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C-6509 Tengigabit port doesn't learn the address of one server.

For a performance problem, I did a SPAN on a C-6509 and captured traffic with WireShark,

and I figured out my 6509 was flooding the trafic destined to server (this is a big NetApp server)

This trafic is overflooding my network (300Mb/s)


This server is on port Ten1/2 of C-6509_02.  (I have 2 x C-6509 with the same hardware configuration).


I checked the mac-address of the server in the "show mac-address dynamic" display, and I discovered this mac-address is not learned by the switch.


Consequently, in order to prevent this flooding, I configured a mac-address static on port Ten1/2, with the mac-address of this server.

The flooding of the traffic to stopped immediatly.


My 2 x C-6509 have exactly the same IOS release and the same hadrware configuration.


On port Ten1/2 of C-6509_01, I have a server PYRBU06 and its mac-address is well registered dynamically.

On port Ten 1/2 of C-6509_02, I have a server PYRBU05, of which the mac-address cannot be learned by the switch.


Anybody has an idea of why my C-6509_02 doesn't learn the mac-address of server PYRBU05 ?


Thank you for any help



I join the configurations of both C-6509


Re: C-6509 Tengigabit port doesn't learn the address of one serv

Do you have any traffic toward or from PYRBU05?

If you don't have traffic, try to force some (ping from a L3 device PYRBU05) and see if mac-address appear on the interface where this server is connected.

The reason behind is that if you didn't had traffic for some time, then the mac is flushed from the mac-address table and it need some request to learn it again (like an ARP request).

Let me know if this is the case.

New Member

Re: C-6509 Tengigabit port doesn't learn the address of one serv

thank you for your posting Calin.

The PYRBU05 server is a big NetApp  server with a lot of traffic (300 Mb/s input traffic to the server)

Of course it was possible that we had a lot of traffic TO this server, without any traffic FROM the server, thus preventing the switch from learning the MAC-address.

Thi is the reason why, I sent many PINGs to the server before configuring a static mac-addr in the switch.

By the way, on the second 6509, I have a second NetApp PYRBU06 on the same port (Ten1/2) and this second one works fine.

So I'm still waiting for any idea from somebody


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