Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
2000-02-08
2002-06-04
Chin, Wellington (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C709S230000
Reexamination Certificate
active
06400730
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to transferring information between storage devices and a network via a switched, packetized communications system. In particular, the present invention relates to methods and apparatus for receiving, translating, and routing data packets between SCSI (Small Computer Systems Interface), Fibre Channel and Ethernet devices in a flexible, programmable manner.
In enterprise computing environments, it is desirable and beneficial to have multiple servers able to directly access multiple storage devices to support high bandwidth data transfers, system expansion, modularity, configuration flexibility and optimization of resources. In conventional computing environments, such access is typically provided via file system level Local Area Network (LAN) connections, which operate at a fraction of the speed of direct storage connections. As such, access to storage systems is highly susceptible to bottlenecks.
Storage Area Networks (SANs) have been proposed as one method of solving this storage access bottleneck problem. By applying the networking paradigm to storage devices, SANs enable increased connectivity and bandwidth, sharing of resources, and configuration flexibility. The current SAN paradigm assumes that the entire network is constructed using Fibre Channel switches. Therefore, most solutions involving SANs require implementation of separate networks: one to support the normal LAN and another to support the SAN. The installation of new equipment and technology, such as new equipment at the storage device level (Fibre Channel interfaces), the host/server level (Fibre Channel adapter cards) and the transport level (Fibre Channel hubs, switches and routers), into a mission-critical enterprise computing environment could be described as less than desirable for data center managers, as it involves replication of network infrastructure, new technologies (i.e., Fibre Channel), and new training for personnel. Most companies have already invested significant amounts of money constructing and maintaining their network (e.g., based on Ethernet and/or ATM). Construction of a second high-speed network based on a different technology is a significant impediment to the proliferation of SANs. Therefore, a need exists for a method and apparatus that can alleviate problems with access to storage devices by multiple hosts, while retaining current equipment and network infrastructures, and minimizing the need for new training for data center personnel.
In general, a majority of storage devices currently use “parallel” SCSI or Fibre Channel data transfer protocols whereas most LANs use an Ethernet protocol, such as Gigabit Ethernet. SCSI, Fibre Channel and Ethernet are protocols for data transfer, each of which uses a different individual format for data transfer. For example, SCSI commands were designed to be implemented over a parallel bus architecture and therefore are not packetized. Fibre Channel, like Ethernet, uses a serial interface with data transferred in packets. However, the physical interface and frame formats between Fibre Channel and Ethernet are not compatible. Gigabit Ethernet was designed to be compatible with existing Ethernet infrastructures and is therefore based on an Ethernet packet architecture. Because of these differences there is a need for new methods and apparatus to allow efficient communication between these protocols.
SUMMARY OF THE INVENTION
The present invention solves the above and other problems, thereby advancing the state of the useful arts, by providing methods and apparatus for transferring data between storage device interfaces and network interfaces. In particular, the present invention brings sophisticated SAN capabilities to existing enterprise computing configurations, without the installation of costly Fibre Channel switches and hubs, by providing the means for Internet Protocol (IP) devices to transparently communicate with SCSI and Fibre Channel devices over an IP network. The present invention accomplishes this through the use of Fibre Channel Protocol (FCP), an industry standard developed for implementation of SCSI commands over a Fibre Channel network. The invention allows the storage devices to retain the use of standard SCSI and Fibre Channel storage interfaces and construct a SAN using a company's existing network infrastructure. Therefore, no changes are required in host bus adapters (HBA) or storage devices (e.g. disk drives, tape drives, etc).
According to the present invention, methods and apparatus are provided for transferring data between IP devices (including, but not limited to, Gigabit Ethernet devices) and SCSI or Fibre Channel devices. The device interfaces may be either SCSI, Fibre Channel or IP interfaces such as Gigabit Ethernet. Data is switched between SCSI and IP, Fibre Channel and IP, or between SCSI and Fibre Channel. Data can also be switched from SCSI to SCSI, Fibre Channel to Fibre Channel and IP to IP. The port interfaces provide the conversion from the input frame format to an internal frame format, which can be routed within the apparatus. The apparatus may include any number of total ports. The amount of processing performed by each port interface is dependent on the interface type. The processing capabilities of the present invention permit rapid transfer of information packets between multiple interfaces at latency levels meeting the stringent requirements for storage protocols. The configuration control can be applied to each port on a switch and, in turn, each switch on the network, via an SNMP or Web-based interface, providing a flexible, programmable control for the apparatus.
According to one aspect of the present invention, a method is provided for routing data packets in a switch device in a network such as a SAN. The method typically comprises the steps of receiving a packet from a first network device at a first port interface of the switch device, wherein the packet is one of a SCSI formatted packet (i.e., SCSI formatted data stream converted into a packet), a Fibre Channel (FC) formatted packet and an Internet protocol (IP) formatted packet, wherein the first port interface is communicably coupled to the first network device, and converting the received packet into a packet having an internal format. The method also typically includes the steps of routing the internal format packet to a second port interface of the switch device, reconverting the internal format packet to one of a SCSI formatted packet, an FC formatted packet or an IP formatted packet, and transmitting the reconverted packet to a second network device communicably coupled to the second port interface.
According to another aspect of the present invention, a network switch device is provided which typically comprises a first port interface including a means for receiving data packets from a network device, wherein the receiving means receives one of a SCSI formatted packet and a Fibre Channel (FC) formatted packet from a first network device, and a means for converting received packets into packets having an internal format, wherein the received data packet is converted into a first packet having the internal format. The switch device also typically comprises a second port interface including a means for reconverting packets from the internal format to an IP format, wherein the first packet is converted into a packet having an IP format, and a means for transmitting IP packets to a network, wherein the IP formatted packet is transmitted to an IP network. A means for routing the first packet to the second port interface is also provided.
According to yet another aspect of the present invention, a network switch device is provided which typically comprises a first port interface including a means for receiving data packets from an IP network, wherein the first interface means receives a packet in an IP format, and a means for converting received packets into packets having an internal format, wherein the received packet is converted into a first packet having an internal format. The
Latif Aamer
Mullendore Rodney N.
Uchino Brian Y.
White Joseph L.
Chin Wellington
Gray Gerald T.
Nishan Systems, Inc.
Townsend and Townsend / and Crew LLP
Tran Maikhanh
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