This paper presents a scalable scheduling scheme

called iterative request-grant-based round-robin (

i

RGRR)

for high-speed crossbars.It overcomes limitation that most traditional scheduling schemes (such as

i

SLIP

PIM) suffer from poor scalability by simplifying the execution process and reducing the scheduling overhead.iRGRR dramatically reduces the complexity of control messages from an order of

O(N)

to

O

(log

N

)

and thus provides fine scalability

and can be used in terabit switches/routers.The simulation results show that

i

RGRR can achieve nearly the same performance as iSLIP under various traffic models

including uniform and non-uniform destin

ation distributions.In addition

i

RGRR provides better fairness and has lower implementation complexity than iSLIP.