First, [any] X release is typically associated with a specific product line. I believe 12.3X54 is specific to ACX. There are a few X trains for SRX.
X trains were done for new feature velocity (time to market).
For newer EX/QFX Juniper got off of X trains, starting with 17.1. This got Junos back to single train for MX/PTX/EX(new - ELS based)/QFX. 17.1 does NOT apply/support legacy/older/non-ELS products.
For legacy EX (non-ELS) 15.1 was targeted as the last supported release. There have been little to no feature additions since 12.3. That is why I said that neither 13.X or 14.X really applied to legacy EX. All SW changes have basically been big fixes, which all continued to go into 12.3. That is why vaste majority of legacy EX were (and continue to be) running 12.3.
As for 15.1, the move of legacy EX to this SW release has not been smooth. There are many instances of people needing to back to 12.3 to regain stability. This is major reason I suggest you or anyone else to remain on 12.3 at this time. If you can wait to make this decision until like end of Q1/2018.
If you are looking to go to 15.1 today or soon, I would suggest only using 15.1R6-S2 or S3 (if out). You can go direct from any 12.3 to any 15.1 directly for any/all legacy EX products, including EX3300 and EX4550/EX45xx.
The end -![Smiley Happy]( "Smiley Happy")
X trains were done for new feature velocity (time to market).
For newer EX/QFX Juniper got off of X trains, starting with 17.1. This got Junos back to single train for MX/PTX/EX(new - ELS based)/QFX. 17.1 does NOT apply/support legacy/older/non-ELS products.
For legacy EX (non-ELS) 15.1 was targeted as the last supported release. There have been little to no feature additions since 12.3. That is why I said that neither 13.X or 14.X really applied to legacy EX. All SW changes have basically been big fixes, which all continued to go into 12.3. That is why vaste majority of legacy EX were (and continue to be) running 12.3.
As for 15.1, the move of legacy EX to this SW release has not been smooth. There are many instances of people needing to back to 12.3 to regain stability. This is major reason I suggest you or anyone else to remain on 12.3 at this time. If you can wait to make this decision until like end of Q1/2018.
If you are looking to go to 15.1 today or soon, I would suggest only using 15.1R6-S2 or S3 (if out). You can go direct from any 12.3 to any 15.1 directly for any/all legacy EX products, including EX3300 and EX4550/EX45xx.
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