[j-nsp] EX series - LACP flapping during ethernet storm.

[Pavel Lunin]

> While those links discuss how the box performs load sharing,
> it isn't actually configurable at all,
This is exactly what I tried to point out when Richard proposed to use 
Broadcom Trident+ as an LSR PFE. EX3200 uses, AFAIR, Marvell something, 
but I don't believe Trident+ much differs in this.
>   nor does it work. The
> issue also affects the EX3200, but not sure about the rest
> of the EX family.
I saw plenty of EXes doing more or less smooth LB both on LAGs and ECMP.

But. It is true that EX does not share traffic sent from its control 
plane (said to be by design). Such traffic always goes to the first 
link. We also ran into issues with L3 ECMP sharing (9.x) and traffic 
from control plane. EX just dropped half of the flows, causing routing 
protocols not working, etc. JTAC did not even understood what I am 
talking about.

I'm almost sure any flooded traffic will also go to a single link.

And, yes, under certain conditions it's not that impossible to have all 
the flows with the same hash-key mod number-of-links value. I saw it myself.
> We opened a case with JTAC and they confirmed that a
> hardware limitation means the switch doesn't actually do any
> kind of load balancing over LAG's. JTAC said there are some
> internal discussions to write software to "sort of make it
> load share", but that's not definite.
We've also been told this strange thing. For some reason. Just don't 
listen :)  I remember at least four cases on LB for EX. Most of which 
were total epic fails from JTAC. When it came to ECMP they just got 
stuck full and truly and I gave up.