Citrix ICA Browser Explained
By Elvin Sosa
Citrix Systems, Inc THE ICA BROWSER EXPLAINED...... 4
ROLES OF THE MASTER ICA BROWSER...... 4
CONDITIONS FOR ICA BROWSER COMMUNICATION...... 4
THE ROLE AND FUNCTION OF THE ICA BROWSER...... 5
MASTER ICA BROWSER ELECTIONS...... 6
OPTIMIZING THE ELECTION PROCESS...... 6
ADVANTAGES OF THE DEDICATED MASTER ICA BROWSER...... 9
ISOLATED CRITICAL FUNCTIONALITY...... 9
ISOLATED MASTER BROWSER PROCESSING...... 9
FASTER CONNECTION TIMES AND DIRECTED CLIENT REQUESTS...... 9
LOWER RATE OF RANDOM BROWSER ELECTIONS...... 9
INCREASED LICENSE AVAILABILITY...... 10
INCREASED LICENSE MANAGEABILITY...... 10
INCREASED CROSS-SUBNET LICENSE AVAILABILITY...... 10
TURNKEY BACKUP MASTER ICA BROWSER...... 10
DEDICATED MASTER ICA BROWSER SET-UP...... 11
REQUIREMENTS...... 11
LICENSING YOUR ICA MASTER BROWSER...... 12
Standard Licensing Plans...... 12
Volume Purchase Licensing Agreements...... 12
CONSIDERATIONS...... 14
CONFIGURATION...... 14
Creating a dedicated WinFrame 1.7 Master ICA Browser...... 14
Creating a dedicated WinFrame 1.8 Master ICA Browser...... 15
Creating a dedicated MetaFrame 1.0 Master ICA Browser...... 16
Creating a dedicated MetaFrame 1.8 Master ICA Browser...... 16
ADVANTAGES OF CREATING A DEDICATED BACKUP ICA BROWSER...... 18
LOWER THE RATE OF RANDOM BROWSER ELECTIONS...... 18
INCREASED LICENSE AVAILABILITY...... 18
BACKUP ICA BROWSER SET-UP...... 19
REQUIREMENTS...... 19
CONSIDERATIONS...... 19
CONFIGURATION...... 20 Creating a WinFrame 1.8 or MetaFrame 1.8 Backup ICA Browser...... 20 The ICA Browser Explained
The most important functionality in a Citrix Environment is the ICA Browser. The ICA Browser provides the following:
Server to Server Communication
Application Publishing Lists and Functionality
Load Balancing
Program Neighborhood Functionality
License Recovery
Client to Server Communication
Roles of the Master ICA Browser
Member ICA Browser
Serves to provide Master ICA Browser with information about host MetaFrame or WinFrame Server. Serves to provide communication with clients.
Backup ICA Browser
Serves to backup the Master ICA Browser database. 2nd in line to takeover should the current Master ICA Browser go down.
Master ICA Browser
Serves to manage server to server communications, applications, server farms, program neighborhood, user connections, load balancing. Provides information about servers to Citrix utilities such as MetaFrame Administration, Citrix Server Configuration, Published Application Manager, and Load Balancing Administration.
Program Neighborhood Management
All types of Browsers retain and send information about Server Farms and Managed Applications to the Master ICA Browsers and clients.
Conditions for ICA Browser Communication
Citrix Server List
New servers get added
Server names change
New ICA Gateway is added
Published Application List
New application is published
New server is added to app list farm
New user connects to application
User disconnects from application User needs list of applications
License Pool Information
New Citrix Server is added
New Licenses are added and pooled
New connection is made
User session disconnects
Program Neighborhood Application connection (seamless applications)
Load Balancing Information
New user connects, disconnects or logs off
Load Information for servers
Program Neighborhood information
New server added to Server Farm
New Application Published to Server Farm
New user connects to server for app list
Nfuse application list
ICA Gateway Information
New ICA Gateway created
New Server added to LAN (Data replication across WAN)
New Application added to LAN (Data replication across WAN)
New licenses added to LAN (License gateway information)
Session Information
New Connected, Disconnected, Shadowed, Seamless sessions
New Load Information
Client Side License Matching (MetaFrame for Terminals License)
User Authentication Information (Username, Client Name)
The Role and Function of the ICA Browser
Member ICA Browsers exist to provide information to the Master ICA Browser and to provide clients with information about connections. Member ICA Browsers provide the Master ICA Browser with the number of licenses they have available, the list of applications that are published from them, and their Load Balancing parameters.
Backup and Master ICA Browsers and maintain a list of servers, applications, licenses, and load balancing parameters for each server. Both the Backup and Master ICA Browsers maintain an active database of Citrix Server and client information. However, only the Master ICA Browser provides access to that active database for clients and servers requesting enumeration.
The application list sent to the Master ICA Browser by each Stand-Alone Browser contains information about Managed and Non-Managed applications. Non-Managed applications are published from a server that is not a part of a server farm. Non- Managed applications are also applications that are published from a servers NT Domain scope. Managed applications are published from a server that is part of a server farm while the server is in a Citrix Server Farm scope. Managed applications are controlled by the ICA Browser and the Program Neighborhood Service. Non-Managed applications require only the ICA Browser service for access.
Load Balancing parameters sent from each Member ICA browser include current load for logged on sessions as well as the parameters set for each server in Load Balancing Administration. Per Server parameters sent are CPU percentage used, Swap File and Page File usage, Memory percentage used, and the number of sessions existing. When a change is made to the Load Balancing parameters of a Citrix Server, those changes are sent and saved at the Master ICA Browser.
When a client tries to connect to an application, the Master ICA Browser requests the current load state from each server that is associated with that application. Using the Load Balancing configuration for each server and the current load state, the Master ICA Browser computes a load index for each server with the requested application. The connection information for the server with the lowest load index gets returned to the client. The client then connects directly to the application.
Master ICA Browser Elections
Master ICA Browser elections take place by the following criteria (In the order specified):
Latest Browser version
Configured as Master Browser
NT Domain Controller or Backup
Longest Uptime
Alphabetical Listing
Since browser elections can occur under any of these conditions, it becomes important to optimize the system for maximum predictability.
Optimizing the Election Process
To minimize Master ICA Browser election by version, make sure that all Citrix servers are maintained at the same service pack and hotfix level.
To optimize election by manual configuration, use Citrix Server Administration to configure servers that will be, could be, and should never be Master ICA Browsers. Servers that are configured to be the Master ICA Browser are first in line to be elected as long as their browser version exceeds or matches that of other servers in your farm. Servers configured with no preference are most likely to become Backup ICA Browsers. Choose one server that will always participate in Master ICA Browser elections. Servers touted to be Backup ICA Browsers should be configured with the “No Preference” setting. All other servers should be configured to never participate. If the only servers left in a farm are configured to never participate in an election and are all of the same browser version, the election process continues on using the election variables described above.
Servers that are elected as Backup ICA Browsers will not necessarily become the Master ICA Browser should the Master fail. They will, however, retain the Master ICA Browser Database, which will be transferred to the new Master upon completion of the election process. For this reason, it is important that machines incapable of being the Master ICA Browser be configured to never participate in the election process. In this way, you can isolate critical functionality to capable machines only. You can also increase the chances of an election in favor of an existing Backup ICA Browser, effectively optimizing the election process.
In large environments where a Multiple Master or Resource Domain Model is implemented, it may be optimal to install a Citrix Server that is the Domain Controller. In smaller implementations, it may not be effective to use a Citrix Server as a PDC. Regardless of which implementation you choose, a domain controller should not be configured to accept user connections. In any environment, the optimal solution is separate components (separate e-mail server, web server, domain controller, file server, application server, etc.) Citrix Servers fall under the application server category and implementations should follow best practices to that end. Following these guidelines minimize the chances of your domain controller being elected as a Master ICA Browser. For maintenance purposes, it is advisable to maintain a regular reboot schedule. This will ensure optimal performance as well as minimizing the election process for browsers that have a longer uptime. It also works to the opposite end. Dedicated Maste ICA Browser implementations can be optimized for elections as well. By minimizing the reboot schedule for your dedicated Master ICA Browser you increase it’s uptime, effectively increasing the chances of this machine winning a random election.
Choosing a logical naming scheme is crucial to any implementation, Server Based Computing or otherwise. Choose a naming scheme with common prefixes such as MF
Master ICA Browser naming convention – MF001...
Non-Managed Multiple Application Servers – MFAPP001…
Mission Critical, ERP or Dedicated Application Servers – MF
Managed Multiple Application Servers – MF
Mission Critical, ERP, or Dedicated Managed Application Servers – MF
With a naming scheme such as the one above, Master ICA Browser candidate servers will be optimized for first in line election in alphabetical order, as well as be easier to manage. In order for this solution to be optimal, the prior optimization guidelines need to be adhered to (Version, Manual Configuration, PDC/BDC, and server uptime optimization). The Dedicated ICA Master Browser
This white paper provides guidelines to help you optimize a Citrix implementation by deploying a dedicated Master ICA Browser. It also discusses how setting a Backup ICA Browser and/or a backup Master ICA Browser can help you manage your Citrix Implementation throughout the Enterprise.
The Citrix ICA Enterprise
Subnet A Subnet B
Dedicated Master ICA Browsers: Network Resources: the focal point of management in an Network Resources: File, Print, E-mail, enterprise class solution. File, Print, E-mail, Database, Web, etc. Database, Web, etc.
ICA Gateway
WAN Production Servers: Production Servers: Some may serve as Some may serve as Backup ICA Browsers. Backup ICA Browsers. They have a backup The They have a backup copy of the Master Internet copy of the Master ICA Database and ICA Database and Become the Master Become the Master ICA Browser in the ICA Browser in the event of a failure. event of a failure.
Citrix ICA Clients: Citrix ICA Clients: Include Win CE, Mac, Include Win CE, Mac, UNIX, Linux, DOS, UNIX, Linux, DOS, Web, Java, and Web, Java, and Windows 98, 98, NT, Windows 98, 98, NT, Web. Clients access Web. Clients access Citrix Servers over Citrix Servers over any connection, any connection, including wireless, including wireless, LAN, WAN, and dial- LAN, WAN, and dial- up. up.
Client can connect over the internet either through applications published to the web or through a VPN solution. Advantages of the Dedicated Master ICA Browser
Isolated Critical Functionality
Use of dedicated Master Browsers provides for increased stability, when compared to the use of production Citrix servers as a Master Browser, because their only function is to house the Master ICA database. When the Master Browser is also a production application server, it must share resources with applications that may have adverse effects on a servers’ available memory, CPU usage, bandwidth utilization, etc. This type of scenario can occur for many reasons – poorly written custom applications, applications with memory leaks, improperly tuned applications, high resource usage or spike resource usage applications, etc.
It is therefore logical to separate the Master Browser function from the Application server , thus ensuring that this critical function of your ICA network is unhampered by contact with unpredictable or unsupported applications.
Isolated Master Browser Processing
In keeping with the separation of critical functionality from a resource intensive environment, in large networks with servers that are providing applications to a large numbers of users simultaneously, it is also advisable to separate Master ICA Browser functionality to a dedicated server.
When users connect to a Citrix server or published application, they first request the availability of servers, applications, licenses, and load balanced application availability, from the Master Browser. In typical Citrix implementations, with many servers where many users are requesting connections at the same time, this type of activity can severely limit a servers’ ability to effectively process existing connections. By separating the Master ICA Browser from the application server, you can ensure that your applications and user sessions will be processed more efficiently.
Faster Connection Times and Directed Client Requests
If you have a dedicated Master ICA Browser you can assign a static IP address to this machine and pre-configure Citrix clients to request information directly from the Master Browser. By default, Citrix clients broadcast a request to all MetaFrame servers on the local subnet asking for the Master Browser. The replying server sends the name of the Master Browser, and the client directly contacts the named server for connection information. When connecting from a different subnet, the client's Server Location setting must be used to direct users to the Master ICA Browser, if there is no ICA Gateway present.
By creating a dedicated Master Browser with a static IP address, you can create a pre-configured client that would allow you to direct all connection requests to your Master ICA Browser. You can use the IP address or DNS name of the Master ICA Browser to configure this in the Server Location utility on the client side. This client can thereafter be deployed using the Auto Client Update Utility, or a modified set of installation disks. Connections initialize faster by directing the client to the Master ICA Browser.
Additionally, you may want to use DNS names for 'Server Locations' where possible. Since DNS gives you the flexibility of centrally managing the actual IP addresses of your ICA servers, it is much better to deploy the clients with the Server Location using DNS names. DNS is cross platform, so even most Windows Based Terminals can get DNS name resolution. This enables you to maintain/manage those entries in a single location for all client types. This does create a dependency on DNS name resolution, so consider the pros and cons before implementing this as a part of your solution.
Lower Rate of Random Browser Elections
The ICA Browser service forces an election under the following conditions:
. Current Master Browser does not respond to another ICA Browser
. Current Master Browser does not respond to an ICA client . New Citrix Server is added
. Two Master Browsers are detected on the same subnet
When an election takes place, the ICA Browser database needs to be recreated through network broadcasts on the newly elected Master. With large numbers of servers, these requests and broadcasts can degrade network performance temporarily. By implementing a dedicated Master ICA Browser and Backups, you ensure a higher rate of response to client requests and to other ICA Browsers, effectively decreasing the number of elections that are likely to take place on your network.
Increased License Availability
By default, a Master ICA Browser that is MetaFrame version 1.8 and above, stores license information for 48 hours after a licensed machine has been removed from your network. This means that if a server goes down, or if you remove a server from your network, the licenses that were pooled from that server are still available for client connections for the next 48 hours. This facility allows you sufficient time to replace the machine with a respective license.
However, if a browser election takes place and there is no Backup ICA Browser (MetaFrame and WinFrame 1.8 and above), the ICA database needs to be rebuilt from scratch. If this happens within the 48-hour period, the pooled licenses are no longer available. Since creating a dedicated Master ICA Browser is more dependable and decreases the number of elections that are likely to take place on your network, you decrease the chances of the ICA database being recreated and losing any pooled licenses whose donating servers are no longer available.
Increased License Manageability
By creating a dedicated Master ICA Browser, your implementation will open itself to a dedicated License server as well. Now, you can install all user bump packs onto the Master ICA Browser, pool them from there and manage all licenses from that server. If a MetaFrame machine goes down in your network, you will not have to reinstall bump packs on that machine. The only things you will have to install are the Citrix Base License and any Management Services licenses such as Load Balancing, Secure ICA, and RMS. If this machine is out of commission for more than 48 hours, you still have access to all of the pooled licenses from the bump packs. Without this, after the 48-hour license retention limit, you would lose not only the pooled base license, but also any bump pack licenses. In this way, you can limit your losses.
Increased Cross-Subnet License Availability
With the introduction of MetaFrame 1.8a for Microsoft Windows NT 2000, Citrix has introduced Dual Subnet License Pooling. Dual Subnet License Pooling is poised to play an integral role in the Business and Disaster Recovery of applications deployed with Citrix.
This solution entails creating 2 Dedicated ICA Master Browsers, one at each site, with a two-way gateway across the two subnets. Install 50% of licenses on each subnet. The result is a stable, centrally manageable, enterprise class solution for the Citrix implementation.
Turnkey backup Master ICA Browser
It is possible to configure a clone machine to take over as the Master Browser should your dedicated machine fail. You don’t need to take the time to troubleshoot problems on your Master ICA Browser. Just turn on the cloned machine, and it will assume its new role. It would act in the same capacity as the dedicated machine, and you would effectively have a business recovery solution for your Master ICA Browser.
Whenever a change is made or licenses added to the Master ICA Browser, make sure that you create a drive image or backup of the new configuration. In the event of a drive or machine failure, replace the failed device with your backup. In this way, your implementation can approach a 100% availability threshold. Dedicated Master ICA Browser Set-Up
Requirements
. Microsoft Windows NT 2000 with Terminal Services
. Citrix MetaFrame 1.8a
. Supported MetaFrame license from “Licensing your ICA Master Browser” section
. 200 Mhz and above Pentium Class Machine (Single Processor)
. 128 MB RAM
. Minimum 10 Mb Ethernet Card
-OR-
. Microsoft Windows NT 4.0 Terminal Server Edition
. Citrix MetaFrame 1.0 or above
. Supported MetaFrame license from “Licensing your ICA Master Browser” section
. 200 Mhz and above Pentium Class Machine (Single Processor)
. 64 MB RAM
. Minimum 10 Mb Ethernet Card
-OR-
. Citrix WinFrame 1.7 or above
. Supported WinFrame license from “Licensing your ICA Master Browser” section
. 200 Mhz and above Pentium Class Machine (Single Processor)
. 64 MB RAM Minimum
. Minimum 10 Mb Ethernet Card
Note Many present implementations of Dedicated Master ICA Browsers use a Pentium-class fat client which can be replaced by a thin client. The main guideline is to implement a machine that satisfies your performance requirements. However, you should not need a machine more powerful than the recommended machine configurations described above. Licensing your ICA Master Browser
Standard Licensing Plans
In order for your dedicated ICA Master Browser to work, it must be licensed properly. If a dedicated ICA Master Browser does not have an activated server license, it will cease to function after 35 days. Also, whenever implementing a solution like this, it is important to remain compliant with Citrix Licensing policies. Supported licensing methods for the ICA Master Browser are as follows:
License Type Limitations
WinFrame or MetaFrame Base None License (15 user included) WinFrame or MetaFrame for Clients, including the administrator, can only connect with a Citrix Client Terminal License. Terminals License WinFrame or MetaFrame for Cannot pool licenses. Does not allow addition of User Bump Packs or Load Management Workgroups (5 user included) Services Option Pack.
From the preceding license group, the WinFrame or MetaFrame for Terminals License is the most cost effective way to license your Dedicated ICA Master Browser. This license also serves as a way to control access to your ICA Master Browser. Each user that accesses a server licensed in this manner requires a client side Citrix Terminal License. Only users with this Client side Terminal License can connect to your Dedicated ICA Master Browser. This effectively reduces the number of administrators that can connect to your server and acts as another layer of security for server access.
The Citrix for Terminals License and the Standard WinFrame or MetaFrame Base License are the only two licenses that allow you to manage user bump packs from one server. With these two licenses, you will add user bump packs only on your Dedicated ICA Master Browser and then pool those licenses for use on your local subnet. Please see the section titled “Advantages of Creating a Dedicated ICA Master Browser - Increased License Manageability” for more information on license manageability.
Furthermore, MetaFrame 1.8a for Microsoft Windows 2000 allows dual-subnet license pooling. This allows you to control more of your user licenses from a single server. Please see the section titled “Advantages of Creating a Dedicated ICA Master Browser – Increase Cross-Subnet License Availability” for more information.
Volume Purchase Licensing Agreements
The following license programs contain unlimited user base licenses. Licenses are audited every month and either leased or purchased. If purchased, monthly audits are performed in which the difference between owned license usage and actual license usage is computed. The result is the number of licenses used, but not purchased. Customers then purchase these licenses in order to remain in compliance with Citrix Licensing. The Corporate Licensing Plan and the Enterprise License Agreement require that a specific volume purchase be met in order to both join these plans and receive the discounts provided by them. For more information on the CLP, ELA, and ASP license plans, please visit our website.
Corporations, Enterprises, and the ASP’s are ideal candidates for ICA Master Browsers and the licensing plans noted below are well suited to accept this type of design. However, all servers must be included in the same licensing model in order for your setup to work properly. You should not have a mixed environment that contains both standard and volume purchase license types as this will have unpredictable results.
License Plans Description Corporate Licensing Plan This licensing plan provides a discount for Corporate volume user license orders. Each server has a zero user license and the number of licenses purchased is determined every month by Citrix. This is a pay as you go license purchasing program. Enterprise Licensing Plan This licensing plan provides a discount for Enterprise volume user license orders. Each server has a zero user license and the number of licenses to be purchased is determined every month through Citrix. This is a pay as you go license purchasing program.
Level E Program This licensing plan provides a discount for Educational volume user license orders. Each server has a zero user license and the number of licenses to be purchased is determined every month through Citrix. This is a pay as you go license purchasing program.
ASP Licensee License Program specific for certified Citrix Application Service Providers. Each server has a zero user license and licenses are leased on an average usage per month basis.
For pricing information, please refer to our website at http://www.citrix.com/csn/skus.htm Considerations
As a general rule of thumb, the highest common denominator of Citrix WinFrame or MetaFrame should be implemented as the Master ICA Browser. By default, the Citrix MetaFrame or WinFrame server with the newest version of the ICA Browser will become the Master ICA Browser. This also includes any machine that has had a hotfix (which includes a newer ICA Browser than any version currently installed on another Citrix Server) installed. This means that if you have a mixed Citrix environment, you have no choice but to implement the newest version of MetaFrame or WinFrame as the Master ICA Browser. Furthermore, if you plan on implementing a solution that includes Backup ICA Browsers, your Master ICA Browsers should be Citrix MetaFrame or WinFrame version 1.8 and above.
When implementing a solution of this kind, it is imperative that all machines be kept at the same service pack and hotfix level. This ensures proper communication between servers. When updating servers with new hotfixes, install on the Master ICA Browser first. This will provide a production test bed as well as allow you to quickly recover from hotfixes that have adverse effects on your particular network. You should also implement a quick recovery backup solution for the Master ICA Browser.
Using a dedicated Master ICA Browser is recommended for implementations as small as 2 or 3 Citrix servers. It is recommended that you test this type of network topology to determine whether it adds value to your specific implementation. You will find, however, that adopting the idea of a dedicated Master ICA Browser per network subnet will make your Citrix Solution even more scalable, stable, and manageable.
You can also implement a dedicated Master ICA Browser on only one subnet and create ICA Gateways th`t would allow Citrix Servers on other subnets to contact the dedicated Master ICA Browser directdy. This creates a situation where you have a central enterprise-wide Master ICA Browser from which to Perform Load Balancing and Application Publishing administration.
When configuring your dedicated Master ICA Browser, remember that this machine should not accept user connections except from administrators. To accomplish this, do the following:
1. Create a TCP Winstation in Citrix Connection Configuration.
2. Change the permissions on the Winstation and remove login permissions for everyone but administrators.
3. Next, access the Properties for the TCP connection itself, and limit the number of ICA connections to include only those who will be remotely administering the machine at any single point in time.
This ensures that only a limited number of administrators are logging in.
Configuration
Creating a dedicated WinFrame 1.7 Master ICA Browser
Setup Note: WinFrame 1.7 Master ICA Browsers should only be implemented in environments with WinFrame 1.7 and earlier, and MetaFrame 1.0.
1. Install WinFrame 1.7 on the machine that you want to designate as a Master ICA Browser.
2. Install one of the supported WinFrame licenses listed in the “Licensing your ICA Master Browser” section.
3. Open regedt32, go to HKLM/System/CurrentControlSet/Services/ICABrowser/Parameters/IsMasterBrowser and change its value to 1.
4. From the command line, run the command qserver /election. This will force a Master ICA Browser election.
5. Run the command qserver and check to see that the entry in the list for your server has an 'M' next to it. This indicates that the server is the Master ICA Browser. 6. Also at the command line, type qserver /update to force the Master ICA Browser to update its ICA Browser database.
7. If you are unable to designate the machine as the Master ICA Browser, you may have to change the registry settings of the server that is currently elected as the Master ICA Browser to prevent it from becoming a Master ICA Browser. It is recommended that you make the following changes to the registry for all servers that should not become the Master Browser.
Server Type Registry Key to Change or Action to Take
WinFrame 1.7 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ and older NotMasterBrowser = 1 MetaFrame 1.0 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ NotMasterBrowser = 1
Creating a dedicated WinFrame 1.8 Master ICA Browser
Setup Note: WinFrame 1.8 Master ICA Browsers should only be implemented in environments with WinFrame 1.8 and earlier, and MetaFrame 1.0.
1. Install Citrix WinFrame 1.8 on the machine that you want to designate as the Master ICA Browser.
2. Install one of the supported MetaFrame licenses listed in the “Licensing your ICA Master Browser” section.
3. Open Citrix Server Administration and select the server that you have chosen to become the Master ICA Browser.
4. Select the ICA Browser tab for that server and click the “Always attempt to become the Master Browser” radio button. Close Citrix Server Administration.
5. From a command line run the command qserver /election. This will force a Master ICA Browser election.
6. Run the command qserver and check to see that the entry in the list for your server has an 'M' next to it. This signifies that the server is the Master ICA Browser.
7. Also at the command line, type qserver /update to force the Master ICA Browser to update its ICA Browser database.
8. If you are unable to designate the machine as the Master ICA Browser, you may have to change the registry settings of the server that is currently elected as the Master ICA Browser to prevent it from becoming a Master ICA Browser. It is recommended that you make the following changes to the registry for all servers that should not become the Master Browser.
9. If the above situation does not occur, you may have to go to the server that is elected as the Master ICA Browser and make a change to its registry to prevent it from becoming a Master ICA Browser. It is recommended that you make the following changes to all servers that will not be the Master Browser.
Server Type Registry Key to Change or Action to Take
WinFrame 1.7 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ and older NotMasterBrowser = 1 WinFrame 1.8 Open Citrix Server Administration and select the WF 1.8 server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button. MetaFrame 1.0 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ NotMasterBrowser = 1
Creating a dedicated MetaFrame 1.0 Master ICA Browser
Setup Note: MetaFrame 1.0 Master ICA Browsers should only be implemented in environments with WinFrame 1.7 and earlier, and MetaFrame 1.0.
1. Install Microsoft Windows NT 4.0 Terminal Server Edition and Citrix MetaFrame 1.0 on the machine that you want to designate as the Master ICA Browser.
2. Install one of the supported MetaFrame licenses listed in the “Licensing your ICA Master Browser” section.
3. Open Regedt32 and go to the HKLM/System/CurrentControlSet/Services/ICABrowser/Parameters/IsMasterBrowser and change its value to 1.
4. From a command line run the command qserver /election. This will force a Master ICA Browser election.
5. Run the command qserver and check to see that the entry in the list for your server has an 'M' next to it. This signifies that the server is the Master ICA Browser.
6. Also at the command line, type qserver /update to force the Master ICA Browser to update its ICA Browser database.
7. If the above situation does not occur, you may have to go to the server that is elected as the Master ICA Browser and make a change to its registry to prevent it from becoming a Master ICA Browser. It is recommended that you make the following changes to all servers that will not be the Master Browser.
Server Type Registry Key to Change or Action to Take
WinFrame 1.7 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ and older NotMasterBrowser = 1 MetaFrame 1.0 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ NotMasterBrowser = 1
Creating a dedicated MetaFrame 1.8 Master ICA Browser
1. Install Microsoft Windows NT 4.0, Terminal Server Edition or Microsoft Windows NT 2000 Server with Terminal Services and Citrix MetaFrame 1.8 on the machine that you want to designate as the Master ICA Browser.
2. Install one of the supported MetaFrame licenses listed in the “Licensing your ICA Master Browser” section.
3. Open Citrix Server Administration and select the server that you have chosen to become the Master ICA Browser.
4. Select the ICA Browser tab for that server and click the “Always attempt to become the Master Browser” radio button. Close Citrix Server Administration.
5. From a command line run the command qserver /election. This will force a Master ICA Browser election.
6. Run the command qserver and check to see that the entry in the list for your server has an 'M' next to it. This signifies that the server is the Master ICA Browser. 7. Also at the command line, type qserver /update to force the Master ICA Browser to update its ICA Browser database.
8. If the above situation does not occur, you may have to go to the server that is elected as the Master ICA Browser and make a change to its registry to prevent it from becoming a Master ICA Browser. It is recommended that you make the following changes to all servers that will not be the Master Browser.
Server Type Registry Key to Change or Action to Take
WinFrame 1.7 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ and Earlier NotMasterBrowser = 1 WinFrame 1.8 Open Citrix Server Administration and select the WF 1.8 server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button. MetaFrame 1.0 HKLM\System\CurrentControlSet\Services\ICABrowser\Parameters\ NotMasterBrowser = 1
MetaFrame 1.8 Open Citrix Server Administration and select the MF 1.8 server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button. MetaFrame 1.8a Open Citrix Server Administration and select the MF 1.8a server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button. Advantages of creating a dedicated Backup ICA Browser
Lower the Rate of Random Browser Elections
The ICA Browser service forces an election under the following conditions:
. Current Master Browser does not respond to another ICA Browser . Current Master Browser does not respond to an ICA client . New Citrix Server is added . Two Master Browsers are detected on the same subnet When an election takes place, the ICA Browser database needs to be recreated through network broadcasts on the newly elected Master. When the network consists of a large numbers of servers, these requests and broadcasts can degrade network performance temporarily. By implementing a dedicated Master ICA Browser and Backup, you ensure that there will be a machine available to take the place of the Master ICA Browser without the need to rebuild the browser database, effectively decreasing the number of random elections that are likely to take place on your network. You also increase your chances of enjoying the 48-hour license recovery period.
Increased License Availability
By default a Master ICA Browser that is MetaFrame version 1.8 and above, stores license information for 48 hours after a licensed machine has been removed from your network. This means that if a server goes down or if you remove a server from your network, the licenses that were pooled from that server are still available for client connections for the next 48 hours to allow you time to replace the machine with a respective license.
However, if a browser election takes place and there is no Backup Master Browser, the ICA database needs to be rebuilt from scratch. If this happens within this 48-hour period, the mentioned licenses are no longer available. Since creating a dedicated Master ICA Browser is more dependable and decreases the number of elections that are likely to take place on your network, you decrease the chances of the ICA database being recreated and losing any pooled licenses whose donating servers are no longer available. If an election does take place, however, you will already have a Backup ICA Browser ready to assume its new role. The more Backup ICA Browsers you make available, the more likely you will be to retain the 48 hour license recovery period. Backup ICA Browser Set-Up
Requirements
. Dedicated MetaFrame 1.8 or WinFrame 1.8 Master ICA Browser
-AND-
. Microsoft Windows NT 2000 with Terminal Services w/ Citrix MetaFrame 1.8a
-OR-
. Microsoft Windows NT 4.0 Terminal Server Edition w/ Citrix MetaFrame 1.8 or above
-OR-
. Citrix WinFrame 1.8
Considerations
By default, MetaFrame 1.8 Servers are configured to have 2 Backup ICA Browsers on their subnet. These machines are simply Citrix Servers that are prepared to assume the role of the Master ICA Browser because they have a copy of the ICA Database. If a machine is not in this position, a Citrix Server will be elected as the Master ICA Browser based on the following ordered election criteria.
1. Latest browser version number
2. Statically configured as a Master ICA Browser or Backup Browser
3. Running on a domain controller
4. Longest running browser
5. Server name in alphabetical order The newly elected Master ICA Browser may be a production server with important applications being published and served from it. Assuming the role of Master ICA Browser can slow this server down. For this reason, it may be important that you designate a Backup. Once re-activated, the original Master ICA Browser can be set to assume its role once again.
To create Backup Master Browsers, it is recommended that you perform the following changes to every Citrix Server on your network except for the dedicated Master ICA Browser and the machine(s) that you wish to designate as your Backup ICA Browsers.
Server Type Registry Key to Change or Action to Take
WinFrame 1 HKLM\System\CurrentControlSet\Services\ICA Browser\Parameters\NotMasterBrowser = 1
WinFrame 1.8 Open Citrix Server Administration and select the WF 1.8 server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button. MetaFrame 1.0 HKLM\System\CurrentControlSet\Services\ICA Browser\Parameters\NotMasterBrowser = 1
MetaFrame 1.8 Open Citrix Server Administration and select the MF 1.8 server that you do not want to become the Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button.
MetaFrame Open Citrix Server Administration and select the MF 1.8a server that you do not want to become the 1.8a Master ICA Browser. Click the ICA Browser tab and check the “Do Not Attempt to Become the Master ICA Browser” radio button.
Configuration
Creating a WinFrame 1.8 or MetaFrame 1.8 Backup ICA Browser
6. Open Citrix Server Administration and select the server that you have chosen to become the Master ICA Browser.
7. Select the ICA Browser tab and enter the number of backup browsers that you wish to have on your network. Close Citrix Server Administration.
8. From a command line run the command qserver /election. This will force a Master ICA Browser election.
9. Run the command qserver and check to see that the entry in the list for your dedicated Backup ICA Browser has an MB next to it. This signifies that the server is the Backup ICA Browser. 6400 NW 6th Way Fort Lauderdale, FL 33309 954-267-3000 http://www.citrix.com
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