Implements the MPLS protocol.

Mpls module is added between layer 2 and 3 in the OSI model for fast packet switching. Mpls should be transparent to signalling protocols. Signalling protocol currently implemented in this simulation is RSVP-TE.

Operations

MPLS packets are represented by the MplsPacket class. The local LIB (Label Information Base) is stored in a LibTable module in the LSR.

For most of the time, the Mpls module will do the label swapping and message forwarding. Upon receiving a labelled packet from another LSR, the Mpls first extract the incoming interface and incoming label pair, and then look up the local LIB table. If an outgoing label and an outgoing interface can be found, the module will perform appropriate label operations (PUSH, POP, SWAP) based on the "outLabel" vector containing label and operation pairs.

Collaborations

Mpls module is required to interact with L2 (Link Layer) and L3 (Network Layer) in the OSI model. In addition, it needs to obtain label information from the LIB component and label query result from the Ldp module. Messages the model communicates with L2 and Network Layers are L2 packets (PPP, Frame Relay, ATM, Ethernet, etc.), and IP native packets. Specifically, Mpls module encapsulates IP packet and is encapsulated in L2 packet. Different L2 protocols may require different methods of encapsulation to inherit the L2's QoS. This implementation follows a generic approach; it assumes no information of QoS from the link layer.

Inheritance diagram

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

Used in compound modules

Name	Type	Description
LdpMplsRouter	compound module	An LDP-capable router.
RsvpMplsRouter	compound module	An RSVP-TE capable router.

Parameters

Name	Type	Default value	Description
interfaceTableModule	string		The path to the InterfaceTable module
libTableModule	string
classifierModule	string		The path to the module which implements the IIngressClassifier C++ interface

Properties

Name	Value	Description
display	i=block/switch

Gates

Name	Direction	Size	Description
upperLayerIn	input
upperLayerOut	output
lowerLayerIn	input
lowerLayerOut	output

Direct method calls (observed)

call to	function	info
MessageDispatcher	inet::MessageDispatcher::arrived	arrived
MessageDispatcher	inet::MessageDispatcher::handleRegisterProtocol	handleRegisterProtocol
MessageDispatcher	inet::MessageDispatcher::handleRegisterService	handleRegisterService
InterfaceTable	inet::InterfaceTable::findInterfaceByName	findInterfaceByName

Called methods (observed)

function	info	call from
inet::Mpls::handleRegisterProtocol	handleRegisterProtocol	MessageDispatcher
inet::Mpls::handleRegisterService	handleRegisterService	MessageDispatcher

Incoming messages (observed)

gate	msg	kind	ctrl	srcModule	tags
lowerLayerIn	Packet	0		Ppp	DispatchProtocolReq, InterfaceInd, PacketProtocolTag
upperLayerIn	Packet	0		Ipv4	DispatchProtocolInd, InterfaceReq, NetworkProtocolInd, PacketProtocolTag, DscpInd?, EcnInd?, HopLimitInd?, InterfaceInd?, L3AddressInd?, MulticastReq?, TosInd?, TransportProtocolInd?

Outgoing messages (observed)

gate	msg	kind	ctrl	destModule	tags
lowerLayerOut	Packet	0		DropTailQueue	InterfaceReq, PacketProtocolTag, DispatchProtocolInd?, DscpInd?, EcnInd?, HopLimitInd?, InterfaceInd?, L3AddressInd?, MulticastReq?, NetworkProtocolInd?, TosInd?, TransportProtocolInd?
upperLayerOut	Packet	0		Ipv4	DispatchProtocolReq, InterfaceInd, PacketProtocolTag

Packet operations (observed)

chunkType	packetAction
	trim, trimFront
Ipv4Header	peekAtFront
MplsHeader	insertAtFront, peekAtFront, popAtFront, removeAtFront
UdpHeader	peekDataAt

Shared Tagging operations (observed)

tagType	tagAction
DispatchProtocolReq	findTag, removeTagIfPresent
InterfaceInd	findTag, getTag
InterfaceReq	addTagIfAbsent, findTag
PacketProtocolTag	addTagIfAbsent, findTag, getTag

Source code

//
// Implements the MPLS protocol.
//
// ~Mpls module is added between layer 2 and 3 in the OSI model for fast packet
// switching. ~Mpls should be transparent to signalling protocols. Signalling
// protocol currently implemented in this simulation is RSVP-TE.
//
// Operations
//
// MPLS packets are represented by the MplsPacket class.
// The local LIB (Label Information Base) is stored in a ~LibTable module
// in the LSR.
//
// For most of the time, the ~Mpls module will do the label swapping and
// message forwarding. Upon receiving a labelled packet from another LSR, the
// ~Mpls first extract the incoming interface and incoming label pair, and then
// look up the local LIB table. If an outgoing label and an outgoing interface
// can be found, the module will perform appropriate label operations (PUSH,
// POP, SWAP) based on the "outLabel" vector containing label and operation
// pairs.
//
// Collaborations
//
// ~Mpls module is required to interact with L2 (Link Layer) and L3 (Network
// Layer) in the OSI model. In addition, it needs to obtain label information
// from the LIB component and label query result from the ~Ldp module. Messages
// the model communicates with L2 and Network Layers are L2 packets (PPP,
// Frame Relay, ATM, Ethernet, etc.), and IP native packets. Specifically,
// ~Mpls module encapsulates IP packet and is encapsulated in L2 packet.
// Different L2 protocols may require different methods of encapsulation to
// inherit the L2's QoS. This implementation follows a generic approach; it
// assumes no information of QoS from the link layer.
//
simple Mpls like IProtocolLayer
{
    parameters:
        string interfaceTableModule;   // The path to the InterfaceTable module
        string libTableModule;
        string classifierModule; // The path to the module which implements the IIngressClassifier C++ interface
        @display("i=block/switch");
    gates:
        input upperLayerIn;
        output upperLayerOut;
        input lowerLayerIn;
        output lowerLayerOut;
}

File: src/inet/networklayer/mpls/Mpls.ned

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