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kcfedun_309158's avatar
kcfedun_309158
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Feb 07, 2017

F5 Causing TCP DUP ACKs and Retransmissions

Hi All,

I have a setup where making a connection to a web service directly works very well and fast, but when I try to connect to the same device via a virtual server with it as a pool member, the web page will take a long time to load and packet captures on the pool member itself will show lots and lots of TCP Dup ACK packets coming from the f5. The page eventually loads, but it's unbearable and is causing a breakdown with some other tools that are also leveraging this VS connection. Guessing there is some tuning to be done on the virtual server but am not sure what to adjust. Have attempted using all pre-built TCP profiles to no avail.

Thanks for your help!

config  tmsh list /ltm virtual

ltm virtual vs_oo-lb {
destination 192.168.2.3:pcsync-https
ip-protocol tcp
mask 255.255.255.255
persist {
    dest_addr {
        default yes
    }
}
pool pool_oo
profiles {
    tcp { }
}
source 0.0.0.0/0
source-address-translation {
    type automap
}
vlans-disabled
}

2 Replies

  • Dear kcfedun,

     

    Were you able to find out the root cause for this problem. I am interested in it as I am seeing a similar issue and suspect that it might be related to Early retransmission on the system.

     

    Regards