BigIP 5200 traffic flow

[AboAmir]

Dear all,

I would like to get your support please to clarify below case:

We have BigIP 5200, and on it we have a standard virtual server configured with a pool includes two nodes.

BigIP external interface is connected to a L3 switch on Vlan X, and the requests to the above virtual server are coming on this interface.

The client that is sending the request to the above interface is connected to the same L3 switch but on different Vlan Y.

There is no route configured on BigIP to the subnet of vlan Y, also there is no gateway configured for that external interface.

Nevertheless when we send a request from the client on vlan Y to BigIP external interface on Vlan X, it is processed, and BigIP returnes the traffic without any issue.

Could you please clarify this case, and how BigIP is able to manage the reverse traffic.

Below drawing for your reference.

your fast reponse is highly appreciated.

Thank you,

[malcooooIm · Accepted solution]

F5 by default returns traffic to MAC address from which traffic come it doesn't look routing, just returns to source MAC. 

It si feature called "Auto last hop"

https://support.f5.com/csp/article/K13876

[AboAmir]

Hi Malcoooolm, 

Thanks for your clarification, and yes it makes sense.

Thank you,