Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2002-03-18
2003-09-23
Harrell, Robert B. (Department: 2142)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
Reexamination Certificate
active
06625689
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to computer networks and, more particularly, to a general purpose programmable platform for acceleration of network infrastructure applications.
BACKGROUND OF THE INVENTION
Computer networks have become a key part of the corporate infrastructure. Organizations have become increasingly dependent on intranets and the Internet and are demanding much greater levels of performance from their network infrastructure. The network infrastructure is being viewed: (1) as a competitive advantage; (2) as mission critical; (3) as a cost center. The infrastructure itself is transitioning from 10 Mb/s (megabits per second) capability to 100 Mb/s capability. Soon, infrastructure capable of 1 Gb/s (gigabits per second) will start appearing on server connections, trunks and backbones. As more and more computing equipment gets deployed, the number of nodes within an organization has also grown. There has been a doubling of users, and a ten-fold increase in the amount of traffic every year.
Network infrastructure applications monitor, manage and manipulate network traffic in the fabric of computer networks. The high demand for network bandwidth and connectivity has led to tremendous complexity and performance requirements for this class of application. Traditional methods of dealing with these problems are no longer adequate.
Several sophisticated software applications that provide solutions to the problems encountered by the network manager have emerged. The main areas for such applications are Security, Quality of Service (QoS)/Class of Service (CoS) and Network Management. Examples are: Firewalls; Intrusion Detection; Encryption; Virtual Private Networks (VPN); enabling services for ISPs (load balancing and such); Accounting; Web billing; Bandwidth Optimization; Service Level Management; Commerce; Application Level Management; Active Network Management
There are three conventional ways in which these applications are deployed:
(1) On general purpose computers.
(2) Using single function boxes.
(3) On switches and routers.
It is instructive to examine the issues related to each of these deployment techniques.
1. General Purpose Computers
General Purpose computers, such as PCs running NT/Windows or workstations running Solaris/HP-UX, etc. are a common method for deploying network infrastructure applications. The typical configuration consists of two or more network interfaces each providing a connection to a network segment. The application runs on the main processor (Pentium/SPARC etc.) and communicates with the Network Interface Controller (NIC) card either through (typically) the socket interface or (in some cases) a specialized driver “shim” in the operating system (OS). The “shim” approach allows access to “raw” packets, which is necessary for many of the packet oriented applications. Applications that are end-point oriented, such as proxies can interface to the top of the IP (Internet Protocol) or other protocol stack.
The advantages of running the application on a general purpose computer include: a full development environment; all the OS services (IPC, file system, memory management, threads, I/O etc); low cost due to ubiquity of the platform; stability of the APIs; and assurance that performance will increase with each new generation of the general purpose computer technology.
There are, however, many disadvantages of running the application on a general purpose computer. First, the I/O subsystem on a general purpose computer is optimized to provide a standard connection to a variety of peripherals at reasonable cost and, hence, reasonable performance. 32b/33 MHz PCI (“Peripheral Connection Interface”, the dominant I/O connection on common general purpose platforms today) has an effective bandwidth in the 50-75 MB/s range. While this is adequate for a few interfaces to high performance networks, it does not scale. Also, there is significant latency involved in accesses to the card. Therefore, any kind of non-pipelined activity results in a significant performance impact.
Another disadvantage is that general purpose computers do not typically have good interrupt response time and context switch characteristics (as opposed to real-time operating systems used in many embedded applications). While this is not a problem for most computing environments, it is far from ideal for a network infrastructure application. Network infrastructure applications have to deal with network traffic operating at increasingly higher speeds and less time between packets. Small interrupt response times and small context switch times are very necessary.
Another disadvantage is that general purpose platforms do not have any specialized hardware that assist with network infrastructure applications. With rare exception, none of the instruction sets for general purpose computers are optimized for network infrastructure applications.
Another disadvantage is that, on a general purpose computer, typical network applications are built on top of the TCP/IP stack. This severely limits the packet processing capability of the application.
Another disadvantage is that packets need to be pulled into the processor cache for processing. Cache fills and write backs become a severe bottleneck for high bandwidth networks.
Finally, general purpose platforms use general purpose operating systems (OS's). These operating systems are generally not known for having quick reboots on power-cycle or other wiring-closet appliance oriented characteristics important for network infrastructure applications.
2. Fixed-function Appliances
There are a couple of different ways to build single function appliances. The first way is to take a single board computer, add in a couple of NIC cards, and run an executive program on the main processor. This approach avoids some of the problems that a general purpose OS brings, but the performance is still limited to that of the base platform architecture (as described above).
A way to enhance the performance is to build special purpose hardware that performs functions required by the specific application very well. Therefore, from a performance standpoint, this can be a very good approach.
There are, however, a couple of key issues with special function appliances. For example, they are not expandable by their very nature. If the network manager needs a new application, he/she will need to procure a new appliance. Contrast this with loading a new application on a desktop PC. In the case of a PC, a new appliance is not needed with every new application.
Finally, if the solution is not completely custom, it is unlikely that the solution is scalable. Using a PC or other single board computer as the packet processor for each location at which that application is installed is not cost-effective.
3. Switches and Routers
Another approach is to deploy a scaled down version of an application on switches and routers which comprise the fabric of the network. The advantages of this approach are that: (1) no additional equipment is required for the deployment of the application; and (2) all of the segments in a network are visible at the switches.
There are a number of problems with this approach.
One disadvantage is that the processing power available at a switch or router is limited. Typically, this processing power is dedicated to the primary business of the switch/router-switching or routing. When significant applications have to be run on these switches or routers, their performance drops.
Another disadvantage is that not all nodes in a network need to be managed in the same way. Putting significant processing power on all the ports of a switch or router is not cost-effective.
Another disadvantage is that, even if processing power became so cheap as to be deployed freely at every port of a switch or router, a switch or router is optimized to move frames/packets from port to port. It is not optimized to process packets, for applications.
Another disadvantage is that a typical switch or router does not provide the facilities that are necessary for the creation
Fall Kevin
Hall Jerry J.
MacAvoy Neil
Narad Charles E.
Rand Leonard M.
Greenberg Robert A.
Harrell Robert B.
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