TODO
	change RawPacketIO constructor to take a timeval (change socketIO also)
	complete API doc in doxygen
	write tutuorial/intro
	big mistake: single output queue; need one per PacketIO object?

OVERVIEW

The Packet Engine (pEng) framework supports generation of network packets,
primarily for network testing.

Control is provided over packet contents and transmit time.

Incoming packets are also monitored and can be used to
control packet transmission, to support request/reply tests.

Packet creation is supported by the Raw Socket Toolkit (link).

***** BASIC USE

For a pEng run, the tester provides three items:

1. IO[0..M-1]: an array of PacketIO objects
A PacketIO object is an abstraction of an Ethernet interface.
The framework provides several PacketIO classes for instantiation.

2. I[0..N-1]: an array of PacketIter objects
A PacketIter object supports the methods
	next: provides a new packet for tx
	hasNext: indicates whether a packet is available
Each packet contains a buffer, an ioId, and a timestamp
NOTE: ioId index into IO array; streamId index into I array.
For packets to be transmitted: ...
For received packets: ...
The tester implements one or more PacketIter classes.

3. A PacketIterId object
provides methods to set and get the streamId in a packet.
The stream id is an index into the I array.

Example: like testTimeIter; 2 CBR iters, with some conflict

***** ARCHITECTURE

TX/RX DIAGRAM HERE: jpg from xfig

TRANSMIT
PacketSchedule polls the iterators and queues the packets
for transmission.
When 2 packets have transmit times close enough to cause a conflict,
the scheduler modifies one or both transmit times.
PacketTransmit removes packets, passing them to
the appropriate packet IO object.

RECEIVE


TimeIter

PacketIO

Tester provides
	vector of iterators
	set of packet iterators
	next, hasNext, notify, id

*** transmit side: multiplex
pEng merges packets from packetIters and queues them for tx
guaranteed: packets from a given iter sent in orde retrieved using next()
attempted: packets tx'ed near timestamp

*** receive side: demultiplex
pEng polls packetIOs and dispatches packets to notify methods using id


Packet
PacketEvent
PacketTrace

PacketPool

PacketSchedule
PacketTransmit
PacketReceive
PacketEngine

TESTER'S TASKS

Write PacketIters, including notify; perhaps TimeIters

Write PacketIterId, including notify

Hack main
	instantiate PacketIters, PacketIterId, PacketPool, PacketIOs
	instantiate and start PacketEngine