Defining the Network Topology and Routes

The example in examples/routes shows how the network topology and routes can be defined in the controller's configuration file.

To build and run this example in the examples/routes directory:

docker compose build; docker compose up

To start, run an iperf3 server in node4:

docker exec -it node4 /bin/bash

node4:/var/nextmini# iperf3 -s

Similarly, run the iperf3 client in node1 to connect to node4, with its Nextmini IP address 10.0.0.4:

docker exec -it node1 /bin/bash

node1:/var/nextmini# iperf3 -c 10.0.0.4

To stop the Docker containers:

docker compose down

Defining the Network Topology

The network topology is defined in the [topology] section of the configuration file. Four types of topologies are supported: full_mesh, ring, fat_tree, and torus, each with its own configuration parameters:

[topology]
type = "full_mesh"
full_mesh_config = { n_nodes = 4 }

[topology]
type = "ring"
ring_config = { n_nodes = 4 }

[topology]
type = "fat_tree"
fat_tree_config = { k = 4 }

[topology]
type = "torus"
torus_config = { dim = 3, n = 4 }

Alternatively, one can choose to define the edges in the network topology directly:

[topology]
edges = [[1, 2], [2, 4], [1, 3], [3, 4]]

Nextmini's controller uses the network topology to determine which neighbouring nodes a new node should connect with when it joins. The dataplane only establishes TCP or QUIC connections between neighbouring nodes in the network topology.

Defining the Routing Protocol or Custom Routes

So far, the shortest path routing protocol is supported by Nextmini's controller to compute the routes between any source-destination pair:

[routing]
protocol = "shortest_path"

If the routing protocol is not defined, one can choose to define all the routes using the configuration file instead. There are two different alternatives to define custom routes between a source node and a destination node using the controller's configuration file (typically named controller-config.toml). If the route is a simple path with a sequence of nodes, it can be defined as follows:

[[routes]]
route = [1, 2, 3, 4]

Alternatively, if the route is a Directed Acyclic Graph (that may involve multiple paths), it can be defined as:

[[routes]]
route = [[1, 2], [2, 4], [1, 3], [3, 4]]

Nextmini's controller will read these routes, and automatically compute the node IDs for the source and destination.

Example: Defining a Ring Topology with the Shortest Path Protocol

Copy and paste the following lines into the controller-config.toml file in the examples/routes directory.

protocol = "tcp"

[topology]
type = "ring"
ring_config = { n_nodes = 4 }

[routing]
protocol = "shortest_path"

With this configuration, Nextmini will create all the routes, such as 1 → 2, 2 → 3, 3 → 4, 4 → 1.

To view the exact routes created and stored in the database, open a new terminal and run:

docker exec -it postgres psql -U pgusr -d nextmini -c "SELECT * FROM routes ORDER BY src_node_id, dst_node_id;"

Example output you can see in the terminal:

 route_id | src_node_id | dst_node_id |      edges
----------+-------------+-------------+------------------
        1 |           1 |           2 | [[1, 2]]
        2 |           1 |           3 | [[1, 2], [2, 3]]
        3 |           1 |           4 | [[1, 4]]
        4 |           2 |           1 | [[2, 1]]
        5 |           2 |           3 | [[2, 3]]
        6 |           2 |           4 | [[2, 3], [3, 4]]
        7 |           3 |           1 | [[3, 2], [2, 1]]
        8 |           3 |           2 | [[3, 2]]
        9 |           3 |           4 | [[3, 4]]
       10 |           4 |           1 | [[4, 1]]
       11 |           4 |           2 | [[4, 1], [1, 2]]
       12 |           4 |           3 | [[4, 3]]
(12 rows)