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

[Marcin Kuczera]

Well,
I'am recalling my issue, maybe someone has a proper contact to someone 
from Extreme R&D.

at the moment we have about 13k in FDB, and up to 25Mbit/s of 
unknown-unicasts traffic...
This is getting nasty...

I need to know if x650 has a probablity that not all MAC may be 
represented in FDB (still below 32k limit).

Regards,
Marcin




Marcin Kuczera wrote:
> 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
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