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traffic sent to all switches of the company


I'm doing backups of data contained in my windows 2k3 server SP2 standard to a NAS disk (Iomega Storcenter of 500 GB) using samba.

I'm connecting to a resource of the NAS to a drive letter.

I use a program for compressing data and then the same program for testing data.

When the test is made all the traffic is sent to all the switches of the company (all Cisco switches).

The server and the NAS are in different subnets of the LAN of the company.

But it's not always in testing when traffic is sent to all switches, one day debugging what is happening traffic sent to all switches when creating zip file.

Another backup is sent to the NAS disk but nothing happens (the traffic is sent directly to the NAS). The other server is a Win2k3 R2 SP2 server Standard but it's in the same subnet as the nas disk and connected at the same switch.

Packets have been captured and seem created ok, origin IP and destination IP are OK. Origin MAC and destination MAC are OK.

The only strange thing that i have seen is that is sent 24 ACKs to destination, 1 or 2 packets SMB and then another 24 acks 1 or two SMB packets,.... The ACK of the SMB packet is the same as the last ACK of the 24 sent.

Another strange thing is that some sometimes is sent duplicated ACKs.

Sorry for my bad english.


Re: traffic sent to all switches of the company

What you describe sounds like having symptoms of an issue that is known as "unknown unicast flooding".

The URL below explains the problem and may help you to resolve it:



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