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davidfisher's avatar
davidfisher
Icon for Cirrus rankCirrus
Sep 23, 2018

Persistence options for UDP Application

Hey Fellas,

I scoured the forums to find some info on achieving persistence for udp applications.

The VS I am using is standard, but the protocol profile is UDP with least conn - member as the load balancing algorithm.

I applied the default universal persistence profile and this irule but could not see any persistence records using 

show ltm persistence persist-records virtual 

when CLIENT_ACCEPTED {
    set src_IP [IP::client_addr]
    if { [session lookup uie $src_IP] equals "" } {
      session add uie $src_IP [UDP::remote_port] 1800
      log local0. "added client port [session lookup uie $src_IP] for client ip $src_IP "
    } else {
      log local0. "existing client port [session lookup uie $src_IP] for client ip $src_IP"
    }
}

Do I have to apply this irule to the VS or to the universal persistence profile itself?

The profile also has an option to include an irule!

BIG-IP
big-ip ltm
iRules
persistence
security
  • davidfisher's avatar
    davidfisher
    Icon for Cirrus rankCirrus
    Sep 25, 2018

    Came across this 

    persist uie
    command, can that be used with the current irule or do I need to change something more?

    Also does the irule go to the profile or to the virtual server?

  • Andy_McGrath's avatar
    Andy_McGrath
    Icon for Cumulonimbus rankCumulonimbus
    Sep 25, 2018

    First why are you using 

    uie
    persistence profile if you all you need/want is source address persistence? If you are using source IP then you do not need to make is this complex with 
    uie
    and simply use source address.

    Second the commands 

    persist
    and 
    session
    do different things, 
    persist
    is purely for creating, looking up and removing persistent records (core session table records). The 
    session
    is used for storing arbitrary/additional information in the session table.

    Use 

    persist
    instead of 
    session
    for what you are trying to achieve, for example:

    when CLIENT_ACCEPTED {
    set src_IP [IP::client_addr]
    if {[persist lookup uie $src_IP]} {
        persist uie $src_IP
        log local0. "existing client port [persist lookup uie $src_IP] for client ip $src_IP"
    } else {
        persist add uie $src_IP 1800
        log local0. "added client port [persist lookup uie $src_IP] for client ip $src_IP "
    }
}

    NOTE: this is just a UIE version of source address persistence and at that more complex than needed as the following does the same:

    when CLIENT_ACCEPTED {
    persist uie [IP::client_addr] 1800
}