摘要:
In an ATM switch, an input port number, an input VPI and an input VCI are used to generate a header appended to the cell when the cell is transmitted. The input port number and the input VPI are combined to form a pointer to a look-up table (LUT). The LUT entry contains a first portion of a pointer to an Input Translation Table (ITT). An ITT entry provides sufficient information to generate the header. The LUT entry contains also some or all of the bits of a mask to be applied to the input VCI to obtain a second portion of the pointer to the ITT. The number of the mask bits is variable. All the mask bits are 1. The mask bits are separated from the first portion of the ITT pointer by a 0 bit.
摘要:
In an ATM switch, queue thresholds vary dynamically depending on switch congestion. All the queues are organized in one or more classes. The thresholds for each class depend inversely on the number of cells in all the queues of the class.
摘要:
A method is provided for the implementation of a time-wheel ATM cell scheduler with very large number of queues that can precisely pace any assigned bandwidth described in [i,m] terms (i cells in m cell-times), as long as m/i>=[number of queues]. The method requires only a small, bounded amount of work per physical connection independent of the number of VCs.
摘要:
A memory interface unit comprising a bus interface unit, a buffer which can store multiple data burst subsets in transit to or from a digital memory, and a switch which includes an externally accessible a master data path for the transfer data to or from the bus interface unit and which includes an externally accessible slave data path for the transfer of data to or from the buffer and which includes a direct data path for the transfer data between the bus interface unit and the buffet.
摘要:
In the first period of time during arbitration, each unit requesting access to the bus examines two or more MSBs of its priority number, and indicates these bits by signals on the bus. Thus, the units are divided into groups based on two or more MSBs of the units' priority numbers; at the end of the first period of time, the bus identifies one of the groups which wins arbitration over the remaining groups. In a second period of time, the units of the winning group that request access to the bus examine the next bits of their priority numbers, and indicate these bits by signals on the bus. Thus, the units of the winning group are divided into subgroups based on the next bits of the priority numbers. At the end of the second period of time, the bus indicates the winning subgroup. Arbitration proceeds in this way until the winning unit is determined. The winning unit changes its priority to the lowest priority. All the units that had lower priority than the winning unit increase their priorities. Initial priority numbers are determined from the device numbers.
摘要:
In a network switch, data received on an input connection can be transmitted on one or more output connections. When the switch receives a command to remove an output connection, the switch queues a marker cell in a queue cells to be transmitted on the output connection. The switch removes the connection when the switch reaches the marker cell as the switch traverses the queue to transmit the cells. A separate queue is provided for each input connection. For each input connection, the switch maintains a linked list of data structures each of which identifies an output connection which is to transmit data received on the input connection but for which the corresponding queue does not have data ready to be transmitted. When the queue gets data ready to be transmitted on all the output connections in the linked list, these output connections are moved to another linked list maintained for output connections for which there is a queue having data ready to be transmitted. The switch mutliplexes two different input connections onto the same virtual output connection. This virtual output connection can be multiplexed with other connections on the same port or sub-port. The cells are transmitted on the virtual output connection in frames. The cells of each frame are transmitted without any intervening cells. Thus, in an ATM network different input connections can be multiplexed on the same virtual output connection using the AAL-5 protocol.
摘要:
A method is provided for the implementation of a fair queuing ATM cell scheduler that can precisely pace virtual channel (VC) traffic by an assigned weight which defines the available bandwidth to be allocated to that VC. The method provides a minimum service rate to each virtual channel on a small, selected time scale, and requires only a small, bounded amount of work per physical connection, independent of the number of VCs.
摘要:
Different units of a system are identified by their device numbers. The device numbers are set during initialization as follows. Each unit has a pin connected to a unique line of the data bus. During initialization, a control unit drives the device number of each unit onto the corresponding line of the data bus. Arbitration cycles proceed in parallel with bus cycles. The above arbitration techniques are suitable to control access to shared resources other than a shared bus.
摘要:
A memory interface unit comprising a bus interface unit, a buffer which can store multiple data burst subsets in transit to or from a digital memory, and a switch which includes an externally accessible master data path for the transfer data to or from the bus interface unit and which includes an externally accessible slave data path for the transfer of data to or from the buffer and which includes a direct data path for the transfer data between the bus interface unit and the buffer.
摘要:
A memory interface unit comprising a bus interface unit, a buffer which can store multiple data burst subsets in transit to or from a digital memory, and a switch which includes an externally accessible a master data path for the transfer data to or from the bus interface unit and which includes an externally accessible slave data path for the transfer of data to or from the buffer and which includes a direct data path for the transfer data between the bus interface unit and the buffer.