THIS IS TO CERTIFY THAT ANNEXED HERETO IS A TRUE COPY FROM
`THE RECORDS OF THE UNITED STATES PATENT AND TRADEMARK
`OFFICE OF THOSE PAPERS OF THE BELOW IDENTIFIED PATENT
`APPLICATION THAT NIET THE REQUIRENIENTS TO BE GRANTED A
`FILING DATE UNDER 35 USC 111.
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`By Authority of the
`COMMISSIONER OF PATENTS AND TRADEMARKS
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`5h 501%
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`E. BORNETT
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`Certifying Officer
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`Pl 485983
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`mymg@WHMTH. EgPRESENlfiggLIIAEECOgm:g5
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`UNITED STATES DEPARTMENT OF COMMERCE
`United States Patent and Trademark Office
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`November 03, 2001
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`APPLICATION NUMBER: 09/675, 484
`FILING DATE: September 29, 2000
`PCT APPLICATION NUMBER: PCT/US01/30150
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` 00/60/60IIIHJIIlllllllllllfllllllllllllll0.0a.01szsor\‘
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`UTILITY PATENT APPLICATION TRANSMITTAL
`_.
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`Attorney Docket No.
`ALA-010A
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`TO THE ASSISTANT COMMISSIONER FOR PATENTS:
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`.co Ea
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`Transmitted herewith is a patent application identified as follows:
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`Inventors: Daryl D. Starr, Clive M. Philbriclg, and Laurence B. Boucher.
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`Title:
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`INTELLIGENT NETWORK STORAGE INTERFACE SYSTEM
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`m an
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`Tim is
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`( X ) Original Patent Application.
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`Enclosed are:
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`50
`4
`1
`23
`(X)
`(X)
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`pages Specification
`pages Claims
`page Abstract
`sheets Drawings
`check in the amount of $858.00
`self—addressed, stamped postcard
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`J
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`CLAIMS AS FILED
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`FOR
`Total Claims
`Indeendent Claims
`Mnltile De-endent Claims ifaa .h'cable
`Assi uent Recordin_ Fee
`Basic Finn Fee
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`NO- EXTRA
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`RATE
`$18.00
`$78.00
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`TotalFilin- Fee
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` 20231.
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`Respectfully submitted,
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`I hereby certify that this is being deposited with the US.
`Postal Service “Express Mail Post Office to Addressee”
`service under 37 CFR § 1.10 on the date indicated below
`and is addressed to: Box PATENT APPLICATION,
`Assistant Commissionerfor Patents, Washington, DC %
`Mark Lauer
`. % °
`Reg. No. 36,578
`Mark Lauer
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`7041 K011 Center Parkway
`Suite 280
`Pleasanton, CA 94566
`Tel: (925) 484-9295
`Fax: (925) 484-9291
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`'
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`Date ofDeposit:
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`2 “g E ”2&3
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`Express Mail Label No.: EK532538280US
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`Please Use the Address Identified by Customer Number 24501 for all Correspondence
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`INTELLIGENT NETWORK STORAGE INTERFACE SYSTEM
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`Inventors
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`Daryl D. Starr, Clive M. Philbrick, Laurence B. Boucher.
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`Background
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`Over the past decade, advantages of and advances in network computing have
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`encouraged tremendous growth ofcomputer networks, which has in tum spurred more
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`advances, growth and advantages. With this growth, however, dislocations and
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`bottlenecks have occurred in utilizing conventional network devices. For example, a
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`CPU of a computer connected to a network may spend an increasing proportion of its
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`time processing network communications, leaving less time available for other work. In
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`particular, demands for moving file data between the network and a storage unit of the
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`computer, such as a disk drive, have accelerated. Conventionally such data is divided
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`into packets for transportation over the network, with each packet encapsulated in layers
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`ofcontrol information that are processed one layer at a time by the CPU of the receiving
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`computer. Although the speed of CPUs has constantly increased, this protocol processing
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`of network messages such as file transfers can consume most of the available processing
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`power of the fastest commercially available CPU.
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`This situation may be even more challenging for a network file server whose
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`primary fimction is to store and retrieve files, on its attached disk or tape drives, by
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`transferring file data over the network. As networks and databases have grown, the
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`volume of information stored at such servers has exploded, exposing limitations of such
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`server-attached storage. In addition to the above—mentioned problems ofprotocol
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`processing by the host CPU, limitations of parallel data charmels such as conventional
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`small computer system interface (SCSI) interfaces have become apparent as storage
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`needs have increased. For example, parallel SCSI interfaces restrict the number of
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`storage devices that can be attached to a server and the distance between the storage
`devices and the server.
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`As noted in the book by Tom Clark entitled “Designing Storage Area Networks,”
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`(copyright 1999) incorporated by reference herein, one solution to the limits of server-
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`attached parallel SCSI storage devices involves attaching other file servers to an existing
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`local area network (LAN) in front of the network server. This network-attached storage
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`(NAS) allows access to the NAS file servers from other servers and clients on the
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`network, but may not increase the storage capacity dedicated to the original network
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`server. Conversely, NAS may increase the protocol processing required by the original
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`network server, since that server may need to communicate with the various NAS file
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`servers. In addition, each of the NAS file servers may in turn be subject to the strain of
`protocol processing and the limitations of storage interfaces.
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`Storage area networking (SAN) provides another solution to the growing need for
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`file transfer and storage over networks, by replacing daisy-chained SCSI storage devices
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`with a network of storage devices connected behind a server. Instead of conventional
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`network standards such as Ethernet or Fast Ethernet, SANS deploy an emerging
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`networking standard called Fibre Channel (FC). Due to its relatively recent introduction,
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`however, many commercially available FC devices are incompatible with each other.
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`Also, a PC network may dedicate bandwidth for communication between two points on
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`the network, such as a server and a storage unit, the bandwidth being wasted when the
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`points are not communicating.
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`NAS and SAN as known today can be differentiated according to the form of the
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`data that is transferred and stored. NAS devices generally transfer data files to and from
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`other file servers or clients, whereas device level blocks of data may be transferred over a
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`SAN. For this reason, NAS devices conventionally include a file system for converting
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`. between files and blocks for storage, whereas a SAN may include storage devices that do
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`not have such a file system.
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`Alternatively, NAS file servers can be attached to an Ethemet-based network
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`dedicated to a server, as part of an Ethernet SAN. Marc Farley further states, in the book
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`“Building Storage Networks,” (copyright 2000) incorporated by reference herein, that it
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`is possible to run storage protocols over Ethernet, which may avoid Fibre Channel
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`incompatibility issues. Increasing the number of storage devices connected to a server by
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`employing a network topology such as SAN, however, increases the amount of protocol
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`processing that must be performed by that server. As mentioned above, such protocol
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`processing already strains the most advanced servers.
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`An example of conventional processing of a network message such as a file
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`transfer illustrates some of the processing steps that slow network data storage. A
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`network interface card (NIC) typically provides a physical connection between a host and
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`a network or networks, as well as providing media access control (MAC) functions that
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`allow the host to access the network or networks. When a network message packet sent
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`to the host arrives at the NIC, MAC layer headers for that packet are processed and the
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`packet undergoes cyclical redundancy checking (CRC) in the NIC. The packet is then
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`sent across an input/output (I/O) bus such as a peripheral component interconnect (PCI)
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`bus to the host, and stored in host memory. The CPU then processes each of the header
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`layers of the packet sequentially by running instructions from the protocol stack. This
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`requires a trip across the host memory bus initially for storing the packet and then
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`subsequent trips across the host memory bus for sequentially processing each header
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`layer. Afier all the header layers for that packet have been processed, the payload data
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`fiom the packet is grouped in a file cache with other similarly-processed payload packets
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`of the message. The data is reassembled by the CPU according to the file system as file
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`blocks for storage on a disk or disks. After all the packets have been processed and the
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`message has been reassembled as file blocks in the file cache, the file is sent, in blocks of
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`data that may be each built from a few payload packets, back over the host memory bus
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`and the I/O bus to host storage for long term storage on a disk, typically via a SCSI bus,
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`that is bridged to the I/O bus.
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`Alternatively, for storing the file on a SAN, the reassembled file in the file cache
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`is sent in blocks back over the host memory bus and the I/O bus to an I/O controller
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`configured for the SAN. For the situation in which the SAN is a PC network, a
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`specialized FC controller is provided which can send the file blocks to a storage device
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`on the SAN according to Fibre Channel Protocol (FCP). For the situation in which the
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`file is to be stored on a NAS device, the file may be directed or redirected to the NAS
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`device, which processes the packets much as described above but employs the CPU,
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`protocol stack and file system of the NAS device, and stores blocks of the file on a
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`storage unit of the NAS device.
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`Thus, a file that has been sent to a host from a network for storage on a SAN or
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`NAS connected to the host typically requires two trips across an 1/0 bus for each
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`message packet of the file. In addition, control information in header layers of each
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`packet may cross the host memory bus repeatedly as it is temporarily stored, processed
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`one layer at a time, and then sent back to the I/O bus. Retrieving such a file from storage
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`on a SAN in response to a request from a client also conventionally requires significant
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`processing by the host CPU and file system.
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`Summary
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`An interface device such as an intelligent network interface card (INIC) for a
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`local host is disclosed that provides hardware and processing mechanisms for
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`accelerating data transfers between a network and a storage unit, while control of the data
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`transfers remains with the host. The interface device includes hardware circuitry for
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`processing network packet headers, and can use a dedicated fast—path for data transfer
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`between the network and the storage unit, the fast-path set up by the host. The host CPU
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`and protocol stack avoid protocol processing for data transfer over the fast-path, releasing
`host bus bandwidth from‘many demands ofthe network and storage subsystem. The
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`storage unit, which may include a redundant array of independent disks (RAID) or other
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`configurations of multiple drives, may be connected to the interface device by a parallel
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`channel such as SCSI or by a serial channel such as Ethernet or Fibre Channel, and the
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`interface device may be connected to the local host by an I/O bus such as a PCI bus. An
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`additional storage unit may be attached to the local host by a parallel interface such as
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`SCSI.
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`A file cache is provided on the interface device for storing data that may bypass
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`the host, with organization of data in the interface device file cache controlled by a file
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`system on the host. With this arrangement, data transfers between a remote host and the
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`storage units can be processed over the interface device fast-path without the data passing
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`between the interface device and the local host over the [/0 bus. Also in contrast to
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`conventional communication protocol processing, control information for fast-path data
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`does not travel repeatedly over the host memory bus to be temporarily stored and then
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`processed one layer at a time by the host CPU. The host may thus be liberated fiom
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`involvement with a vast majority of data traffic for file reads or writes on host controlled
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`Additional interface devices maybe connected to the host via the 110 bus, with
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`each additional interface device having a file cache controlled by the host file system, and
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`providing additional network connections and/or being connected to additional storage
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`units. With plural interface devices attached to a single host, the host can control plural
`storage networks, with a vast majority ofthe data flow to and from the host—controlled
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`networks bypassing host protocol processing, travel across the I/O bus, travel across the
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`host bus, and storage in the host memory. In one example, storage units may be
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`connected to such an interface device by a Gigabit Ethemet network, offering the speed
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`and bandwidth of Fibre Channel without the drawbacks, and benefiting from the large
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`installed base and compatibility ofEthernet-based networks.
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`Brief Description of the Drawings
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`FIG. 1 is a plan view diagram of a network storage system including a host
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`computer connected to plural networks by an intelligent network interface card (INIC)
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`having an I/O controller and file cache for a storage unit attached to the INIC.
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`FIG. 2 is a plan View diagram of the functioning of an INIC and host computer in
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`FIG. 1.
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`FIG. 5 is a plan View diagram of a network storage system including a host
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`computer connected to plural networks and plural storage units by plural INICs managed
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`by the host computer.
`FIG. 6 is a plan view diagram ofa network storage system including a host
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`computer connected to plural LANs and plural SANS by an intelligent network interface
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`card (INIC) without an I/O controller.
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`FIG. 7 is a plan view diagram of a one of the SANS of FIG. 6, including Ethernet-
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`SCSI adapters coupled between a network line and a storage unit.
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`FIG. 8 is a plan view diagram of one of the Ethemet-SCSI adapters of FIG. 6.
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` message packet to a network in response to a request from the network by the system of
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`transferring data between plural networks according to the present invention.
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`FIG. 3 is a flowchart depicting a sequence of steps involved in receiving a
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`message packet from a network by the system of FIG. 1.
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`FIG. 4 is a flowchart depicting a sequence of steps involved in transmitting a
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`FIG. 9 is a plan View diagram of a network storage system including a host
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`computer connected to plural LANs and plural SANS by plural INICs managed by the
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`host computer.
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`FIG. 10 is a diagram of hardware logic for the INIC embodiment shown in FIG. 1,
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`including a packet control sequencer and a fly—by sequencer.
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`FIG. 11 is a diagram of the fly—by sequencer of FIG. 10 for analyzing header
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`bytes as they are received by the INIC.
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`FIG. 12 is a diagram of the specialized host protocol stack ofFIG. 1 for creating
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`and controlling a communication control block for the fast-path as well as for processing
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`packets in the slow path.
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`FIG. 13 is a diagram of a Microsoft® TCP/IP stack and Alacritech command
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`driver configured for NetBios communications.
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`FIG. 14 is a diagram of a NetBios communication exchange between a client and
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`server having a network storage unit.
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`FIG. 15 is a diagram of hardware functions included in the INIC ofFIG. 1.
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`FIG. 16 is a diagram of a trio ofpipelined microprocessors included in the INIC
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`of FIG. 15, including three phases with a processor in each phase.
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`FIG. 17A is a diagram of a first phase of the pipelined microprocessor ofFIG. 16.
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`FIG. 17B is a diagram of a second phase of the pipelined microprocessor of FIG.
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`FIG. 17C is a diagram of a third phase of the pipelined microprocessor of FIG. 16.
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`FIG. 18 is a diagram of a plurality of queue storage units that interact with the
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`microprocessor of FIG. 16 and include SRAM and DRAM.
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`FIG. 19 is a diagram of a set of status registers for the queue storage units of FIG.
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`FIG. 20 is a diagram of a queue manager that interacts with the queue storage
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`units and status registers of FIG. 18 and FIG. 19.
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`FIGS. 21A—D are diagrams of various stages of a least-recently—used register that
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`is employed for allocating cache memory.
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`FIG. 22 is a diagram of the devices used to operate the least-recently—used register
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`of FIGS. 21A—D.
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`FIG. 23 is another diagram of the INIC of FIG. 15.
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`FIG. 24 is a more detailed diagram of the receive sequencer 2105 of FIG. 23.
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`Detailed Description
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`An overview of a network data communication system in accordance with the
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`present invention is shown in FIG. 1. A host computer 20 is connected to an interface
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`device such as intelligent network interface card (INIC) 22 that may have one or more
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`ports for connection to networks such as a local or wide area network 25, or the Internet
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`28. The host 20 contains a processor such as central processing unit (CPU) 30 connected
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`to a host memory 33 by a host bus 35, with an operating system, not shown, residing in
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`memory 33, for overseeing various tasks and devices, including a file system 23. Also
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`stored in host memory 33 is a protocol stack 38 of instructions for processing of network
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`communications and a INIC driver 39 that communicates between the INIC 22 and the
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`protocol stack 38. A cache manager 26 runs under the control of the file system 23 and
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`an optional memory manager 27, such as the virtual memory manager of Windows® NT
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`or 2000, to store and retrieve file portions, termed file streams, on a host file cache 24.
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`The host 20 is connected to the INIC 22 by an I/O bus 40, such as a PCI bus,
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`which is coupled to the host bus 35 by a host I/O bridge 42. The INIC includes an
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`interface processor 44 and memory 46 that are interconnected by an INIC bus 48. INIC
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`bus 48 is coupled to the I/O bus 40 with an INIC I/O bridge 50. Also connected to INIC
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`bus 48 is a set of hardware sequencers 52 that provide upper layer processing of network
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`messages. Physical connection to the LAN/WAN 25 and the Internet 28 is provided by
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`conventional physical layer hardware PHY 58. Each of the PHY 58 units is connected to
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`a corresponding unit of media access control (MAC) 60, the MAC units each providing a
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`conventional data link layer connection between the ]NIC and one of the networks.
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`A host storage unit 66, such as a disk drive or collection of disk drives and
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`corresponding controller, may be coupled to the I/O bus 40 by a conventional I/O
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`controller 64, such as a SCSI adapter. A parallel data charmel 62 connects controller 64
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`to host storage unit 66. Alternatively, host storage unit 66 may be a redundant array of
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`independent disks (RAID), and I/O controller 64 may be a RAID controller. An I/O
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`driver 67, tag, a SCSI driver module, operating under command of the file system 23
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`interacts with controller 64 to read or write data on host storage unit 66. Host storage
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`unit 66 preferably contains the operating system code for the host 20, including the file
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`system 23, which may be cached in host memory 33.
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`An INIC storage unit 70, such as a disk drive or collection of disk drives and
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`corresponding controller, is coupled to the INIC bus 48 via a matching interface
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`controller, INIC I/O controller 72, which in turn is connected by a parallel data channel
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`75 to the INIC storage unit. INIC I/O controller 72 may be a SCSI controller, which is
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`connected to INIC storage unit 70 by a parallel data channel 75. Alternatively, INIC
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`storage unit 70 may be a RAID system, and I/O controller 72 may be a RAJD controller,
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`with multiple or branching data channels 75. Similarly, I/O controller 72 may be a SCSI
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`controller that is connected to a RAID controller for the INIC storage unit 70. In another
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`implementation, INIC storage unit 7O is attached to a Fibre Channel (FC) network 75,
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`and I/O controller 72 is a PC controller. Although INIC I/O controller 72 is shown
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`connected to INIC bus 48, 1/0 controller 72 may instead be connected to I/O bus 40.
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`INIC storage unit 70 may optionally contain the boot disk for the host 20, fi'om which the
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`operating system kernel is loaded. INIC memory 46 includes frame buffers 77 for
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`temporary storage of packets received from or transmitted to a network such as
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`LAN/WAN 25. INIC memory 46 also includes an interface file cache, INIC file cache
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`80, for temporary storage of data stored on or retrieved fiom INIC storage unit 70.
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`Although INIC memory 46 is depicted in FIG. 1 as a single block for clarity, memory 46
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`may be formed of separate units disposed in various locations in the INIC 22, and may be
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`composed of dynamic random access memory (DRAM), static random access memory
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`(SRAM), read only memory (ROM) and other forms of memory.
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`The file system 23 is a high level soflware entity that contains general knowledge
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`ofthe organization of information on storage units 66 and 70 and file caches 24 and 80,
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`and provides algorithms that implement the properties and performance of the storage
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`architecture. The file system 23 logically organizes information stored on the storage
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`units 66 and 70, and respective file caches 24 and 80, as a hierarchical structure of files,
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`although such a logical file may be physically located in disparate blocks on different
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`disks of a storage unit 66 or 70. The file system 23 also manages the storage and
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`retrieval of file data on storage units 66 and 70 and file caches 24 and 80. 1/0 driver 67
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`software operating on the host 20 under the file system interacts with controllers 64 and
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`72 for respective storage units 66 and 70 to manipulate blocks of data, i.e., read the
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`blocks from or write the blocks to those storage units. Host file cache 24 and INIC file
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`cache 80 provide storage space for data that is being read from or written to the storage
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`units 66 and 7O, with the data mapped by the file system 23 between the physical block
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`format ofthe storage units 66 and 70 and the logical file format used for applications.
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`Linear streams ofbytes associated with a file and stored in host file cache 24 and INIC
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`file cache 80 are termed file streams. Host file cache 24 and INIC file cache 80 each
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`contain an index that lists the file streams held in that respective cache.
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`The file system 23 includes metadata that may be used to determine addresses of
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`file blocks on the storage units 66 and 70, with pointers to addresses offile blocks that
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`have been recently accessed cached in a metadata cache. When access to a file block is
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`requested, for example by a remote host on LAN/WAN 25, the host file cache 24 and
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`INIC file cache 80 indexes are initially referenced to see whether a file stream
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`corresponding to the block is stored in their respective caches. If the file stream is not
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`found in the file caches 24 or 80, then a request for that block is sent to the appropriate
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`storage unit address denoted by the metadata. One or more conventional caching
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`algorithms are employed by cache manager 26 for the file caches 24 and 80 to choose
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`which data is to be discarded when the caches are full and new data is to be cached.
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`Caching file streams on the INIC file cache 80 greatly reduces the traffic over both I/O
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`bus 40 and data channel 75 for file blocks stored on INIC storage unit 70.
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`When a network packet that is directed to the host 20 arrives at the INIC 22, the
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`headers for that packet are processed by the sequencers 52 to validate the packet and
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`create a summary or descriptor of the packet, with the summary prepended to the packet
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`and stored in frame buffers 77 and a pointer to the packet stored in a queue. The
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`summary is a status word (or words) that describes the protocol types ofthe packet
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`headers and the results of checksurnming. Included in this word is an indication whether
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`or not the frame is a candidate for fast-path data flow. Unlike prior art approaches, upper
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`layer headers containing protocol information, including transport and session layer
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`infonnation, are processed by the hardware logic of the sequencers 52 to create the
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`summary. The dedicated logic circuits of the sequencers allow packet headers to be
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`processed virtually as fast as the packets arrive fiom the network.
`The INIC then chooses whether to send the packet to the host memory 33 for
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`“slow-pat ” processing of the headers by the CPU 30 running protocol stack 38, or to
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`send the packet data directly to either INIC file cache 80 or host file cache 24, according
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`to a “fast-path.” The fast-path may be selected for the vast majority of data traffic having
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`plural packets per message that are sequential and error-free, and avoids the time
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`consuming protocol processing of each packet by the CPU, such as repeated copying of
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`the data and repeated trips across the host memory bus 35. For the fast—path situation in
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`which the packet is moved directly into the INIC file cache 80, additional trips across the
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`host bus 35 and the I/O bus 40 are also avoided. Slow—path processing allows any
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`packets that are not conveniently transferred by the fast—path ofthe INIC 22 to be
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`processed conventionally by the host 20.
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`In order to provide fast-path capability at the host 20, a connection is first set up
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`with the remote host, which may include handshake, authentication and other connection
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`initialization procedures. A communication c'ontrol block (CCB) is created by the
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`protocol stack 38 during connection initialization procedures for connection-based
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`messages, such as typified by TCP/[P or SPX/IPX protocols. The CCB includes
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`connection information, such as source and destination addresses and ports. For TCP
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`connections a CCB comprises source and destination media access control (MAC)
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`addresses, source and destination IP addresses, source and destination TCP ports and
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`TCP variables such as timers and receive and transmit windows for sliding window
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`protocols. After a connection has been set up, the CCB is passed by INIC driver 39 from
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`the host to the INIC memory 46 by writing to a command register in that memory 46,
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`where it may be stored along with other CCBs in CCB cache 74. The INIC also creates a
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`hash table corresponding to the cached CCBs for accelerated matching of the CCBs with
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`packet summaries.
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`When a message, such as a file write, that corresponds to the CCB is received by
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`the INIC, a header portion of an initial packet of the message is sent to the host 20 to be
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`processed by the CPU 30 and protocol stack 38. This header portion sent to the host
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`contains a session layer header for the message, which is known to begin at a certain
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`offset of the packet, and optionally contains some data from the packet. The processing
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`ofthe session layer header by a session layer of protocol stack 38 identifies the data as
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`belonging to the file and indicates the size of the message, which are used by the file
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`system to determine Whether to cache the message data in the host file cache 24 or INIC
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`file cache 80, and to reserve a destination for the data in the selected file cache. If any
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`data was included in the header portion that was sent to the host, it is then stored in the
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`destination. A list of buffer addresses for the destination in the selected file cache is sent
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`to the INIC 22 and stored in or along with the CCB. The CCB also maintains state
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`information regarding the message, such as the length ofthe message and the number and
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`order of packets that have been processed, providing protocol and status information
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`regarding each of the protocol layers, including which user is involved and storage space
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`for per-transfer information.
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`Once the CCB indicates the destination, fast-path processing of packets
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`corresponding to the CCB is available. After the above-mentioned processing of a
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`subsequently received packet by the sequencers 52 to generate the packet summary, a
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`hash of thepacket summary is compared with the hash table, and ifnecessary with the
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`CCBs stored in CCB cache 74, to detennine whether the packet belongs to a message for
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`which a fast-path connection has been set up. Upon matching the packet summary with
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`the CCB, assuming no exception conditions exist, the data of the packet, without network
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`or transport layer headers, is sent by direct memory access (DMA) unit 68 to the
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`destination in file cache 80 or file cache 24 denoted by the CCB.
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`At some point afier all the data from the message has been cached as a file stream
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`in INIC file cache 80 or host file cache 24, the file stream of data is then sent, by DMA
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`unit 68 under control of the file system 23, from that file cache to the INIC storage unit
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`70 or host storage unit 66, under control of the file system. Commonly, file streams
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`cached in host file cache 24 are stored on INIC storage unit 66, while file streams cached
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`in INIC file cache 80 are stored on INIC storage unit 70, but this arrangement is not
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`necessary. Subsequent requests for file transfers may be handled by the same CCB,
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`assuming the requests involve identical source and destination IP addresses and ports,
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`with an initial packet of a write request being processed by the host CPU to determine a
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`location in the host file cache 24 or INIC file cache 80 for storing the message. It is also
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`possible for the file system to be configured to earmark a location on INIC storage unit
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`70 or host storage unit 66 as the destination for storing data from a message received
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`from a remote host, bypassing the file caches.
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`An approximation for promoting a basic understanding of the present invention is
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`depicted in FIG. 2, which segregates the main paths for information flow for the network
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`data storage system of FIG. 1 by showing the primary type of information for each path.
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`FIG. 2 shows information flow paths consisting primarily of control information with
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`thin arrows, information flow paths consisting primarily of data with thick white arrows,
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`and information flow paths consisting ofboth control information and data with thick
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`black arrows. Note that host 20 is primarily involved with control information flows,
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`while the ]NIC storage unit 70 is primarily involved with data transfer.
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`Information flow between a network such as LAN/WAN 25 and the INIC 22 may
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`include control information and data, and so is shown with thick black arrow 85.
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`Examples of information flow 81 between network such as LAN/WAN 25 and the INIC
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`22 include control information, such as connection initialization dialogs and
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`acknowledgements, as well as file reads or writes, which are sent as packets containing
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`_ file data encapsulated in control information. The sequencers 52 process control
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`information from file writes and pass data and control information to and from INIC
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`frame buffers 77, and so those transfers are represented with thick black arrow 88.
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`Control information regarding the data stored in flame buffers 77 is operated on by the
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`processor 44, as shown by thin arrow 90, and control information such as network
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`connection initialization packets and session layer headers are sent to the protocol stack
`38, as shown by thin arrow 92. When a connection has beeniset up by the host, control
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`information regarding that connection, such as a CCB, may be passed between host
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`protocol stack 38 and INIC memory 46, as shown by thin arrow 94. Temporary storage
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`of data being read from or written to INIC storage unit 70 is provided by INIC file cache
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`80 and frame buffers 77, as illustrated by thick white arrows 96 and 98. Control and
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`knowledge of all file streams that are stored on INIC file cache 80 is provided by file
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`system 23, as shown by thin arrow 91. In an embodiment for which host storage unit 66
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`does not store network accessible data, file system information is passed between host
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`file cache 24 and host storage unit 66, as shown by arrow 81. Other embodiments, not
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