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