Method and device for the management of resources in ATM technique for weighted fair queuing (WFQ) applications

Claim 2

Method according to claim 1, characterized by the fact that said step of scanning said high priority storage structure (FGB) includes, for each cell time (tc), the following steps: serving the transmission queue (Qa i ) indicated by said high priority storage structure (FGB); decreasing by one unit the number of tokens (TKN i ) at the disposal of said transmission queue (Qa i ); removing the indicator of said queue from said high priority storage structure (FGB); re-inserting, if in said just served transmission queue (Qa i ) further cells to be transmitted are present, the indicator of this transmission queue (Qa i ) inside said high priority storage structure (FGB) if a number of tokens (TKN i ) over zero remains available to this transmission queue, and, in the negative, inside said low priority structure (FAB).

Claim 3

Method according to claim 1, characterized by the fact that said step of scanning said low priority storage structure (FAB) includes, for each cell time, the following steps: serving the transmission queue (QA i ) indicated by said low priority storage structure (FAB); removing the indicator of said queue of said low priority storage structure (FAB); re-inserting, if further cells to be transmitted are present in said just served transmission queue (QA i ), the indicator of said transmission queue (Qa i ) inside said low priority storage structure (FAB).

Claim 4

Method according to claim 1, characterized by the fact that said input link (B i ) also includes flows of ATM cells which transmit at peak and which do not exploite therefore said further bandwidth possibly available on said output link (B o ), and, for each renewal time (TR), including the following further steps: inserting said cells of each of said flows which transmit at peak in a common queue (QNA); transmitting the cells present in said common queue (QNA) on said output link (B o ) until said common queue (QNA) is empty (IS_RT_EMPTY); only after having transmitted all the cells present in said common queue (QNA), resuming said scanning step (SERVING_FGB) of said high priority storage structure (FGB) or eventually said scanning step (SERVING_FAB) of said low priority storage structure (FAB).

Claim 5

Method according to claim 4, characterized by the fact that said input link (B i ) also includes flows of ATM cells pertaining to connections with unspecified bit rate (UBR) whose transfer is not guaranteed in a certain time and, for each renewal period (TR), the method includes the following further steps of: inserting said cells of said flows with non-guaranteed transfer time in a third buffer of very low priority FIFO type (FUB) in an equal number of transmission queues; scanning said third very low priority FIFO (FUB) whenever said common queue (QNA) of said high priority buffer (FGB) is empty, and all the transmission queues inserted in said high priority FIFO buffer (FGB) and the transmission queues inserted in said low priority FIFO buffer (FAB) ar empty.

Claim 6

Device according to claim 1, characterized by the fact that said input link (B i ) also includes flows of ATM cells of connections requiring a peak bandwidth control so as not to exceed a predetermined maximum bandwidth value in the transmission of said flows through said output link (B o ), and by the fact that, for each renewal period (TR) the method includes the scheduling of the transmission through said output link (B o ) of cells belonging to flows with limited peak bandwidth, inserting the cells coming from said input link (B i ) in a respective queue of one of said FIFO buffers (FGB, FAB or FUB), depending on the class of the relevant flow; the insertion of each cell belonging to said flows with limited peak bandwidth being conditioned by a peak control table with two bits updated by a scheduler.

Claim 7

Method according to claim 6, characterized by the fact that one of said two bits of said peak control table is generated as wait bit from the WFQ system and the other bit of said pair is a flag set by said scheduler.

Claim 8

Method according to claim 1, characterized by the fact that said high and low priority storage structures operate according to FIFO approach.

Claim 9

Management system of resources in ATM technique for Weighted Fair Queuing (WFQ) applications, including an input link (B i ) on which transit flows of ATM cells belonging to service classes with different quality (QoS), to each of said flows being associated a respective guaranteed minimum bandwidth (Ra i ) at the set up step of the service, and an output link (B o ), and each of said flows exploiting the possibility to have further bandwidth assigned on said output link (B o ), characterized by the fact of including: a number of transmission queues (QA 1 , QA 2 , QA n ) equal to the number of said flows of cells, each of said queues containing the ATM cells of a respective flow of cells, and assigning to each transmission queue, in a renewal period (TR) a whole multiple of the transmission time of a cell (tc) on said output link (B o ), a respective nember of access rights to said output link (B o ) or token (TNK i ) proportional to said minimum bandwidth (Ra i ); a control block (SCB) including a storage device (TK_COUNTER) which contains, for each of said transmission queues, a respective number of access rights to said output link (B o ) or token (TKN i ) proportional to said minimum bandwidth (Ra i ); a high priority storage structure (FGB) which contains indicators (Qid i ) of the transmission queues (Qa i ) which have at their disposal a number of tokens (TKN i ) over zero; a low priority storage structure (FAB) which contains indicators (Qid i ) of the transmission queues (Qa i ) which have at their disposal a number of tokens (TKN i ) equal to zero, said high priority storage structure (FGB) being connected with said low priority storage structure (FAB) in such a way that: one of said indicators (Qid i ) present in said high priority storage structure may be transferred to said low priority storage structure as the exhaustion of the tokens at its disposal stored in said storage device (TK_COUNTER) occours; a transmission queue indicated in said low priority storage structure (FAB) can only be served when said high priority storage structure (FGB) does not contain transmission queue indicators.

Claim 10

System according to claim 9, characterized by the fact that said input link (B i ) also includes flows of ATM cells which transmit at peak and which do not have therefore the possibility of exploiting said further bandwidth possibly available on said output link (B i ), and further caracterized by the fact of including a further transmission queue (QNA) which contains the cells of all those flows of ATM cells which transmit at peak and an indicator device (RT_EMPTY) which contains an indication on the filling state of said further transmission queue, said indicator device being connected with said high priority storage structure (FGB) and said low priority storage structure (FAB) in such a way that a transmission queue indicated in said high priority storage structure (FGB) or in said low priority storage structure (FAB) can only be served when said indicator device (RT_EMPTY) indicates the absence of cells to be transmitted inside said further transmission queue (QNA).

Claim 11

System according to claim 10, characterized by the fact that from said input link (B i ) also includes flows of ATM cells relating to connections with unspecified rate (UBR) whose transfer is not guaranteed in a certain time and said system also including: a third very low priority storage structure (FUB) containing the indicators (Qidm, Qidk,...) of transmission codes relating to said connections with unspecified rate (UBR); scanning means of said third very low priority storage structure (FUB) whenever said common queue (QNA) is empty, and all the transmission queues whose indicators are inserted in said first high priority storage structure (FGB) and the transmission codes whose indicators are inserted in said second low priority storage structure (FAB) are empty.

Claim 12

System according to claim 10, characterized by the fact that said input link (B i ) includes flows of ATM cells of connections requiring a peak rate control in order not to exceed a certain maximum rate value in the transmission of said flows through said output link (B o ), and said system also includes means adapted to schedule the transmission through said output link (B o ) of cells belonging to flows with limited peak rate, inserting the relevant cells coming from said input link (B i ) in a respective queue of one of said storage structures (FGB, FAB, FUB), depending on the class of the relevant flow; said means using a peak rate control table with two bits, one of said two bits being generated as wait bit from said control block (SCB) and the other of said two bits being a flag updated by a scheduler.

Claim 13

System according to any of the previous claims, characterized by the fact that said storage structures are FIFO type memories.