[j-nsp] EX4550 (Un-)known unicast flooding at session start for up to 100ms

[Tim]

Hi Brian,

yes we're using MSTP. The bridge-priority of EX4550 and QFZ are all on
default (32k afaik), because the QFX is connected to a Cisco 6500,
which is the Core.

We're in the middle of a Cisco -> Juniper migration.

regards,
Tim


2017-08-11 16:55 GMT+02:00 Brian Nelson <brian.nelson at utdallas.edu>:
> Tim,
>     Basic question: do you have spanning tree enabled and what is the
> bridge-priority of each boxen?
>
> Brian Nelson
>
>
> On 8/11/2017 5:00 AM, Tim wrote:
>
> Hi everybody,
>
> the last half year (since we extend some monitoring/logging things) we
> observe multiple times a day strom control triggering across the
> network. We could trace it back, that it happen on a regular basis if
> heavy stream are initiated (database copy jobs, vmotion stuff, etc.)
> it seems that the EX4550 Switches in the data path needs up to 100ms
> for mac learning unit he stops the (un-)known unicast flooding.
> Because of the heavy nature of the traffic streams we are talking
> about 7-8 MB flooded traffic during the 100ms.
>
> The topology is quite simple and straight.
>
> SRV1 - EX4550 - QFX5100 - EX4550 - SRV2
>
> With a sniffing server attached to a normal port on the EX4550 Switch
> near SRV1. Normal port means, that it is of course not a mirror port
> to only got the flooded stuff.
>
> We've open a case at our service partner, but recieved a at least
> disputable answer "Hey, works as designed. Normal behavior like Cisco,
> etc.)"
>
> In my personal 15 years experience with Cisco, Extreme/Enterasys
> Networks and Nortel Networks i've never see this magnitude of MAC
> learning latency / unicast flooding.
> If i imagine that this behavior is normal, it would mean that just a
> dozen concurrent heavy streams would fuck up all other ports and even
> a 40G uplink has no chances and gets heavily overloaded in this time
> frame.
>
> What brings me to my question. Does anyone here have any experience
> with "typical" MAC learning latencies or similar problems with Juniper
> / $vendor like this?
>
> Best regards,
> Tim
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