Help understanding IOS versions

Whistlestop

Very much newbie questions.sorry. I did try finding the answer by speaking to colleagues but couldn't shed any light on it.

need some help understanding what IOS versions do what and deciphering what the codes mean. for example, I have c3640-jk9s-mz.124-16.bin which when i run show version gives me


filename: c3640-jk9s-mz.124-16.bin

R2#show version
Cisco IOS Software, 3600 Software (C3640-JK9S-M), Version 12.4(16), RELEASE SOFTWARE (fc1)
Technical Support: Support and Documentation - Cisco Systems
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Wed 20-Jun-07 11:43 by prod_rel_team

can anyone tell me what the JK9S-M means? and what (16) refers to? i assume 12.4 is the major release value
is this a good IOS version to use?

I also have:
filename: C2691-AD.BIN
R1#show version
Cisco IOS Software, 2600 Software (C2691-ADVENTERPRISEK9-M), Version 12.4(23), RELEASE SOFTWARE (fc1)
Technical Support: Support and Documentation - Cisco Systems
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Sat 08-Nov-08 21:17 by prod_rel_team

ROM: ROMMON Emulation Microcode
ROM: 2600 Software (C2691-ADVENTERPRISEK9-M), Version 12.4(23), RELEASE SOFTWARE (fc1)

and


filename: c3725-AD.BIN
R3#show version
Cisco IOS Software, 3700 Software (C3725-ADVENTERPRISEK9-M), Version 12.4(15)T5, RELEASE SOFTWARE (fc4)
Technical Support: Support and Documentation - Cisco Systems
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Wed 30-Apr-08 18:27 by prod_rel_team

what does the T5 mean? what is adventerpriseK9-M?

are these images I have
OK?
or would something like c3725-adventerprisek9-mz.124-7 be better. if so why?

are there any IOS versions which support EIGRP IPv6?

thanks

clarson

well there is a lot of information out there on cisco's version methods
Understanding the Cisco IOS Software
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=7&ved=0CEsQFjAG&url=http%3A%2F%2Fnag.ru%2Fgoodies%2Fdocs%2FCisco%2520IOS%2520Reference%2520Guide.PDF&ei=sImVVP7GE8y3yATasYKgAw&usg=AFQjCNFJSfj_Athnn-rPs-NgcRxFRECzKQ&bvm=bv.82001339,d.aWw
are these images I have OK?
yes they are for this hardware

or would something like c3725-adventerprisek9-mz.124-7 be better. if so why?
Not really

are there any IOS versions which support EIGRP IPv6?
use cisco's feature navigator to look it up: Cisco Feature Navigator - Cisco Systems

theodoxa

For Pre-12.4T IOSes (IOS names were utter jibberish before then), your best bet is just to paste the filename into Cisco Feature Navigator. Since 12.4T, Cisco has made their IOS names more readable and standard. Advanced IP Services should support everything you need for Cisco exams (in particular IPv6). You can also use Advanced Enterprise, but the only thing extra you get is support for some old protocols that are not used very much anymore and aren't on any Cisco exam I know of.

Cisco Feature Navigator - Cisco Systems

NOTE: look for "k9" after the version ("ipbase", "ipvoice", "advipservices", "adventerprise", etc...) This indicated that the IOS includes support for encryption.

c1700-advipservicesk9-mz.124-15.T14.bin

c1700 -- Cisco 1700 Series
advipservices -- Advanced IP Services
k9 -- Includes Encryption
mz -- IOS is run from DRAM (m) and File is Compressed (z). This is standard for every IOS except some very old devices (some 1600 Series for example).
124-15.T14 -- IOS 12.4(15)T14

theodoxa

Whistlestop wrote: »

what does the T5 mean?

T-Train. (15)T5 I believe indicates that there were bugs in (15)T4, which were patched and a new IOS released, rather than new features being added as might be indicated if they went to (16)T.

There are 2 main "Trains" - T & M. M or Mainline is intended for stability, whereas T gets all the newest features, but therefore may have more bugs.