the DUT silently discards the packets (some DUTs may send an ICMP parameter problem)
• Try setting IPv4 TTL to 1 and verify
  • traffic is not forwarded by the DUT
  • DUT sends back ICMP TTL Exceeded (you can capture and view captured packets)
• Try IPv6 traffic streams

Learn more about Ostinato traffic streams.

Cleanup#

To stop the lab, use:

sudo containerlab destroy --cleanup