Cisco Technology, Inc.

Integrated Device Technology, Inc.

Gurmohan Singh Samrao

Gene K Chui

Gary Kipnis

Frank Chui

Onchuen D Lau

David Anthony Hughes

Madhav V Marathe

Eugene T Wang

Christopher Bergen

Neil King

Lionel A King

Dan Klausmeier

Daryn Lau

An apparatus and method reduce jitter in SPE data transmitted to a switch fabric. A processor receives STS channel requests from the switch fabric, and retrieves SPE data in buffers assigned to the requested STS channels. The processor loads the SPE data in the PDU of a TDM cell, the TDM cell in the PDU of a PIC, and a length of the SPE data in the header of the PIC. The PIC is then embedded in a CSIX frame that is transmitted to the switch fabric through a CSIX interface. The length of the SPE data in the PIC PDU is variable since the processor retrieves SPE data upon demand from the switch fabric. Thus, even if enough data to fill an entire PDU is not in a channel buffer at the time of a channel request, the available data is transmitted so that the opportunity to transmit available SPE data is not lost.

Method and apparatus for transmitting streamed ingressing data through a switch fabric that provides read requests at an ingress independent request rate

An apparatus and method determine byte gain and loss adjustments that compensate for frequency differences between ingress and egress data rate signals in a SONET/SDH NE. The count of ingress data rate signal pulses at the time that data is requested by a switch fabric is compared to the count of egress data rate signal pulses at the time the requested data is passed through the switch fabric. If a delta phase equal to the difference in counts less a reference phase, is continuously greater than a positive value threshold for at least a time threshold period, then a byte gain adjustment is determined. On the other hand, if the delta phase is continuously less than a negative value threshold for at least the time threshold period, then a byte loss adjustment is determined.

Apparatus and method for determining byte gain and loss adjustments in a SONET/SDH network element

A synchronization state for a local clock generating circuit of a first of a number of components of a distributed system is maintained according to a number of local clock cycles recorded between successive occurrences of a global synchronization signal provided to the components within the distributed system. The local clock generating circuit may enters the synchronization state only after observing a predetermined number of occurrences of successive local clock cycles between instances of the global synchronization signal. The local clock generating circuit continues to provide local control signals for the first of the components at time instants corresponding to the number of local clock cycles even after an instance of the global synchronization signal is observed at a time instant corresponding to one local clock cycle more or less than the number of local clock cycles. However, the local clock generating circuit enters an alarm state when the global synchronization signal is observed at time instants corresponding to more than one local clock cycle more or less than the number of local clock cycles.

Scheme for maintaining synchronization in an inherently asynchronous system

An apparatus is described comprising an ingress port and a plurality of switch planes where each of the switch planes has a dedicated scheduler and each of the switch planes are communicatively coupled to the ingress port. The switch planes may further have at least one input control port and at least one output control port where each of the input control ports are coupled to each of the output control ports in a crossbar arrangement. The communicative coupling may further comprise one of the input control ports coupled to the ingress port. Furthermore, the ingress port may have at least one unicast queue which is dedicated to a specific egress port. The ingress port may also have a multicast queue. The dedicated scheduler may further comprise a pointer to determine priority between multicast and unicast traffic, a pointer to determine priority between contending input control ports having multicast traffic and/or a pointer for each of the output control ports to determine priority between contending input control ports having unicast traffic. The apparatus may also further comprise a plurality of ingress ports where each of the ingress ports are communicatively coupled to one of each of the input control ports.

Crosspoint switch with independent schedulers

A method of managing a network switch. The method having the first step of detecting a status of a set of physical ports on an interface card in the network switch. Then, determining if the status is in a first state that indicates that all physical ports in the interface card are inaccessible. If the status is in the first state, then accepting all traffic for the set of physical ports. Also disclosed is an apparatus for performing the method.

Method and apparatus of handling data that is sent to non-existent destinations

An apparatus and method for reducing congestion in a network switching node. A congestion mask that indicates which of a plurality of destination ports in a network switching node are congested is generated and combined with a destination port field included in a packet in a multicast queue of the switching node to mask destination port designations in the destination port field that are indicated by the congestion mask to be congested if a drop eligibility field within the packet indicates that destination port designations are permitted to be masked. The packet is dequeued from the multicast queue to be forwarded to destination ports in the network switching node indicated by destination port designations in the destination port field not masked by the combination of the congestion mask with the destination port field.

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San Jose, CA, United States of America

Gurmohan Singh Samrao