Summary: VirtualCredit: Efficient EndtoEnd Credit Based Flow
Yehuda Afek \Lambda Yishay Mansour y Zvi Ostfeld z
Computer Science Department,
TelAviv University, Israel 69978.
A new flow control scheme, called virtual credit that may be considered either as a
credit based flowcontrol algorithm without a queue per session at the ports, or as a way
to modify the credit based scheme and to bring it closer to an endtoend rate based
scheme, is presented. The new scheme brings the credit based and rate based flowcontrol
schemes closer to each other, giving an attractive compromise between the two schemes.
The new scheme enjoys the main advantages of the credit based flowcontrol scheme while
not requiring a queue per session at the switches. A possible disadvantage of the scheme is
the large buffer requirement at the switches to ensure very low cell loss rate (but no more
than the corresponding buffer requirements in rate based schemes).
Key words: Flowcontrol, Creditbased, Ratebased, ABR, Round robin.
Flow control is a distributed network protocol whose goal is is to prevent and resolve data traffic
congestion while ensuring high utilization and fairness among the different connections. This
task is achieved by controlling the flow of traffic that enters the network, and the flow of traffic