Nextmini | A New Research Testbed for Network Emulation and Experimentation

Reference for controller settings, topology, routing, flows, and database fields.

The controller binary reads ./config.toml at startup (get_config("config.toml")). Examples often keep a source file named controller-config.toml and mount or copy it to ./config.toml at runtime. This file defines network topology, routing, flows, and database settings.

Server Settings

Field	Type	Default	Description
`port`	`u16`	`3000`	Port for the controller WebSocket server.
`max_server_port`	`u16`	`8081`	Port for connection-on-demand TCP server.

Network Address Configuration

Field	Type	Default	Description
`base_addr`	`Ipv4Addr`	`10.0.0.0`	Base IPv4 address for the TUN network.
`net_mask`	`Ipv4Addr`	`255.255.0.0`	Network mask (accommodates up to 65,535 nodes).
`user_space_base_addr`	`Ipv4Addr`	`192.168.0.0`	Base address for user-space smoltcp network.
`external_base_addr`	`Ipv4Addr`	`172.16.8.3`	Base address for external network traffic.

Multicast Configuration

Field	Type	Default	Description
`multicast_pool_base`	`Ipv4Addr`	`239.255.0.0`	Base address for multicast group IP allocation.
`multicast_pool_mask`	`Ipv4Addr`	`255.255.0.0`	Netmask for multicast pool (/16 = 65,535 groups).

Protocol Settings

Field	Type	Default	Description
`protocol`	`Protocol`	`tcp`	Transport protocol: `tcp`, `udp`, or `quic`.
`flow_transport`	`FlowTransport`	`tcp`	Transport for controller-managed flows: `tcp` or `lossless_unicast`.
`scheduler_type`	`SchedulingDiscipline`	`fifo`	Scheduler discipline: `fifo` or `wrr` (weighted round-robin).

Topology Configuration

[topology]
type = "full_mesh"  # full_mesh | ring | fat_tree | torus

type is the canonical key. The legacy alias topology is still accepted for backward compatibility.

Full Mesh

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

Ring

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

Fat Tree

[topology]
type = "fat_tree"
fat_tree_config = { k = 4 }  # k must be even

The fat tree topology creates k^3/4 server nodes and 5k^2/4 switch nodes.

Torus

[topology]
type = "torus"
torus_config = { dim = 2, n = 4 }  # 2D torus with 4 nodes per dimension = 16 nodes

Supports 1D, 2D, and 3D torus topologies. Total nodes = n^dim.

Custom Edges

[topology]
edges = [[1, 2], [2, 3], [3, 4], [4, 1]]
n_nodes = 4  # Required when using custom edges

Routing Configuration

[routing]
protocol = "shortest_path"

Currently only shortest_path is supported. The [routing] section is optional; when omitted, no topology-derived routes are generated and only explicit [[routes]] entries are used.

Custom Routes

Routes can be defined as simple paths or DAGs:

# Simple path: 1 -> 2 -> 3 -> 4
[[routes]]
route = [1, 2, 3, 4]

# DAG with multiple paths
[[routes]]
route = [[1, 2], [2, 4], [1, 3], [3, 4]]

Link Rate Configuration

[[link_rates]]
src_node_id = 1
dst_node_id = 2
rate = 100_000_000         # bytes per second
bucket_size = 312_000_000  # token bucket size in bytes

Flow Configuration

[[flows]]
src_node_id = 1
dst_node_id = 2
flow_spec = { flow_len = { Bytes = 10_000_000 }, flow_rate = 10_000_000, flow_weight = 1, transport = "tcp" }

FlowSpec Fields

Field	Type	Description
`flow_len`	`FlowLen`	`{ Bytes = n }` or `{ Duration = seconds }`
`flow_rate`	`Option<usize>`	Rate in bytes per second (required for Duration flows with lossless_unicast).
`flow_weight`	`Option<usize>`	Weight for weighted round-robin scheduling.
`transport`	`FlowTransport`	`tcp` or `lossless_unicast`.

Node Specifications

Per-node configuration overrides:

[[nodes]]
node_id = 1
operating_mode = "max"  # normal (default) | max

Database Configuration

[db]
user = "pgusr"
password = "pgpwrd"
host = "172.16.8.2"
database = "nextmini"
port = "5432"

Controller Configuration