ns3--Global Routing

原文：

https://www.nsnam.org/doxygen/group__globalrouting.html

Detailed Description

Performs pre-simulation static route computation on a layer-3 IPv4 topology.

Model

ns-3 global routing performs pre-simulation static route computation on a layer-3 IPv4 topology. The user API from the script level is fairly minimal; once a topology has been constructed and addresses assigned, the user may call ns3::GlobalRouteManager::PopulateRoutingTables() and the simulator will initialize the routing database and set up static unicast forwarding tables for each node.

The model assumes that all nodes on an ns-3 channel are reachable to one another, regardless of whether the nodes can use the channel successfully (in the case of wireless). Therefore, this model should typically be used only on wired topologies. Layer-2 bridge devices are supported. API does not yet exist to control the subset of a topology to which this global static routing is applied.

If the topology changes during the simulation, by default, routing will not adjust. There are two ways to make it adjust.

Set the attribute Ipv4GlobalRouting::RespondToInterfaceEvents to true
Manually call the sequence of GlobalRouteManager methods to delte global routes, build global routing database, and initialize routes. There is a helper method that encapsulates this (Ipv4GlobalRoutingHelper::RecomputeRoutingTables())