Hi everyone.

I have a problem concerning 'IP CLASSLESS' on cisco routers
I have quite a lot of vpn tunnels with IP CLASSLESS enabled on the
router and some that it is not enabled.
i have noticed that there are some application that i'm using that are
not working fine when it's not enabled.
i've tried to enable it on those routers but it doesn't seem to change
anything.
i typed 'IP CLASSLESS' and when i look in the running config it's
nowhere

for example:
cisco 871w with IOS Version 12.4 = no IP CLASSLESS = not working ( but
i don't seem to be able to enable it)
cisco 851 with IOS Version 12.3 = IP CLASSLESS enabled = works fine

any explanation?

Max wrote:
There are numerous commands that do not show up in the configuration
file when set to their default state. Furthermore, the default may
change from one IOS release to another, as well as whether they show up
when configured to their default state.

The behavior of "Default Routing" is very much dependent on the setting
of "IP Classless", and is likely the functional issue you have observed.

Best Regards,
News Reader

AFAIK these commands are a special case of what is displayed by show
running-config; typically default commands are not displayed.

Both of the commands "ip classless" and "no ip classless" will show up
in output of sh running-config.

At least this is the behavior with IOS 12.3

Hi Max,

Somewhere around IOS V12.0 the DEFAULT for alI versions of IOS was
changed from CLASSFULL to CLASSLESS. As the DEFAULT does not always
show up, this may explain why it appears to be not working.

If your Router is in CLASSFULL mode, then you would not be able to
configure a Subnetted mask on any command that needed it. If you CAN
configure it, then its in CLASSLESS mode.

Cheers.......................pk.

--
Peter from Auckland.

Please post output of show version from the 871W

Thanks everyone!
I thought that would be the problem why some program aren't working
through the VPN,
but then i guess it's not... i'll have to look somewhere else. It's
because it's mainly the
only difference i could find in the 2 configs...
thanks a lot for yout help!!

On May 7, 9:02 am, Max <lec.max...@gmail.com> wrote:
You may have a defective 12.4 image on the 871W.

Post the output of show version

Max wrote:
Are you abandoning pursuit of the theory because the state of the "ip
classless" command is not displayed the way you expected, or because you
have confirmed that there is no behavioral change resulting from the
removal of "no ip classless" (by entering "ip classless")?

I'm confused by your conclusion.

Your initial post stated:

But you can enable IP Classless; it just may not show up as you expected
(the "no ip classless" will disappear).

Change anything in terms of seeing the command as you expected, or
change anything in terms of a resolution to the VPN issues when "no ip
classless" has been removed (by entering "ip classless")?

When "no ip classless" has been removed by entering "ip classless", is
there a change in the VPN behavior?

Depending on your addressing scheme, "no ip classless" could cause
undesired behavior due to its impact on "Default Routing".

Best Regards,
News Reader

~ AFAIK these commands are a special case of what is displayed by show
~ running-config; typically default commands are not displayed.
~
~ Both of the commands "ip classless" and "no ip classless" will show up
~ in output of sh running-config.
~
~ At least this is the behavior with IOS 12.3

Ordinarily the default state of a command is not shown in the config
("NVGEN'd".)

However, an exception is made when we change a command's default. What
is supposed to happen there, is this:

First, we start NVGEN'ing the old behavior.

Then, some time later, we switch to the new behavior, and NVGEN both the
old and new behavior.

Then, we stop NVGEN'ing the new behavior.

The idea is to make it apparent that the defaults are changing.

Aaron

Aaron Leonard wrote:
NVGEN?

It would be helpful for your audience if you specified what your acronym
stood for.

Best Regards,
News Reader

from CCO

"
Cisco IOS Software Configuration Storage

In the Cisco IOS software configuration model, the configuration state
is maintained in a distributed manner, with each component storing its
own configuration state. To retrieve configuration information, the
software must poll every component to collect the distributed
information. This configuration state retrieval operation is performed
by a process known as nonvolatile generation (NVGEN), and it is used
by command line interpreter (CLI) commands such as show running-
configuration, write memory, and copy system:running-configuration to
display or copy the running system configuration. When invoked, NVGEN
queries each system component and each instance of interface or other
configuration objects. A running configuration file is constructed as
NVGEN traverses the system performing these queries.

"

Merv wrote:
Thank you Merv.

Best Regards,
News Reader

To make this a bit clearer perhaps:

When a command is "NVGEN'd", its state is written ("GENerated", I guess)
to nonvolatile (NV) memory.

----

~ Aaron Leonard wrote:
~ > ~ AFAIK these commands are a special case of what is displayed by show
~ > ~ running-config; typically default commands are not displayed.
~ > ~
~ > ~ Both of the commands "ip classless" and "no ip classless" will show up
~ > ~ in output of sh running-config.
~ > ~
~ > ~ At least this is the behavior with IOS 12.3
~ >
~ > Ordinarily the default state of a command is not shown in the config
~ > ("NVGEN'd".)
~ >
~ > However, an exception is made when we change a command's default. What
~ > is supposed to happen there, is this:
~ >
~ > First, we start NVGEN'ing the old behavior.
~ >
~ > Then, some time later, we switch to the new behavior, and NVGEN both the
~ > old and new behavior.
~ >
~ > Then, we stop NVGEN'ing the new behavior.
~ >
~ > The idea is to make it apparent that the defaults are changing.
~ >
~ > Aaron
~
~ NVGEN?
~
~ It would be helpful for your audience if you specified what your acronym
~ stood for.
~
~ Best Regards,
~ News Reader

On 8 May, 00:31, Merv <merv.hr...@rogers.com> wrote:
That explains why it takes so much CPU for a sh run,
wr mem.

This has puzzled me for some time. "... what is it /doing/ ????"

Thanks.

By the way at least some platforms (maybe 4500/6500) have
a way of displaing the defaults config "entries" if required.

sh run include-default ! - sort of thing - I just made the keyword
up.

On 9 May, 10:54, Bo...@hotmail.co.uk wrote:
show running-config all

To display the entire operating configuration, including defaults,
that
is running on the security appliance, use the show running-config
all command in privileged EXEC mode.

It is buidlinbg a text version of the internal running-config

compare what happens with the tow commands


show startup-config

notice that the config is displayed immediately - this is because it
is stored as a text file

versus

show running-config

NOTICE the "Building configuration ..." message

This would lead me to conclude that the running-config is not stored
as a text file
and that iit needs to be created dynamically each time the show run
command is entered