From: Brian Hescock (bhescock@xxxxxxxxx)
Date: Thu Dec 28 2000 - 20:31:16 GMT-3
I've only taken the lab once but they tell you what you need to know for
the most part (at least that's what I thought). You just need to watch
out for an gotchas they throw in later, which is why it's important to
read the whole exam at least twice before starting. For example, let's
say you configure your ip addressing in the morning then at 3pm you get to
a section where it tells you to summarize your two ethernets on router
2. Well, if you numbered them 10.1.1.1 /24 and 172.16.1.1 /24 then you
have a problem.
I tried to come up with ways to address my networks that was intuitive,
would allow summarization easily, and I would also easily know if the
proctor messed with it. Example: an ethernet link between routers 1 and 2
I would number 192.168.12.0 /24. Between routers 2 and 3, 192.168.23.0 /24
Use /24 networks everywhere if they let you, why make it more difficult
than it is?
For ipx, use node 1.1.1 for router 1, 2.2.2 for router 2, etc. Set it
manully, don't let the router do it for you. There are a lot of things
like this that you can do but don't sweat it too much. I was actually
surprised most of the time about how specific they were. I'm sure others
will disagree but that was my experience anyway.
B.
On Thu, 28 Dec 2000, fwells12 wrote:
> 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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