| |
This section contains information about the following topics:
Origin Web Server on the Internet provides a visual map for the information in this section.
NOTE: The letters in Figure 6 are referenced in the table that follows. The addresses shown are for illustration purposes only. You will need to substitute actual addresses for your network.
Although Figure 6 shows the origin Web server on the Internet, it could be on the same network as the DNS server and the Web server accelerators and the browsers could be on the Internet, as shown in Web Server Accelerator Setup.
Figure 6
Origin Web Server on the Internet
| To | Do This | Notes |
|---|---|---|
Ensure that your basic network configuration is complete |
|
|
Set up two or more appliances as Web server accelerators to the same origin Web server |
See A in Figure 6. If you want the appliances to share cached objects, configure them as ICP peers. |
|
Modify DNS |
|
See B in Figure 6. Round-Robin DNS is a standard DNS function. |
There are two basic ways to host multiple Web sites through a single IP address and port combination.
Multiple Web Servers Through a Single IP Address and Port: This requires that each DNS name in the Web server accelerator definition is unique and that none of the Web servers uses SSL. (See Configuration Considerations When Using Proxy Server Multi-homing Features.) To do this you simply configure the proxy server with a Web accelerator for each DNS name.
Multi-homed Web Servers: You can also accelerate multi-homed Web servers, which are Web servers that host multiple virtual Web servers with different DNS identities.
The following sections contain simplified examples for each scenario.
A company named Server Consolidation Inc. offers acceleration services to several small companies, each of which has its own Web server. Server Consolidation Inc. knows that it can provide enough bandwidth to handle the combined Web traffic on one IP address, 30.1.1.1.
Server Consolidation Inc. installs a appliance and configures it with multiple Web server accelerators that each use the same IP address, 30.1.1.1, and fill from different Web servers.
Each company then arranges to have its DNS name (or names) resolve to 30.1.1.1.
After the DNS changes are complete, Server Consolidation Inc.'s appliance is accelerating multiple Web servers through IP address 30.1.1.1.
Since iChain Proxy Services uses the DNS name to determine which Web server to fill a request from, one accelerator definition is required for each DNS name accelerated by the appliance.
NOTE: In this example, none of the Web servers could use SSL. See Configuration Considerations When Using Proxy Server Multi-homing Features for more information.
A company named A Web Host, Inc. provides hosting services for 50 different companies on a single Web server with an address of 10.1.1.1.
DNS resolves browser requests to each of the 50 DNS names to the same IP address, 10.1.1.1. The Web server routes each request to the appropriate area on its hard disks, based on the DNS name in the request.
A Web Host, Inc. decides to accelerate its Web server and installs an appliance. The company assigns 10.1.1.1 to the appliance and 10.1.1.2 to the origin Web server. It then defines an accelerator service on 10.1.1.1 that fills from 10.1.1.2.
DNS resolves requests to each of the 50 Web sites to 10.1.1.1 just as before, but the appliance now receives and services the requests, obtaining uncached objects from the origin Web server when necessary.
Since the appliance has only one accelerator defined on 10.1.1.1 and since it is accelerating a single Web server on that address, it does not need the DNS name to resolve requests.
IMPORTANT: When an IP address is used for accelerating a single Web server, you need only one Web server acceleration service, even if the server is a multi-homed server servicing browser requests to multiple DNS names.
However, if you configure iChain Proxy Services to accelerate more than one Web server on any given IP address, you must create a separate accelerator service for each DNS name that might appear in browser requests, including all the DNS names used on any multi-homed servers.
We recommend you avoid the overhead of creating multiple accelerator services for a multi-homed server by ensuring that its accelerator service has a dedicated IP address and port combination---one that is not used by another accelerator service.
There are a number of possible ways to configure the iChain Proxy Server as a Web server accelerator:
NOTE: In the following descriptions, the term Web server farm can be either a single Web server, or a bank of mirrored Web servers.
No Multi-homing: iChain Proxy Services accelerates a single, non-multi-homing Web server farm that has one DNS name.
Host-Based Multi-homing: iChain Proxy Services accelerates a single, multi-homing Web server farm.
The Web server farm is configured to support multi-homing (multiple DNS names). Both the appliance and the Web server farm use browser host headers to select the correct content. The appliance routes all fill traffic to this single Web server farm.
Appliance-Based Multi-homing: iChain Proxy Services accelerates multiple, non-multi-homing Web server farms, each of which has one unique DNS name.
The appliance uses browser host headers to select the correct cached content and to route fill requests to the correct Web server farm.
Path-Based Multi-homing: iChain Proxy Services accelerates multiple, non-multi-homing Web server farms from a single host name.
The appliance uses the path portion of the URL to select the correct cached content and to determine which Web server farm to fill content from.
Appliance-Based Path-Based Multi-homing: iChain Proxy Services accelerates multiple, non-multi-homing Web server farms.
The appliance uses both the hostname sent from the browser as well as the URL path to select the correct cached content and to determine which Web server farm to fill content from.
Path-based multi-homing can be configured to use either the beginning or the ending portion of the path to select cached content and determine which Web server farm to fill content from.
The ZXY Company wants to accelerate their support and sales Web sites as a single external Web site.
They set up two accelerators for www.zxy.org on the same IP address and port number, and configure them with path-based multi-homing rules.
One accelerator has a rule for paths that start with /sales, the other has a rule for paths that start with /support.
Customers can now access the single www.zxy.org Web site and have all requests starting with www.zxy.org/sales get directed to the sales Web server farm, and all requests starting with xxx.zxy.org/support get directed to the support Web server farm.
The ZXY Company can decide whether a URL such as www.zxy.org/sales/newproducts.html gets sent to the Web server with sales included in the path (www.zxy.org/sales/newproducts.html) or without sales included in the path (www.zxy.org/newproducts.html) by selecting whether the matching starting substring is removed from the path.
CAB Unlimited has a Web site consisting of the following components:
CAB Unlimited sets up four accelerator services for www.cab.org on the same IP address and port, and configures them with path-based multi-homing rules.
One accelerator has a rule for paths that end with .ASP. The second has a rule for paths that end with JPEG. The third accelerator has a rule for paths that end with GIF. The fourth accelerator is configured as the default for all other paths.
Browsers can now access the single www.cab.org Web site and have requests for www.cab.org/main.asp get directed to the ASP Web server farm, requests for www.cab.org/logo.gif and www.cab.com/photo.jpg get directed to the graphics Web server farm, and requests for www.cab.com/directory.html get directed to the third Web server farm.
| |