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senthil147_1421's avatar
senthil147_1421
Icon for Nimbostratus rankNimbostratus
Jun 06, 2017

F5 LTM sending reset packets to Pool member

F5 LTM has a pool member listening on port 8003 and its mainframe server. Pool member is UP but Mainframe console shows consistently F5 is rejecting the connection ( No issues in accessing the VIP )....
BIG-IP
LTM
security
senthil147_1421's avatar
senthil147_1421
Icon for Nimbostratus rankNimbostratus
Jun 07, 2017

HI

 

I have enabled reset cause in the logs and I see following error.

 

What does this mean also no issues reported in accessing the VIP. its purely communication between LTM to Node.

 

Jun 7 07:04:08 local/tmm2 err tmm2[6122]: 01230140:3: RST sent from server91.test.com:8003 to 172.31.x.x:53005, [0x11ca629:5165] RST from BIG-IP internal Linux host Jun 7 07:05:08 local/tmm2 err tmm2[6122]: 01230140:3: RST sent from server91.test.com:8003 to 172.31.x.x:53005, [0x11ca629:5165] RST from BIG-IP internal Linux host

 

  • dragonflymr's avatar
    dragonflymr
    Icon for Cirrostratus rankCirrostratus
    Jun 07, 2017

    Hi,

     

    If I can recall RST from BIG-IP internal Linux host is most often related to monitor. Are you using monitor for your Pool or nodes? If so is it marking members/nodes up - guess yes so maybe this counter is unrelated to your issue.

     

    Best option is to trace connection on both sides of BIG-IP:

     

    client -> VIP

     

    BIG-IP -> mainframe

     

    Original trace looks just fine, there is 3WHS, some packets from mainframe to BIG-IP, ACK for those frames and then RST

     

    To be honest it looks like monitor connection from BIG-IP, is src IP 172.31.x.x for packets == to self IP on VLAN facing mainframe?

     

    If so this is most probably monitor traffic - what monitor are you using for your pool/nodes? Is pool monitor http?

     

    HTTP monitor is issuing RST if it received expected Receive String and more packets are coming from monitored host.

     

    Piotr