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dimka___104021's avatar
dimka___104021
Icon for Nimbostratus rankNimbostratus
Jan 31, 2006

LB_FAILED, but pool is UP

Hi,

 

 

I'm terminating SSL on F5 and sending http requests to backend

 

Weblogic pool. In this pool i have only 1 member.

 

 

This part of irule logs failed pool information:

 

 

when LB_FAILED {

 

log local0. "[LB::server pool]:[LB::server addr]:[LB::server port] - status: [LB::status]"

 

}

 

 

In /var/log/ltm there're a lot of LB_FAILED errors.

 

But LB::status is always "up".

 

 

Jan 30 18:07:35 tmm tmm[13018]: Rule vs_1_irule : wl_pool:192.168.88.238:8000 - status: up

 

 

MSIE browsers show error "Page cannot be displayed". When i

 

change in TCP profile "Maximum Syn Retransmissions" to 12

 

(default is 4) all errors are gone. Everything works as it should.

 

 

Why LB_FAILED is triggered if LB::status is "UP"?

 

What does "max syn retransmission" mean and how high

 

number can affect performance?
application delivery
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  • dimka___104021's avatar
    dimka___104021
    Icon for Nimbostratus rankNimbostratus
    Jan 31, 2006
    Hi,

     

     

    I'm using http health monitor for pool with Interval=5 and Timeout=16 seconds.

     

    Same backend is used by our current iPlanet webserver and there're no issues/errors for clients.

     

    Through F5 i'm passing couple percents of whole traffic (approx. 100-150 active connections).

     

     

    tcpdump shows a lot of retransmission from F5 to backend:

     

     

    13:20:44.741601 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:20:45.941601 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:20:47.141602 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:20:49.341602 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:20:53.541601 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:21:01.741601 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

    13:21:17.941601 193.40.195.59.1867 > hnet.crebit.ee.8000: S 3215066501:3215066501(0) win 4380 (DF)

     

     

    p.s. And there're no errors on F5 interfaces