Hello Colleagues,
We are planning to upgrade 5100 QFX VCF of 10 switches (2 spines and 8 leaves), to minimize the downtime we will divide it to ODD VCF (S1,L1,L3,L5,L7) and Even VCF (S2,L2,L4,L6,L8) , re-route traffic via one and upgrade the other and vice versa, I know we sill have 10sec down time during the re-route but it is best we can get.
My question,
I know that switches in the same VCF should have the same Junos version in order to work properly, but I noticed in some tests that line cards even though when they are using different versions they are still seen in the VCF so the question are the line cards in VCF with different Junos version are still able to forward the traffic as L2 device?
Asking for such strange possibility as it seems we have a lot of possible single point of failures (servers that connected with 2 connections to Odd leaves only or Even leaves only), and since we will upgrade the half VCF with odd numbers all together then the half VCF with even numbers all together, those few servers will suffer, so if these leaves continue to forward traffic even with different Junos version then we can upgrade one leave a time and avoid some downtime for these unlucky servers.