Performance Layer4 virtual server is sending packets to gateway defined in default route instead of configured pool

Pruduct: BIG-IP LTM 11.2.0 Build 2557.0 Hotfix HF2.

 

Problem: probably i have a configuration problem but i did not find the cause. We have a Performance Layer4 virtual server enabled on three VLANs (3012, 3050, 1901), any destination and any service. The traffic was coming on VLAN 3050 and going out balanced between the two pool members, on vlan 1900 and 1901 as it should be.

 

We have changed some internal network structures and now the traffic comes on VLAN 3012. But instead of balancing between the pool members the packets are sent to the gateway defined in the static routing table in the default route.

 

I made a tcpdump on the bigip and I can see that incoming packets have the 3012 tag and outgoing traffic have the tag 1902. VLAN 1902 is associated with a selfip (190.13.109.5) in the same range as the default gateway (190.13.109.30) in routing table. Also the outgoing packets have the 190.13.109.5 as source IP, that is how i know that is going out on the wrong gateway.

 

This is how it is:

 

internal network ---------- 3012 -----------bigip--------1902--------default gateway------------internet

 

How it should be:

 

internal network ---------- 3012 -----------bigip------1900,1901------gw1/2 in pool ----------- internet

 

What can be the problem and how can i correct it?