Abstract: Methods and systems consistent with the present invention provide a programmable table which allows software to define a plurality of branching functions, each of which maps a vector of condition codes to a branch offset. This technique allows for a flexible multi-way branching functionality, using a conditional branch outcome table that can be specified by a programmer. Any instruction can specify the evaluation of arbitrary conditional expressions to compute the values for the condition codes, and can choose a particular branching function. When the processor executes the instruction, the processor's arithmetic/logical functional units evaluate the conditional expressions and then the processor performs the branch operation, according to the specified branching function.

Abstract: In one embodiment, a method can include receiving at an egress schedule module a request to schedule transmission of a group of cells from an ingress queue through a switch fabric of a multi-stage switch. The ingress queue can be associated with an ingress stage of the multi-stage switch. The egress schedule module can be associated with an egress stage of the multi-stage switch. The method can also include determining, in response to the request, that an egress port at the egress stage of the multi-stage switch is available to transmit the group of cells from the multi-stage switch.

Abstract: A network device receives a packet with a multicast nexthop identifier, and creates a mask that includes addresses of egress packet forwarding engines, of the network device, to which to provide the packet. The network device divides the mask into two portions, generates two copies of the packet, provides a first portion of the mask in a first copy of the packet, and provides a second portion of the mask in a second copy of the packet. The network device also forwards the first copy of the packet to an address of a first egress packet forwarding engine provided in the first portion of the mask, and forwards the second copy of the packet to an address of a second egress packet forwarding engine provided in the second portion of the mask.

Abstract: In one embodiment, a method includes sending a first flow control signal to a first stage of transmit queues when a receive queue is in a congestion state. The method also includes sending a second flow control signal to a second stage of transmit queues different from the first stage of transmit queues when the receive queue is in the congestion state.

Abstract: A method may include receiving a packet at an ingress line interface in a forwarding plane of a network element, the packet including header information. The method may also include conducting a flow table lookup in the forwarding plane to identify an existing flow for the packet and determining, in the forwarding plane and based on the header information, whether a predicted flow can be identified for the packet if an existing flow can not be identified. The method may further include performing a service access control list (ACL) lookup in the forwarding plane if a predicted flow can not be identified; and forwarding the packet to one of a services plane or an egress line interface in the forwarding plane based on one of the existing flow, the predicted flow, or the service ACL lookup.

Abstract: In one embodiment, a processor-readable medium can store code representing instructions that when executed by a processor cause the processor to receive a value representing a congestion level of a receive queue and a value representing a state of a transmit queue. At least a portion of the transmit queue can be defined by a plurality of packets addressed to the receive queue. A rate value for the transmit queue can be defined based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue. The processor-readable medium can store code representing instructions that when executed by the processor cause the processor to define a suspension time value for the transmit queue based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue.

Abstract: In one embodiment, edge devices can be configured to be coupled to a multi-stage switch fabric and peripheral processing devices. The edge devices and the multi-stage switch fabric can collectively define a single logical entity. A first edge device from the edge devices can be configured to be coupled to a first peripheral processing device from the peripheral processing devices. The second edge device from the edge devices can be configured to be coupled to a second peripheral processing device from the peripheral processing devices. The first edge device can be configured such that virtual resources including a first virtual resource can be defined at the first peripheral processing device. A network management module coupled to the edge devices and configured to provision the virtual resources such that the first virtual resource can be migrated from the first peripheral processing device to the second peripheral processing device.

Abstract: In one embodiment, a method, comprising receiving at a receive side of a physical link a request to suspend transmission of data from a queue within a transmit side of a first stage of queues and to suspend transmission via a path including the physical link, a portion of the first stage of queues, and a portion of a second stage of queues. The method includes sending, in response to the request, a flow control signal to a flow control module configured to schedule transmission of the data from the queue within the transmit side of the first stage of queues. The flow control signal is associated with a first control loop including the path and differing from a second control loop that excludes the first stage of queues.

Abstract: In one embodiment, a method includes sending a first flow control signal to a first stage of transmit queues when a receive queue is in a congestion state. The method also includes sending a second flow control signal to a second stage of transmit queues different from the first stage of transmit queues when the receive queue is in the congestion state.

Abstract: In one embodiment, a processor-readable medium can store code representing instructions that when executed by a processor cause the processor to receive a value representing a congestion level of a receive queue and a value representing a state of a transmit queue. At least a portion of the transmit queue can be defined by a plurality of packets addressed to the receive queue. A rate value for the transmit queue can be defined based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue. The processor-readable medium can store code representing instructions that when executed by the processor cause the processor to define a suspension time value for the transmit queue based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue.

Abstract: In one embodiment, a method, comprising receiving at a receive side of a physical link a request to suspend transmission of data from a queue within a transmit side of a first stage of queues and to suspend transmission via a path including the physical link, a portion of the first stage of queues, and a portion of a second stage of queues. The method includes sending, in response to the request, a flow control signal to a flow control module configured to schedule transmission of the data from the queue within the transmit side of the first stage of queues. The flow control signal is associated with a first control loop including the path and differing from a second control loop that excludes the first stage of queues.

Abstract: Methods and systems consistent with the present invention provide a programmable table which allows software to define a plurality of branching functions, each of which maps a vector of condition codes to a branch offset. This technique allows for a flexible multi-way branching functionality, using a conditional branch outcome table that can be specified by a programmer. Any instruction can specify the evaluation of arbitrary conditional expressions to compute the values for the condition codes, and can choose a particular branching function. When the processor executes the instruction, the processor's arithmetic/logical functional units evaluate the conditional expressions and then the processor performs the branch operation, according to the specified branching function.

Abstract: A front-to-back cooling system allows cooling of an apparatus containing two orthogonal sets of modules. Each set of modules is independently cooled. A vertical set of modules is cooled with vertical air flow across the modules that enters from a front of the apparatus and exhausts from a back of the apparatus. A horizontal set of modules is cooled with horizontal front-to-back air flow. When the horizontal set of modules is at the front of the apparatus, a plenum extending exterior to the vertical set of modules allows exhausting horizontally flowing air to the rear of the apparatus. When the horizontal set of modules is at the rear of the apparatus, a plenum extending exterior to the vertical set of modules allows moving air from the front of the apparatus to a chamber holding the horizontal modules.

Abstract: In some embodiments, a system includes a first switch fabric device, a second switch fabric device, a first access switch operatively coupled to the first switch fabric device by a first cable, and a second access switch operatively coupled to the second switch fabric device by a second cable. The second access switch is operatively coupled to the first access switch by a third cable. The first access switch is configured to send data to the first switch fabric device via the first cable. The first access switch is configured to send data to the second switch fabric device via the third cable, the second access switch, and the second cable.

Abstract: A front-to-back cooling system allows cooling of an apparatus containing two orthogonal sets of modules. Each set of modules is independently cooled. A vertical set of modules is cooled with vertical air flow across the modules that enters from a front of the apparatus and exhausts from a back of the apparatus. A horizontal set of modules is cooled with horizontal front-to-back air flow. When the horizontal set of modules is at the front of the apparatus, a plenum extending exterior to the vertical set of modules allows exhausting horizontally flowing air to the rear of the apparatus. When the horizontal set of modules is at the rear of the apparatus, a plenum extending exterior to the vertical set of modules allows moving air from the front of the apparatus to a chamber holding the horizontal modules.

Abstract: Methods and systems consistent with the present invention provide a programmable table which allows software to define a plurality of branching functions, each of which maps a vector of condition codes to a branch offset. This technique allows for a flexible multi-way branching functionality, using a conditional branch outcome table that can be specified by a programmer. Any instruction can specify the evaluation of arbitrary conditional expressions to compute the values for the condition codes, and can choose a particular branching function. When the processor executes the instruction, the processor's arithmetic/logical functional units evaluate the conditional expressions and then the processor performs the branch operation, according to the specified branching function.

Abstract: A method for emulating a nexthop instruction in microcode with the assistance of dedicated hardware to extract read and write addressing from the nexthop instruction instead of performing this operation in microcode. A method for emulating a nexthop instruction in microcode with the assistance of dedicated hardware to compare a nexthop read address to a special value and to indicate whether the nexthop read address matches the special value, instead of performing this operation in microcode. A method for determining a network address by performing a single extraction of bit fields of a tree instruction to allow multiple tree search processes to be performed.

Abstract: In general, techniques are described for packet queuing within ring networks. In accordance with the techniques, a network device of a ring network comprises a memory having a different queue for each order-dependent pair of the network devices. Each pair represents a different order-dependent combination of the network devices that includes an ingress network device that provides an ingress to the ring network and an egress network device that provides an egress from the ring network. The network device further comprises an interface for receiving a packet from a neighboring one of the plurality of network devices and a control unit that, in response to receiving the packet, stores the packet to one of the queues based on which network devices is the ingress and which network device is the egress for the packet. The control unit forwards the stored packet via the ring network according to a scheduling algorithm.

Abstract: In one embodiment, an apparatus can include a policy vector module configured to retrieve a compressed policy vector based on a portion of a data packet received at a multi-stage switch. The apparatus can also include a decompression module configured to receive the compressed policy vector and configured to define a decompressed policy vector based on the compressed policy vector. The decompressed policy vector can define a combination of bit values associated with a policy.

Abstract: A network device receives a packet with a multicast nexthop identifier, and creates a mask that includes addresses of egress packet forwarding engines, of the network device, to which to provide the packet. The network device divides the mask into two portions, generates two copies of the packet, provides a first portion of the mask in a first copy of the packet, and provides a second portion of the mask in a second copy of the packet. The network device also forwards the first copy of the packet to an address of a first egress packet forwarding engine provided in the first portion of the mask, and forwards the second copy of the packet to an address of a second egress packet forwarding engine provided in the second portion of the mask.