Forum Discussion

John_Heyer_1508's avatar
John_Heyer_1508
Icon for Cirrostratus rankCirrostratus
Dec 13, 2014

How do I enable the TCP Window Scaling option?

I've been doing some performance tests uploading and download large files over SSL with an F5 LTM in the middle. The virtual server setup is standard, using the default tcp profile.   In most per...
application delivery
deployment
LTM
performance
TMSH
  • nitass_89166's avatar
    nitass_89166
    Dec 13, 2014

    what version are you running? have you tried to increase send/receive buffer e.g. 65536 bytes?

    Note: Beginning in 11.4.0, the window scale functionality is built into the TCP profile and cannot be manually disabled or enabled; it will be negotiated if the send or receive buffer is larger than 65535 bytes.

    sol7559: Overview of the TCP profile

    https://support.f5.com/kb/en-us/solutions/public/7000/500/sol7559.html
nitass_89166's avatar
nitass_89166
Icon for Noctilucent rankNoctilucent

what version are you running? have you tried to increase send/receive buffer e.g. 65536 bytes?

Note: Beginning in 11.4.0, the window scale functionality is built into the TCP profile and cannot be manually disabled or enabled; it will be negotiated if the send or receive buffer is larger than 65535 bytes.

sol7559: Overview of the TCP profile

https://support.f5.com/kb/en-us/solutions/public/7000/500/sol7559.html
John_Heyer_1508's avatar
John_Heyer_1508
Icon for Cirrostratus rankCirrostratus
Dec 13, 2014
That's probably something to do with it. I had created a custom TCP profile in order to turn on Rate Pace (which significantly speed things up) and also set these per F5 recommendations: Proxy Buffer Low: 98304 bytes Proxy Buffer High: 131072 bytes Send and receive buffer are not changed though: Send Buffer: 65535 bytes Receive Window: 65535 bytes