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Community Member

TCP Fast Re-transmissions

Hello,

After running a coupple different protocol analyzers I am seeing 10,000+ fast retransmissions.  Could this be an issue?  I have a lot of clients complaining about slow server response time, and I'm wondering if this could be causing it.

What would cause these fast transmissions to happen?  Any ideas on how to address this?

Thank you,

Scott

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3 REPLIES

Re: TCP Fast Re-transmissions

Re-transmissions of TCP packets can happen due to network congestion, traffic load balancing, or other unpredictable network behavior, IP packets can be lost or delivered out of order. TCP detects these problems, requests retransmission of lost packets, rearranges out-of-order packets.

Is this happening only with single server or to whole VLAN.

Regards

Ganesh.H

Community Member

Re: TCP Fast Re-transmissions

Hi Ganesh,

Thank you for your response; I am seeing these retransmissions primarly on my Exchange Clusters, and our clients are complaining about performance issues.  Unfortunately I'm working on an older network and the servers/clients all reside on the same /16 network (VLAN 1).  Is there anything I can try to help alleviate these retransmissions?

Thank you,

Scott

Re: TCP Fast Re-transmissions

Check out the NIC configuration of the cluster server, If the server NIC are teamed with ACTIVE/ACTIVE configuration then try with ACTIVE/PASSIVE configuration and do check the duplex setting from server end and switch end also.

Regards

Ganesh.H

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