Graded Channel Reservation with Path Switching in Ultra High
Capacity Networks
Reuven Cohen, Niloofar Fazlollahi, David Starobinski
ECE Dept., Boston University
Gridnets Workshop 2006San Jose, CA
Acknowledgements
US Department of Energy Dr. N. Rao, ORNL
Outlines
Advanced Channel Reservation Contributions Models and Algorithms Related work Variants Performance Evaluation Conclusion
Motivation
Grid computation : Large Hadron Collider (LHC) at CERN
Exabytes (1018
bytes) → need for new
protocol to support huge file transfers
http://lhc.web.cern.ch/lhc/LHC_Experiments.htm
Advanced Channel Reservation
Emergence of new protocol stack complements TCP/IP Properties: 1 - Users request resources for connection
in advance (bandwidth/duration, file size) 2 – Dedicated resources allocated by a
scheduler (centralized or replicated) 3 – Implemented directly on top of layer 2
UltraScience Net
http://www.csm.ornl.gov/ultranet/
ACR Challenges
Scheduling
Routing
Goal: maximum utilization of resources
EarliestShortest
A
B
Graded Channel Reservation (GCR)Contributions: path grading multi-criteria path optimization (shortest,
earliest)
path switching connection can switch between paths
Complexity analysis (small polynomial) Performance evaluation
ModelModel: G (V,E) V: {A, B, C} E: {AB, AC, BC}
requests:
response: (time,path) Objective: Highest grade path
A
B
C
SourceDestination BandwidthDuration
Grading Example
Primary grading criterion: earliest path
Secondary grading criterion: Shortest Widest
Example (Cont.) Thm:
GCR always returns the earliest time at which a path satisfying requested bandwidth B and duration T can be established between nodes s and d.
Return path with highest grade (e.g., earliest-shortest)
GCR
Algorithm: Time slots: connection set up/ tear
down Steady state residual graph Graph intersection yes - highest grade path no – start from next slot Reserve bandwidths
BFS path search
Related Work
Most closely related: Guerin & Orda, INFOCOM, 2000 Rao, Wing, Carter & Wu, IEEE ComSoc Mag.,
2005
Focus on single criterion optimization
No path switching Limited performance evaluation
Advantage of path switching
A
CSlot 1: [1,1:30]
Slot 3: [4,8]
Slot 2: [1:30,4]
Request: (A,C) at time 2:00 pm, duration = 4 hours
B
A
C
B
A
C
B
A
C
B
Slot 3: [2,4]Slot 2: [1:30,2]
A
C
B
Slot 5: [6,8]Slot 4: [4,6]
Variants to GCR
GCRswitch
Switch to best grade path available at each slot
Reducing Path Switches
GCRminimum
Thm: GCRminimum returns the earliest path and minimizes number of path switches.
GCRlimitx
Heuristic: limits up to x switches
Simulation measures & parameters
Performance measures:
1- average delay 2- saturation throughput Requests: (s,d,B,T)
Parameters: uniform source uniform or hot-spot destination uniform or 80/20 bandwidth exponential or heavy-tailed connection length
Topologies
Performance Evaluations
Performance Evaluations
Conclusion
Framework: grading & switching 1st and 2nd path optimization
important Path switching widely improves
performance
Future Work
Time window: simulating blocking probability
Cost of switching