Forum Discussion

escman's avatar
escman
Icon for Cirrus rankCirrus
Aug 18, 2023

Outbound iRule / BGP routing

Hey sirs,

I would like to ask a question about the order of precedence/execute of a connection that consumes a forwarding virtual server/routing table.

Currently, we have a forwarding any:0 virtual server, which load balances internet outgoing traffic through a pool_default_gateway that has the IP of 3 routers from different ISP associated with it, including some irules that make the SNAT decision based on LAN-segment.

We are planning to include the F5 pair in the BGP neighbors of each ASN ISP and receive the default route and advertise the Virtual Server public IP.

Does anyone know if the F5 when reads the dynamic routing table obtained via BGP, the traffic that is handled by the virtual servers of forwarding any:0, including those that are manipulated via iRule can show any kind of intermittence?

thanks in advance 

application delivery
bgp
cloud
irule
outbound
security
  • Paulius's avatar
    Paulius
    Icon for MVP rankMVP
    Aug 20, 2023

    escman Can you please rephrase what you're asking because I'm not understanding that last sentence.

    • escman's avatar
      escman
      Icon for Cirrus rankCirrus
      Aug 20, 2023

      Hi Paulius,

      My main question is how does a connection is handled by F5 (which triggered first, routing table or vip behavior), assuming that I have a BGP session for route the outbound traffic and also have a forwarding IP VIP with default_gateway_pool and irule.

      Thank you

      • JRahm's avatar
        JRahm
        Icon for Admin rankAdmin
        Aug 21, 2023

        HI escman, the important thing to understand is that the routing table is HOW packets are forwarded on BIG-IP, but that is completely moot if a listener (virtual server) is not configured to allow traffic to flow through the BIG-IP. As far as precedence is concerned with the virtual servers, that information is covered in knowledge article K14800.