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Yannick_Vranck1's avatar
Yannick_Vranck1
Icon for Nimbostratus rankNimbostratus
Sep 16, 2017

F5 BIG IP LTM & Assymetric Routing

Hello,

 

We have an operational case where the F5 is presented with Assymetric Routing, the routing does not occur when the traffic needs to be load balanced but when the traffic is heading back out to form a response.

 

The traffic will leave the pool towards the F5 (being the default gateway), but when it leaves the VIP it will find another route towards the client. The F5 should map the client's source address using the auto-last hop feature if i am not mistaken, but does it make a difference if the path is different?

 

I would say yes as we are confronted with the scenario:

 

  • Connection towards FTP servers via the BIG IP caps the connection out at 15 Mpb/s, when the traffic leaves the VIP to get back to the client it will take more hops back then the traffic came into the VIP

     

  • Connection towards the FTP servers and not via the BIG IP will give us 2,5 Gbp/s and the same scenario exists, the response from the server is router via another way it came in.

     

I have tried setting a TCP profile for loose initation and loose close, but that does not seem to work.

 

We have the issue with VIP's doing FTP,RDP & HTTP.

 

application delivery
BIG-IP
LTM

1 Reply

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  • Stanislas_Piro2's avatar
    Stanislas_Piro2
    Icon for Cumulonimbus rankCumulonimbus
    Sep 17, 2017

    Hi,

     

    FTP behavior opens a new tcp connection for data channel.

     

    Auto last hop is recorded in connection table for each connection. The data channel and control channel connections are 2 different connections and doesn't share auto last hop.