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WP2 UPC Contribution to A2.2.1: Route Management. Route management. Network models Packet-switched/wavelength-switched model Routing models / Route management models Static routing model(s) [ETH, UPC, all partners] Combined intra- and inter domain routing model(s) [ETH, UPC]

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route management
Route management
  • Network models
    • Packet-switched/wavelength-switched model
  • Routing models / Route management models
    • Static routing model(s) [ETH, UPC, all partners]
    • Combined intra- and inter domain routing model(s) [ETH, UPC]
    • Adaptive routing model(s)
    • Predictive routing model(s)
    • Multicast routing model

NOBEL: Berlin May 18-19, 2004

optical packet and optical burst vs wavelength switched model
Optical Packet and Optical Burst vsWavelength Switched Model
  • Physical
    • Technological requirements – how advanced optical components are expected
    • Complexity of the hardware (node architecture)
  • Computational
    • Node control algorithms complexity
    • Routing algorithms complexity
  • Performance
    • Efficiency, network utilization
  • Flexibility
    • Data formats, bitrates, ...
    • Label switching paradigm – paths (connections) granularity, scalability

NOBEL: Berlin May 18-19, 2004

optical packet and optical burst vs wavelength switched model1
Optical Packet and Optical Burst vsWavelength Switched Model
  • QoS
    • Difficulty in quality guarantees
    • Hardware and control algorithms complexity
  • Network
    • Control Plane implementation
    • Signalization overhead
    • Adaptation to traffic demands
  • Interworking
    • With legacy networks – edge node operation complexity (adaptation, aggregation, ...)
  • Costs
    • Hardware (node), building of the network, ...

NOBEL: Berlin May 18-19, 2004

physical technological hardware requirements
Physical – technological, hardware requirements

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

computational complexity
Computational complexity

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

optical packet and optical burst vs wavelength switched model2
Optical Packet and Optical Burst vsWavelength Switched Model

Performance

Network utilization, efficiency

  • Wavelength switching
    • Not dynamically adopted (in real time) to the actual traffic demands
    • Efficiency up to 9 times worse than in OBS/OPS, very high wavelength consumption
    • Medium blocking probability
  • Burst switching
    • Network utilization higher than at WS (due to statistical multiplexing in optical domain)
    • High blocking probability - optical buffers need for fine network performance
  • Packet switching
    • Very high network utilization (statistical multiplexing in optical domain)
    • Needs FDLs and WC’s for high performance (low PLR)
    • Even with FDLs, packet delay is low due to fast optical switching (without O/E conversion of packet payload)

NOBEL: Berlin May 18-19, 2004

flexibility
Flexibility

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

slide9
QoS

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

network aspects
Network aspects

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

optical packet and optical burst vs wavelength switched model3
Optical Packet and Optical Burst vsWavelength Switched Model

Interworking

With legacy networks,edge node operation complexity (adaptation, aggregation, ...)

  • Wavelength switching
    • Lack of aggregation problem
    • Adaptation only in physical layer (e/o or wavelength conversion)
  • Burst switching
    • Burst assembly problem
  • Packet switching
    • Necessity of adaptation the data coming from legacy network to optical packet payload field
    • Packets disordering problem

NOBEL: Berlin May 18-19, 2004

optical packet and optical burst vs wavelength switched model4
Optical Packet and Optical Burst vsWavelength Switched Model

COSTS

Hardware (node), building of the network

  • Wavelength switching
    • Lower costs then in OBS/OPS case
    • But very high wavelength consumption
  • Burst switching
    • May use cheeper low speed switching elements than in OPS
    • Costs of advanced optical components
    • Low wavelength consumption
  • Packet switching
    • Very high costs of advanced optical components (FDLs units (for buffering, synchronization), very fast tunable wavelenght converters, very fast switching elements, …)
    • Costs of high performance electronic control unit
    • Low wavelength consumption

NOBEL: Berlin May 18-19, 2004

summary
Summary

Optical Packet and Optical Burst vsWavelength Switched Model

NOBEL: Berlin May 18-19, 2004

nobel wp3 upc works ops environment
Nobel-WP3 UPC worksOPS environment
  • Previous works - studies on contention resolution algorithms for a single switch
    • UPC contributions in asynchronous, variable length packets scenario
  • Next step - studies on routing strategies for a network scenario
    • Adaptive vs. Multipath
    • Per-packet vs. per-connection
  • Further works
    • QoS management taking into account previous results

NOBEL: Berlin May 18-19, 2004

nobel wp3 upc works obs environment
Nobel-WP3 UPC worksOBS environment
  • Previous works
    • Studies on contention resolution algorithms for a single switch
    • Burst assembly mechanisms
    • Signaling protocols
  • Next step
    • Studies on the effectiveness of multi-domain contention resolution in a network scenario
    • Studies on different routing strategies for a networks scenario
  • Further works
    • QoS management taking into account the previous results

NOBEL: Berlin May 18-19, 2004

route management1
Route management
  • Network models
    • Packet-switched/wavelength-switched model
  • Routing models / Route management models
    • Static routing model(s) [ETH, UPC, all partners]
    • Combined intra- and inter domain routing model(s) [ETH, UPC]
    • Adaptive routing model(s)
    • Predictive routing model(s)
    • Multicast routing model

NOBEL: Berlin May 18-19, 2004

combined intra and inter domain routing model
Combined Intra and Inter-Domain routing model
  • Our Research Focus is on QoS Routing (QoSR) in Optical Networks:
    • Dynamic Intra-AS QoS light-path provisioning (Optical QoS aware IGP)
    • Dynamic Inter-AS QoS light-path provisioning (Optical QoS aware EGP)
      • Coupling between both QoSR mechanisms

NOBEL: Berlin May 18-19, 2004

slide18

Combined Intra and Inter-Domain routing model

  • Research Goal: provide a combined Intra and Inter-AS QoS Routing model with the following characteristics:
    • Highly scalable
    • Resilience: survivability
    • Loop-free
    • Support for different CoS and Policy Control
    • Clear cut between QoS aware IGP and QoS aware EGP
    • Per-CoS fast re-route provisioning
    • Efficiency in terms of the trade-off between the updating frequency, and distributing and maintaining routing state information (inaccuracies)
    • Suitable signaling for QoS: requirements of the Control Planes for both routing protocols, IGP and EGP

NOBEL: Berlin May 18-19, 2004

slide19

Combined Intra and Inter-Domain routing model

  • Line of work:
    • Survey optical extensions to classical IGPs and EGPs
    • Development of Metrics and Routing Algorithms for both Intra and Inter-Domain QoS Routing
    • Efficient coupling between both Routing Algorithms
    • We also plan to carefully manage how traffic flows so that no starvation of best effort traffic occurs

NOBEL: Berlin May 18-19, 2004

adaptive routing analyzing the effects of flooding on global network performance
Adaptive routing: analyzing the effects of flooding on global network performance
  • Routing and Wavelength assignment problem (RWA)
    • Not tractable problem, so divided into:
      • Routing sub-problem
      • Wavelength assignment sub-problem
  • Routing sub-problem
    • Static routing
    • Dynamic (adaptive) routing
  • Static routing:
    • Fixed-routing
    • Fixed-alternate routing
    • Does not consider network dynamics
  • Dynamic (adaptive) routing:
    • Adaptive shortest-path routing
    • Least Congested Path (LCP)
    • Includes network dynamics in the route selection

NOBEL: Berlin May 18-19, 2004

slide21

Adaptive routing: analyzing the effects of flooding on global network performance

  • Dynamic vs static?
    • Static routing is simpler and not so complex
    • Dynamic routing is more appropriate for high dynamic networks
  • Dynamic routing issues:
    • Route selection must be adapted to network dynamics
    • Flooding mechanism is required
      • Mainly for high dynamic networks
    • Is the network state databases information accurate enough?
      • Routing inaccuracy problem
      • Non-suitable path selection because of having inaccurate network state information

NOBEL: Berlin May 18-19, 2004

slide22

Adaptive routing: analyzing the effects of flooding on global network performance

  • Flooding mechanism
    • In an N nodes network, each change results in a N2 messages to be flooded
      • Leads to instability and scalability
    • There are not many contributions on optical networks
    • New techniques must be sought
    • Approaches could be based on:
      • Updating by time (hold-down timer) as an IP extension
      • Updating by number of network state changes
      • Updating by minimum number of available resources

NOBEL: Berlin May 18-19, 2004

slide23

Adaptive routing: analyzing the effects of flooding on global network performance

  • Routing inaccuracy problem:
    • Routing algorithms must reduce the impact of selecting routes based on inaccurate routing information
    • New routing algorithms must be sought
    • Not many contributions in optical networks:
    • Approaches based on:
      • Dynamic bypass concept (BBOR):
        • Rerouting through alternative pre-computed paths
      • Prediction (PBR):
        • Route decision according to a “novel” concept of predicted network state information
        • Simultaneously, flooding is “almost” removed
  • In short, efforts must be done to develop new adaptive routing mechanisms which include these factors in the route decision

NOBEL: Berlin May 18-19, 2004

slide24

Prediction Based Routing

Usual Routing Algorithms need update messages with information about the network state

Network state information is not accurate:

- Aggregating information

- Triggering of update messages

- latency associated in flooded the update messages

Routing Algorithms utilise inaccurate state information (RIP)

NOBEL: Berlin May 18-19, 2004

slide25

Prediction Based Routing

  • Idea: Source nodes can learn which is the better path and wavelength without update messages
  • Dynamic learning according to the routing information obtained in previous connections set-up. (Based in branch prediction)
  • For each wavelength on a path there is a prediction table, PT, to predict the possibility of blocking
  • For each wavelength on a path there is a history register, WR, with information about if in the last cycles the wavelength on that path has been used

NOBEL: Berlin May 18-19, 2004

prediction based routing
Prediction Based Routing

Index to access PT from wavelength register histories

Prediction: Read two-bit counter value < 2 not blocked, value > 1 blocked

NOBEL: Berlin May 18-19, 2004

prediction based routing1

Count PT lambda 0

of SP1

Count PT lambda 1

of SP1

Count PT lambda N-1

of SP1

Count PT lambda 0

of SP2

Count PT lambda N_1

of SP2

...

...

>1

>1

>1

>1

<2

<2

<2

SP1

lambda 0

SP1

lambda 1

SP1

lambda N-1

SP2

lambda 0

SP2

lambda N-1

Prediction Based Routing
  • Update PT: PT are updated increasing counter if connection request is blocked and decreasing otherwise
  • Update WR: WR of the wavelength used is updated with 0, and the WR of the unused wavelength are updated with 1
  • Prediction Algorithm:

Two shortest path, SP1, SP2 and N wavelengths

NOBEL: Berlin May 18-19, 2004

multicast approach in optical transport networks
Multicast approach in optical transport networks
  • Main idea: to optimize optical resources utilization
  • Lightpaths are established point-to-multipoint to overcome the mismatching between optical and client granularities
  • 1xN Splitters are placed at the optical terminations in order to extend the lightpath to N destinations (N=3 in the example)

NOBEL: Berlin May 18-19, 2004

multicast approach in optical transport networks1

3

S

1

1

1

2

1

4

1

3

3

5

2

2

1

4

5

Multicast approach in optical transport networks
  • Example: When a connection from 1 to 3 is requested, the optical channel is transparently extended to nodes 4 and 5 (to allocating future connections from 1 to these nodes)

Although resources are wasted firstly, they will be recovered in the future (when new connections from 1 to 4 or 5 arrive).

NOBEL: Berlin May 18-19, 2004

multicast approach in optical transport networks2
Multicast approach in optical transport networks
  • As it seems difficult to fill a lightpath with traffic generated by a single source to an only destination, the lightpath capacity will be better used if it collects traffic from this source to many destinations.
  • This will only be true if the granularity difference between lightpath and connections accomplish some constraints.
  • Some preliminary simulations show that the applied strategy can perform well under certain conditions.

NOBEL: Berlin May 18-19, 2004

multicast approach in optical transport networks3
Multicast approach in optical transport networks
  • Work Plan:
    • Start simulations to study the feasibility of the proposed strategy
    • Study how to physically implement the multicast approach
    • Find the ratio between granularities and optimal N
    • To analyze different algorithms to implement the multicast approach
    • Simulate different traffic patterns

NOBEL: Berlin May 18-19, 2004