Overview - Cisco Explorer Series Staging Manual

Appendix C
Setting Up Multiple Bootloader Carousels

Overview

This section discusses the benefits of using multiple bootloader carousels and
provides examples of ways you might configure multiple bootloader carousels.
With multiple bootloader carousels, the BFS can send set-top software version
images using more than one carousel. This enhancement gives you the flexibility you
need to reduce download times and maintain system performance by creating the
optimal number of bootloader carousels for your system.
Note: You must have DNCS System Release 4.3 or later to use the multiple
bootloader feature.
Why Use Multiple Bootloaders?
Using more than one carousel can help you use the Broadcast File System (BFS)
more efficiently. The packet interleave algorithm used by the DNCS allows a 1 MB
image (file) to download in the same amount of time as an 8 MB file. In each case, it
takes one full revolution of the carousel.
One way to optimize the carousels is to arrange the files so that each carousel is
approximately the same size. Another option is to put the images for the new types
of devices being staged (M-Card modules and hosts, for example) on one carousel
and put the images for all legacy types on another.
We recommend that you place the images of similar devices on their own bootloader
(for example, standalone M-Card module images on one bootloader and SSC set-top
images on another). That way, you can keep the image sizes and cycle times
appropriate for each device type.
Important: When you use more than one carousel, you should make certain that the
BFS QAM has enough bandwidth to support a second bootloader carousel. Go to
Determine Available Bandwidth for Multiple Bootloaders (on page 136) for more
information.
134 734375 Rev H