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Community Member

Am i having an issue

Hi all,

I have just done a packet capture on my Cisco 3750G VLAN that hosts all our servers. I am noticing a load of [TCP Dup ACK], [TCP Out-of-Order], [TCP Fast Retransmissions] packets on that segment. Is this something that is expected on a switch that is sending traffic between two devices in the same VLAN on the Same Switch ?

The most concerning thing is the [TCP Out-of-order] packets, this is because i tried to plug in a Pix535 Firewall and it appeared to cause issues with internet traffic, then i read somewhere that the FragGuard (which cannot be turned off in Version 7) will not accept fragmentation packets out of order. I really need to resolve this issue so if anyone has any explinations to whats going on or any help/advise in diagnosing this ?




Re: Am i having an issue

Are you using "teamed" NICs from your server to the switch?

This is basically Etherchannel and the traffic will be rotated through the group links.

If you somehow managed to use different bandwidths for one of the links, I could see something happening like you describe.

Good Luck


Community Member

Re: Am i having an issue

Hi Scott,

Thanks very much for your reply. We are not using "Teamed" NICs however one of the servers is WNLB and one of the WNLB is off-line. We also have two of the fibre ports plugged into two Nortel Passport switches using the PortChannel command on them ports. I have not really been looking at this side of the switch because the issues are just with two servers on the Gig Copper Ports.

Any other suggestions ?



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