Showing papers on "Fast packet switching published in 1994"

Method and apparatus for virtual switching

Abstract: A physical switching device for use in a communication network to switch Open Systems Interconnection (OSI) network layer packets and method of use therefor is provided. The physical switching device includes at least a first and a second virtual switch. Each virtual switch includes a decision mechanism for determining an associated directive based on a destination identifier within a particular packet received at a data port. A processor is coupled to each virtual switch to insert the particular packet into an outgoing data stream on another data port to deliver the packet. Both data ports are associated with a plurality of data interfaces in the physical switching device. A management apparatus is coupled to each virtual switch to maintain information on an association between the plurality of data interfaces and the virtual switches. The management apparatus limits each processor to only inserting the particular packet on another data port associated with the same virtual switch which received the particular packet.

Apparatuses and mobile stations for providing packet data communication in digital TDMA cellular systems

Abstract: Apparatuses and mobile stations are described which provide packet data services in TDMA (Time Division Multiple Access) cellular systems, based on providing shared packet data channels optimized for packet data. A first 'integrated' embodiment utilizes the current cellular infrastructure to the extent possible consistent with functional and performance requirements. Shared packet data channels (PDCHs) in base stations (BTS, BSC) may be provided dynamically determined by demand. A packet data (PD) controller in each Mobile services Switching Centre (MSC) controls access to the packet data services. A packet data router in each MSC routes packets to and from the MSC service area. A backbone network interconnects packet data routers and Interworking Functions (IWF) providing internetworking with external network(s). A second 'separated' embodiment, in order to minimize the impact on the current cellular system, primarily utilizes the base station portion of the cellular system, for the remaining network parts relying on a separate mobile packet data infrastructure.

Photonic packet switches: architectures and experimental implementations

Abstract: Photonic packet switches offer high speed, data rate and format transparency, and flexibility required by future computer communications and cell-based telecommunications networks. In this paper, we review experimental progress in state-of-the-art photonic packet switches with an emphasis on all-optical guided-wave systems. The term all-optical implies that the data portion of a packet remains in optical format from the source to the destination. While the data remain all-optical, both optical and optoelectronic techniques have been used to process packet routing functions based on extremely simple routing protocols. An overview of the design issues for all-optical photonic packet switching is given and contrasted with electronic packet switch implementations. Low-level functions that have been experimentally implemented include routing, contention resolution, synchronization, and header regeneration. System level demonstrations, including centralized photonic switching and distributed all-optical multihop networks, will be reviewed. >

Packet delivery system

Abstract: A packet switching system (100) having a packet switch (140) employs an acknowledgment scheme in order assure the delivery of all fragments (310) comprising a fragmented data packet (300) to improve overall system throughput during the handling of packets (310) that require reassembly. When packet fragments (310) are lost, corrupted or otherwise unintelligible to a receiving device (92, 94), the acknowledgment scheme permits retransmission of the missing data. In addition, a second acknowledgment signal is scheduled by system processing resources (110) in order to verify the successful delivery of all retransmitted data.

Two-dimensional round-robin schedulers for packet switches with multiple input queues

Abstract: Presents a new scheduler, the two-dimensional round-robin (2DRR) scheduler, that provides high throughput and fair access in a packet switch that uses multiple input queues. We consider an architecture in which each input port maintains a separate queue for each output. In an N/spl times/N switch, our scheduler determines which of the queues in the total of N/sup 2/ input queues are served during each time slot. We demonstrate the fairness properties of the 2DRR scheduler and compare its performance with that of the input and output queueing configurations, showing that our scheme achieves the same saturation throughput as output queueing. The 2DRR scheduler can be implemented using simple logic components, thereby allowing a very high-speed implementation. >

Traffic management for ATM local area networks

Abstract: Asynchronous transfer mode (ATM) is the first switching technology to be capable of supporting circuit switching and packet switching within a single integrated switching mechanism. This was one of the research goals that led to the development of ATM. Considerable progress has already been made in implementing constant bit-rate services, similar to conventional circuit switching, over ATM. The authors briefly consider how to support LAN emulation over an ATM network and then explore how to offer the dynamic bandwidth sharing in the local area. Considerable progress has already been made in implementing constant bit-rate services, similar to conventional circuit switching, over ATM. However, the bursty nature of data traffic requires dynamic bandwidth sharing similar to packet switching, and this is still under investigation. >

Method and apparatus for providing cryptographic protection of a data stream in a communication system.

Abstract: A method and apparatus for providing cryptographic protection of a data stream are described in accordance with the Open Systems Interconnection (OSI) model for a communication system This cryptographic protection is accomplished on the transmitting side by assigning a packet sequence number to a packet derived from a data stream received from a network layer (110) Subsequently, a transmit overflow sequence number (124) is updated as a function of the packet sequence number (116) Then, prior to communicating the packet and the packet sequence number on a physical layer, the packet is encrypted as a function of the packet sequence number (116) and the transmit overflow sequence number (124) On the receiving side, the packet sequence number is extracted (166) from the physical layer (160) In addition, a receive overflow sequence number (174) is updated as a function of the packet sequence number (172) Finally, the encrypted packet is decrypted as a function of the packet sequence number (176) and the receive overflow sequence number (178) In addition, a transmitting and a receiving communication unit for use in a communication system which includes cryptographic protection of a data stream is described

Scheduling transmissions in WDM broadcast-and-select networks

Abstract: Considers a broadcast-and-select, wavelength division multiplexed (WDM), optical communication network that is packet switched and time slotted. The amount of time it takes transmitters and receivers to tune from one wavelength to another is assumed to be T slots. The authors consider all-to-all transmission schedules, which are defined to be ones that schedule a packet transmission between each input-output pair. They present upper and lower bounds for the minimum length of such schedules. In particular, if each of N inputs has a tunable transmitter and each of N outputs has a tunable receiver then the minimum length is between (N+o(N))(/spl radic/T+1) and ((N+o(N))/spl radic/T. This provides some insight into the relationship between packet delay and T. The authors also consider schedules that do not allow packet transmissions while a transmitter or receiver is tuning from one wavelength to another. >

Method and apparatus for transmission of high priority traffic on low speed communication links

Abstract: In a packet switched communications system an incoming real-time packet is imbedded after the next block of data of the non-real-time packet being transmitted. This object is accomplished by transmitting each packet along with at least a 1-byte trailer which is used to indicate the packet type, whether the current block of non real time data is preempted or whether the current block of non real time data is resumed.

Generalized processor sharing networks with exponentially bounded burstiness arrivals

Abstract: Considers virtual circuit packet switching communication networks that employ processor sharing type service disciplines and studies their stability when the offered traffic to the network has exponentially bounded burstiness (EBB). The authors employ an exponential characterization (EBB) introduced in a previous work to analyze this type of system in a stochastic setting. They first examine the GPS and PGPS servers in isolation, and demonstrate their superiority to a general server in the stochastic environment. They then show that a network of servers, that are all either GPS or PGPS, is stable whenever the service rate of each node is larger than the total arrival rate to it. In addition, they provide exponential upper bounds to the traffic flows within the network links, and to the backlogs of each session in the various nodes on its path. >

Method and appartus for controlling multimedia information communication

Abstract: A system in which multimedia information communication is performed between two terminal stations connected to each other through a packet switching network, each of the terminal stations having a control device for performing send control for sending a video packet including coded video data and a voice packet including coded voice data to the packet switching network and supply control for supplying the video packet and voice packet received from the packe switching network to a video codec and a voice codec respectively. One of the two terminal stations operating as a receive side issues a video data transmission mode change request to the other terminal station located at a multimedia information transmission side in accordance with a status of delay of video packets and/or voice packets received from the packet switching network, and the other of said terminal stations changes the video data transmission mode in response to the transmission mode change request, so that when the delay generated in the voice packet arrival interval exceeds a predetermined threshold value, video transmission is stopped and the operation mode is made to be a communication mode of only voice data.

System and method for providing multiple loss and service priorities

Abstract: A system and method for implementing quality of service features in a packet switch calculates quality of service parameters, and inserts these parameters into the packet header before the packet reaches the switch fabric itself. When a packet is received, errorcode processing takes place and the no longer needed error code is discarded. Packet header information is used to determine, via lookup table or other means, the service class and loss priority to be assigned to the packet. These parameters are inserted in the errorcode field of the packet header before the packet is provided to the switch fabric itself.

Non-blocking dynamic fast packet switch for satellite communication system

Abstract: The present invention overcomes the limitations encountered by conventional packet switching using virtual circuits. The present invention utilizes a "datagram" approach that routes every packet (22) conveyed by the system independently at every node in the network. The packets (22) are directed along an optimized pathway through the network by a fast packet switch (38) that directs traffic based on instructions from an adaptive routing processor (12A) that continuously runs an adaptive routing software (12B). This adaptive routing processor (14) supplies an output (12C) to a routing cache memory (20) which stores fast packet switch routing port output tags (30). An input packet processor (28) extracts a supercell address from the header (24) of each packet (22) and uses the supercell address (21A) as an index to retrieve a fast packet switch output port tag (30) stored in the routing cache memory (20). This tag (30) is prepended to the packet (22), and sent to an input port (36) of the fast packet switch (38), which includes a number of multi-stage self-routing switch modules (132) and a number of asynchronous packet multiplexors (134). The modules (132) and multiplexors (134) route the tagged packet (34) to an output port (40) which is connected either to a scanning beam antenna (SBA) or an intersatellite link antenna (ISA).

Fast packet adaptation method for ensuring packet portability across diversified switching type networks

Abstract: The present invention provides for fast packet information transfer from a first type switching system to a diverse, i.e., different, type switching system by adaptation of a format of each fast packet from the first type switching system to a format that is portable across the second type switching system. For example, the present invention enables transport of fast packets from a fast packet switching system across a cell relay system and vice versa, from a fast packet switching system across an asynchronous transfer mode system and vice versa, and so on.

Queueing analysis for multicast packet switching

Abstract: The development of broadband transmission and ATM switching technologies opens up an opportunity for providing high bit-rate multipoint and multimedia services such as video conferencing. Also, wireless communication has the inherent advantage of multicast transmission and may be used for multipoint information services. The authors consider multicast packet switching for which an input may send the same packet to many outputs within an ATM time slot. A host of multicast queueing disciplines can be exercised. Assuming only independent head of line (HOL) service to an output from slot to slot, they derive the delay performance and saturation throughput. They then examine the accuracy of the assumption for different disciplines via extensive simulation. The FCFS HOL service discipline not only has almost completely identical results for simulation versus analysis, but also provides the best saturation throughput, fairness, and delay performance among all disciplines considered. The analysis shows that implementing packet priorities can significantly improve delay performance. >

Method for controlling computer network security

Abstract: A filter module allows controlling network security by specifying security rules for traffic in the network and accepting or dropping communication packets according to these security rules. A set of security rules are defined in a high level form and are translated into a packet filter code. The packet filter code is loaded into packet filter modules located in strategic points in the network. Each packet transmitted or received at these locations is inspected by performing the instructions in the packet filter code. The result of the packet filter code operation decides whether to accept (pass) or reject (drop) the packet, disallowing the communication attempt.

Method for indicating packet errors in a packet-based multi-hop communications system

Abstract: A method is disclosed for providing packet error indication in a multi-hop communications system in which packets of data are transmitted from a transmission site to a reception site via a plurality of successive physical links. According to the method, at the transmission site, a pre-defined bit in a packet to be transmitted is set to a first value, the first value indicating that no errors are present in the packet. Then, at each successive physical link in the communication system, after transmission of the packet over that physical link, the following steps are performed: (a) detecting whether any uncorrectable errors occurred in the packet during transmission over that physical link; (b) if an uncorrectable error is detected, setting the pre-defined bit in the packet to a second value wherein the second value is indicative of an uncorrectable error in the data of the packet; and (c) relaying the packet to the next successive physical link for transmission over that next link. A decoder at the reception site may, upon receiving a given packet, examine the value of the pre-defined bit to determined the integrity of the data contained in that packet.

Channel sharing and memory sharing in a packet switching system

Abstract: The present invention concerns a method and apparatus for memory and channel sharing in a communication switching network which uses packet switching. In one form of the invention memory and channel sharing is provided within a packet switch. The packet switch includes a memory for storing a plurality data packets and a router that routes data packets from the memory to a particular output port. The router is operable to route data packets to either a dedicated output port, in other words, an output port defined by the virtual circuit path of the data packet, or a shared output port. In another form of the invention memory and channel sharing is provided by a packet switch in conjunction with a terminal. Protection lines which are provided in transmission systems can be used as the shared channels.

Terabit per second packet switch having distributed out-of-band control of circuit and packet switching communications

Abstract: A telecommunications switch which has a central switch fabric made up of multiple crossbars that can be used to switch either circuit switched or packet switch communications as long as appropriate input and output interfaces and controllers are provided. Thus, a large, high throughput telecommunications switch is provided where the expensive switch fabric core can remain the same and the interfaces and control cards changed as the relative demands for circuit switched communications and packet switched communications, such as ATM, evolve. Besides being flexible, this switch may also be fault tolerant.

Adaptive control for packet video

Abstract: Describes a portable and robust software mechanism for adaptive frame rate control for real time packet video transfer and viewing in workstation environments. No special hardware or system support is assumed. It includes (1) a responsive feedback system for dynamic presentation layer rate control in response to network load, (2) a simple and effective transport layer flow control scheme built upon an unreliable network protocol, and (3) data structures and scheduling support for integrating the rate and flow control mechanisms. The authors demonstrate that excellent jitter control is achieved by gracefully trading image resolution, and loss rates can be drastically reduced by appropriate flow control. >

Method for overload control in a packet switch that processes packet streams having different priority levels

Abstract: A system and method that controls potential overload of packet switches when the packet switch has multiple packet streams with different priority levels. A counter is associated with the higher priority packet stream, so that when the counter reaches a predetermined number, the higher priority packet stream is disabled, so that the lower priority packet stream may be processed. When the counter reaches the predetermined number, interrupts are disabled, thus inhibiting processing of the higher priority packet stream. Advantageously, a predetermined number of polled packets are processed before interrupts are enabled.

Network layer packet structure

Abstract: A packet switching communication system is improved by using a packet header structure which does not require a fixed format. The packet header comprises a chain of 2 byte command/data segments. Each command/data segment contains generic bits and a routing field. One of the generic bits (bit 1) allows the header to be extended with another command/data segment.

Scheduling nonuniform traffic in a packet switching system with small propagation delay

Abstract: A new model of nonuniform traffic is introduced for a single-hop packet switching system. This traffic model allows arbitrary traffic streams subject only to a constraint on the number of data packets which can arrive at any individual source in the system or for any individual destination in the system over time periods of specified length. The nonuniform traffic model is flexible enough to cover integrated data networks carrying diverse classes of data. The system model is rather general and includes passive optical star wavelength division networks. Transmission algorithms are introduced for a single-hop packet switching system with such nonuniform traffic and with propagation delay that is negligible relative to the packet length. The algorithms are based on collision-free scheduling of packets using graph matching algorithms, since the global state of the system is known to all stations at any time. >

Method and apparatus for buffering data within stations of a communication network with mapping of packet numbers to buffer's physical addresses

Abstract: Method and apparatus for buffering data packets in a data communication controller environment. In general, the communication controller is interfaceable with a host processor and includes a control unit for accessing a communication medium. Each data packet to be transmitted or received is assigned a unique packet number. Packet number assignment is carried out by a memory management unit which dynamically allocates to each assigned packet number, one or more pages in data packet buffer memory for the storage of the corresponding data packet. If requested storage space is unavailable at the time of request, the memory management unit will allocate a page or pages to an available packet number as the pages become free. Upon issuing the assigned packet number, the physical addresses of the allocated pages of buffer memory storage space are generated in a manner transparent to both the host processor and the control unit. With these physical addresses, a data packet can be accessed from buffer memory, in a simple manner. Upon completion of each data packet loading operation, the corresponding packet number is stored in a packet number queue maintained for subsequent retrieval in order to generate the physical addresses at which the corresponding data packet has been stored.

Radio packet transfer method

Abstract: PROBLEM TO BE SOLVED: To suppress a control channel capacity from being oppressed by allowing each mobile station to monitor a packet channel and allowing a base station to send immediately an incoming packet through the packet channel so as to reduce the transfer delay time of a received packet. SOLUTION: When an incoming packet 32-1 reaches a base station from an incoming call control station, a call signal 41 is sent immediately through a packet channel. Since each mobile station always monitors the packet channel, a destination mobile station of the incoming packet 32-1 returns a reply signal 42 with respect to a call signal 41 through a packet channel. Upon the receipt of the reply signal 42, an incoming packet 32-2 is sent. Thus, an incoming packet transfer delay 35 is reduced more in a conventional method. The mobile station adopts an intermittent standby mode by a control channel without monitoring continuously the station. The base station stores the standby mode of each mobile station and begins with the call of a destination mobile station through the control channel. The same method as the conventional method is used altogether.

Control of consecutive packet loss in a packet buffer

Abstract: A circuit and method provides for optimal packet dropping to directly control consecutive packet loss (also called "average packet gap") in a packet buffer. The circuit and method can be used in a packet switched system having either a single packet class or multiple packet classes. The invention can be used at any point of the packet switched system, e.g., source buffers, switching node buffers, and destination buffers. A detailed proof shows that depending on configuration, the packet dropping policy is optimal for either minimizing or maximizing the average packet gap. More generally, the circuit and method can be used for controlling the source gaps created in any service system with a finite buffer. When a subset of customers from an ordered sequence of customers must be denied service due to to system overflow.

Terabit per second packet switch

Abstract: A physically realizable one terabit or more ATM packet switch that has a large number of input interfaces connected to a single stage switching fabric which is in turn connected to a number of output modules, generally according to the growable packet switch architecture. This ATM packet switch is different from other growable packet switches in that it has a single stage switch fabric controlled by an out-of-band controller, yet it has significantly reduced complexity with respect to comparably sized electronic crossbar switches or their isomorphs.

A recursive concentrator structure with applications to self-routing switching networks

Abstract: A technique for constructing an N-input concentrator from two (N/2)-input concentrators and a stage of 2/spl times/2 switching elements is described. Recursive decomposition of each of the (N/2)-input concentrators yields a log/sub 2/N-stage switching network similar in topology to the inverse omega network. The control algorithm for setting the switching elements is shown to be a simple logic function of the activity bits of the inputs. An iterative cell that combines the functions of the control logic and the 2/spl times/2 switching element can be used as a building block to realize the entire concentrator. Applications of the concentrator structure as an interconnection fabric in fast packet switching is explored. This leads to an efficient self-routing network, similar in topology to the transposed Batcher-banyan network. >

Flow control apparatus and method for a computer interconnect using adaptive credits and flow control tags

Abstract: A flow control mechanism for packet-switched computer interconnect relates a packet in the interconnect to another packet in the interconnect by one or more various means. A packet is deemed stalled if it is stuck inside a switch packet buffer waiting to be forwarded due to unavailability of appropriate output ports. When an incoming packet begins to arrive, the switch checks to see if its internal packet buffers already contain a related packet that is currently stalled. If so, the switch immediately rejects the incoming packet. The incoming packet is only accepted if there are no related packets stalled inside the receiver. A switch may simultaneously contain several related packets that are in the process of being forwarded, but it may never contain more than one stalled packet. Adaptive routing is also limited by the assignment of adaptivity credits to each packet.

Packet signal selecting apparatus and mobile switching center including the same

Abstract: A mobile switching center of this invention includes a public network interface, a communication signal processing unit for performing code translation, a packet switching unit for performing switching of a packet signal between the communication signal processing unit and a radio base station in accordance with the destination of the packet signal, and a packet signal selecting apparatus. The packet signal selecting apparatus includes one input terminal, a plurality of signal storage sections for respectively storing a plurality of packet signals input through the input terminal, a switching means for distributing a plurality of continuously input packet signals to the plurality of signal storage sections and causing them to respectively store the signals, and a discrimination unit for comparing some or all of the packet signals stored in all the signal storage sections with each other to select one packet signal, and outputting the selected packet signal.