Forum Discussion

ZAHIDHASEEB's avatar
ZAHIDHASEEB
Icon for Nimbostratus rankNimbostratus
Nov 26, 2019
Solved

Does F5 load balancer intelligent in case of ports are down

Does F5 load balancer intelligent in case of ports are down? Suppose, if there are 2 servers behind F5 load balancer and in case application got down(who is listening on port 80) on one server so how can the F5 load balancer stop sending transactions on infected machine.

devops
LTM
  • Heinrichm5's avatar
    Heinrichm5
    Nov 27, 2019

    It depends on where you've added your health monitor and how you've configured it

    Typical scenario: you want the other ports to remain active after a single port has stopped responding

    You need to have configured several pools, each with their own port, eg

    PoolA:

    name: http_pool

    members: 10.10.10.10:80, 10.10.10.12:80

    monitor: tcp_half_open (no port denfined in the monitor settings)

     

    PoolB

    name: https_pool

    members: 10.10.10.10:443, 10.10.10.12:443

    monitor: tcp_half_open (no port denfined in the monitor settings)

     

    If 443 stops responding 80 will still work. Same if it is the other way around.

     

    The monitor can be configured in the GUI

    Selecting a monitor: Local Traffic > Pool > Select your pool > find the monitor in the right window and move it to the left

    Creating a custom monitor: Local Traffic > Monitor > Create

     

5 Replies

Sort By
  • nathe's avatar
    nathe
    Icon for Cirrocumulus rankCirrocumulus
    Nov 26, 2019

    Zahid,

     

    In this case, the bigip will mark the faulty pool member as Down and new connections will only get directed to the healthy pool member. Existing connections are dealt with by the "Action on Service Down" setting see link

     

    Hope this helps,

     

    N

  • Simon_Blakely's avatar
    Simon_Blakely
    Icon for Employee rankEmployee
    Nov 26, 2019

    It is the job of the monitor assigned to the pool or node determine whether a service is available.

    If the monitor fails, then the pool member (or node) is marked down, and the pool member will not be selected during load-balancing.

  • Vijay_E's avatar
    Vijay_E
    Icon for Cirrus rankCirrus
    Nov 26, 2019

    You would have to configure the monitor that is attached to the pool to check relevant application by performing GET or HEAD. Monitor helps to detect if the pool member is down.

     

    The action to be performed after the pool member is detected to be down is seen here.

    • ZAHIDHASEEB's avatar
      ZAHIDHASEEB
      Icon for Nimbostratus rankNimbostratus
      Nov 27, 2019

      Currently I am reading the referred link regarding the monitoring actions or behavior which you shared in last post.

      As per my understanding in case the provided service/port is down on node behind F5 LB then the node will be marked as down and F5 LB will not entertain the new connections until the port on node UP again. Now here I have another concern. Actually my node hosted an application which receives connections requests on different ports means different services are LISTENING on different ports. Suppose if a single port become down then complete node will be marked as down and the rest of ports will also not be able to facilitate the new connections

       

      Second point. Does the monitor configuration setting is available thru GUI. Please share any technote if available

      • Heinrichm5's avatar
        Heinrichm5
        Icon for Altocumulus rankAltocumulus
        Nov 27, 2019

        It depends on where you've added your health monitor and how you've configured it

        Typical scenario: you want the other ports to remain active after a single port has stopped responding

        You need to have configured several pools, each with their own port, eg

        PoolA:

        name: http_pool

        members: 10.10.10.10:80, 10.10.10.12:80

        monitor: tcp_half_open (no port denfined in the monitor settings)

         

        PoolB

        name: https_pool

        members: 10.10.10.10:443, 10.10.10.12:443

        monitor: tcp_half_open (no port denfined in the monitor settings)

         

        If 443 stops responding 80 will still work. Same if it is the other way around.

         

        The monitor can be configured in the GUI

        Selecting a monitor: Local Traffic > Pool > Select your pool > find the monitor in the right window and move it to the left

        Creating a custom monitor: Local Traffic > Monitor > Create