Redline and NetScaler unburden networks

The load-balancing market grows more complex every year. Appliances that used to simply distribute incoming client requests to a virtual cluster of Web servers for improved fault tolerance and better scalability now provide several types of Web-site acceleration, security, and more.

Among these more advanced load balancers are Redline Networks’s E|X 3250 and the NetScaler 9400 Secure Application Switch. Both are 1U, rack-mount appliances, with two 10/100 ports each (as opposed to their switch-based counterparts). Both are members of families that range from basic two-port models to four-port Gigabit Ethernet devices with extended functionality.

The E|X 3250 and NetScaler 9400 both provide substantial functionality well beyond basic load balancing, including SSL acceleration, TCP offloading, HTTP compression, caching, content redirection, and more.

The benefits your Web site will reap from the acceleration technologies will vary, depending on the types of applications you use, the kinds of data your Web site delivers, and the types of clients connecting to your site.

For instance, in my tests, requests for pre-compressed JPG files showed far less improvement than text requests. Many clients making lots of small requests benefited greatly from the TCP-consolidation functions.

Overall, in most applications, both appliances reduced network bandwidth by more than half and response times by as much as 2,000 percent.

NetScaler 9400 Secure Application Switch

The NetScaler 9400 is really several appliances in one. It includes sophisticated load balancing, Web-site acceleration technologies such as HTTP compression and TCP-session consolidation, SSL acceleration, intrusion detection and prevention, Web caching, and SSL VPN capabilities.

As a load balancer, the 9400 offers a number of features not found in the more basic load balancers, such as the Coyote Point Equalizer E350. These features include extra load balancing algorithms and persistence methods, as well as policies for special responses depending on client type or location. It can also load-balance outgoing connections across multiple firewalls or routers.

More than just a sophisticated load balancer, the 9400 increases the performance of Web sites by consolidating the dozens, or even hundreds, of TCP connections used between a client and server to one, reducing TCP/IP traffic and load on the server. Further, it buffers TCP connection information from slower clients, reducing TCP overhead. Using the compression capability built into HTTP 1.1-compliant browsers, it reduces traffic over the Internet connection and speeds up response times. It offloads SSL processing and can handle 4,400 new SSL sessions per second, according to the company.

The 9400 also provides protection from DoS attacks and can even protect against buffer overflow and other application-layer attacks by checking for valid HTML content. It offers content redirection and priority queuing based on client ID and provides “surge protection” by buffering incoming requests to prevent servers from reaching 100 percent utilization.

The SSL VPN capability allows users to access applications via an SSL browser connection, rather than having to initiate an IPSec connection.