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Jimmy20
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Jun 10, 2020

Custom Monitor

Hi Everyone,

 

We have to migrate F5 configuration to other LB, We found some Custom monitor on F5 ..where Alias Address and Alias Service Port has been defined.

 

tried searching some article to understand purpose of this configuration, but did'nt approach the correct one probably.

 

requesting if anyone help to understand the purpose of defining Alias Address and Alias Service Port with some example. Where this is recommended. Alias IP should be Public IP or Private IP.

1 Reply

  • Hello,

     

    Here is the complete description:

    https://techdocs.f5.com/en-us/bigip-15-1-0/big-ip-local-traffic-manager-monitors-reference/monitors-settings-reference.html

    Alias Address*All AddressesSpecifies an alias IP address for the monitor to check, on behalf of the pools or pool members with which the monitor is associated. The default setting is *All Addresses. If the health check for the alias address is successful, the system marks all associated objects up. If the health check for the alias address is not successful, then the system marks all associated objects down.

    Alias Service Port*All PortsSpecifies an alias port or service for the monitor to check, on behalf of the pools or pool members with which the monitor is associated. The default setting is *All Ports. If the health check for the alias port or service is successful, the system marks all associated objects up. If the health check for the alias port or service is not successful, then the system marks all associated objects down.

     

    -------

    In another words, you set this values when you need to monitor a specific address or port that differs from pool member or node setup.

     

    e.g cases:

    #1. You need to monitor port 443 on node server object instead of this as a member within a pool. Since nodes only have IP address, you must create a tcp monitor or take builtin https_443 where set port alias to 443.

     

    #2. You have a pool with members that serves port 443 and you need to guarantee service is UP if port 80 are UP as well. So, put one monitor to 443 (no alias by default) and another monitor setting alias to port 80.

     

    #3. You need to monitor next hop for a pool of internet gateways.

    You create a transparent monitor and set the next hop IP address as alias. This way you monitor the next hop, even though the gateways are the members in pool.

     

    Anyway, the monitor will use the address and port from object when has no alias on monitor.

     

    Easier and powerful than it looks.

     

    You got it?

    Regards.