Q. I want to use Windows NT/2000 Load Balancing Service for multiple webservers in a cluster. What do I need to consider when using WLBS and/or Microsoft Application Center (MAS) with AuthentiX/WebQuota?
You will need to authenticate against a centralized ODBC database.
Basic Authentication will work just fine if a user is switched from one machine to another.
Unlike session based systems (see the white paper on affinity below) AuthentiX works great on clusters. If you have any problems, please let us know.
In the white paper for
Microsoft Windows NT/2000 Load Balancing Service,
the section on Affinity and Session Support provides the key information:
So long as the domain name (eg www.domain1.com) remains the same across requests, then the browser will continue to supply the cookie-based or Basic Authentication logon credentials in the http request. If you have AuthentiX installed on each machine in the cluster, then users will not have to login each time they are served by a different machine in the cluster.
The white paper goes on to say:
WLBS also allows modification of session support to direct all client requests from a TCP/IP Class C address range to a single cluster host. This feature ensures that clients which use multiple proxy servers to access the cluster will have their TCP connections directed to the same cluster host. The use of multiple proxy servers at the client's site causes requests from a single client to appear to originate from different systems. Assuming that all of the client's proxy servers are located within the same 256 host Class C address range, WLBS ensures that client sessions are properly handled with minimum impact on load distribution among the cluster hosts."
WebQuota and WLBS both use this same method of dealing with proxy clients such as AOL.
Another opinion on load balancing from Adwait Ullal:
More info from Hank:
Anytime you move nodes, your GUI will work. Here is the catch to making this work. Copy the flicksflt (sorry am at home and don't remember the exact name of the filter for IIS) DLL and the OCX to a location on your C: or OS drive. You will have to go to IIS MMC and point to the filter that you copied to the C: or OS drive. Do this on each node.
The reason why I had to do this is that whenever the nodes were moved, the web sites would fail and try to roll back to the node that initiated the move. I think the reason why this happens is that IIS is not ready because of the filter DLL and OCX are trying to be started from that shared drive array. If you move them to the C: or OS drive, IIS is happy because it always has a copy of the IIS filter.
Hope this helps.
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