Response to load-balancing RFP: ArrowPoint

ArrowPoint Content Smart(tm) Web Switches optimize Web performance, relieving busy or overloaded sites, providing users a fast, reliable and error-free Web experience.

Web traffic patterns are significantly different from the traffic patterns of client/server computing. Web traffic is both highly content driven and event driven. Network congestion occurs rapidly and randomly across the Internet depending on events of public interest that occur every minute. Hot content induced network traffic, or "flash crowds", are one of the major reasons why Web site congestion occurs. In addition, the following fundamental technical challenges exist:

1. Today's IP networks are address based. They assume that the destination IP address is where the "actual server" is located and where the actual service is to be performed. This delivery methodology can not adequately support fast Web response times when target servers become congested.

2. On average, Web flows are short-lived. Thus, connection overhead, as related to TCP and HTTP, has a significant impact on Web response time. This results in HTTP server and, in some cases, back-end database server performance degradation due to over-capacity.

3. Internet Web page access is unevenly distributed, with 10% of available Web pages accessed 90% of the time. Even worse, "hot content" changes over time. As such, hot content cannot be administratively identified. This leads to the conclusion that Web traffic management must be keenly aware of changing hot content over time.

ArrowPoint's vision to address the above problems is to enable a Web-centric networking paradigm via its Content Smart Web Switching technologies. Content Smart Web Switching transforms the passive Internet of today into the Content Smart Internet of the future while maintaining interoperability with the present and future Internet infrastructure.

With its Content Smart Web Switching technology, ArrowPoint's Web switches operate independent of the Web browser and do not require any server-resident software agent. This approach significantly reduces site operation costs while providing the highest level of content intelligence and Web site performance.

Conventional LAN switches establish a TCP session and forward packets to a fixed destination IP address prior to receiving the actual URL requested from the browser, so are unable to select the best site and server for a specific content request. ArrowPoint Web Switches support delayed binding, where the session connection is intelligently established only after the switch receives and examines a Web page (URL) request. In this way ArrowPoint can direct each content request to the optimal server at that moment based on the requested URL, server loading, and content availability. The ability to dynamically connect a TCP request to the right server across the Internet based on the requested content allows all available server and network resources to collaborate on providing a consistently positive Web experience for each end user.

Server Load-balancing

Only ArrowPoint's Content Smart Switches apply policies and direct Web traffic in real time based on the information in layer 2, layer 3, layer 4, and layer 5. Layer 5 is the highest layer within TCP/IP which represents the content being requested (the URL and HTTP header), and even the users "cookie". This allows the switch to provide an overall improvement in Web response time by directing HTTP requests to the optimum site and server, and applying policies based on the content being requested at that point in time.

For the Acme web site, the ArrowPoint switch can route all HTTP requests for product and corporate information, and all FTP requests among the 5 corporate servers, and all commerce traffic among the 3 commerce servers. The switch can do this at very high speeds by using "delayed binding" - evaluating the URL for each request, then switching all of the traffic for the duration of the flow in the high speed forwarding plane of the switch.

ArrowPoint's Web switches were designed for name-based switching and are the only switches to use the entire URL and cookie to select the best site and server. This is illustrated in the following example:

• Example #1 shows the same page being requested by two different users

• Example #2 shows two different types of content (ASP vs. real audio) on two different servers being requested by two different users

Each of the sample requests shown below has the same network address information, but each request is for a different URL. The significance of the URL may be in the uniqueness of a specific file name, or the general properties of a file type based on the file extension. Only ArrowPoint's Web Switches apply policies and intelligently direct Web traffic in real time based on the information in layers 2, 3, and 4, the content being requested (the URL in the HTTP header), and even the cookie. This allows the switch to provide an overall improvement in Web response time by directing HTTP requests to the optimum site and server, and applying policies based on the content being requested at that point in time.

Load Balancing Algorithms

Once the switch determines the candidate servers for the content being requested, ArrowPoint's server load balancing takes into account actual (dynamic) server response time for each server, and selects the server with the fastest response time for the content being requested. In addition, because ArrowPoint maintains state for actual HTTP flows, it tracks such things as long versus short flows, content request frequency, content access history, and cache coherency considerations.

The e-commerce servers may also use a Least Connections algorithm with Max Connection limits if the database has known limitations on the amount of transactions it can support. ArrowPoint also offers an API that would allow the Web servers to control their own distribution weighting in the load balancing algorithms in the switch.

In any authenticated Web application, it is necessary to provide a persistent or "sticky" connection between a browser (the user) and the Web or database server to which it is connected. Examples of these applications include shopping baskets, financial transactions, and some forms of interactive gaming. Because HTTP does not carry any state information for these applications, it is important for the browser to be mapped to the same server for each HTTP request until a user's transaction is complete. This ensures that the user is not load-balanced in mid-session to a different server and forced to log in again. Web switches support sticky connections not only based on IP address/TCP port, and SSL session ID, but also the user's cookie, ensuring sticky client-server connections for each individual's e-commerce transaction. Further, this is the only way to ensure sticky connections when thousands of users are coming into a site from a mega proxy (e.g. AOL users) - all accessing the same application and all coming from the same source IP address!

Web site security and NAT

Acme can ensure availability of their Web site because the ArrowPoint switch eliminates any and all Denial of Service attacks, and provides high speed packet filtering and URL blocking. These capabilities ensure the site is always available for customers and employees. The ArrowPoint switch also supports full bi-directional NAT capabilities, keeping server addresses from being exposed to the outside world, and because it is done in hardware at each port, it operates at wire speed.

Dynamic FTP Support

The ArrowPoint switch supports bi-directional load balancing enabling it to optimize server-initiated flows of complex Web information such as streaming media. This capability also enables Dynamic (passive) FTP in addition to FTP, ensuring that the server initiated data channel will be mapped correctly back to the client no matter what TCP port is used, with full NAT support so the server addresses are not exposed to the outside world.

Ensuring Availability of Servers, Content, and Applications

ArrowPoint can test server availability using all of the same techniques, plus ArrowPoint can test HTTP GETs, POSTs, and HEADs, comparing the complete response and detecting the most minute change in content. In fact, using its Intelligent Content Probe capability, the ArrowPoint switch can probe the servers for a specific content request and automatically select and configure the optimum keep alive method for the application. Finally, in the event of a failed HTTP keep alive, the ArrowPoint switch will direct only requests for that particular content or application to another server, continuing to utilize the server for surviving content, application, or services. For example, if a back end cgi process is not responding there is no need to remove the server from rotation for serving HTTP requests.

Content Replication and Staging

The ArrowPoint solution includes an optional software component that runs entirely on the ArrowPoint Web switch and can manage the staging and distribution of content among multiple servers. It is completely independent of Server OS and works equally well with UNIX or NT servers. It can be configured to replicate specific files or directories, or a page and all of it's associated links from the staging server to the target server based on updated content, demand thresholds, or time of day. The switch can detect that content is changed based on the responses it receives from the server, addressing the concern stated in the last section of the RFP.

Summary

The ArrowPoint Content Smart Web Switches were optimized from the ground up to provide the high system performance and intelligence to enable next generation load balancing, with maximum up-time and content availability. The solution will scale as the site gains in popularity with more available ports for Web servers or multiple uplinks, and the ability to grow into our CS-800 chassis based switch. As Acme depends on the Web for more and more revenue, the Web site can be distributed to multiple locations using ArrowPoint's Distributed Web site services and Smart Content Replication.

With the capability to offer 24x7 support and support engineers in your area, ArrowPoint can design a support program to meet your needs.

Cost

CS-100-LAN-01	
12 Port Content Smart Web Switch $17,995

CS-100-SW-02
Enhanced Feature Set 
software (optional)               $7,995 	
Smart Content Replication and 
Distributed Web site support

Includes 90 days warranty for software, and a one-year warranty for the hardware.

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