# Failover-LAGG Across Technologies?



## fr33bsd (Aug 19, 2021)

Hi,

can failover LAGG be set up across ethernet nic (secondary) and infiniband nic (primary) on FreeBSD?


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## SirDice (Aug 19, 2021)

lagg(4) (LACP) on the switch side often can only be done on the same switch. You can't spead it over multiple switches. Not so sure about failover, it might be possible but you need to make sure the MAC addresses are the same for both interfaces, which could cause other problems. See the example in the handbook where lagg(4) is used to automatically switch between wired and wireless. 

If you need a fail-over to attach to two (or more) switches then you should use a bridge(4) with (R)STP.


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## fr33bsd (Aug 19, 2021)

SirDice said:


> If you need a fail-over to attach to two (or more) switches then you should use a bridge(4) with (R)STP.


Ah, ok. I have done bridging on linux before. With success. I thought on FreeBSD you have to use LAGG. My bad. Ok, I will try it as soon as possible, and if it works, I will post setup here and close this thread.


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## SirDice (Aug 19, 2021)

While you can certainly do failover with lagg(4) it's more commonly used to bundle two or more ethernet connections to increase the bandwidth (LACP). When you build a network with failover switches however you're likely going to be using (R)STP to prevent network loops. In that case bridge(4) is the better option (it supports RSTP/STP).


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