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madhava's avatar
madhava
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Jun 21, 2023

Http server node receives partial http request big-ip load balancer

I am trying to setup BIG-IP load balancer first time, here is my setup.

Client send traffic to virtual server and I have a node behind internal server. I am sending a simple get request to virtual server like

http://172.16.0.50 

But my node server not receiving comple http request seems like a partial one just "GET //". This is causing server reponding as "Bad request", what am I missing in settings? any help would be appreciated.

Attaching pcaps for reference, 172.16.0.50  is my VS , 192.168.1.50 is my internalip and 192.168.1.2 is my node ip.

Client

Server

 

application delivery
devops
  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Jun 22, 2023

    Hi madhava , 

    I see in the Pcap that no completed flow between client side and server side , Bigip Resets the connection when seeing the HTTP GET request , I see also this GET request maybe truncated , something corrupted in this Request and not follow the standard of http. 

    Please test the below steps : 
    1) change the standard http Virtual server to >>> Performance layer 4 , you have to remove http profile prior to changing the virtual server type. 
    Performance layer 4 Virtual server  means that >>> Bigip will forward all requests ( somehow acts as a router ) Not http Checks.

    2) repeat the Tcpdump command that I sent in the first reply , and upload it. 

    Let us see what will be the behavior and decide what is the suitable workaround for your issue. 

    Look forward to hearning from you soon 🙂 

  • Mohamed_Salah_'s avatar
    Mohamed_Salah_
    Icon for MVP rankMVP
    Jun 24, 2023

    Hello madhava ,

    Can you please provide us with virtual server configuraiton in both scenarios (standard, and performance)

    just type the below command after and before changing the virtual server configuration.

    #tmsh list ltm virtual "virtual server name"

    So we can start checking both output.

    Thanks,

    • madhava's avatar
      madhava
      Icon for Altocumulus rankAltocumulus
      Jun 27, 2023

      Hi Mohamed_Salah_ 

      I just started everything a fresh from the start (creating new VS etc...). It magically started working, I don't remember doing anything diffrent but worked (still not clear why it sends truncated http request), but some of the responses here helped to give some direction. I am good for now, will use these suggestions in future if I  encounter the issue again.

      Thanks

      Madhava

  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Icon for MVP rankMVP
    Jun 22, 2023

    Hi madhava , 
    First,  I'm reviewing with you your flow and Ips , So Am I correct in the below diagram according your configuration and design : 



    Please confirm : Do you use SNAT Automap feature or not in Virtual server properities , you must configure it !

    2nd ) 
    I need you to execute only one TCPdump command to capture the Client and server sides traffic at the same time and to make it clear to follow the http and tcp stream well. 
    use the below command : 

    tcpdump -nni 0.0:nnnp -s0 -c 100000 -w /var/tmp/capture.pcap host 172.16.0.2

#where 172.16.0.2 is the IP of your machine or your client ip address.

    using this command will capture all needed information in both sides ( Client & server side ) 
    Please attach it in your reply to have a look on. 

    Looking forward to hearning from you soon. 

    • madhava's avatar
      madhava
      Icon for Altocumulus rankAltocumulus
      Jun 22, 2023

      Hi Mohamed_Ahmed_Kansoh 

      Thanks! My fix not working anymore, after changing "Standard" to "Performance(HTTP)" it worked for brief period then I am seeing same issue again. This time I tried with SNAT "Auto Map", but no luck still has same issue as described originally, yes diagram you described is correct and I am not using any specific profiles in VS configuration everything I left as default. Here I am attaching TCP dump as you suggested, appreciate your help.,

      Thanks

      Madhava

      • Mohamed_Ahmed_Kansoh's avatar
        Mohamed_Ahmed_Kansoh
        Icon for MVP rankMVP
        Jun 22, 2023

        Hi madhava , 

        I see in the Pcap that no completed flow between client side and server side , Bigip Resets the connection when seeing the HTTP GET request , I see also this GET request maybe truncated , something corrupted in this Request and not follow the standard of http. 

        Please test the below steps : 
        1) change the standard http Virtual server to >>> Performance layer 4 , you have to remove http profile prior to changing the virtual server type. 
        Performance layer 4 Virtual server  means that >>> Bigip will forward all requests ( somehow acts as a router ) Not http Checks.

        2) repeat the Tcpdump command that I sent in the first reply , and upload it. 

        Let us see what will be the behavior and decide what is the suitable workaround for your issue. 

        Look forward to hearning from you soon 🙂 

  • madhava's avatar
    madhava
    Icon for Altocumulus rankAltocumulus
    Jun 21, 2023

    It seems like worked after changing virtual server type from "Standard" to "Performance(HTTP)", Weired but works ðŸ™‚

    • Paulius's avatar
      Paulius
      Icon for MVP rankMVP
      Jun 22, 2023

      madhava In order to figure out why it wasn't working it would be helpful if you could provide the virtual server configuration, pool configuration, and any associated profiles configured on the virtual server when it wasn't working. Switch from Standard to Performance(HTTP) should fix an issue like this and most likely another setting is no longer available that was configured in the standard virtual server and that is why it's working now.

      • madhava's avatar
        madhava
        Icon for Altocumulus rankAltocumulus
        Jun 22, 2023

        Hi Paulius Thanks.

        Unfortunately my fix of changing type from "Standard" to "Performance(HTTP)" is short lived, now I am again seeing my original issue. As  suggested by Mohamed_Ahmed_Kansoh earlier I configured SNAT setting as "Auto Map" but no luck. My VS settings are all default except I selected 80 as port and Ip address, I can provide any specific information you want, here is a snap shot of it. I have a single node server in the pool which is basic http server. Server does establish TCP connection but receives only part of HTTP requests (no http version or uri info) causing server responding with bad request error 400 .

         

        Thanks

        Madhava

         

    • whisperer's avatar
      whisperer
      Icon for MVP rankMVP
      Jun 22, 2023

      I would be interested in root cause here as well. You can always allocate another VIP on client side referencing the same pool. This would allow testing at leisure. Performance HTTP loses quite a bit of capabilities when it comes to traffic modification.

       

  • whisperer's avatar
    whisperer
    Icon for MVP rankMVP
    Jun 22, 2023

    So, you must have self IPs in VLAN used for Virtual Servers on the F5. Does the internal network have a route for this subnet pointing to the floating self IP on the F5? Sounds like the server is not routing the connection back via the F5. Could have async routing in play.