From: Jim Graves (jtg@xxxxxxxxxx)
Date: Tue May 29 2001 - 10:22:43 GMT-3
I can't think of any reason a 0.0.0.0 wildcard mask should make a
difference either -- but it does. Give it a try. Last night, I set up the
situation Walter talks about, and to my shock and horror he was right. I
used a 0.0.0.0 wildcard mask, and the network didn't show up. When I
changed the network statement to use a 0.0.0.255 wildcard mask, the network
showed up in EIGRP. Huh.
The same thing happens in bootcamp lab 3 if you replace the EIGRP LAN
network with some other network outside 137.20.0.0/16. I tried it with
both 192.168.50.0/24 and 172.20.50.0/24 (to rule out any kind of classful
silliness). Again, when I used 0.0.0.0, the connected network didn't show
up. With 0.0.0.255, it did. The same thing happened when I tried RIP v2
or a second OSPF process instead of EIGRP.
Why? Beats the heck out of me. I tested this using IOS versions 12.0(11),
12.0(15), and 12.0(7)T. I don't know if it's a bug of a feature, but it
sure is weird.
Jim
At 10:35 PM 5/28/2001 -0400, Brian Hescock wrote:
>I can't think of any way using a 0.0.0.0 wildcard bits would affect
>redistribution, unless it's a bug. All the ospf network command does is
>turn on ospf on
>the interface(s) covered by the network statement, that's all it does. It
>has zero effect on the network mask being advertised and no effect on
>redistribution. To everyone that said use a 0.0.0.0 mask (wildcard bits
>actually), thumbs up, it's the preferred method unless you have a lot of
>interfaces you need to turn
>ospf on. Not just for lab use but for production networks as well. Less
>chance for error and easier to troubleshoot.
>
>Brian
>
>On Mon, 28 May 2001, Jeff K. wrote:
>
> > You are exactly right with all the shortcuts. I've never considered using
> > aliases because I never use them day to day and know that it will wind up
> > slowing me down since I type pretty fast. I know that I can calculate a
> > wildcard mask easily and don't have a problem with it. Not my point,
> > though... I was merely asking for an explanation as to why using the
> > 0.0.0.0 area mask would affect route redistribution, which is a question
> > that hasn't been answered. In my opinion, it makes good common sense
> as you
> > put it to use the 0.0.0.0 mask except when using a wildcard mask that will
> > allow you to group multiple interfaces into a single area (i.e., a single
> > statement versus multiple statements). Since I always use logic when
> > assigning my interface addressing schemes, the all 0 mask allows me to
> > double check everything quickly and easily - I know what interface has what
> > address and where it should be. Not that the wildcard mask makes that any
> > more difficult - just my personal preference. If a bug or other
> > 'undocumented feature' requires me to use the exact mask, I will be fine as
> > well... Anyway, if you have an answer for my original question about why
> > the area mask affects route redistribution (what I originally responded
> to),
> > please respond. I am more curious than anything.
> >
> > Thanks,
> >
> > -Jeff
> > ----- Original Message -----
> > From: "Mike Hess" <mahess@home.com>
> > To: <ccielab@groupstudy.com>
> > Sent: Monday, May 28, 2001 7:06 PM
> > Subject: RE: how anal is the lab grading
> >
> >
> > > Why not just be smart and use a network statement and the right wildcard
> > > mask for every interface that you are putting into OSPF? It seems common
> > > sense to me not to try and get too pretty or cut too many corners and
> then
> > > get end up with a problem with 15 minutes left just because you were too
> > > lazy to be more specific in the first place.
> > >
> > > Some people advocate the use of too many shortcuts. I see a lot of people
> > > advocating shortcuts such as this, using a whold slew of alias commands,
> > > etc. Just learn the material and don't try to save seconds when it's the
> > > minutes and hours that really matter.
> > >
> > > Back to my original point, if you cannot at this point calculate a simple
> > > wildcard mask then you are going for the wrong certification. Perhaps it
> > is
> > > not the grading.... :-)
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > > Jeff K.
> > > Sent: Monday, May 28, 2001 5:27 PM
> > > To: Walter Chen; Peter Van Oene; ccielab@groupstudy.com
> > > Subject: Re: how anal is the lab grading
> > >
> > >
> > > You lost me on the second paragraph. Why would using the 0.0.0.0
> > wild-card
> > > mask for interface area identification affect redistribution? This mask
> > > just allows you to use the interface's address. Obviously the subnet
> mask
> > > of your interfaces will affect redistribution, but I don't see how the
> > > 0.0.0.0 area mask will. You can definitely mess up your OSPF topology by
> > > using the wrong mask (i.e., interfaces in the wrong area, interfaces
> added
> > > to OSPF that weren't supposed to be). Let me know what your thoughts are
> > on
> > > this. Maybe I am forgetting something or am just misunderstanding
> > > something.
> > >
> > > Thanks,
> > >
> > > -Jeff
> > > ----- Original Message -----
> > > From: "Walter Chen" <wchen@iloka.com>
> > > To: "Peter Van Oene" <pvo@usermail.com>; <ccielab@groupstudy.com>
> > > Sent: Monday, May 28, 2001 3:04 PM
> > > Subject: Re: how anal is the lab grading
> > >
> > >
> > > > IMHO, you can use 0.0.0.255 mask if you have other 1.1.1.x/29 networks
> > > onthe
> > > > same router and they also belong to the same OSPF area. However, if
> > these
> > > > networks should not be in OSPF or in the same area, you definitely
> > should
> > > > not use 0.0.0.255 mask. The absolutely sure and correct way is to use
> > > > 0.0.0.7 mask for 1.1.1.0/29 network.
> > > >
> > > > You can use 0.0.0.0 mask in cases if you do not need to redistribute
> > > > 1.1.1.0/29 into other routing protocols on this same router. However,
> > if,
> > > > say, your 192.168.1.0/24 belongs to EIGRP and you want to reistribute
> > > > between OSPF and EIGRP, the 1.1.1.0/29 network will NOT be passed into
> > > EIGRP
> > > > if you have used 0.0.0.0 mask.
> > > >
> > > > Walter
> > > >
> > > > ----- Original Message -----
> > > > From: Peter Van Oene <pvo@usermail.com>
> > > > To: <ccielab@groupstudy.com>
> > > > Sent: Monday, May 28, 2001 9:35 AM
> > > > Subject: Re: how anal is the lab grading
> > > >
> > > >
> > > > > Personally, I'd not use 0.0.0.255 in any case, lab or otherwise. The
> > > full
> > > > 0's mask is the safe and accurate way to add interfaces to the OSPF
> > > process
> > > > and unless you need to add 20 odd interfaces, I'd suggest you use it.
> > As
> > > > far as the lab goes, I can attest that lab grading is fair. You
> > shouldn't
> > > > worry about trivial semantics. If your prepared, you'll likely have a
> > > good
> > > > idea when you are using an illegal shortcut.
> > > > >
> > > > > Pete
> > > > >
> > > > >
> > > > > *********** REPLY SEPARATOR ***********
> > > > >
> > > > > On 5/28/2001 at 7:48 AM Don Dettmore wrote:
> > > > >
> > > > > >Question - How nit-picky are the graders of the lab? F0r example,
> > > > > >something
> > > > > >occurred to me when I was working in the lab:
> > > > > >
> > > > > >192.168.1.0 /24 ------ R1 ----- 1.1.1.0 /29
> > > > > >
> > > > > >When configuring R1 for OSPF, would the following be acceptable:
> > > > > >
> > > > > >network 1.1.1.0 0.0.0.255 area 0.0.0.0
> > > > > >
> > > > > >Or would that be considered wrong because of the 'wrong' (or I
> should
> > > > say -
> > > > > >not specific enough) wildcard mask.
> > > > > >
> > > > > >Just wondering how anal I must train myself to be.
> > > > > >
> > > > > >Don Dettmore
> > > > > >**Please read:http://www.groupstudy.com/list/posting.html
> > > > > **Please read:http://www.groupstudy.com/list/posting.html
> > > > **Please read:http://www.groupstudy.com/list/posting.html
> > > **Please read:http://www.groupstudy.com/list/posting.html
> > > **Please read:http://www.groupstudy.com/list/posting.html
> > **Please read:http://www.groupstudy.com/list/posting.html
>**Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:30:55 GMT-3