More than 1Gbps -- etherchannel / trunking not the solution?

Hi folks -- I thought I had this issue solved but now I'm not so sure....

 

 

Here's my initial configuration:

 

 

Cisco 3750 <-----1Gbps-----> F5 LTM

 

 

My network is a single VLAN (10.10.10.*/24) and I have multiple virtual servers and pools, so a lot of traffic was flowing through the single interface of my F5.

 

 

Rather than reconfigure my network into different VLANs I talked with a someone who manages the Cisco switches, did some reading and we decided to create this:

 

 

Cisco 3750 <---------1Gbps--------> F5 LTM

 

<----------1Gbps-------->

 

 

etherchannel trunk

 

 

On the Cisco side, it's using a SRC-MAC Etherchannel load balancing method. On the F5 I'm using a "trunk" with LACP configured. I thought I would be now getting a 2Gbps 'pipe' between the two appliances, and initially my performance was a lot better.

 

 

But recently, I'm driving a lot more traffic, and -- worse -- one of the links is getting preferred, so it's at 97% saturation with multiple packet drops, while the other link has capacity.

 

 

Is there a way to 'combine' the two 1Gbps links into a single 2Gbps link? The choice above isn't working as I thought now that I see the src/mac load balancing algorithm is choosing 1 link the majority of the time. Thx!