12.2(3)SE is different from 12.2(4)SE through what's called the "Maintenance Identifier": generally, having
a higher Maintenance Identifier means additional software fixes.
The Cisco IOS Software 12.2S release family is comprised of the following Trains: 12.2S, 12.2SB, 12.2SE,
12.2SG, 12.2SR and 12.2SX. Different trains generally means different available IOS features.
To exemplify the differences, I took a couple of the trains' descriptions from the Cisco White Paper:
12.2SE - Provides Cisco IOS Software functionality and hardware support for mid-range and low-end Ethernet LAN switching for enterprise access and distribution networks, and mid-range and low-end Metro Ethernet for service provider edge networks that include the Cisco Catalyst 2960 Series, Cisco Catalyst 3550 Series, and Cisco Catalyst 3750 Series Switches.
12.2SX - Provides Cisco IOS Software functionality and hardware support for high-end Ethernet LAN switching for enterprise access, distribution, core, and data center networks.
What one can gather from this is that 12.2SE will more likely be available for lower-end switches (CAT2900
range) while 12.2SX would be installed on higher-end switches (CAT 6000).
The difference then between 12.2(3)SE, 12.2(3)SEE and 12.2(3)SED is given by the third uppercase
letter called the "New Technology Introduction Identifier", where each new individual release includes new
features and/or hardware support.
Finally, the "Rebuild Identifier", the last number that can be used in a release name, such as 12.2(4)SXC15
or 12.2(4)SXC16 typically includes fixes to a limited number of caveats deemed by the IOS developers as a
sufficiently significant reason for releasing a newer version.
Each new fix and software feature implemented in a release is then inherited by the next software iteration.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
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