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boo_radley_1114's avatar
Icon for Nimbostratus rankNimbostratus
Oct 18, 2011

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





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!






1 Reply

  • Hamish's avatar
    Icon for Cirrocumulus rankCirrocumulus
    I suspect that the channel that's not being configured is receiving the traffic via s ingle router on the VLAN? In which case the SRC-MAC is always the same. And thus uses the same physical link all the time (Or amazingly all the directly attached MAC addresses on the clan just happen to has to the same physical link, but I don't really believe that would happen in real-life :)



    Change to using src-ip or dst-ip (One may give better results than the other depending on the distribution of IP's in the hash).