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The net Entry

 

The net entries in the xsim.data file specify the kinds of networks to include in the simulated internet, the parameters for these networks (e.g., bandwidth, latency), and the IP addresses for all networks, routers, and hosts involved in the simulation. The connectivity for the entire internetwork is specified by the

net entries alone.

In the xsim.data file, a particular net entry must come after the entries of all hosts and routers that it connects. The syntax of a network entry is defined as follows:

net <type> <net address>;
  connections = <name> [instance] <address>, <name> [instance] <address>,... ;
  args = <arg>, <arg>, ... ;

The net line specifies the type of network. Two types of networks are currently defined: Ethernet ( ETH) and point-to-point ( PP). The properties of each type are documented in subsequent sections. The <net address> field specifies the network IP address. The host portion of this address can be 0, although the full address may be specified, as is done in the example given in the previous section.

The connections line lists the IP addresses of the hosts and routers connected to this particular network; only the host part of the IP address should be specified. The optional instance is used only when specifying a host, and indicates the name of the driver instance that is connected at that IP address (e.g., ethd/1).

There are several things to keep in mind when specifying IP addresses for networks, hosts, and routers.

The args line includes parameters specific to the type of the network being defined, and are used to define aspects of the network such as its bandwidth, the network MTU, and the associated framing overhead. Parameters for Ethernet are listed in Section 3.3.1, paremeters for point-to-point links are given in Section 3.3.2. A syntactic point to be aware of is that no spaces should be included anywhere between the argument and its value: rate=10Mb.





next up previous contents
Next: Ethernet ( ETH) Up: File xsim.data Specification Previous: The convert Entry



Larry Peterson
Mon Jun 24 16:40:03 MST 1996