Flow control for high speed networks

Claim 1

A method of regulating data flow in a packet transmission network with a plurality of sessions, each session being established between a sender and a receiver exchanging windows of variable size, said method comprising: transmitting a pacing response to said sender (PRS) indicating the size of a subsequent window (WS) to be transmitted in a session between said sender and said receiver, said size of said subsequent window being a number of packets that said sender can transmit in a subsequent window, said subsequent window size (WS) being determined by decreasing a previous window size if when said window size is to be calculated, either QL ≠ 0, or QL = 0 and a pacing request was not received within a specified time interval, said window size thus being adjusted according to the following formula: WS = max (W min, CNT-QL+B) where CNT is the number of packets received by said receiver from said sender during a round trip delay which is the time needed for a first packet to be transmitted from said sender to said receiver plus the time needed for a second packet to be transmitted from said receiver to said sender after said first packet is received by said receiver, where QL is the number of packets stored in a queue of said receiver for future transmission to another node of said network, where W min is a prespecified parameter denoting a minimum window size, and where B is also a prespecified parameter, said subsequent window size (WS) being determined by increasing a previous window size if when said subsequent window size is to be calculated, QL = 0 and a pacing request was received in said specified time interval, said subsequent window size thus assuming a value between CNT and W max where W max is a prespecified parameter.

Claim 6

A method as recited in claims 4 or 5, wherein a step of transmitting an acknowledgment bit (WR) to said receiver from said sender, said acknowledgment bit being transmitted in the next packet immediately following the reception of said pacing response by said sender, said acknowledgment bit indicating the reception of said pacing response, is succeeding said step of transmitting, in response to said pacing request (PRQ), said pacing response to said sender indicating the size of said subsequent window to be transmitted in said session between said sender and said receiver, said step of determining said subsequent window size (WS) being executed upon reception of said acknowledgment bit (WR), and said window size being included in said pacing response which is to be the next pacing response transmitted to said sender after the reception of said acknowledgment bit.

Claim 7

An apparatus for regulating data flow in a packet transmission network with a plurality of sessions, each session being established between a sender and a receiver exchanging windows of variable size, said apparatus comprising: means for transmitting a pacing response (PRS) to said sender indicating the size of a subsequent window (WS) to be transmitted in a session between said sender and said receiver, said size of said subsequent window being a number of packets that said sender can transmit in a subsequent window; and means for determining said subsequent window size (WS) wherein said subsequent window size is determined by decreasing a previous window size if when said window size is to be calculated, either QL ≠ 0, or QL = 0 and a pacing request was not received in a specified time interval, then said subsequent window size being a size decreased from said previous window size according to the following formula: WS = Max (W min .CNT-QL+B) where CNT is the number of packets received by said receiver from said sender during a round trip delay which is the time needed for a first packet to be transmitted from said sender to said receiver plus the time needed for a second packet to be transmitted from said receiver to said sender after said first packet is received by said receiver, where QL is the number of packets stored in a queue of said receiver for future transmission to another node of said network, where W min is a prespecified parameter denoting a minimum window size, and where B is also a prespecified parameter, and wherein said subsequent window size is determined by increasing said previous window size if when said window size is to be calculated, QL = 0 and a pacing request was received in said specified time interval, said subsequent window size thus assuming a value between CNT and W max , where W max is a prespecified parameter.

Claim 11

An apparatus as recited in claims 9 or 10, further comprising means for transmitting an acknowledgment bit (WR) to said receiver from said sender, said acknowledgment bit being transmitted in the next packet immediately following the reception of said pacing response (PRS) by said sender, said acknowledgment bit indicating the reception of said pacing response, succeeding said means for transmitting, in response to said pacing request (PRQ), said pacing response to said sender indicating the size of said subsequent window to be transmitted in said session between said sender and said receiver.

Claim 12

A method of regulating data flow in a packet transmission network with a plurality of sessions, each session being established between a sender and a receiver exchanging windows of variable size, said method comprising: polling each of said sessions to determine if a send queue corresponding to said each session has packets stored therein for transmission; storing, for each of said selected sessions, at least one pacing credit in a shared credit pool (SCP) if a send queue corresponding to said each selected session has no packets stored therein for transmission when said each selected session is polled; and distributing pacing credits stored in said shared credit pool (SCP) to those of said selected sessions whose corresponding send queues have packets stored therein for transmission.

Claim 17

An apparatus for regulating data flow in a packet transmission network with a plurality of sessions, each session being established between a sender and a receiver exchanging windows of variable size, said apparatus comprising: means for polling each of said sessions to determine if a send queue corresponding to said each session has packets stored therein for transmission; means for storing, for each of said selected sessions, at least one pacing credit in a shared credit pool (SCP) if a send queue corresponding to said each selected session has no packets stored therein for transmission when said each selected session is polled; and means for distributing pacing credits stored in said shared credit pool (SCP) to those of said selected sessions whose corresponding send queues have packets stored therein for transmission.