Enterasys' Server Load Balancing Solution

Solution Paper Introduction

In today's competitive business environment, companies strive to increase market share, deliver better service, and provide high returns for their shareholders. The IT infrastructure is playing an increasingly important role in accomplishing these goals. Be it internal requirements such as the timely provision of mission-critical applications such as SAP or Oracle Financial, or outward facing requirements such as web hosting and e-commerce, the very importance of the IT infrastructure mandates lightning fast, high-availability, scalable solutions.

In the past year, important advancements have been made towards this end. Gigabit Ethernet accelerated network performance and Layer 3 switching removed the router bottleneck. On the server side, performance has improved dramatically and maintenance and support costs have dropped, as servers are increasingly located in server farms or arrays.

However, application availability can still be threatened by content failure, software failure or server failure. Accounting information that can be used for benchmarking and resource planning is rarely collected, and when gathered, comes at a dramatic cost to performance. Resources are often out of balance, with low-performance resources receiving more requests than high-performance resources. These are just a few of the problems furrowing the collective brows of IT professionals across the corporate landscape.

Solving these problems requires an integrated approach including high-performance servers, multilayer switches, and server load balancers. Cabletron is uniquely positioned to provide this integrated solution.

Issue

When client-server network operating systems (NOS) first emerged, servers were generally placed close to their clients, due to a lack of centralized management and a lack of capacity in the network infrastructure. This arrangement simplified installation and maintenance. But as the applications delivered via these NOS became more advanced, the computers running them also increased in capacity and complexity. Moreover, applications that ran over these NOS such as e-mail, intranet web sites, and Internet gateways became ubiquitous. As a result, maintaining and supporting these larger, more critical computing platforms became more important, and proved far too complex when servers were widely distributed within the enterprise. It soon became a standard practice to consolidate such resources into server farms.

However, consolidating servers is only part of the solution to the rise of networked applications. Servers are now used to host extranets and e-commerce, and to increase the productivity of mobile workers. They are expected to increase application performance, and provide 24x7 availability to all content. In this new environment, application availability, security and prioritization, as well as application-level accounting have risen to the forefront. It is through a combination of a server farm, a Layer 3/4 switch, and a specialized load balancer that those issues can be resolved.

The Cabletron Server Array Solution

The Cabletron Solution brings together the industry's highest performance and most richly featured switches and server load balancers. This solution positions Cabletron's SmartSwitch Router family and the BIG/ip server load balancer between the server array and the network.

The SmartSwitch Router and BIG/ip integrate wire-speed Layer 3 and 4 switching and routing with high-availability server load balancing to optimize server arrays. The SmartSwitch Router and the BIG/ip reside logically between the enterprise network or Internet and the server array, separating the two domains via VLANs and routed subnets (see diagram below).

The SmartSwitch Router minimizes network congestion by routing or switching up to 30 million packets per second, orders of magnitude beyond the performance of conventional high-end routers. The SmartSwitch Router's non-blocking switching fabric delivers full-function unicast and multicast IP/IPX routing at gigabit switching speeds. The SmartSwitch Router's ASICs can switch or route traffic based on Layer 2, Layer 3 and Layer 4 information at wire speed. These ASICs also store QoS policies and security filters, providing wire-speed performance even when QoS policies and security filters are enabled. As a result, network managers no longer need to make compromises when it comes to performance and functionality; the SmartSwitch Router delivers both. The SmartSwitch Router's SmartTRUNK capability improves server performance by guaranteeing that servers will not be constrained by their network connection. This feature allows multiple, active Fast Ethernet links between the SmartSwitch Router and each server. Additionally, the SmartSwitch Router integrates the industry's most richly featured Layer 3 and Layer 4 switch with the BIG/ip through its management interface, providing an ease of use not found in any other company's solution.

The BIG/ip server load balancer is a unique high-availability, intelligent load-balancing device for a company's front-end server farms, be they external web hosts or internal application servers. Situated between the SmartSwitch Router and server array, the BIG/ip continuously monitors each local server to ensure that they are available and performing correctly, and then automatically routes incoming service requests to the most available server. Before initiating a user connection, the BIG/ip system uses Extended Server, Application and Content Verification to ensure that the server is available and that the requested application is running and returning valid responses. The BIG/ip can even complete an entire sample transaction before establishing a user connection. The BIG/ip is designed for unparalleled power, flexibility and simplicity of administration. Not only will you save time, but you'll enjoy peace of mind knowing your users can access content and applications critical to your business--100% of the time.

Differentiated Services

Cabletron's Server solution allows Service Providers to differentiate their services and market varying levels of data throughput and Quality of Service. Under periods of peak load, high priority user traffic can be guaranteed to be switched first and have priority access to the content servers. Lower priority traffic can be allocated a portion of the bandwidth, thereby assuring they will not be starved. The SmartSwitch Router and BIG/ip both provide Layer 3 and Layer 4 Quality of Service (QoS) and rate limiting which means the data can be further segregated by combinations of source/destination address and application type. Service Providers can now price multiple services based on the performance desired by customers. And this can be done today with a single investment and product set!

Typical Deployment of Server Array Solution

The Cabletron Server Solution Provides the Business Benefits of Server Consolidation

Using Cabletron's Server Solution allows companies to enjoy faster application response time, reduce server workload, ease maintenance requirements, and guarantee 100% content availability. The 10/100/1000 Mbps Layer 2, 3 and 4 switching inherent in Cabletron's solution eliminates network bottlenecks by removing the delays associated with software-based routers. This means faster application response time, higher availability, and increased revenue to the bottom line in the form of increased e-commerce sales and reduction of wasted man-hours spent waiting for resources to become available.

High Availability/Server Load Balancing

Adding a high-availability/load-balancing solution can add scalability, availability and security over and above basic routing and caching functionality. These techniques reduce workload, increase server performance and are the key to maximizing the usefulness of server arrays.

Cabletron's Server Array Solution uses advanced load-balancing methods to intelligently distribute network traffic to the server best capable of handling the traffic. User-configurable options allow administrators to easily scale processing power in non-homogenous server mixes using methods best suited to their environment. Load balancing can not only improve performance, but also protect the investment made on servers. The BIG/ip ensures that all servers in an array are fully utilized, and provides monitoring of each server's load, thereby delaying the need to increase the number of servers required. This reduces expensive upgrades to the server array.

Load Balancing Benefits

• Reduced workload on servers

  
  

• Faster response to users' requests

  
  

• Server array scalability

  
  

• Redundancy through automatic failover

  
  

• Load-balancing method customizable to users environment through seven configurable algorithms

The BIG/ip offers seven load-balancing techniques that allow the IT administrator to choose the load balancing method best suited to the server environment. These methods include standard round robin, weighted ratio, priority, fastest connection, least connections and two methods using historical and/or predictive data to choose the server. The BIG/ip will provide the user with the fastest response.

High availability ensures that customers will be able to access the information or service they want 24 hours a day, seven days a week. High availability means verifying not only that a server is available, but also that the application is running and returning correct information. This enhanced availability and content verification, combined with full-featured load balancing, provides unparalleled Quality of Service to administrators and users.

High Availability Benefits

• 24x7 content availability of extranets and e-commerce sites maximizes revenue opportunities
• Extended software and content verification guarantee that users don't receive "Application Unavailable" errors or incorrect responses from applications
• Server verification allows managers to maintain or upgrade servers without affecting user requests
• Allocates requests across servers, recognizing overloaded servers and sending user requests to less burdened servers
• Secure administration protocol protects servers from unauthorized access
• Agent-free technology does not require additional software on servers

Before establishing a user connection, BIG/ip pings the server to ensure that it is responding, and checks whether the requested application is operating and whether it is providing correct content. Should any of these tests fail, the BIG/ip will remove the server or application from the active search table and rerun the load-balancing algorithm and choose a new server. If a server or application is removed from the active search table, the BIG/ip will continue to check the status in the background. When the device begins responding again, BIG/ip returns it to the active search table. This allows IT managers to maintain and upgrade servers or applications without affecting users and without performing time-consuming, manual configuration.

Reduce Cost of Ownership and Complexity by Deploying Appropriate and Secure Access to Applications

Cabletron's solution can implement extensive traffic filtering and multilayer access control lists (ACL) as well as integrated firewall for secure access serving internal and external users.

• Protects against unauthorized access, reducing the costs associated with external network attacks or internal misuse of server and network resources
• Allows IT managers to identify devices, protocols, or even applications that should be limited or controlled
• Layer 4 ACLs allow access control on an application residing on a sever, not just the sever itself

Server Application Customization via Layer 4 (Application) Control Capabilities

Cabletron's Server Array Solution provides a Layer 4 capability from end to end, allowing users to set up applications on a subset of the server array. This increases the utility of server arrays as they can be customized to meet business needs without technological restraints. This means that applications do not need to be loaded on all servers. Cabletron's solution can also use Layer 4 information to prioritize mission-critical traffic.

• Reduces the cost of software licenses purchased to only those required to provide adequate performance

  
  

• Priority queuing guarantees network responsiveness during peak loads

Each application has a known Layer 4 port number associated with it. By configuring these port numbers into the BIG/ip, it will recognize which applications reside on which servers and will only load balance between those servers when that application is requested. The SmartSwitch Router recognizes Layer 3 DA/SA and Layer 4 port numbers and can place specified users and/or applications in one of four priority queues. Users and applications in the highest queue will always be switched at wire speed regardless of the network load.

Eliminates Link Technology Limits

The Cabletron Server Array Solution delivers the SmartSwitch Router, a true multilayer, wire-speed Gigabit Ethernet switching device. As such it eliminates the worry about users experiencing network bottlenecks, allowing the network's routed core to scale in performance as the periphery areas and server link technologies increase in capacity.

• Eliminates network associated bottlenecks resulting in higher server performance
• Reduces solution cost by providing LAN and WAN technologies in a single chassis
• Increases revenue generation by prioritizing e-commerce traffic
• Lowers WAN charges through traffic shaping and compression algorithms

Deliver Valuable Network Usage Data Through Accounting

With server farms creating a central traffic flow on the enterprise, the need for extensive accounting and monitoring becomes much greater.

• Allows for intelligent capacity planning
• Reduce costs through better informed network growth management
• Increased revenues through accurate billing models

Conclusion

With more and more users requiring unfettered access to the applications and content residing on the servers, these servers will continue become increasingly critical to a company's bottom line. Technological advances have altered the way in which companies plan their network infrastructure, moving the hot spots from the wiring closet to the backbone router and now, finally, to the server itself. Increasing server availability and application performance is comparable in network terms to increasing network bandwidth and guaranteeing reliability through redundancy. Based on these requirements, Cabletron's Server Array Solution represents the most advanced, high-performance server solution set for the common issues associated with server consolidation and collapsed backbone networking--providing tremendous increases in data delivery, availability, security and traffic prioritization while maintaining control and management services typically lost with such performance increases. Bottom line, Cabletron's solution increases return on investment by decreasing the costs and increasing the performance associated with consolidating server arrays.

Questions and Answers

When Does Cabletron's Server Array Solution Make Sense?

Cabletron's solution solves three basic issues associated with networked server arrays: availability, scalability and maintainability. If you answer yes to any of the following questions, then the Cabletron Sever Array Solution is right for you.

Availability

• Are your servers and/or applications considered mission-critical?
• Is it important that these servers and/or applications are always available to users?
• Are you unable to guarantee their availability now?

• Is growth and scalability of your servers and applications an issue?
• Are you in need of a method to prevent system overload problems now and prioritize traffic when it occurs?
• Do you need additional server or other network capacity?

• Do you desire to manage the maintenance and upgrade of servers and operating systems?
• Do you want to manage and plan for the growing needs of your site?
• Can the Cabletron Server Array Solution be used to load balance transparent devices like firewalls or caches?
• Yes, Cabletron's solution can simultaneously load balance transparent devices and servers, and guarantees availability of firewalls and caches. End users are directed to a single virtual address, easing administration and maintenance of devices too.
• What is the maximum number of concurrent connections that Cabletron's solution is capable of load balancing?
• The maximum number of concurrent connections capable of being load balanced is determined by the amount of memory (RAM) that the BIG/ip unit contains. When configured with the maximum amount of RAM, BIG/ip will maintain session state for 1,000,000 SSL-based connections (the connection type which requires the most state information). Up to 8,000 of these connections can be achieved per second on a BIG/ip system.
• Does Cabletron's solution provide local failover and load balancing for multiple servers in a LAN?

Problems

Network congestion accessing servers

Description: Traffic cannot access servers due to latency in router interface.

Solution Feature: Using SmartSwitch Router, traffic is switched at wire-speed Gigabit Ethernet rates.

Benefit: Users don't experience delays due to network congestion from the server access device.

Servers requests inefficiently directed

Description: Lower performing servers receiving excessive requests while higher performance servers are underutilized.

Solution Feature: Cabletron's BIG/ip uses advanced load-balancing techniques to properly direct traffic to the server able to best handle it.

Benefit: Increased efficiency and reduced workload on servers, thereby protecting the capital investment made in high-performance server arrays.

Greater access control to servers desired

Description: Server performance may be degraded by unauthorized or undesired use by users.

Solution Feature: Access Control Lists (ACL) can be designed to block or limit certain users or applications from running on servers.

Benefit: Greater performance from servers as usage is limited to mission-critical applications and users. Policy accounting (future) will allow IT managers to further design access control schemes that best match the IT administrator's goals.

Server failure

Description: Server becomes unavailable due to a hardware or OS failure.

Solution Feature: Using the BIG/ip system with two or more servers, traffic is automatically routed around any server that fails or becomes unavailable.

Benefit: By proactively monitoring servers, the BIG/ip system keeps failures transparent to users. Once a server responds properly, it is automatically added back to the server farm, easing administration.

Software failure

Description: Individual applications can hang or stop responding, even though other applications are healthy.

Solution Feature: The BIG/ip system's proactive monitoring detects the failure and sends requests to another server that has that service running properly.

Benefit: Proactive monitoring of individual services keeps failures transparent to users. Once the service becomes available again, the BIG/ip system resumes sending requests to it, easing administration.

Content failure

Description: Server and application are working properly but are responding to requests with "404 Object Not Found" or another response with erroneous content.

Solution Feature: The BIG/ip system actively queries individual servers at the application level and, if an application is not returning the right content, it redirects requests to applications that are responding properly.

Benefit: Users never receive "404 Object Not Found" or erroneous content. Also allows sites to extend protection to backend applications such as databases.

Too much traffic

Description: As traffic increases, servers are able to respond to requests promptly until the server reaches a point at which it stops responding to any requests.

Solution Feature: The BIG/ip system enables you to set thresholds for acceptable performance, automatically redirecting requests if a server, service or application is not responding within the acceptable threshold. Maximum number of connections can also be set for each server, eliminating server overload.

Benefit: Users always experience acceptable response times and receive desired QoS. Servers never receive the "last connection" that causes all other existing connections to slow down.

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