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

[Tim Harman]

Hi,

Have just encountered a situation where a 1GB/s customer sending me
~800Mb/s of traffic caused a number of Aggregated Interfaces running
LACP on EX series switches to start flapping.

The switches themselves are all interconnected using 2 x 1GB ae's.
There's no spanning tree in the network.

The customer has explained they did something which caused a storm
in their network, which fed into us.  We have both storm control
(which triggered, but was only configured to drop traffic, not
disable ports) but also an ingress filter of 100Mb/s

This policer seems to have worked, but other switches upstream that
saw the ~100Mb/s of "bad" storming traffic also started flapping
their LACP interfaces.

JTAC thus far has given me a few vauge answers like "lots of traffic
could swamp the CPUs".  No doubt there was lots of mac flapping - but
I'd have thought that, bad though it is, it shouldn't cause the CPU
to forget to do its other tasks like keep LACP alive.

Anyone encountered anything like this before?  Any ways to mitigate?

As one of the fixes, I'll look at enabling storm control to shut
down the customer's port.  I'd much rather just let the customer go
nuts with their 100Mb/s limited storm though.

If anyone's interested, PM me privately and I'll let you know the
final outcome of the JTAC case (if there is one)

Regards,

Tim