HP switch ....Port Flapping ....

[Sashasor]

Recently we have port flapping in all  HP switches ... Does anyone know why ? and how we cant prevent this ? because it cause network performance issue in our network ...

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I 06/28/16 08:12:31 00076 ports: port B6 is now on-line
I 06/28/16 08:12:32 00077 ports: port B6 is now off-line
I 06/28/16 08:12:35 00076 ports: port B6 is now on-line
I 06/28/16 08:12:35 00077 ports: port B6 is now off-line
I 06/28/16 08:12:38 00076 ports: port B6 is now on-line
I 06/28/16 08:12:39 00077 ports: port B6 is now off-line
I 06/28/16 08:12:42 00076 ports: port B6 is now on-line

[TerjeAFK]

Have you had these switches for a long time, and this only started recently? Have you made any changes to the network lately? Upgraded firmware on the switches? Do the logs say anything besides ports going down and up?

[parnassus]

And also: which device type is connected to that B6 port? was its configuration changed (both on Device side and on Switch side)?

In the past I had an issue with a printer that caused a similar behaviour...setting on the Printer's NIC and on the related Switch's port the Speed from Auto to (say) 100M fixed...resolved the issue immediately. No more port flapping.

[TerjeAFK]

He said "in all  HP switches" so I'm assuming this must be more than just one buggy endpoint.

[parnassus]

Yep but, as example, he reported what's happening on a very specific port (a B6)...what he described was a little bit unclear or uncomplete (to me) and so I shared my experience based on very few assumptions I'm able to do reading what he wrote (for sure: port B6's log).

Without any other relevant data I often like to follow the Occam's Razor principle: exactly the widespread layman's formulation that "the simplest explanation is usually the correct one" (from Wikipedia).

If I've a lot of Switches and they all report port flapping all around (on different ports) then I would do a deeper diagnostic than a copy&paste (of just one port's log of a unkown Switch), just to provide a better description of what is really going on on the entire net. Wouldn't I?

[16again]

Power saving on NICs can also cause this. When idle, link speed is reduced, resulting in down/up event in switch. 

[Vince-Whirlwind]

Find out what device is connected to B6 on that switch.
Find out how the device is being used, what it should be doing, what it isn't doing, and what it is doing.