Whats so difficult about ISSU

Fri Nov 9 04:13:26 UTC 2012

On Thu, 8 Nov 2012, Phil wrote:

> The major vendors have figured it out for the most part by moving to 
> stateful synchronization between control plane modules and implementing 
> non-stop routing.

NSR isn't ISSU.

ISSU contains the wording "in service". 6 seconds of outage isn't "in 
service". 0.5 seconds of outage isn't "in service". I could accept a few 
microseconds of outage as being "ISSU", but tenths of seconds isn't in 
service.

> The main remaining hurdle is updating microcode on linecards, they still 
> need to be rebooted after an upgrade.

... and as long as this is the case, there is no ISSU. There is only 
"shorter outages during upgrade compared to a complete reboot".

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se