Implements the Address Resolution Protocol for IPv4 and IEEE 802 6-byte MAC addresses.

ARP packets are represented by the ARPPacket class.

Communication Between ARP and IPv4 modules: IPv4 module call the ARP::getMACAddressFor(ipv4Address) method for get the MACAddress of next hop. If this method could not resolve an IPv4 address to MAC address, then IPv4 uses the ARP::startAddressResolution() method. ARP emit a completedARPResolution signal, when added/modified an entry in ARP table. ARP emit a failedARPResolution signal when an ARP request failed (ARP request sent retryCount times and retryTimeout elapsed).

ARP resolution is used over broadcast interfaces only, that is, over interfaces that have the isBroadcast() flag set in InterfaceEntry (see InterfaceTable). Since routing files (.irt or .mrt files, given as parameter to IPv4RoutingTable) may modify the default interface configuration, you must take care that these files don't contain the word BROADCAST e.g. for PPP interfaces.

Inheritance diagram

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

Parameters

Name	Type	Default value	Description
interfaceTableModule	string		The path to the InterfaceTable module
routingTableModule	string
retryTimeout	double	1s	number seconds ARP waits between retries to resolve an IPv4 address
retryCount	int	3	number of times ARP will attempt to resolve an IPv4 address
cacheTimeout	double	120s	number seconds unused entries in the cache will time out
respondToProxyARP	bool	true	reply to proxy ARP requests (i.e. for IP addresses that this node can route)

Properties

Name	Value	Description
display	i=block/layer

Gates

Name	Direction	Size	Description
netwIn	input		incoming ARP requests and replies
netwOut	output		outgoing ARP requests/replies, and datagrams with resolved next hop

Signals

Name	Type	Unit
sentReply	long
failedARPResolution	inet::IARP::Notification
sentReq	long
initiatedARPResolution	inet::IARP::Notification
completedARPResolution	inet::IARP::Notification

Statistics

Name	Title	Source	Record	Unit	Interpolation Mode
sentReply	ARP replies sent		count, vector
failedARPResolution	ARP failed resolutions		count
sentReq	ARP request sent		count, vector
initiatedARPResolution	ARP initiated resolutions		count
completedARPResolution	ARP completed resolutions		count

Source code

//
// Implements the Address Resolution Protocol for IPv4 and IEEE 802 6-byte
// MAC addresses.
//
// ARP packets are represented by the ~ARPPacket class.
//
// Communication Between ARP and IPv4 modules:
// IPv4 module call the ARP::getMACAddressFor(ipv4Address) method for get the MACAddress
// of next hop. If this method could not resolve an IPv4 address to MAC address, then IPv4
// uses the ARP::startAddressResolution() method.
// ARP emit a completedARPResolution signal, when added/modified an entry in ARP table.
// ARP emit a failedARPResolution signal when an ARP request failed (ARP request sent
// retryCount times and retryTimeout elapsed).
//
// ARP resolution is used over <i>broadcast</i> interfaces only,
// that is, over interfaces that have the <tt>isBroadcast()</tt> flag set in
// <tt>InterfaceEntry</tt> (see ~InterfaceTable). Since routing files
// (<tt>.irt</tt> or <tt>.mrt</tt> files, given as parameter to ~IPv4RoutingTable)
// may modify the default interface configuration, you must take care that
// these files don't contain the word <tt>BROADCAST</tt> e.g. for PPP
// interfaces.
//
simple ARP like IARP
{
    parameters:
        string interfaceTableModule;   // The path to the InterfaceTable module
        string routingTableModule;
        double retryTimeout @unit("s") = default(1s); // number seconds ARP waits between retries to resolve an IPv4 address
        int retryCount = default(3);   // number of times ARP will attempt to resolve an IPv4 address
        double cacheTimeout @unit("s") = default(120s); // number seconds unused entries in the cache will time out
        bool respondToProxyARP = default(true);        // reply to proxy ARP requests (i.e. for IP addresses that this node can route)
        @display("i=block/layer");
        @signal[sentReq](type=long);
        @signal[sentReply](type=long);
        @signal[initiatedARPResolution](type=inet::IARP::Notification);
        @signal[completedARPResolution](type=inet::IARP::Notification);
        @signal[failedARPResolution](type=inet::IARP::Notification);
        @statistic[sentReq](title="ARP request sent"; record=count,vector);
        @statistic[sentReply](title="ARP replies sent"; record=count,vector);
        @statistic[initiatedARPResolution](title="ARP initiated resolutions"; record=count);
        @statistic[completedARPResolution](title="ARP completed resolutions"; record=count);
        @statistic[failedARPResolution](title="ARP failed resolutions"; record=count);
    gates:
        input netwIn @labels(ARPPacket+Ieee802Ctrl); // incoming ARP requests and replies
        output netwOut @labels(ARPPacket+Ieee802Ctrl,IPv4Datagram+Ieee802Ctrl);  // outgoing ARP requests/replies, and datagrams with resolved next hop
}

File: src/inet/networklayer/arp/ipv4/ARP.ned

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