Questions and Answers Alteon's Virtual Matrix Architecture What is Alteon s Virtual Matrix Architecture (VMA)? Alteon s Virtual Matrix Architecture (VMA) is a revolutionary new approach to scaling the performance and capacity of Alteon Web Switches by taking advantage of unused resources within the Web switch. It combines the best features of a centralized memory architecture with those of a distributed processing environment to enable scalable and highly available Web switching services. Why is it called Virtual Matrix Architecture? The Matrix of processors and memory is now Virtually connected to provide a distributed processing and centralized memory architecture. As a simple software upgrade to new and existing Alteon Web switches, VMA enables all switch resources, such as buffering, session tables, and per port processors, to be dynamically accessed and utilized at any given time by any port. How does VMA work? Currently, the Alteon architecture is based on a distributed processing architecture that employs one WebIC network processing ASIC per port. Each WebIC contains a layer 2 forwarding engine and dual RISC cores. Once upgraded to VMA technology, this paradigm is changed so that the layer 2 functionality is physically split from higher layer processing. At each ingress port, layer 2 traffic is switched in hardware; traffic that requires layers 3 to 7 processing is automatically forwarded to one of 18 available processors based on its source or destination IP address. When received by the designated processor, all processing is performed on that processor and then sent to the egress port for transmission. A simple, but powerful algorithm ensures fair and even distribution of sessions across available processors. The algorithm also ensures that packets with the same IP address will always be sent to the same designated processor. Will VMA make your current switches run faster over your existing software architecture? If so how much faster? Yes. Because VMA enables traffic on any ingress port to leverage all processors at any given time, performance increases. In WebBench 3.0 tests conducted by the Tolly Group, we have seen a 364 percent performance increase in HTTP operations per second using VMA. See Tolly Group report on VMA for detailed test results (see http://www.alteonwebsystems.com/tolly2.pdf). Alteon WebSystems, Inc. 50 Great Oaks Boulevard San Jose, California 95119 408-360-5500 408-360-5501 fax How will you handle IP proxy traffic (where all incoming sessions have the same source IP address even though they were sent from different clients) so as to ensure any one processor does not get overloaded? The absolute worst case scenario in a VMA architecture is equal to a best case scenario in a centralized CPU architecture. If all traffic came from a single source IP address, then all sessions would have to be processed by the same designated processor in the same way as any load balancing device with a centralized CPU architectures. http://www.alteonwebsystems.com
2 How will VMA work with traffic from an IP proxy environment when persistence is required? Persistent connections (i.e., consecutive connections from each unique user must be sent to the same server) from a proxied location (which alters the users IP addresses) will be identified by a unique user cookie (or session identifier for SSL sessions) embedded in the session content. With VMA, persistence is maintained through session table synchronization. One of the ports on the switch will be used exclusively as a synchronization point to track persistence. On the AD3/180e, the persistence port is located at the switch uplink. This port will keep track of all cookie to server bindings, and it will provide the information to designated processors when the designated processors receive an incoming request with a cookie that they do not recognize. After VMA, what will be the maximum number of concurrent sessions that customers can support per Web switch? VMA allows customers to support up to 336K concurrent sessions on our 180e and AD3 platforms, regardless of connectivity and topology. Companies doing business on the Web are experiencing traffic spikes and dramatic increases in the number of users hitting their site at any one given time. Foundry claims support for up to one million concurrent connections, but your high-end box today now supports only one-third of that amount, how do you respond? The question is not how many connections you can support at any one given time but rather how many connections is the Web switch able to effectively process at any given moment. Supporting a large number of connections is merely a function of adding more memory. But if your Web switch cannot process those connections in a timely manner, it doesn t make any different how many concurrent connections can be "supported." It s akin to being in a crowded restaurant. As people sit down, service is great up to a certain capacity (sessions). Beyond that, as more people are seated in the restaurant, service times go down for EVERYBODY who is seated. Single CPU Web switch architectures, such as Foundry s, simply cannot take advantage of their large connection table capacities. Today s most trafficked Web sites such as Ticketmaster, Buy.com, iwon.com, Yahoo all serviced by Alteon Web switches do not require such connection capacities but DO require fast connection processing rates. That is where we have focused our efforts and have clearly excelled. So why haven t you merely added more memory to your switches to solve the session capacity limitations before? Adding memory does increase session capacity on a per port basis but does nothing to maximize processor performance or optimize session flow processing. Though we continue to add memory to our Web switches as customer demand dictates, we have taken a more flexible and intelligent approach to solving this problem.
3 VMA not only solves the issue of increased session capacity but does so in a way that is backward compatible with existing switching while providing better overall performance due to the ability to share processing power and memory across all ports. Does VMA require any new hardware? No. VMA is backward compatible with Alteon s ACEdirector and 180 Web switch families. Does VMA require any existing software? Yes. Web OS 5.2.99 or later is required to install and run VMA. Is VMA really an architecture or merely just new software? It s both. VMA is included in an upcoming version of our award-winning Web OS software that enables a uniquely new type of Web switching architecture - currently unavailable in the industry. This architecture leverages a distributed processor and memory approach to enable large concurrent connection capacities coupled with ultra-fast linear processing scalability. Think of it as having eight checkout lines at the store whether or not there are customers waiting. Everytime a new customer arrives he gets the fastest possible service. What will customers be able to do with VMA that they haven t been able to do before? Customers will now be able to: - Support five times more concurrent connections even when traffic ingresses on a single port - Utilize all the processing power within Alteon s Web Switches at any given time thereby scaling performance - Perform more sophisticated cookie and URL load balancing with the ability to search up to 4.5K bytes into a connection for a match What are the basic benefits of VMA for customers? Improved scalability and performance. Because VMA uses all the port processors in each switch to process the traffic from any or all of the ports simultaneously, customers will experience improved performance and scalability. With VMA, instead of only 2 RISC processors available at each ingress port along with a finite amount of session capacity on any given port, now up to 18 processors are used to handle the traffic with all the memory available to support session table entries for that port. This is an extreme benefit to users that use only one port as an uplink port because now the full power of the switch is working to move the traffic faster. Other benefits include: - Long-term investment protection - Maximized performance for both asymmetric and symmetric topologies - Ability to support more users - Support for more sophisticated content-intelligent switching services (i.e., increased packet buffering for more sophisticated parsing such as the ability to search up to 4.5K into a URL for a match)
4 When will VMA be generally available? VMA is being beta tested now and will become available following the beta testing as part of Web OS 8.0. Why are you announcing VMA now if it won t be generally available until the May timeframe? Our customers are making long-term decisions about their infrastructures today. As a result, they need to understand those technologies, features and capabilities that will play a critical role in the evolution of their networks. VMA is one such technology. On which platforms will VMA be available? VMA will be available on all existing platforms including the ACEdirector line and Alteon 180 family of Web switches. Will VMA be available on the 700? VMA is not currently planned for Alteon s 700-series switches, since their architecture provides for a greater amount of per-port memory already. Nevertheless, the VMA model can be applied to 700-series devices should the need arise. Is VMA a free Web OS upgrade to customers? Yes. Any customer qualified to receive free updates for Web OS will receive VMA in the next new release. How will VMA affect memory usage and overall session capacity? On the ACEdirector 2 and 180, customers will now have 8 MB of memory and 16 processors available for any given port. Concurrent session capacity available on any one given port will be increased by a factor of five. For the ACEdirector 3 and Alteon 180e platforms, VMA now enables any switch port to access up to 18 MB of memory and utilize up to 18 network processors. Won t VMA add latency due to the fact that an additional decision must be made as to which port to send the traffic to for processing? When a packet is initially received, it is forwarded to a designated processor based on a hash of the source/destination IP address. This process is extremely fast. In addition, the packet is switched from one processor to another over a 8Gbps backplane. Thus VMA adds negligible latency - approximately 50 microseconds for a 64-byte packet. Will VMA affect performance in any way? If so, how? Yes. Because of the parallel processing that will take place for any layer 3-7 features, it is expected that performance for all Web switching applications will increase - allowing for advanced features to be used extensively without the penalty typically associated with activating advanced features on network hardware.
5 If filtering is performed on a per port basis, how will this work with VMA? Filters are mirrored across all ports. In other words, each port keeps track of the ingress port from which the frame was received, and applies the filters based on that port. There is no change to the number of filters available on a per port basis. That number is currently 224. Will VMA affect URL load balancing? Yes. Because processors are shared, URL load balancing performance will increase. Using a single port, the URL processing speed should approach 100,000 sessions a second an order of magnitude more than the nearest competitor.