On Thursday, January 26, 2012 02:57:59 AM George Bonser wrote:
If there is a hardware change, you might need to update the FPGA images. That is a second file but doesn't happen with every release. In fact, you might not even need it of they DO release a new one because the change might be for the addition of FPGA images or changes to an image for blade you don't even have. But again, it is one combined file for all blades.
The issue we have now with IOS XR-based systems is the SMU's. Most times, the SMU's need to reload bits of the hardware, and it will be different files making different updates that each need to reload bits of the hardware (fabric, line cards, e.t.c.). Needless to say, a software upgrade of the main OS on IOS XR systems is very lengthy. I'm yet to do it in less than one hour, particularly if you're doing SMU's at the same time. Here, Junos wins (although, in all fairness, the systems aren't the same so maybe not a proper comparison to begin with). But I understand Cisco are working on streamlining this in future releases of IOS XR, which would be welcome. While I prefer SMU's to ISSU, the majority of them are not entirely hitless (contrary to the documentation accompanying an SMU), although it will take a shorter time to update via an SMU than the main OS, as of today anyway. Mark.