2X LoadBalancer - A Great Value (25-04-2006)
The ?PROBLEM?:
Most network admins have at one point deployed a terminal server for their users. Admins start by using the terminal for remote access for a few users. The next step is a full blown terminal solution for the LAN and the WAN. Of course now ?full blown? problems start to show themselves.
One of the most irritating problems is user sessions not reconnecting. It is a well known fact that a ?reconnect to disconnected sessions? only works reliable when the sessions was disconnected at will by the user, but often does not work when the session was disconnected due to network problems. Reconnects working correctly are necessary before an advanced feature such as load balancing can work effectively. Reconnects really become problematic once you add that 2nd terminal server and users need advanced features such as load balancing as well. Imagine the scenario where a ?heavy app? userA gets disconnected only to open a new session on the 2nd terminal server and the lame session continues resource usage. Then userA gets disconnected on the 2nd terminal server only to start a 3rd session using 50 MB of memory, all the while calling the admin complaining that his /her work is not saving correctly.
Some admins try to use or enable ?KeepAlives?? It can help to stabilize a connection, or at least let the server detect the earlier session that was disconnected. Admins can then set a very short time-out limit on disconnected sessions. Not a real solution, and of course there are ways to script this too. But why bother? Never mind that it should work that way ?out of the box?, although MS has introduced ?session directory? but only for those that feel like parting with large amounts of cash for Microsoft Enterprise Server.
Accordingly, Microsoft Windows Server 2003, has also included the possibility to load balance across Terminal Servers by using Microsoft Network Load Balancing. Microsoft Network Load Balancing bases its load calculations solely on network load and does not use Resource Based Load Balancing or Fault Tolerant Load Balancing like 2X.
Whats an admin to do?
2X LoadBalancer has the following features:
? Resource Based Load Balancing
? Fault Tolerant Load Balancing
? Disconnected Session Reconnection Support
? SSL Gateway Features
Some of the benefits/features I experienced from using the 2X solution:
1. 2X LoadBalancer can operate in three modes, Gateway mode, SSL Gateway mode, and Direct Connect mode.
Gateway mode allows clients to connect to the 2X LoadBalancer server (can be an XP box). The connect to the least worked Terminal Server is established through the 2X LoadBalancer server. This is good for clients working remotely as the 2X LoadBalancer server is the only machine exposed to the internet.
SSL Gateway - Of course the connection from the client to the 2X LoadBalancer can be SSL encrypted. This feature gives secure gateway access to your company Terminal Server from the Internet.
Direct Connect Mode - works the same as the gateway feature, except that the RDP connection is not routed thru the 2X LoadBalancer server. The client is assumed to have a LAN connection itself to the terminal server(s). The 2X LoadBalancer is eliminated as a single point of failure on the LAN and of course SSL is not supported in Direct Connect. Why uses extra resources to SSL encrypt on the LAN?
2. The load balancing worked like a charm! I really liked the fact that Resource Based Load Balancing and Fault Tolerant Load Balancing worked as well as my experiences with Citrix and its similar features!!! You are given the option for ?Resource Based Load Balancing? or ?Round Robin Load Balancing?. You didn?t buy 2X Loadbalancer to do something MS already does, so it is a no-brainer to use the ?Resource Based Load Balancing?. I didn?t even try ?Round Robin Load Balancing? because it is just not real Load Balancing. The counters 2X LoadBalancer uses can load balance with 4 counters:
Auto: it chooses the best server based on a proprietary algorithm that uses all the counters available.
Sessions: it redirects the connection to the server with the smaller number of sessions in use.
Memory Utilization: it retrieves memory utilization on all the servers and based on this information it redirects the user to the right terminal server.
CPU Utilization: it retrieves CPU utilization on all the servers and based on this information it redirects the user to the right terminal server.
Important Notes:
2X LoadBalancer Agent for Terminal Servers MUST be installed on every single terminal server that will be part of the farm AND if 2X admits ?that in this version, the reconnection feature will work ONLY if the
client computer is NOT behind a NAT network. In this case a VPN must be in place to make sure users can get reconnected properly AND from the SAME machine they were working on. If the client is behind a NAT, the IP address of the incoming connection will be the external device IP address and NOT the local IP address on the computer. As these two do NOT match, the 2X LoadBalancer is NOT able to reconnect the client properly. This will be addressed on the next release of the 2X LoadBalancer Client.?
Installation
2X has made server installation a snap. Just execute the msi. Files and basically it?s a ?click-click? install.
Each server needs an agent and of course you need to setup the gateway machine.
The 2X client is basically a modified version of the Windows XP remote desktop client. The installer comes in a msi package which can be easily modified to provide an unattended setup. Admins familiar with msi files can easily deploy this with a GPO, although home MS machines will be a little more problematic. 2X provides great documentation for an unattended install of the client on home MS machines using script or GPO. Additionally 2X is currently supporting MS clients only for the 2X client (but others are on the way). The 2X Client has additional functionality in that it enables you to provide a proxy server setup in the ?Network? tab complete with the ability to enter proxy user credentials for your gateway server.
NOTE: The 2X client will only be needed remotely as there is no need for it on a LAN. Per 2X ?If you will use the Regular Gateway Mode (simply connecting to the 2X LoadBalancer, not in Direct Connection Mode, or even directly to a terminal server), there is no need to use the 2X Client. In this case any RDP client (Microsoft RDP Client for Windows, Windows CE, Windows CE.NET, Mac OS X client, DOSRDP XP, Java, Linux, etc) is supported when connecting to the 2X LoadBalancer.?
Configuration
Although the install of 2X LoadBalancer requires a reboot, configuring is a simple as walking thru the tabs on the 2X LoadBalancer GUI.
General tab.
1. Select the farm protocol ? either Microsoft RDP or Citrix ICA.
2. Make sure that the gateway machine answers on something other than 3389 for terminal services by changing that in the registry (search mike-tech.com for ts port).
3. Add the terminal servers to the farm, and make sure that all the Terminal Servers listed listen to the same protocol. (RDP or ICA ? not a mix)
4. After adding all your terminal make sure to use Resource Based Load Balancing. 2X LoadBalancer can load balance based upon, the Auto algorithm, sessions, memory utilization, and CPU utilization. Make sure you select the 'Reconnect Disconnected Sessions' checkbox.
Options tab.
Here is where you setup the gateway and SSL connections as well as generate a homemade certificate.
Other tabs such as logging, licensing tab are self explanatory. The services tab allows you to stop and start the service. The Logging tab allows you to log every load-balanced login attempt.
The client config is very similar to the MS mstsc client. The only difference being the ?mode? option to select either Gateway mode, SSL Gateway mode, and Direct Connect mode.
Nice features of 2X LoadBalancer:
? Just about everything that ?out of the box? terminal services is missing related to load balancing. 2X can make Microsoft terminal services do things previously only done by an expensive application such as Citrix.
? Great pricing
? Easy setup / administration
? SSL Gateway functionality
? Session Reconnects
Points to be aware of using the 2X LoadBalancer:
? No minuses, rather, some ?wishlist? extra pieces.
? The client terminal client that uses SSL and gateway needs to be MS based. Support for other platforms would be nice.
? Nat clients cannot use the SSL gateway. (In progress of being fixed)
? Does require an agent on every Terminal Server ? thus a reboot.
? Session management from MS necessary to manage sessions. It would be nice to have a built-in ?2X Farm Sessions? manager.
Verdict:
This product I reviewed in this case is almost all you could ask for in an add-on load balancing solution. I cannot wait until the at least part of the ?wishlist? becomes reality (nat client support is a must). As for working as promised, 2X LoadBalancer is right on!
