IBM REDP-4372-00 manual Network Bandwidth Considerations, Unicast, Multicast

4372ch06.fm Draft Document for Review November 15, 2007 3:27 pm

6.3 Network Bandwidth Considerations

Depending on the number of computers you are deploying simultaneously and on your infrastructure, you should select one of the following networking modes:

6.3.1 Unicast

Use unicast if you are deploying computers one by one, or if your network administrator does not allow you to use multicast.

Note: that when deploying several computers simultaneously in unicast, the deployment time will tend to increase dramatically with the number of clients, as the result of network saturation

6.3.2 Multicast

Use multicast without explicit synchronization to use Tivoli Provisioning Manager for OS Deployment soft-synchronized multicast protocol. Using this protocol, every client will independently start downloading images at soon as it is ready, and continue with the deployment as soon as it has downloaded all required material. But when two or more hosts (using the same deployment scheme) are downloading files in parallel, they will automatically share the same bandwidth using a multicast protocol. The fastest client will have the priority for the choice of the next shared files that will be sent by the server, but the slower clients will also be able to receive them if they need them. This is a scalable solution that nevertheless allows for a rolling deployment scenario.

6.3.3 Multicast with synchronization

Multicast with synchronization to use a classical synchronized multicast method. This mode is adequate when you want to install computers by batches. You must then enter the synchronization parameters, e.g. the number of hosts to wait for before starting the download, and the maximum timeout before starting anyway. You can also select an upper bound to the peak network bandwidth used by the file downloads. It may be useful to set a limit in case the network is used for other services or to avoid the saturation of old routers. The bandwidth limitation boundary value is indicative. Depending on the hardware of the server, the client and the network components, the exact throughput may change. You can choose between no bandwidth limitation and limitations down to 2 Megabits per second.

132Tivoli Provisioning Manager for OS Deployment in a Retail Environment