Advanced lightpath provisioning in interdomain optical networks

1
Advanced light-path provisioning in inter-domain
optical networks
April 14th 2005
Dr. H. Hakim Université de
Montréal M.G. Khair Dr. A. Maach
University of Ottawa Université de Montréal
2
Outline

• BGP overview weak points
• Objective
• AORBGP Design
• Network example
• Blocking types
• Results
• Conclusion

3
BGP-4 Overview

• Definition
• The Border Gateway Protocol (BGP) is an
  Inter-domain routing protocol.
• BGP is a Path Vector (PV) type protocol.
• PV defines the route as a pairing of
  ltattributes, destinationgt RFC 1322.

• BGP-4 messages
• Open Message To identify the BGP participants
• UPDATE Message used to add or withdraw a
  prefix/route
• Notification Message used to report a fault
  during a BGP session
• Keep Alive Message used to confirm that the BGP
  session is still alive

4
BGP Operation Mode

• E-BGP
• used between two edge routers that belong to
  different ASs.
• There is always a physical link between the two
  participants
• I-BGP
• this mode is used to exchange routing information
  among routers that belong to the same AS.
• There are no physical link among the
  participants logical connection/Full mesh

5
BGP-4 weak points

• BGP is Distance Vector (DV) based protocol, DV
  algorithm tries to find the paths that have the
  minimum number of hops to the desired destination
  RFC1771
• Unlike OSPF, BGP routers pick their routes based
  on configured policy.
• Result routing Oscillation.

6
BGP-4 weak points

• I-BGP router need to peer directly with every
  other BGP edge router in the same domain. Full
  mesh I-BGP
• The more peers the BGP router has, the greater
  the number of transport connections. more
  complicated.
• Routing miss-configuration is more likely to took
  place with I-BGP.

7
Objective

• Exchange the future availability of wavelengths
  along all the desired paths.
• Guarantee a reliable mechanism to exchange the
  future optical routing information.
• interaction mechanism between Intra-domain and
  Inter-domain routing protocols.
• Allow enough time for resource negotiation
• Reallocate resources for better bandwidth
  utilization
• Ability to work through an Advance reservation
  framework model that allows user to
• Request a Reservation between a source and a
  destination over a period of time.
• Modify Reservation For example, modify the
  duration of a session
• Cancel Reservation One can cancel and release
  the resources.
• Reservation Status discover the status of a
  request.
• Relocation Notice to notify the user that
  wavelength has been changed to another one.

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AORBGP

• Exchange Future availability
• Exploits BGP operation
• Extent some new features that is required for
  Optical routing such as
• Defining a new attribute called optical
  attribute.
• Define two new scheme for advertising
• Advertising based on the number of reserved or
  released wavelengths that took place in the link
  table OR
• Advertising based on a refreshing period

9
AORBGP Example
AS_1
AS_3
S
D
X
Y
AS_2
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AORBGP Design

• Optical Update Message

• Routing Table
• Shows all available ?s to all destinations over
  time

• Link Table
• Each edge node link keeps track of available
  wavelengths with the neighbor edge router over
  time

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Simple Architecture
AS Autonomous system Av_V ? Availability Vector
ARW Advance Reservation Window
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Routing table
Table 1 Routing table for Node 1
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Blocking Types

• Justified Refusal (PJR)

D
Link 3
Link 1
Link 2
A
C
B
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Blocking Types

• Unjustified Acceptance (PUA).

D
Link 3
Link 1
Link 2
A
C
B
15
Blocking Types

• Unjustified Refusal (PUR).

D
Link 3
Link 1
Link 2
A
C
B
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Simulation goals

• Advance Reservation Window (ARW) effect
• Refreshing schemes effect on PJR, PUA, PUR
• To refresh based on a fixed period of time, or
• To refresh based on the number of changes that
  occurs at the link table
• The effect of the network diameter on the three
  types of blocking

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Simulation parameters

• Size of Advance reservation Window (ADW)
• Parameters of Advertising schemes
• Refreshing period how long the node has to wait
  to trigger the advertisement of change
• Updating Threshold Number of changes at the link
  table
• Life time of lightpath Service time for the
  requested lightpath.
• Number of wavelengths exist in each fiber
• Rate of coming requests.

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Network Topology
ARPANET
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Refreshing period effect
Average life time of lightpath 400msec Number
of ? 10
20
Threshold change percent
Average life time of lightpath 400msec Number
of ? 64
21
Network diameter effect onPJR, PUA PUR.
Average life time of lightpath 400msec Number
of ? 64
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Conclusion

• Exchanging the future availability allows the
  user to get the optimal resources
• Allows better utilization because the service
  provider can reallocate the resources
• Diameter of the network and the connectivity has
  a great effect on the blocking.
• Advertising based on number of changes is better
  than based on time, because the node advertise
  based on its need

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Future work

• Wavelength assignment
• investigating other wavelength selection
  techniques other than (first-fit) and
• evaluate their impact on the performance of the
  scheme
• Wavelength rearrangement
• formulate the rearrangement problem of the
  already scheduled lightpaths
• find solutions that maximizes the acceptance rate
  of future lightpath requests.

24
Acknowledgment

• The authors would like to thank
• Dr. G. Bochmann
• Dr. T. Hall
• for their support of this research and for their
  reviews and suggestions to this work.

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Thank you!!
Contact Info H. Hakim hakim_at_research.telcordia.c
om Université de Montréal M. G. Khair
mkhair_at_site.uottawa.ca University of Ottawa A.
Maach amaach_at_site.uottawa.ca Université de
Montréal