From: fwells12 (fwells12@xxxxxxxxxxx)
Date: Thu Dec 28 2000 - 20:07:19 GMT-3
This is exactly what I am getting at. Without any idea of the address space
one will get allotted, we must learn to cover all possibilities.
Unfortunately I am so green at OSPF, I am unable to articulate the question
precisely the way I need to.
In the comment you made earlier: Since each loopback interface will be a
host route, use 4 network statements like: network 192.168.20.2 0.0.0.0
area X, did you mean by 'host route' that those networks will be advertised
with a /32 prefix?
Thanks again.
----- Original Message -----
From: Connary, Julie Ann <jconnary@cisco.com>
To: Eric Lemmons <ericlemmons@yahoo.com>
Cc: fwells12 <fwells12@hotmail.com>; <ccielab@groupstudy.com>
Sent: Thursday, December 28, 2000 1:48 PM
Subject: Re: OSPF network statement
> I understood that in the lab you were given an address space to use and
you
> had to use it across the network as you saw fit - i.e. you need to read
the
> whole lab and
> then utilize the address space the best you can and the most efficiently
> while still opting
> for simplicity of summarization etc.,
>
> Julie Ann
> At 01:31 PM 12/28/2000 -0800, Eric Lemmons wrote:
> >The key to summarizing is to do it in binary.
> >Let me say, that I don't think you will see a "bizarre" summarization
> >in the lab. I could be wrong, of course :).
> >Let's look at your example.
> >ip address 162.124.6.6 255.252.0.0
> >ip address 162.128.6.6 255.252.0.0
> >ip address 162.132.6.6 255.252.0.0
> >ip address 162.136.6.6 255.252.0.0
> >
> >To summarize any addresses, you have to find out what bits they all
> >share. Let's look at the 2nd octet in the addresses above. This is
> >where the "action" is for summarizing. If addresses don't share the
> >2nd octet bits, the 3rd and 4th octet don't matter. The summary won't
> >work. Here are the 2nd octet addresses:
> >
> >124 = 0111 1100
> >128 = 1000 0000
> >132 = 1000 0100
> >136 = 1000 1000
> >
> >The problem we have we summarizing these 4 addreses is the 124
> >address. Since it doesn't share the 1st bit of the 2nd octet with the
> >other 3 addresses, we have to summarize with this address:
> >
> >162.0.0.0 255.0.0.0
> >
> >This is because the ONLY bits these 4 addresses all have in common is
> >the 1st octet. We could summarize the 128, 132, 136 addresses like
> >so:
> >
> >162.128.0.0 255.240.0.0
> >
> >And just use an individual statement for the 124 address.
> >Why the 128 and the 240 mask? Because that's what those 3 addresses
> >have in common in the 2nd octet:
> > Same Not the same
> >128 = 1000 - 0000
> >132 = 1000 - 0100
> >136 = 1000 - 1000
> >
> >The 240 mask says the 1st 4 bits match.
> >
> >Usually, in the real world, you try to work from the other direction.
> >Meaning that you design your address scheme to be simple, and
> >efficient to summarize. You don't always have that luxury, but that's
> >the way it should be done.
> >
> >--- fwells12 <fwells12@hotmail.com> wrote:
> > > Thanks for your reply Earl.
> > > 192.168.8.0 0.0.63.255 area 2 is what I came up with by reading
> > > some basic
> > > tutorials in Doyles book. It is working fine. I also used area 2
> > > range
> > > 192.168.0.0 255.255.192.0 for inter-area summarization and it
> > > appears to
> > > work OK.
> > >
> > > I am experimenting with creating various IP addressing scenarios in
> > > an
> > > effort to help me get OSPF down cold. The tutorials I have are
> > > sketchy at
> > > best and I need to be able to blaze these configs out quickly
> > > without too
> > > much thought. My goal is to come up with an addressing scheme for
> > > any
> > > possible IP address range I get in the lab, that can be easily
> > > summarized
> > > for redistribution etc. I want to be prepared in case I dont get a
> > > IP
> > > add/mask combo that is easy to summarize...
> > >
> > > I just created this one:
> > >
> > > interface Loopback0
> > > ip address 162.124.6.6 255.252.0.0
> > > !
> > > interface Loopback1
> > > ip address 162.128.6.6 255.252.0.0
> > > !
> > > interface Loopback2
> > > ip address 162.132.6.6 255.252.0.0
> > > !
> > > interface Loopback3
> > > ip address 162.136.6.6 255.252.0.0
> > >
> > > It is giving me a hard time. How would you deal with this ?
> > >
> > > ----- Original Message -----
> > > From: Earl Aboytes <Earl@dnssystems.com>
> > > To: 'Connary, Julie Ann' <jconnary@cisco.com>; fwells12
> > > <fwells12@hotmail.com>
> > > Cc: <ccielab@groupstudy.com>
> > > Sent: Thursday, December 28, 2000 12:09 PM
> > > Subject: RE: OSPF network statement
> > >
> > >
> > > > I think this is the answer that you are looking for.
> > > >
> > > > Network 192.168.0.0 0.0.63.255 area 0
> > > >
> > > > This would put all networks 192.168.0.0 through 192.168.63.0 in
> > > area 0
> > > >
> > > > Watch out that you don't have any other conflicts. To be
> > > cautious I
> > > always
> > > > make separate entries and make sure that my masks match my
> > > wildcards.
> > > >
> > > > Earl Aboytes CCIE 6097
> > > >
> > > > PS. Sam@datastreet, if you read this post I want you to know that
> > > I think
> > > > that it's pretty cool how involved you are in this CCIE thing.
> > > My dad
> > > can't
> > > > even remember the meaning of the four letters C-C-I-E.
> > > >
> > > > -----Original Message-----
> > > > From: Connary, Julie Ann [mailto:jconnary@cisco.com]
> > > > Sent: Thursday, December 28, 2000 11:51 AM
> > > > To: fwells12
> > > > Cc: ccielab@groupstudy.com
> > > > Subject: Re: OSPF network statement
> > > >
> > > > Since each loopback interface will be a host route, use 4 network
> > > > statements like:
> > > >
> > > > network 192.168.20.2 0.0.0.0 area X
> > > >
> > > > Julie Ann
> > > >
> > > > At 11:17 AM 12/28/2000 -0800, fwells12 wrote:
> > > > >I have the following IP addresses configured as loopback
> > > interfaces on =
> > > > >an OSPF router. What is the correct command to insert these
> > > networks =
> > > > >into the OSPF process in the most efficient manner? By that, I
> > > mean =
> > > > >conserving the maximum amount of IP addresses.
> > > > >
> > > > >interface Loopback0
> > > > > ip address 192.168.20.2 255.255.248.0
> > > > >!
> > > > >interface Loopback1
> > > > > ip address 192.168.28.2 255.255.248.0
> > > > >!
> > > > >interface Loopback2
> > > > > ip address 192.168.36.2 255.255.248.0
> > > > >!
> > > > >interface Loopback3
> > > > > ip address 192.168.44.2 255.255.248.0=20
> > > > >
> > > > >Cheers.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
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