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Making Your Corporate Web Site Reliable

Novell Cool Solutions: Feature
By Blair Thomas, Jeff Hughes

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Posted: 24 May 2000

For example, if your organization is like most companies you have many departments that have discovered how great a place the Internet is to stay in communicate to the outside world. Before long web servers were popping up for every occasion! You may have a training web server running on an NT platform, a support web server running on a NetWare platform, and the corporate web server running on a UNIX platform. Security has become a pain, because each of the different web server platforms is maintained separately with completely different security policies. In addition, a couple of the web servers are de-centralized from the others. For example, the training and support want to maintain their own web servers, because information is changing daily and they want to keep it up to date. Traffic has become an issue especially going to and from the remote departments. Your clients are complaining of performance issues. With all the complaints, the IS department is considering redesigning the WAN connections with larger "pipes". This would be a tremendous cost to the company as well as an implementation nightmare.

Before you make any drastic decisions, consider centralizing your corporate web content set. Centralizing the web content will make it easier to provide higher availability or redundant systems. The redundant system may include immediate or hot backups, or just mirroring the web data or content. Thus, if you have web content on different servers or on servers across multiple locations, you need to bring the content back to only on one server. You may think that the putting all the content back on one server is even more susceptible to failure, and that, you originally split the content up to avoided this problem. However, centralizing the web content on your central server will make it possible for you to make duplicates of the same content set to other central servers creating redundant systems for higher availability of the corporate web site.

Based on your experience, you know that having too many web servers makes managing the web site difficult. In addition, having fewer web servers in your company is easy and better. In the example, remember that security was a big problem with each server using a different platform (NT, NetWare, and UNIX). You may not have enough people on staff that are cross trained, so on any given day, security policies may have to wait until someone understanding their systems is there to manage it. In addition, with a lot of web servers the staff could become backlogged with changes, causing clients and departments to complain that the information on the web servers is out-of-date or incorrect.

If your corporate web site is currently stored on a third party provider, you need to decide whether it makes sense to move the content back in-house and have someone manage it there. If you do decide to move the content back in-house, then you should slowly move the HTML pages back making sure that you have the proper infrastructure built to handle the load. For example, start by installing the main web server and store just the home page of your corporate web site. You need to monitor the number of web hits, adding horsepower and bandwidth as needed to your infrastructure.

After you have consolidate or centralized the content of your web site, the next step is to make the web site reliable. You can accomplish this by distributing duplicate copies of the same content to be distributed across multiple servers. We recommend that you add two additional servers that would be mirror servers to the original web server. These servers would be identical in web content and provide fail-over capability in case of a server crash.

After the three web servers are installed, you need to register the IP addresses of each server as The result of registering each IP address, is that DNS resolutions to your corporate web site are provided at random. The requesting clients are given one of the three web server addresses regardless of their location in the world. This strategy not only provides redundant servers that automatically cover for a down server, but also distributes the workload to each of the servers. Each server will handle approximately one third of the workload. The result is a communications infrastructure for your web site with better access than with only a single point of presence.

At this point the consolidation of the web content simplifies the management process and making the web site reliable. However, having all your web content in one place reduces the overall performance. In order to improve the performance of access in this situation, you should implement content caching. Content caching is not a new concept it has been used for several years to filter incoming content from corporate web user. However, in this situation, the caching is performed in reverse (called "reverse proxy" or "HTTP acceleration") where the content been cache is the outgoing corporate web site. By placing a reverse proxy in front of your web servers, the cache responds as if it were the web server. This allows your content publishers to push information from the web servers out to border servers to reduce the load on their web servers. Requests that are not serviced out of cache are forwarded on to the real web server. Using this technology of reverse proxy cache, your web site will provide greater throughput and reliability to requesting users, as it becomes more popular.

Although, one reverse proxy server can be configured to represent one or more real web servers, we recommend that you use at least a couple of servers. This will avoid falling into the same trap as only having one central web server. In addition, we recommend that when designing your infrastructure and access plan, you should place the proxy servers on the same segment as the web servers they represent. With this design, the traffic associated with the caching of the HTML pages and other objects from the web servers to the proxy will be done on a single (possibly dedicated) segment.

There are several different organizations that can provide you with reverse proxy caching software. For example, there is content caching software called Harvest developed by the Computer Science Departments at the University of Southern California and the University of Colorado -- Boulder ( Another source for content caching software is the Squid cache developed by the National Laboratory for Applied Network Research (NLANR). They can be contacted at the following URL: In addition, other companies such as Netscape, Microsoft and Novell have developed content caching (sometimes called proxy caching). For example, Novell Inc. has developed content caching within their BorderManager product line.

As an example, you can configure the BorderManager product from Novell, using the Network Administrator (NWADMIN) utility. You simply configure a server to "front-end" or reverse proxy one or all of your corporate web servers. You simply identify the web server(s) that the reverse proxy will represent. Again, we recommend that you at least have two or three reverse proxy servers configured to front-end the three web servers. It is strongly recommended that each reverse proxy represent each of the three web servers. In turn, the firewall servers are setup so that the web servers can only communicate with the reverse proxy. The DNS tables are changed so that all requests to your corporate web site are responded with the reverse proxy's IP addresses. This requires you to register the IP addresses of the reverse proxy servers as This configuration allows you to "virtually" keep all your corporate web servers hidden from everyone. This gives the content authors easy access (those who have rights) to change their material and information while maintaining 100% service.

The results of properly publishing and maintaining a 24x7 corporate site will be immediately felt throughout your organization. Your corporation will notice costs saving due to centralized administration of the web content and tighter security. The fault tolerance or reliability of the corporate web site will increase without jeopardizing performance. The traffic loads and bandwidth requirements decrease because to the faster response times from the reverse proxy. And finally, your customers will appreciate being able to view your product offerings quicker and more frequently.

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