Duration limited statistical multiplexing in packet networks
First Claim
1. A method for transmitting delay sensitive packets in a packet switching network comprising a plurality of nodes interconnected by links, said method comprising the steps of:
- assigning each of said packets to a specific loss priority class out of a plurality of loss priority classes before the packet is transmitted between nodes in the network,designating at each node in said network, a packet arriving in a specific arriving frame at said node as eligible for transmission during a specific department frame on an outgoing link which is adjacent to said specific arriving frame in which the packet arrived at said node, andtransmitting during said adjacent frame on said outgoing link packets eligible for transmission in an order determined by loss priority class, and dropping eligible packets which cannot be served before the expiration of said adjacent frame.
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Accused Products
Abstract
A method and associated node structure (11) for the efficient and reliable transmission of delay sensitive traffic in a packet network (10) is disclosed. The method provides bounded end-to-end delay for all delay sensitive traffic and can guarantee loss-free transmission to that part of the delay sensitive traffic which has such a stringent requirement. To achieve statistical multiplexing gain, some loss is permitted for the rest of the delay sensitive traffic, with discrimination among different loss priority classes based on the corresponding degree of loss sensitivity. Bounded end-to-end delay is obtained by performing statistical multiplexing at the switching nodes (11) on a duration limited basis through use of a unique queuing discipline at the network nodes (11). This queuing discipline is instrumental in guaranteeing loss free transmission for the class of traffic with such a requirement.
130 Citations
27 Claims
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1. A method for transmitting delay sensitive packets in a packet switching network comprising a plurality of nodes interconnected by links, said method comprising the steps of:
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assigning each of said packets to a specific loss priority class out of a plurality of loss priority classes before the packet is transmitted between nodes in the network, designating at each node in said network, a packet arriving in a specific arriving frame at said node as eligible for transmission during a specific department frame on an outgoing link which is adjacent to said specific arriving frame in which the packet arrived at said node, and transmitting during said adjacent frame on said outgoing link packets eligible for transmission in an order determined by loss priority class, and dropping eligible packets which cannot be served before the expiration of said adjacent frame. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for transmitting delay sensitive packets belonging to particular connections between a source node and a destination node in a packet switching network comprising an array of nodes interconnected by links, each of said connections belonging to a particular traffic group g. g=1, . . . ,G and each of said packets belonging to a particular loss priority class pg out of a plurality of loss priority classes pg =1, . . . ,Pg associated with each traffic group, each of said traffic groups being allocated a predetermined fraction of the transmission capacity on each link, said method comprising the steps of:
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on each link in said network, defining a sequence of time frames for each traffic group, the time frames on each link for the traffic group g having a duration Tg, admitting a connection k to the network in a traffic group g only if a transmission bandwidth rk is available for the traffic group g on each link in a path between a source node and a destination node for the connection k such that the aggregate length of packets of the connection k in the highest loss priority class Pg does not exceed rk Tg in a frame of duration Tg, and delaying a packet belonging to the traffic group g and arriving at a node of said network on an incoming link during a specific arriving frame of duration Tg and addressed for transmission by an outgoing link at least until the beginning of an adjacent departing frame of duration Tg on the outgoing link, and dropping any packet which cannot be served by an outgoing link in its corresponding adjacent departing frame. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A node for use in a packet network for routing delay sensitive packets, each of said delay sensitive packets belonging to a particular connection in a particular traffic group and belonging to a particular loss priority class, said node comprising
a plurality of incoming and outgoing links, receiving means for receiving said delay sensitive packets via said incoming links, said receiving means receiving each of said packets belonging to a particular connection of a particular traffic group in arriving frames of a particular duration associated with the particular traffic group, storage means associated with each of said outgoing links for storing said packets addressed for transmission on each of said outgoing links, and controller means associated with said storage means for controlling the transmission of said received packets on said outgoing links by designating each of said received packets being received in an arriving frame of a particular duration as eligible for transmission in a first departing frame of said particular duration on the outgoing link to which said each received packet is addressed which starts at or after the end of the frame of said particular duration in which said each received packet arrived at the node and by enabling each outgoing link to serve the packets designated as eligible for service by it during a department frame in an order determined by the loss priority class of the eligible packets, whereby packets which cannot be served by the outgoing link to which they are addressed in the departing frame for which they are designated as eligible are dropped.
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27. A method of transmitting delay sensitive packets in a packet switching network comprising a plurality of nodes interconnected by links, said method being CHARACTERIZED BY the steps of:
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assigning each of said packets to a specific loss priority class out of a plurality of loss priority classes before the packet is transmitted between nodes in the network, designating at each node in said network, a packet arriving in a specific arriving frame at said node as eligible for transmission during a specific departing frame on an outgoing link which is adjacent to said specific arriving frame in which the packet arrived at said node, and transmitting during said adjacent frame packets eligible for transmission in an order determined by loss priority class, and dropping eligible packets which cannot be served before the expiration of said adjacent frame.
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Specification