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
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

nathe
Cirrocumulus
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
Employee
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
Cirrus
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
  Nimbostratus
  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
    Altocumulus
    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