Case Study: Content-Aware Server Load Balancing


Having deployed Layer 4 load balancing and ensured that the design and servers are capable of handling the necessary traffic, the IT staff at Foocorp, Inc. would like to create a more personalized and easy to manage environment by having certain servers distribute specific high value content.

Using these powerful content switches will allow Foocorp to activate the Layer 7 load balancing functionality with very little infrastructure changes, merely configuration changes. What Foocorp is hoping to achieve:

  • Provide application persistence based on user rather than IP address

  • Increase the server capacity to handle specific applications and objects for image based files

  • Use the same IP address for some of their online e-commerce businesses

  • Still maintain the Layer 4 functionality previously deployed

When Enabling Layer 7 functionality, the basic requirements and features provided by Layer 4 are still available, such as private address space for security, VRRP for high availability, and so forth.

Deploying Content-Aware Server Load Balancing

If deploying Layer 7 content switching from day one, you should review the checklist from Chapter 5. However if adding it at a later date, remember to cover these important steps:

  1. If using cookie persistence, decide on the best method for your requirements. If you are using Passive or Active Cookie mode, make sure that you discuss with the server administrator what values to associate with the server-generated cookies.

  2. Understand that Layer 7 processing, while fast in some content switches, will be slowly than Layer 4 processing. Determine the throughput required and ensure that the calculation will be acceptable.

  3. If using URL load balancing, make sure that the policies or rules for this configuration will send data to a server if a Layer 7 load balancing string is not matched. There should always be a back-end server that will accept the incoming session.

  4. If using Host: header load balancing, remember to configure the correct header for the associated VIP.

  5. Remember to update DNS with the new site names , even though they are using the same IP address.

  6. Test failure of a switch using VRRP to ensure that you do not have an asymmetric route, as the content switch will need to see the return packet in order to manipulate it back to its original form. Ensure that this works for Layer 7 traffic as well.

We can see how this has been achieved by Foocorp in Figure 6-21.

Figure 6-21. Foocorp, Inc. Layer 7 load balancing.

graphics/06fig21.gif

By deploying Layer 7 load balancing, Foocorp has been able to achieve the following:

  • Personalize user access offering a better customized service

  • Ensure that specific servers respond to specific content types

  • Allow multiple online e-commerce business to use the same precious public IP address

  • Allow new services and applications to be deployed with no or very little new hardware

Content networking at Layer 7 allows for very tight control of the networks. We discussed a brief and simple area of this exciting technology in this case study. We recommend engaging the content switch manufacturers who will provide quality resources who will be able to work with you to identify the best methodology for your Layer 7 infrastructure.



Optimizing Network Performance with Content Switching
Optimizing Network Performance with Content Switching: Server, Firewall and Cache Load Balancing
ISBN: 0131014684
EAN: 2147483647
Year: 2003
Pages: 85

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