One thing I didn't try, which you might be alluding to, is allowing OSPF
to advertise the default (which was causing classless behavior) but then
also manually add a static default on router B. I have not tried that
yet. I did try the manual static default route without OSPF advertising
the default and the router behaved classfully.
Then, as you suggest, I could change the distance on the manually added
default to see what happens. So, there are two more things to try right
there.
You're right Bob, this just keeps going and going and going.... I just
want to hear someone from Cisco say "Whoops, didn't we tell you about
that? Sorry, forgot...we'll go document that feature now."
Either that or I want to find out I've been missing something this
whole time. Certainly I can't be the first person to notice this,
especially since I've tried this with older IOS versions.
>>> "Bob Vance" <[EMAIL PROTECTED]> 3/29/01 9:53:36 AM >>>
Excellent !!
This is like the Energizer Bunny!
Hmmm.
You already tested adding a static default route (with lower admin
distance) and it changed the classless behavior, right?
Then you deleted the static and classless returned.
Just for completeness :) , it might be mildly interesting to add the
static with a higher admin than OSPF -- it won't show up in the
routing
table and thus it shouldn't change the classless behavior like the
lower
admin one did -- or would it ;>)
Also, allow OSPF also to advertise the default, along with RIP, and
see
that since the OSPF route is in the table, it still subverts to
classless even though it knows that it also received a RIP route that
it
is currently ignoring.
-------------------------------------------------
Tks | <mailto:[EMAIL PROTECTED]>
BV | <mailto:[EMAIL PROTECTED]>
Sr. Technical Consultant, SBM, A Gates/Arrow Co.
Vox 770-623-3430 11455 Lakefield Dr.
Fax 770-623-3429 Duluth, GA 30097-1511
=================================================
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
John Neiberger
Sent: Thursday, March 29, 2001 10:16 AM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: FW: UPDATE: OSPF overriding 'no ip classless'
Well, there are two different issues. You're talking about the way
the
routing protocols themselves behave: whether they pass subnet mask
information or not. The issue here is routing table lookups, not how
those routes are installed.
With 'no ip classless' configured, even if there is a valid supernet
route in the routing table--including a 0.0.0.0/0 default route--the
router should not choose it. For some reason, at least on my routers,
if OSPF is running it changes this behavior.
This is pretty odd. To be consistent Cisco should cause the
configuration to change to 'ip classless' when an OSPF process is
configured.
Hey, here's something I didn't try! Someone should do this during the
day since I won't be able to do it until tonight. Run OSPF *and*
another routing protocol, let's say RIP, but use RIP to advertise the
default route, not OSPF. That would be an interesting test to see if
the router is behaving classlessly only for OSPF-learned routes or if
it
really makes the router become completely classless.
Okay, I need to get started on my coffee. <g>
John
>>> "Stull, Cory" <[EMAIL PROTECTED]> 3/29/01 7:50:04 AM >>>
John,
I haven't followed this as closely as I should have before answering
but I
hope I am guessing correctly here... OSPF sends the subnet
information
along with it when it does its routing updates, the only way to have
it
behave classfully is to manually summarize. The reason the other
protocols
were working the way they were is because they either A) don't send
subnet
information in the updates or B) were autosummarizing at the classful
network boundary like EIGRP does.
Am I way off base here? I'm working on an OSPF type lab right now
too
so
let me know.
Cory
-----Original Message-----
From: Bob Vance [mailto:[EMAIL PROTECTED]]
Sent: Thursday, March 29, 2001 8:22 AM
To: CISCO_GroupStudy List (E-mail)
Subject: RE: UPDATE: OSPF overriding 'no ip classless'
Interesting :)
And, of course, if it were a designed feature, it should be
documented.
Someone should call this in.
-------------------------------------------------
Tks | <mailto:[EMAIL PROTECTED]>
BV | <mailto:[EMAIL PROTECTED]>
Sr. Technical Consultant, SBM, A Gates/Arrow Co.
Vox 770-623-3430 11455 Lakefield Dr.
Fax 770-623-3429 Duluth, GA 30097-1511
=================================================
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
John Neiberger
Sent: Thursday, March 29, 2001 12:23 AM
To: [EMAIL PROTECTED]
Subject: UPDATE: OSPF overriding 'no ip classless'
Okay, here are my latest findings. Bob and others wanted me to try
various
supernet routes to see how the routers reacted. Well, I did, and the
router
with 'no ip classless' is definitely behaving classlessly when OSPF is
running.
First, a recap. I have router A connected to router B and am running
OSPF.
Router A is originating a default route, and Router B has 'no ip
classless'
configured. The prefix for the link is 10.1.1.0/24.
By all official explanations of 'no ip classless', in this scenario if
I
tried to ping an unknown subnet of 10.0.0.0/8, it would fail and
debugging
would show that the packets were unroutable. This is true when I used
RIP
v1, RIP v2, IGRP, and EIGRP. However, when I use OSPF it's a whole
'nuther
story! It shouldn't matter how the routes are installed, but for some
reason, Router B behaves as if 'ip classless' were configured if I run
OSPF.
Tonight, I first tried the original experiment and originated
0.0.0.0/0.
Router B behaved classlessly and would route packets for ANY
destination
to
Router A.
Next, I tried redistributing the static route for 10.0.0.0/8. Packets
for
any subnet of 10.0.0.0/8 would be routed, all other destinations would
fail.
Again, classless behavior.
Thirdly, I redistributed a route for 8.0.0.0/5 just for grins.
Packets
destined for anything in that range were routed (8.0.0.0/8 throught
11.0.0.0/8) but all other unknown subnets failed.
Aggggh!! I've tried this on two different routers and three different
IOS
versions and I get the same results. Where is it written that when
OSPF
is
running that the router will now behave classlessly in spite of 'no ip
classless' being in the configuration?
I guess I have no problem with this, I just wish they would document
it
somewhere. If someone would like to try these tests to verify the
results
I'd appreciate it. I'd love to get some verification so I know I'm
not
just
losing my mind.
Thanks!
John
_______________________________________________________
Send a cool gift with your E-Card
http://www.bluemountain.com/giftcenter/
_________________________________
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
_________________________________
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
_________________________________
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
_________________________________
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
