[c-nsp] ISSU on SXF -> SXI

Phil Mayers p.mayers at imperial.ac.uk
Fri Feb 12 07:29:50 EST 2010

On 12/02/10 12:20, Jason Shearer wrote:
> It is my understanding that ISSU will be supported for the same feature set in the same dev line.
> IE - Will work going from SXI to SXI3 but will not work going from SXI to SXJ. (I know J doesn't exist yet).
> Is this how everyone else understands ISSU?  Any other known restrictions?

Sorry, yes - I'm confusing things. There are 3 scenarios:

  * The old and new image are not ISSU-compatible (different major 
releases or feature sets) - in which case an RPR upgrade is the best you 
can do.

  * The old and new images are ISSU compatible, and the linecard 
software has not changed. In this case, the linecards do not need to be 
restarted, and downtimes of 0-3 seconds can be achieved because it's 
basically just an SSO switchover.

  * The old and new images are ISSU compatible but the linecard software 
is different, so the linecards need to be restarted into the new image - 
this can be a faster, warm boot (if the linecard has enough RAM) or a 
slower, cold boot (if not)

I think that's about right?

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