UnetStack - Routing Protocols

Question

1. How to deploy a testbed to experiment routing protocols for UnetStack acoustic modems communication in an underwater network?
2. Which modem (model) is more suitable for this experiment?

Answer 1

Answer to Q1

The default stack when you boot up a Unet simulator or a modem with UnetStack support has two agents that relate to routing protocols.

The router agent (org.arl.unet.net.Router) does packet routing based on its routing tables. The routes, addroute, delroute, delroutesto and delroutes closures allow you to manually modify the routing tables. Just type help router in the Unet shell to get more information:

> help router
router - access to routing agent

Examples:
  routes              // display routing table
  routes 2            // display routes to node 2
  addroute 27, 29     // add a route to node 27 via node 29
  delroute 2          // delete route number 2
  delroutesto 27      // delete all routes to node 27
  delroutes           // delete all routes

Parameters:
  MTU - maximum data transfer size
  auto1hop - automatically assume single hop routes
  link - default link to use
  routes - routing table (read-only)

The rdp agent (org.arl.unet.net.RouteDiscoveryProtocol) populates the routing table for the router agent. The rreq and trace closures allow you to interact with this agent. Type help rdp for more information:

> help rdp
rdp - access to route discovery protocol agent

Examples:
  rreq 27             // start route discovery to node 27
  rreq 27, 3, 2, 10   // find <3-hop route to node 27 with 2 RREQs 10s apart
  trace 27            // trace current route to node 27

If you want to implement your own routing protocol, the easiest option is to create your own agent that populates the routing table for router. This is done by sending RouteDiscoveryNtf messages to the router agent. For many routing protocols, this is sufficient, and easy to do.

If your routing protocol is more complicated and cannot be implemented by changing routing tables dynamically, you can remove the default router agent (from etc/setup.groovy file) and add your own routing agent implementation instead. Your routing agent must support the Routing service: A routing agent essentially accepts datagrams for any destination and sends them on the next hop. The agent also listens to datagram notifications from the Link agent, and forwards them on the next hop, if they are meant to be packets to be routed. Typically, a routing agent will have to add its own headers to know which packets are to be routed and to where, based on the protocol being implemented.

Answer to Q2

Any modem that supports UnetStack should work. Here's a list of known modems that currently support UnetStack.