Class IPControlInfo

File: src/networklayer/contract/IPControlInfo.msg

Control information for sending/receiving packets over IP.

To send a packet over IP, fill in an IPControlInfo object, attach it to the packet with the C++ method setControlInfo(), the send it to the IP module.

When sending, the following fields are required:

protocol: a value from IPProtocolId
destAddr

Optional fields:

srcAddr: it will be set to the address of the outgoing interface
diffServCodePoint: used in DS_Field (RFC 2474) instead of TOS (default: 0)
timeToLive: default defined as module parameter
dontFragment: default: false

Not supported:

options: IP Options currently not used
Identifier is currently always chosen by the IP layer

When IP delivers a packet to higher layers, it also attaches an IPControlInfo to it. It fills in the following fields:

srcAddr, destAddr, protocol, diffServCodePoint: values from the original datagram
interfaceId: the interface on which the datagram arrived, or -1 if it was created locally

IP also puts the original datagram object into the control info, because it may be needed by higher layers (for example, by ICMP for error reporting).

Usage diagram:

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Inheritance diagram:

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Fields:

Name	Type	Description
protocol	short	encapsulated protocol
dontFragment	bool	"don't fragment" bit
interfaceId	int	interface on which the datagram was received, or should be sent (see InterfaceTable)
destAddr	IPAddress	destination IP address
srcAddr	IPAddress	source IP address
diffServCodePoint	unsigned char	for QoS
timeToLive	short	maximum hop count

Source code:

//
// Control information for sending/receiving packets over \IP.
//
// To send a packet over \IP, fill in an IPControlInfo object,
// attach it to the packet with the C++ method setControlInfo(),
// the send it to the IP module.
//
// When sending, the following fields are required:
// - protocol: a value from IPProtocolId
// - destAddr
//
// Optional fields:
// - srcAddr: it will be set to the address of the outgoing interface
// - diffServCodePoint: used in DS_Field (RFC 2474) instead of TOS (default: 0)
// - timeToLive: default defined as module parameter
// - dontFragment: default: false
//
// Not supported:
// - options: \IP Options currently not used
// - Identifier is currently always chosen by the \IP layer
//
// When IP delivers a packet to higher layers, it also attaches an IPControlInfo 
// to it. It fills in the following fields: 
//  - srcAddr, destAddr, protocol, diffServCodePoint: values from the original datagram
//  - interfaceId: the interface on which the datagram arrived, or -1 if it was
//    created locally
//
// IP also puts the original datagram object into the control info, because
// it may be needed by higher layers (for example, by ICMP for error reporting).
//
class IPControlInfo
{
    @customize(true);
    IPAddress destAddr;   // destination IP address
    IPAddress srcAddr;    // source IP address
    int interfaceId = -1; // interface on which the datagram was received, or
                          // should be sent (see InterfaceTable)
    short protocol @enum(IPProtocolId);  // encapsulated protocol
    unsigned char diffServCodePoint;  // for QoS
    short timeToLive;     // maximum hop count
    bool dontFragment;    // "don't fragment" bit
}