I have been looking into this for a while now, but I can't find an explanation anywhere (the closest I could find was in wikipedia and cisco )
The switch is a 2960s that I need to stack to a 2960x (so I need the exact ios versions on both), I can download these two versions for the 2960S 15.0.2-EX5(ED) and 15.0.2-SE10a(MD)
Basically it seems to say that:
- S Consolidates mainline, E, and other S, which supports
high-end backbone routers, and fixes defects. - E Targets enterprise core and SP edge, supports
advanced QoS, voice, security, and firewall, and fixes
But what means SE? It's a mix of S and E? What means the X in EX?
**UPDATED:**As @hertitu said in the comments, it's also important the release designation codes (list here), and the MD (manteinance deployment) means software more stable than the ED releases (Early Deployment)
Best Answer
Sometimes the one/two letter designation is the branch/train/platform identifier.
Here is an old list of common branch identifiers:
M/T – 800 Series ISR, ISRg2 (1900, 2900, 3900), Connected Grid Router 2000
S – 7600 Series Router, ME 3600X, ME 3800X
GC – 5900 Series Embedded Router
SE – Catalyst 2960, 3560, 3750, IE 3000 Switches
SG – Catalyst 4500E (Sup 6E and earlier)
SY – Catalyst 6500E, 6807-XL, 6880
EA – IE 2000 Switches
Reference: https://www.packetmischief.ca/2013/12/09/ios-and-nx-os-platform-identifiers/
As you already identified, "S" could also be a consolidated release. It is hard to say whether the "SE" is merely an identifier or whether it has deeper ties to the "E" releases.
"X" however in this case, most likely refers to an IOS "Special Release". This is supported by the "ED" designation that you have already identified as "Early Deployment".
X Special Releases are defined as:
This illustrates how Special Releases are integrated back into a parent train.
(Slides 15 and 18) https://www.cisco.com/c/dam/en_us/training-events/le21/le34/downloads/689/academy/2005/BRK-101.pdf
The release notes from Cisco on IOS Release 15.0(2)EX call out the new features introduced in this special release.
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/release_notes/OL30810.html#pgfId-246822