Hi,
Traffic loss/ping loss is expected as the traffic/ping was previously hashed between three links.
Now it has to accomodate and hash the traffic between two links instead of three (time taken to detect the failure link and switching over will impact loss percentage).
if you want to minimise the loss (faster detection of member links failure ), please enable micro bfd . This will enable bfd session on member links resulting in faster detection if any of the member link goes. But even this will result in loss , but loss will be in the gravity of few milli seconds.
I am not sure which EX series support micro BFD feature ,but Higher end MX boxes do support this feature .
Please refer below draft for very detailed explanation of the same:
https://tools.ietf.org/html/draft-mmm-bfd-on-lags-06
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