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6807xl + SUP2T IOS upgrade: 15.2 or 15.5

I'm performing an upgrade of a single-sup, VSS pair of 6807xl, and wanted to get anyone's feedback on the stability or critical features of either 15.2 or 15.5 IOS. both are MD release right now. 15.2 has been around a fair bit longer. im running older 15.2 and may just patch this to the newest release of 15.2 or go to 15.5. Any comments/feedback, etc? TAC doesn't like to recommend IOS.

Leo Laohoo
VIP Community Legend

Kindly read the Release Notes very carefully.
If it is possible to upgrade the ROMMON (even though it is not required), do so.
Reza Sharifi
Hall of Fame Expert


Is the recommended version by Cisco but reading a feedback, it say that this version is not stable and had cause 6807 VSS to produce tracebacks which is not good. So, he loaded 15.5.1-SY3 and everything is stable now. Read the release notes carefully and I would use SY3.


Same here, Reza.
We're starting to load 15.5(1)SY3.

Thanks, Leo!

Let me know how it goes. I need to upgrade a set of 6807 VSS as well.


Thx guys lots of good information here! Any thoughts on sticking with the latest version of 15.2? Any major features advantage of 15.5?
Leo Laohoo
VIP Community Legend

The Release Notes should be everyone's first call.
Read it because it will provide a wealth of information as to Open and Closed bugs, new features introduced, gotchas, hardware support, etc.

thx for everyone's feedback. in the end, I made the choice based on features and bug counts; and the advice that the 15.5(sy4) image had VSS issues.


looking at resolved caveats for the last 2 - 15.5 releases, i see ~25 resolved bugs. for the latest releases of 15.2(SY8), i see only 1-2 resolved caveats. this implies the bug count should be fairly low in 15.2.


in scanning 15.5 features, i didn't see anything compelling, compared to 15.2, so sticking with 15.2. If anyone knows of anything, please chime in.


Will also attempt rommon upgrade, as that seems like a nice precaution: pyramid_rm2.srec.122-50r.SYS4


the bug im trying to address is inability to look at log in the buffer on the device. its kind of hard to work on the thing, with no quick, easy real-time logging:


Doing upgrade in about 1 week, waiting for maintenance window now. :)