Forum Discussion

Yaniv_99962's avatar
Icon for Nimbostratus rankNimbostratus
Jul 13, 2011

"Layer 1" load balancing




Is it possible to simply define physical ports (interfaces) as group members so that a load balancing decision will force a a certain traffic/connection/packet to be persistently sent via some interface without changing anything in the packet (including not changing the MAC addresses)?


This can be useful where the servers connected to those interface work in a "bump-in-the-wire" mode that they only observe the packets in promiscuous mode and maybe drop some for bandwidth shaping (like DPI).








4 Replies

  • Hamish's avatar
    Icon for Cirrocumulus rankCirrocumulus
    Hmm... I can see what you're trying to do...



    (Late edit, changing my mind :)



    Have you tried using the nexthop command? You can set the VLAN and the nexthop mac address from an iRule using it...






  • But the point is that Ii don't want the F5 to change anything in the packet including the MAC address...



    Imagine the F5 connected via a 4 interfaces trunked together to a another router which will be the next hop.


    on each of those 4 cables there is a "tapper" that just looks at the packets (it doesn't bridge or route them, just observes them).



    Sound like using a trunk with a desired 'Frame Distribution Hash' can actually be the solution. However in case one of those 4 cables fails I don't want the entire remaining 3 cables to rehash, just the failed server.




    For example:


    I have 4 bump-in-the-wire servers on each of the 4 cables in the trunk.


    user with IP under normal circumstances goes via cable 1 and user with IP under normal circumstances goes via cable 2.


    Now server on cable 1 fails, I want that will be moved to one of the other 3 cables but I don't want to move from cable 2 to any other cable (as cable 2 didn't fail)



    Normal trunk can't achieve that...


    I need something like the CARP algorithm just that the group members will be physical interfaces rather than IP entities.



    Hope it's clear....







  • Hi Yaniv,



    It is possible to assign individual VLAN's to specific interfaces and then trunk interfaces together, but do not believe that you can get as granular as you are wanting to (at least that I know of).



    I would suggest opening up a case with F5 for a definitive answer.