I have setup LACP, and LAG on our Netgear Switches (GS724T). I have bound(?) two ports together to create one 2Gbps connection between two of the switches.

I was wondering if there is a way of testing the increased bandwidth? I know it's setup because the switch no longer creates a routing loop, and the switch management (on both switches) show the two ports as members of the LAG.

Obviously if I ping the two switch IP's they succeed at the same speed as before because its bandwidth not transfer that I am trying to view.

  1. Failover: Unplug each cable and ensure traffic continues to flow between the switches.

  2. Bandwidth: iperf seems to be the standard took for testing these kinds of things. If you can get a setup like this:

    A ----- |--------|===L1===|---------| ------ C
            | Switch |        | Switch2 | 
    B ----- |________|===L2===|_________|

    Then setup Iperf on all 3 boxes and try various client/server setups or you can also just SCP over some files if your on linux. Simultaneously transfer files form A to C and B to C. Try unplugging L1 or L2, or L1 and then L2 and observe if the bandwidth drops. The reason you need to do 2 simultaneous transfers is becasue each transfer(TCP) can only use one line(L1 or L2 in this case). Depending on your switches, you might be able to transfer between 2 boxes(for example A and C) if the transfers are on different ports, but thats only newer switches, most hash based on src and dst IP addresses.


You can transfer a file and watch it go faster... but it might not. Some cheap LACP implementations do per-MAC address hashing, so that any 1 transaction between any 2 stations is only on one actual link to prevent out of order packets. Generally speaking, if all sides say that the LACP is active, it is active.


Aside from actual throughput testing you ought to be able to clear then view traffic stats on the interfaces themselves (not sure with netgear) or monitor via SNMP with a network management tool to verify utilization on the link.

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