----- Original Message -----
From: Control Program <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, April 08, 2001 8:36 AM
Subject: Cisco IOS Documentation: How useful is it, really?
> I'm interested in thoughts and opinions on the practical utility of the
> official Cisco IOS Configuration Guides and Command References available
in
> print, on CCO, and on the documentation CD-ROMs that ship with Cisco
> products. There have been a number of allusions on and off this list to
the
> importance (or even necessity) of studying the official docs if "you're
> serious about CCIE preparation." I even recall seeing some advice given
by
> someone that one should read the entire set of configuration guides and
> command references before attempting the lab exam.
>
First off, the "practical utility" for the IOS Config guides is in the
configuration of the devices (duh), and not for light reading unless you
have a photographic memory (which actually might be a detriment ;-)
If you've ever put together a configuration for multiple routers (for
example, even a small 5 site WAN), you discover that the parameters set on
one device are dependent on its neighbors, and that if you don't get the
commands right, the results that you want will not be realized. Sometimes
it can be easy (point-to-point T1's and RIP all using fixed subnet masks),
but the complexity rises as the routing protocol is implemented and features
required are added, and WAN technologies used.
> How useful do you all find the IOS documentation, both with respect to
CCIE
> study, and in general?
>
VERY. You go to http://www.cisco.com and click on Training and
Certifications. From there, there are links that take you to the CCIE
Blueprint, which lists a plethora (ad nauseum) of the material that you need
to be familiar with, and it is NOT all Cisco documentation. But there are
lots of links to Cisco IOS Documentation there, and some good white papers,
too.
> Have you succeeded in using it to learn to configure services you were
> previously unfamiliar with, or is it just useful as a reference once you
> already mainly know what you're doing? Is it even useful as a reference?
>
Yes - ergo ATM (LANE) and LECS/LES/BUS configuration at a router and ATM
switch level (two different devices, two different IOSes). Also, the
interface buffers (queuing commands), and it has really helped me in my BGP
configurations and in route redistribution. Again, if you haven't had
experience on the console, its almost impossible to study the configuration
guides except to get familiar with how these device commands are entered.
Many times, the configuration examples at the bottom of the Config Guides
are good starting points, but don't provide sufficient detail to solve my
particular problem. Knowing the context of a router (one big ARP table)
helps alot, and knowing the capabilities and limitations of the router in
terms of filtering and traffic movement also help. Interface-specific
commands versus global commands also proves to be valuable, because it gives
me a reference point to search the documentation.
>
> My own thoughts:
>
> I ask because I find the IOS documentation hard to digest at best, and
> actively confusing at worst. I use it frequently, but almost exclusively
as
> a reference to look up command options and syntax details. Even then,
half
> the time I find that there either isn't enough detail in the manual to
> answer the question I have, or there's so much detail that the information
> I'm looking for is buried in an avalanche of optional parameters and
> unrelated features. The idea of resorting to the IOS documentation to,
say,
> learn how to set up async and ISDN interfaces using a combination of
static
> and dynamic addressing to support user dialin and backup/DDR functions on
an
> access server makes my blood run cold. It could be done - eventually -
but
> it would require piecing the information together from eight different
> chapters, one of which would provide 200 pages of information just on PPP,
> another of which would provide 150 pages of information on ISDN signaling,
> and so on.
>
If you're just reading the configuration guides without live equipment to
see what the config command does, then it *is* confusing at best,
frustrating at worst. I've studied the configuration guides without
equipment around, but I also have the benefit of setting up lots of
equipment, so when the config guide refers to a command, I know the basic
context of why it needs to be done. Much of the configuration can be trial
and error, much like any other programmable device, as they don't put every
possible combination of every command into the config guides, but that's why
the TAC has resorted to providing sample configurations which are now very
well documented:
http://www.cisco.com/public/technotes/serv_tips.shtml
As far as detail is concerned, I agree with you that there often is a big
(sometimes HUGE) disconnect between the config guide and command reference,
and I've complained about it (and the poor quaility documentation on the
output of the show and debug commands). You end up having to dig deeper
than the documentation in the TAC area on CCO. And I'll allude to my
disgust with the undocumented commands, but not expound on it here.
Basically, what you're asking for is analogous to asking Intel to provide a
complete guide of applications for the Pentium processors, and giving all
the various commands in a particular flow in the order that you need them.
I doubt that would ever happen, which is why experienced CCxx's are in such
high demand.
> I just can't imagine the official documentation as the preferred means to
> learn to do something new. Should you be familiar with the structure and
> contents? Of course. It's still the last word when it comes to resolving
> ambiguities or finding information on that one option you knew was there
but
> couldn't remember the keyword for. Is it time well-spent to sit there and
> study these manuals as an attempt to increase your knowledge and
> proficiency? Not in my experience. That's not to say you won't learn
> anything by doing it - just that there are better ways to use your time.
>
It isn't the preferred means to learn something new, but again, unless you
have some experience in configuration of multiple devices (for example, ATM
LANE between a LS1010, LANE Module in a 5500, and 7x00 and 3600 routers),
new is probably not the context that you'd be using. I'm unfamiliar with
your level of expertise, but to try and read the manuals to learn to
configure Cisco routers, you'd be very wise to have a router there with the
capabilities that you need to use.
When I've had to configure something new (for example, ISDN DDR for serial
circuit restoral, or PPP over X.25), I just had to use the documentation
(ver 11.0) and fiddle with it until I got the configuration right. The
Config Guide gave me a good starting point, but then I had to customize the
configuration for my own use. I had to learn how to generate a floating
static route, which is not covered in the DDR part of the Config Guide
> Comments encouraged! Maybe some of you have actually devised a way to
> triage the documentation and learn a lot from it despite the way it's
> organized. If so, I'd love to hear your strategies.
>
I actually feel that Cisco's attempt to change the documentation has been
very positive, but I still use the basic 10.3 and 11.0 configuration guides
because it is what I "grew up" with, and if there is something that I really
don't know how to do with the new commands, then I'll open up the 12.0 and
12.1 documentation.
>
> --
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