For more information on Relays, see the product documentation: http://www-01.ibm.com/support/knowledgecenter/SS6MER_9.2.0/com.ibm.tivoli.tem.doc_9.2/Platform/Adm/c_using_relays.html%23c_using_relays.
TEM Relays allow an N-tier hierarchy to be created for the transmission of information from the TEM Clients to the TEM Server in the TEM Enterprise. Following are Frequently Asked Questions about TEM Relays.
What do TEM Relays do?
- TEM Relays "relay" information to and from the TEM Client and another TEM Relay or the TEM Server.
- TEM Relays enable TEM Clients to gather the latest information about new Fixlet messages, new actions, or new downloads.
- TEM Relays enable TEM Clients to pass status messages to the TEM Server including action results, retrieved properties, and relevant Fixlet messages.
- TEM Relays enable TEM Clients to register their last known IP address so they can be "pinged" later if there is new information to gather.
- TEM Relays enable TEM Clients to download patches and other files.
Do I need to find/buy a separate dedicated computer to be a TEM Relay?
- No! TEM Relays are specially designed to work on shared systems.
- Any TEM Client (on a supported TEM Relay OS) can be a TEM Relay.
- Most customers will deploy TEM fully without purchasing a single TEM Relay (even the largest deployments with over 3000 TEM Relays).
- It is very common to deploy the TEM Relay on server computers that already exist in the enterprise infrastructure. AV distribution servers, file servers, print servers, Active Directory servers, and more are all commonly used as TEM Relays. Server computers make a good choice because servers tend to exist in the same places you want to place a TEM Relay and they are rarely turned off; however, a server class computer is not a requirement of a TEM Relay.
- A TEM Relay uses minimal computer resources and is idle most of the time and it is designed to have minimal impact on a computer so there are no conflicts with other applications/services running on the same computer.
- TEM Relays do not need server-class fault-tolerant hardware because the nature of the TEM architecture makes the system fault-tolerant (because TEM Clients will automatically fail-over to other near-by TEM Relays in the event of a problem).
- TEM Relays can also be deployed on standard desktop computers with no problems. Examples from current customers include TEM Relays on secretarys' computers, kiosk computers in retail stores, IT administrators' computers, and deprecated old desktop hardware that would have been thrown away but instead were used as TEM Relays.
- TEM Relays require no additional 3rd party software (e.g., SQL Server, IIS, and other applications are not required for the TEM Relay).
Why use TEM Relays?
- Bandwidth Savings - Often the TEM Clients are not in the same geographic location as the TEM Server, and often the different locations are connected by thin network pipes. By downloading from a TEM Relay instead of the main TEM Server, the information about the action and -- more importantly -- any files associated with the actions only need to be transferred across the thin pipe one time to the TEM Relay instead of one time per TEM Client. The TEM Relay then distributes the information over the LAN to the TEM Clients. The result is a substantial bandwidth savings. Without TEM Relays, it would often be impossible to administer remote computers because of the bandwidth limitations.
- TEM Server Scaling - The TEM Server has a database and a webserver and is the central communication piece of the whole system. A single computer can only accept so many inbound connections from TEM Clients, TEM Consoles, etc. Without using TEM Relays, even a very powerful computer could easily be overwhelmed by only a few thousand TEM Clients. By using TEM Relays, you effectively distribute the load from the TEM Server to the TEM Relays allowing for the TEM Server to scale to handle many more TEM Clients, use less expensive hardware, and be more efficient.
How do TEM Relays work?
- TEM Relays are TEM Clients that are running two extra services (BESGather and BESRelay).
- TEM Relays act as a mini TEM-specific webserver.
- TEM Clients connect using standard HTTP on the specified port number (default 52311).
- TEM Clients will request downloads, the latest Fixlet sites, and the latest action sites from the TEM Relay.
- If the TEM Relay does not have the latest information, it gets the data from another TEM Relay or from the TEM Server.
- TEM Clients will send action results and retrieved property reports to the TEM Relay, which will bundle and compress them and send them to another TEM Relay or to the TEM Server (the bundling and compression also saves network bandwidth).
- TEM Relays will cache downloaded files so that it will not have to re-download the files if they are needed later. TEM Relays (default cache size is 1 GB, but is configurable) use a least-recently-used (LRU) cache replacement scheme for when the cache fills up.
How do you administer TEM Relays?
- Installing TEM Relays is done by using an "Install TEM Relay" task in the TEM Console to designate a TEM Client as a relay.
- To uninstall the TEM Relay, you simply run the "Uninstall TEM Relay" task in the TEM Console.
- TEM Clients can be told which TEM Relay to point to by using the TEM Console to set a TEM Client (or groups of TEM Clients based on properties like subnet, location, etc.) to use a primary and secondary relay.
- TEM Clients can also be set to automatically find their closest TEM Relays based upon network hops.
- TEM Relays can be manually set to create a hierarchy or the TEM Relays can establish a hierarchy automatically.
How does the TEM Client/TEM Relay Auto Selection work?
- TEM Clients will choose their closest TEM Relay by periodically "pinging" each TEM Relay to determine which relay is the closest based upon the number of network hops. The default TEM Relay selection period is 6 hours and is configurable.
- Each TEM Client will make a list of their closest TEM Relays. If they cannot reach their closest TEM Relay because it is off or down, they will try the second closest, and so on.
- If a TEM Client cannot find any TEM Relays or they are all down, the TEM Client will connect directly with the main TEM Server.
- If more than one TEM Relays are the same distance away from a TEM Client, the TEM Client will randomly choose amongst them.
What are the system requirements to be a TEM Relay?
Do you have a "best practices" list for maintaining a healthy TEM Relay deployment?
Yes. Please see the TEM Relay Health page for more information.
Top Level BigFix Relay Requirements *
|System Specs||Supported BigFix Clients (for child relays)|
|Dual 2.8 Ghz P4, 2 GB RAM||100,000|
|Dual 2.0 Ghz P4, 2 GB RAM||70,000|
|Dual 1.8 Ghz P4, 1 GB RAM||30,000|
|Dual 1.4 Ghz P4, 512 MB RAM||20,000|
|2.4 Ghz P4, 512 MB RAM||15,000|
|1.3 Ghz PIII, 256 MB RAM||10,000|