3 Replies Latest reply on Jul 10, 2011 9:21 AM by Ian

    Multicast (cache only)




      I cannot find a description of exactly how Multicast (cache only) works.


      Do I just include all the machines I want to push to, in my scope, and the Multicast (cache only) delivery method will choose a few of the best reps to deploy to? Then when I do my policy-push it will download from these cache reps to do the installs?


      I just want to make sure I have the right methodology on this feature.




        • 1. Re: Multicast (cache only)

          The following information was taken directly from the ldmsuser.pdf manual


          Multicast (cache only):


          Multicasts the package to the target devices, no other action is

          taken on the managed device. The result is the package is cached locally on managed

          devices. Use this option to multicast the package to a few devices on each multicast

          domain. You can then create a task that uses the Peer download (only install from

          cache or peer)option. This allows you to regulate network bandwidth used for the

          distribution so it doesn't span multicast domains






          • 2. Re: Multicast (cache only)
            Catalysttgj Expert

            "Cache only" bit means its going to just park the files in the cache on the targeted machines. It won't do anything else with them on the targeted machines. This is a future use prep step. Saves time when you get ready to actually make the stuff install. This is a good thing if you have some really large payload involved and you want to have a tight window for the actual installation from time of deployment.


            Multicast means its going to push a copy of the payload to a subnet rep, then the remaining devices in that subnet are going to pull from the subnet rep that has the copy saving the pipe usage back to your core. When you put these two things together Multicast + Cache only, you're basically just getting the payload out to all your stuff at once. You could just select a computer or two from every subnet, and target those and "cache only" the files. Then when the times comes to push the installation, the devices that don't have the payload are still going to look for a peer to copy the payload from, before going back to the core to get it. In other words, if the payload isn't terribly big, and the subnets are plenty fast to copy a file from a local peer, you may get away with this method, but then why bother when you could just multicast + cache only to ALL the machines involved? That way the payload is already in place everywhere.


            Be careful with multicasting for the first time. You may flood your network with the wrong settings. We actually discovered significant flaws in 8.7 agents doing this. I think those flaws are all gone now, but ya never know. Do some tests first, and make sure you're not going to kill anything.


            Good luck!

            • 3. Re: Multicast (cache only)


              What you refer to as "cache reps" are the devices that will do the local multicastion on the different subnets. As you say they are chosen dynamically (by default). The files will be in their cache but they will not try and install. The files will also end up in the cache of any devices that you chose as targets for the job. So at the end of the job both the Multicast Domain Reps and the Targets will have the files in cache but will not attemptto install the software. When you start another job to install the software the target devices for the second job will find the files already in the cache of local devices.