The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links.

There are various versions of Spanning Tree algorithm and protocol. This module implements it according to the IEEE 802.1D-1998 specification.

STP makes use of per-port configuration data such as cost and priority. They can be set using L2NetworkConfigurator. Port state is kept in the switch's InterfaceTable.

See also: L2NetworkConfigurator, InterfaceTable

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Parameters

Name	Type	Default value	Description
helloTime	double	2s	The hello time is the time between each bridge protocol data unit (BPDU) that is sent on a port. This time is equal to 2 seconds (sec) by default, but you can tune the time to be between 1 and 10 sec.
forwardDelay	double	15s	The forward delay is the time that is spent in the listening and learning state. This time is equal to 15 sec by default, but you can tune the time to be between 4 and 30 sec.
maxAge	double	20s	The max age timer controls the maximum length of time that passes before a bridge port saves its configuration BPDU information. This time is 20 sec by default, but you can tune the time to be between 6 and 40 sec.
bridgePriority	int	32768	The bridge priority determines which bridge is elected as the root bridge. If the switch has a bridge priority that is lower than all the other switches, the other switches automatically select the switch as the root switch.
interfaceTablePath	string	"^.interfaceTable"	The path to the InterfaceTable module
macTablePath	string	"^.macTable"	The path to the MACAddressTable module
visualize	bool	false	Shows the spanning tree by coloring connections in the network graphics. Label ethernet interface with port role and status. Mark root switch

Properties

Name	Value	Description
display	i=block/network2

Gates

Name	Direction	Size	Description
relayIn	input
relayOut	output

Source code

//
// The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free
// topology for any bridged Ethernet local area network. The basic function of STP
// is to prevent bridge loops and the broadcast radiation that results from them.
// Spanning tree also allows a network design to include spare (redundant) links to
// provide automatic backup paths if an active link fails, without the danger of
// bridge loops, or the need for manual enabling/disabling of these backup links.
//
// There are various versions of Spanning Tree algorithm and protocol. This module
// implements it according to the IEEE 802.1D-1998 specification.
//
// STP makes use of per-port configuration data such as cost and priority.
// They can be set using ~L2NetworkConfigurator. Port state is kept in the switch's
// ~InterfaceTable.
//
// @see L2NetworkConfigurator, InterfaceTable
//
simple STP like ISpanningTree
{
    parameters:

        // The hello time is the time between each bridge protocol data unit (BPDU) that is sent on a port.
        // This time is equal to 2 seconds (sec) by default, but you can tune the time to be between 1 and 10 sec.
        double helloTime @unit("s") = default(2s);

        // The forward delay is the time that is spent in the listening and learning state. This time is equal to 15 sec by default,
        // but you can tune the time to be between 4 and 30 sec.
        double forwardDelay @unit("s") = default(15s);

        // The max age timer controls the maximum length of time that passes before a bridge port saves its configuration BPDU information.
        // This time is 20 sec by default, but you can tune the time to be between 6 and 40 sec.
        double maxAge @unit("s") = default(20s);

        // The bridge priority determines which bridge is elected as the root bridge. If the switch has a bridge priority that is lower than all
        // the other switches, the other switches automatically select the switch as the root switch.
        int bridgePriority = default(32768);

        // The path to the InterfaceTable module
        string interfaceTablePath = default("^.interfaceTable");

        // The path to the MACAddressTable module
        string macTablePath = default("^.macTable");

        // Shows the spanning tree by coloring connections in the network graphics.
        // Label ethernet interface with port role and status. Mark root switch
        bool visualize = default(false);

        @display("i=block/network2");
    gates:
        input relayIn;
        output relayOut;
}

File: src/inet/linklayer/ieee8021d/stp/STP.ned

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