Smart WDM IP Flow Technology (SWIFT)
		Joe Touch, Joe Bannister, Alan Willner
			       USC/ISI

	WDM optical networks provide an opportunity for extraordinary
gains in network bandwidth capacity, and are poised to dominate the
backbones of the Next-Generation Internet. These networks require fast
IP routing, that supports native optical transmission. SWIFT examines an
alternate processing path for packets in a WDM router. We augment
conventional low-bandwidth, high-latency software IP forwarding and
high-bandwidth, low-latency all-optical switching with an
intermediate, smart optical processing, to provide higher capability
than the all-optical path, with higher throughput than the
all-electronic path.
	A variety of techniques for flow-based processing are being
applied to IP router designs, in which sequences of similar packets
are routed using link-level labels and rapid, hardware-based label
demultiplexing and switching, including flow-switching and
tag-switching. These techniques take advantage of properties of link
and virtual link protocols designed to control electronic switches,
such as ATM. These properties include connection-oriented
communication, per-hop label modifications, a large, per-hop
connection identifier space, and variable per-flow bandwidth.
	The properties of WDM switches hinder the use of existing
flow-based processing. Specifically, WDM components lack support for
label modifications, have a very small (5-6 bit) global label space,
and have large, fixed channel bandwidth. These properties defeat
current label-swapping flow switching techniques. SWIFT augments the
conventional WDM capabilities with new techniques for dynamic
wavelength translation, dynamic dispersion compensation, and
all-optical header modification to support flow switching using
modified flow switching techniques.
	In addition, SWIFT utilizes optical contention detection and
wavelength translation to provide dynamic contention resolution, where
contending packets are sent on alternate channels to the same
destination.  This optical 'jog' in the switching path avoids
unnecessary contention due to global interference in channel
assignment, by using local alternate channels dynamically for short
bypass paths. SWIFT also utilizes all-optical packet alignment to
support striping and multiplexing, which reduces the constraint of
fixed bandwidth channels by supporting channel sharing, and which also
supports the use of multiple channels for link diversity to for fault
tolerance.
	SWIFT examines the differences in the properties of electronic
and WDM switches, and explores how this difference affects the
opportunity for flow-based processing. In SWIFT, we examine emerging
optical capabilities, and how they can be uniquely combined to support
flow-based switching. In particular, we are interested in a broader
view of flow protocols, in which these optical properties individually
do not replace the missing capabilities, but together provide an
opportunity for alternate implementations of flow processing to
support native optical flows.