Optical Burst Switching

1
Optical Burst Switching

• An optical transport technology with the
  capability of transmitting data in the form of
  bursts in an all-optical, bufferless network,
  using either circuit switching (light paths),
  flow switching (persistent connection), or
  per-hop switching (single burst) services,
  depending on connection set-up message.
• The network is transparent to the content of a
  burst (analog or any digital format) as well as
  to the data rate by separating the control plane
  (electrical) from the data plane (optical).

2
Burst definition

• A burst can be defined as a contiguous set of
  data bytes or packets. It can be as short as a
  few microseconds or as long as several hours.

3
Control plane vs. data plane

• The fundamental premise of OBS is the separation
  of the control and data planes, and the
  segregation of functionality within the
  appropriate domain (electronic or optical).
• a set-up message (control message) to an OBS
  ingress switch. The control processor forwards
  the message along the data transmission path
  toward the destination.
• Control messages are processed at each node
  (requiring OEO conversions) they inform each
  node of the impending data burst, and initiate
  switch configurations to accommodate the data
  burst.
• The data burst is launched after a small offset
  delay. Bursts remain in the optical plane
  end-to-end, and are typically not buffered as
  they transit the network core.

4
OBS features

• OBS has the potential of meeting several
  important objectives
• high bandwidth, low latency, deterministic (very
  little if any network elasticity no buffers)
  transport required for high demand (grid)
  applications
• all-optical data transmission with ultra-fast
  user/application-initiated light path setup
• implementable with cost effective COTS optical
  devices.

5
E2E burst transmission
Application/user initiated Control message
OEO
OEO
- -
X
Control signal created Cross connection, awaiting
burst
Control signal has not been processed yet, but
will arrive ahead off burst by time offset delay
6
When will carriers have it?

• Many in the networking research community believe
  that optical burst switching (OBS) can meet the
  needs of the scientific community in the near
  term (2-3 years).
• Research test beds in several Labs globally
• ATDnet MAN testbed
• The opportunity work on a networking technology
  during pre-standardization development for the
  purpose of meeting service management needs and
  requirements (not an after thought!).

7
Optical Packet Switching (OPS)

• OPS is the ultimate optical switching technology
  
• requires optical buffering (beyond todays coarse
  fiber delay lines)
• also, requires line-rate header parsing.
• Many experts do not expect OPS to be commercially
  feasible for at least a decade.
•  

8
OBS Network Architectures

• Most OBS research has focused on edge-core,
  overlay architectures.
• Few (myself included), are looking at e2e
  user/application initiated connections.
• Working on OBS NICs
• User/application initiated optical network
  connections.
• Use Just In Time (JIT) protocol for connection
  signaling.

9
OBS and QoS

• 1) Application layer QoS (latency, jitter,
  datarate)
• Handled at edges during burstification (similar
  to SAR in ATM) and scheduling not in
  cut-through optical network (no buffering)
• 2) Physical layer QoS (BER)
• Function of optical components, optical fiber,
  length of transmission controlled and monitored
  at the optical layer
• 3) QoS and priority
• Pre-emption during congestion

10
OBS Service Requirements

• Network feedback mechanisms to user
• Status
• Alarms
• Availability and reach

11
OBS Service Requirements

• Policy based routing algorithms user or
  carriers decide on how forwarding tables are
  created.
• Integrating security concerns at both the
  protocol level as well as control and management
  plane.
• Incorporating necessary inter-domain information
  exchange in protocol definitions.
• Providing necessary flexibility in architectures
  to meet both carrier-owned and user-owned
  networks.

12
OBS Service Requirements

• Understanding the requirements for both physical
  layer QoS and application layer QoS and
  incorporating them into protocol definitions.
• Determine how users will get billed for the
  network service.
• Determine what is meant by SLAs and how the
  network can provide them.