[e-nsp] x650 and MAC addresses missing in FDB ????

[Marcin Kuczera]

Marcin Kuczera wrote:
> hello,
> 
> I have noticed an issue, that sometimes some mac addresses are not 
> visible in FDB on x650 stack.
> 
> I have several x450 in chain-patch from customer and then x650 where 
> router is connected to.
> 
> I could see MAC addresses for particular hosts in all x450 chain, but it 
> was missing in x650 for most of the time. Then sometimes it appeard.
> 
> How do I catch them ? I'am monitoring unicast flooding on all vlans and 
> I have a lot of such cases...
> 
> 
> EXOS release is 12.5.4.5 v1254b5-patch1-4
> numer of MAC addresses in FDB osscilates around 14k max, but this is not 
> a problem because fdb capacity in x650 is 32k.
> 
> Nothing in logs..
> 
> It is not tooo nasty, but I'am wondering if it is not some bug that may 
> affect some other services, i.e. multicasts.

well, I spoke to an extreme engineer and he mentioned, that this might 
be some issue related to fdb hashing mechanism..

It is supposed to be multi-level hashing, however it might be, that the 
lowest level "container" capacity, that contains whole MAC address - is 
limited.
So, if there are some MAC addresses that will match this lowest level 
"container", and let's say - the limit per "container" is 16, and we 
have 17th MAC matching - it will not be placed there due to no space, 
and the traffic will be flooded...


Is there anyone here that could verify this thesis ?
How do I debug it ?


Regards,
Marcin