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Exercise5

README.md

Exercise 5 - PINS Fabric Demonstration

PINS launched at the OCP Global Summit in November 2021. If you have not already watched the complete video of the demonstration, here is a link that jumps to the beginning of the Weighted Cost MultiPath (WCMP) Demo (link starts at 4:43 and lasts 6:18 minutes).

This demonstration brings P4 and SDN to SONiC, using ONOS for a control plane to manage routes and set up the flow objectives. It is a pure play SDN solution that uses a multi-purpose L2/L3 leaf-spine switching fabric without traditional control protocols such as BGP. The SDN Controller (ONOS) is decoupled from the data plane and runs the segment routing application that powers Trellis and SD-Fabric. (Normally, the segment routing application relies on MPLS rules in the spines, but we use IPv4 routes in this case.) The result is that the fabric acts as one big router. For more information on the switch pipeline, you can find the P4 SAI tables here: sonic-net/sonic-pins/sai_p4. The middleblock.p4 instantiation of the SAI pipeline is close to what we used for our demonstration.

The PINS demonstration topology is a 2x2 leaf-spine fabric and server(s) with the following setup:

  • 4 PINS switches connected in a 2x2 leaf-spine topology
    • Spine: Arista 7060DX4-C32, Broadcom Tomahawk3
    • Spine: Accton Wedge100BF-32X, Intel Barefoot Tofino
    • Leaf: Arista 7060DX4-C32, Broadcom Tomahawk3
    • Leaf: Arista 7170-64C, Intel Barefoot Tofino
  • Server:
    • A server (could be a laptop) must run ONOS with access to the management network of the switches.
    • Hosts are on the two leaf devices. Instead of physical hosts, network namespaces or mac vlan interfaces can emulate hosts on a server. We used namespaces in our demo.

Figure 2 - PINS Demonstration Topology

alt_text

Create a PINS Demonstration on Your Network (Advanced)

If you have access to four switches to create this demonstration, you can download the PINS demonstration software and experiment on your network.

WCMP depends on your network topology. In the future, we will have tools such as gNMI to determine route weights and enable WCMP. For now, you have to choose the weights manually, as we did in the demonstration. Then use the config files found in the demonstration software to achieve WCMP in your network.

There are five folders containing configuration files in this exercise, one for each switch/ASIC combination and one for ONOS. Each switch needs a config_db.json file. The switches that contain a Broadcom ASIC also require port_config.ini and *.config.bcm to implement SAI.

  1. spine-arista-TH3: Arista 7060DX4-C32, Broadcom Tomahawk3
  2. spine-accton-BF: Accton Wedge100BF-32X, Intel Barefoot Tofino
  3. leaf-arista-TH3: Arista 7060DX4-C32, Broadcom Tomahawk3
  4. leaf-arista-BF: Arista 7170-64C, Intel Barefoot Tofino
  5. onos-topology: ONOS configuration file, netconfig.json, for segment routing and gRPC connections (i.e. the P4Runtime connection)

The docker container with ONOS that you got in Exercise 4 has the PINS driver and SAI pipeliner installed. There are two pipelines in org.onosproject.pipelines.sai and org.onosproject.pipelines.sai_fixed. The latter does not include ACLs. If your topology has other requirements and you need to create other pipelines, explore the SONiC ONOS Driver repository, especially the loader. You will also need follow the instructions in Build ONOS with PINS instead of using the docker image we built for you in Exercise 4.