Forum Discussion

LabanM's avatar
LabanM
Icon for Nimbostratus rankNimbostratus
Jul 27, 2022

Load Balance UDP (Retain Source Client IP)

Good afternoon all. I'm hoping someone on here can point me in the right direction.  I am working on a project to load balance UDP traffic to a few backend nodes for some IOT devices. When the IOT d...
application delivery
  • PeteWhite's avatar
    PeteWhite
    Jul 28, 2022

    The short answer to this is yes - normal SNAT will work fine. When a request comes into a UDP virtual server, the response will be allowed for an Idle Timeout time ie it emulates the TCP functionality. This timeout is configurable in the UDP profile. You can also disable the treating of this traffic as a flow, and instead treat each UDP packet as a new connection ( useful where using iRules and you want to inspect each packet ). This is called Datagram LB.

    Take a look at K7535: Overview of the UDP profile  for more info

xuwen's avatar
xuwen
Icon for Cumulonimbus rankCumulonimbus
Jul 28, 2022

if F5 enable automap or snat，Unlike the TCP protocol, TCP has tcp option filling options(such as tcp option 28,29,254). If it is not a specific UDP protocol, such as DNS, the edns field of DNS can be inserted into the client ip (this belongs to the application layer inserting the client ip), it can only be used in your UDP data. The first 4 bytes or the last 4 bytes are inserted into the client's ipv4 address. This makes you have to retrofit your application, the useful data is to skip the first 4 bytes or discard the last 4 bytes