Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

Vishwanath's avatar
Vishwanath
Icon for Nimbostratus rankNimbostratus
Oct 12, 2017

VS with anycast Setup behavior

Hi Folks,   I have a ongoing issue at my network. Below is the scenario -   I have 2 Virtual Servers with same IP address( Anycast IP), one of them is listening on port 8081 and another is lis...
application delivery
big-ip
LTM
Leonardo_Souza's avatar
Leonardo_Souza
Icon for Cirrocumulus rankCirrocumulus
Oct 12, 2017

Yes, is normal behaviour.

 

And here is the explanation...

 

First, there is something called delay binding, or delayed binding as per Wikipedia.

 

https://en.wikipedia.org/wiki/Delayed_binding

 

The F5 will wait until it receives the required information, to open a connection to the back-end server. If at the time it tries to open the connection with the backend server it is down, it closes the connection. The required information depends on what you have on the virtual server.

 

If it has just TCP, it will open the TCP connection, and close as soon you press a key.

 

If it has HTTP as well, it will wait until you send something like (GET /), and close as soon you press the enter.

 

Try your self, as you can easily see the behaviour.

 

Anyway, in case you don't believe me, here is the full explanation about that. :P

 

https://support.f5.com/csp/article/K8082