Radware Alteon Application Manual page 226

Alteon Application Switch Operating System Application Guide
Server Load Balancing
Virtual Hosting
Alteon enables individuals and companies to have a presence on the Internet in the form of a
dedicated Web site address. For example, you can have a "www.site-a.com" and "www.site-b.com"
instead of "www.hostsite.com/site-a" and "www.hostsite.com/site-b."
Service providers, on the other hand, do not want to deplete the pool of unique IP addresses by
dedicating an individual IP address for each home page they host. By supporting an extension in
HTTP 1.1 to include the host header, Alteon enables service providers to create a single virtual
server IP address to host multiple Web sites per customer, each with their own hostname.
The following list provides more detail on virtual hosting with configuration information:
• An HTTP/1.0 request sent to an origin server (not a proxy server) is a partial URL instead of a
full URL.
The following is an example of the request that the origin server receives:
GET /products/Alteon/ HTTP/1.0
User-agent: Mozilla/3.0
Accept: text/html, image/gif, image/jpeg
The GET request does not include the hostname. From the TCP/IP headers, the origin server
recognizes the hostname, port number, and protocol of the request.
• With the extension to HTTP/1.1 to include the HTTP Host: header, the above request to retrieve
the URL www.radware.com/products/Alteon would look like this:
GET /products/Alteon/ HTTP/1.1
Host: www.radware.com
User-agent: Mozilla/3.0
Accept: text/html, image/gif, image/jpeg
The Host: header carries the hostname used to generate the IP address of the site.
• Based on the Host: header, Alteon forwards the request to servers representing different
customer Web sites.
• The network administrator needs to define a domain name as part of the 128 supported URL
strings.
Note: It is also possible to provide virtual hosting for SSL encrypted sites (HTTPS), using the SSL
protocol Server Name Indication (SNI) extension.
To configure virtual hosting based on HTTP Host: headers
1. Define the hostnames as HTTP content classes. If needed, associate multiple hostnames to the
same HTTP content class. For an example of creating a content class, see
Load Balancing, page
Both domain names "www.company-a.com" and "www.company-b.com" resolve to the same IP
address. In this example, the IP address is for a virtual server on Alteon.
2. Define dedicated real server groups for each of the customer's servers.
Servers 1 through 4 belong to "www.company-a.com" and are defined as Group 1. Servers 5
through 8 belong to "www.company-b.com" and are defined as Group 2.
3. Create Layer 7 content switching rules on the virtual server's HTTP service, assigning HTTP
content classes and groups to each rule. For an example of creating a content class, see
Hashing for Server Load Balancing, page
4. Alteon inspects the HTTP host header in requests received from the client.
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URL-Based Server
Document ID: RDWR-ALOS-V2900_AG1302
URL