Abstract: Additional routing information is added to a transaction packet without recalculating an ECRC by inserting the additional routing information at predetermined bit positions in the transaction packet known to have predetermined bit values. The modified transaction packet can then be routed using the additional routing information. The predetermined bit values can subsequently be reinstated at the predetermined bit positions in the packet.

Abstract: A register access request for control and/or status operations from a link is detected using a hardware mechanism and is forwarded to a software-controlled entity for access to a virtual register for control and/or status operations. The software-controlled entity can provide virtual registers in memory associated with the software-controlled entity. The hardware mechanism can form part of an interconnect device and the software-controlled entity is external to the interconnect device.

Abstract: One embodiment of the invention provides a method of operating a switch in a communications network. The method includes storing a set of routings for each port in the switch. When a packet is received at a port in the switch, the set of routings corresponding to the port at which the packet was received is accessed. A port from which to forward the packet from the switch is determined in accordance with the set of routings. The packet is then duly forwarded over the network from the port as determined by the routings.

Abstract: A configuration space operation packet is received from a link. The configuration space operation packet is detected using a hardware mechanism. The configuration space operation packet is forwarded to a software-controlled entity for processing. A received packet can be detected as a configuration space operation packet from an address range of an address in a header of the received packet. The software-controlled entity can provide configuration space virtualisation.

Abstract: A method is provided for supporting device sharing between hosts via a bus fabric. A master host owns a device tree and provides IO services to at least one client host. The client host comprises generic device drivers and subscribes to IO services provided by the master host.

Abstract: An interconnect apparatus, for example a switch, supports PCI-Express. The apparatus has a first plurality of ports configurable as upstream ports, each connectable to a respective host, and at least one port configurable as a downstream port connectable to a device. The apparatus is operable to support sharing of the device resources between hosts.

Abstract: In an interconnect apparatus for interconnecting at least one host to at least a plurality of presentation registers provide a presentation interface for the device to the host. The interconnect apparatus includes memory for holding the presentation registers and a governor operable to manage the presentation registers in the memory.

Abstract: An infrastructure element can receive a first DMA request including a first address and the data, generate a meta request that comprises a resource key value and a doorbell address, and transmit the meta request via the infrastructure using the doorbell address. A remote DMA adapter can receive the meta request at the doorbell address and generate a remote direct memory access request message using the resource key, the first address and the data from the received meta request.

Abstract: PCI Express transactions can be transmitted via a shared PCI Express infrastructure. At an infrastructure ingress point an additional header comprising at least a source identifier and a target identifier is generated for a transaction packet that comprises a header portion, a data portion and an end-to-end CRC portion. The transaction packet is then transmitted with the additional header from the ingress point to an egress point. At the egress point the additional header is removed. The additional header can further include a resource key. It can further include protection information such as a CRC.

Abstract: In an apparatus and method for providing device sharing, a first plurality of upstream ports are each connectable to a respective host and at least one downstream port is connectable to a device. A virtual port is defined that is associated a routing table to effect device virtualization by redirection of information packets received by the virtual port.

Abstract: One embodiment of the invention provides a method of handling an incoming packet at a node in a network. The method includes associating at least one source identifier with a link into the node. A packet is then received at the node over the link, and a source identifier is extracted from the received packet. The extracted source identifier is compared with the source identifier(s) associated with the link in order to authenticate the packet.

Abstract: One embodiment of the invention provides apparatus and a method for handling an incoming packet at a port in a network. The port belongs to one or more partitions, and at least one service level is associated with each of the partitions. When a packet is received at the port, a partition key and a service level are extracted from the packet. The extracted partition key is used to determine the partition to which the received packet belongs. The service level extracted from the packet is then compared against the service level(s) associated with the determined partition in order to authenticate the packet. In another embodiment, the service level is correlated against a destination identifier from the packet instead of the partition key.

Abstract: At an ingress point to a shared transaction infrastructure, for example a shared PCI Express infrastructure, an entry in a segment table maps an address in a transaction packet to a target for the transaction packet. The entry in the segment table identifies one of a plurality of channel descriptors providing one or more of forwarding information for the transaction packet and information for constructing an additional header for the transaction packet.

Abstract: A novel N×N Crossbar Packet Switch is disclosed, which crossbar switch is based on a distributed port architecture, asynchronous output port arbitration, support of non fixed-size packets (cells), support for virtual channels (VC) and/or priority, and which only requires 2*N*N control lines for the arbitration.