For QFX3500's, some interface names will change after upgrading from 12.3 or earlier versions to 14.1 or later versions.
This article explains how those interface names changed along with the mapping.
If upgrading QFX3500 from 12.3 or earlier versions to 14.1, the xle interfaces (40GE interface from the pic 2) and xe ports from the pic 1(xe-0/1/x) will disappear. Also, the total 10G interface becomes 64, while the previous version only supported 63 10GE interfaces. The 40GE interfaces is still 4.
The software upgrade will NOT copy the interfaces configuration to the new interfaces, so understanding how these interfaces map together is very important. This change will only have an impact in a case where you have configured the interface from pic1 and pic2.
The interface names changed as the following:
Version 12.3 or earlier 14.1
xle-0/2/x >>>>>>(40G) >>>> et-0/1/x xe-0/1/x >>>>>>(10G) >>>> xe-0/1/x:y
Here are the interfaces mapping:
xe-0/1/1 >>>>> xe-0/1/0:1 xe-0/1/2 >>>>> xe-0/1/0:2 xe-0/1/3 >>>>> xe-0/1/0:3 xe-0/1/4 >>>>> xe-0/1/1:0 xe-0/1/5 >>>>> xe-0/1/1:1 xe-0/1/6 >>>>> xe-0/1/1:2 xe-0/1/7 >>>>> xe-0/1/1:3 xe-0/1/8 >>>>> xe-0/1/2:0 xe-0/1/9 >>>>> xe-0/1/2:1 xe-0/1/10 >>>>> xe-0/1/2:2 xe-0/1/11 >>>>> xe-0/1/2:3 xe-0/1/12 >>>>> xe-0/1/3:0 xe-0/1/13 >>>>> xe-0/1/3:1 xe-0/1/14 >>>>> xe-0/1/3:2 xe-0/1/15 >>>>> xe-0/1/3:3 et-0/1/0 >>>>> xle-0/2/0 et-0/1/1 >>>>> xle-0/2/0 et-0/1/2 >>>>> xle-0/2/0 et-0/1/3 >>>>> xle-0/2/0
You can use the command 'replace pattern' to update the configuration after upgrading.
'replace pattern'